[PATCH 0/2] Add power10 IEEE 128-bit min/max/conditional move support

[PATCH 0/2] Add power10 IEEE 128-bit min/max/conditional move support

[Michael Meissner]

The following two patches are new versions of the patches I've submitted in the
past to add support for the power10 IEEE 128-bit XSMAXCQP, XSMINCQP, XSCMPEQQ,
XSCMPGTQ, and XSCMPGEQ instructions.

This time I'm not trying to share code with the DFmode/SFmode min, max, or
conditional move support.  One reason is going between VSX registers (SF/DF)
and Altivec registers (KF/TF) adds to the complexity.

The first patch adds support for the XSMINCQP and XSMAXCQP instructions.  GCC
will generate these instructions if a built-in function is used or if the use
has turned on fast math.

The second patch adds support for the XSCMPEQ, XSCMPGEQ, and XSCMPGTQ
instructions and conditional moves.  With conditional move support, the
compiler will generate XSMINCQP and XSMAXCQP more often without fast math.

Too keep the complexity down, the conditional move support only supports both
the type for the items being compare and the items being move being the same.
Note, there is code to allow SF/DF inter-mixing for contiional move, and that
is not changed with this patch.

I.e. for conditional move, this will use the XSCMPEQP and XXSEL instructions:

	__float128 cmp1, cmp2;
	__float128 result, move1, move2;
		/* ... */
	result = (cmp1 == cmp2) ? move1 : move2;

I have done bootstrap builds with this patch on the following 3 systems:
    1)	power9 running LE Linux using --with-cpu=power9
    2)	power8 running BE Linux using --with-cpu=power8, testing both
	32/64-bit.
    3)	power10 prototype running LE Linux using --with-cpu=power10.

There were no regressions to the tests, and the new test added passed.  Can I
check these patches into trunk branch for GCC 12?

I would like to check these patches into GCC 11 after a cooling off period, but
I can also not do the backport if desired.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

[PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[Michael Meissner]

[PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

This patch adds the support for the IEEE 128-bit floating point C minimum and
maximum instructions.  The next patch will add the support for using the
compare and set mask instruction to implement conditional moves.

This patch does not try to re-use the code used for SF/DF min/max
support.  It defines a separate insn for the IEEE 128-bit support.  It
uses the code iterator <minmax> to simplify adding both operations.

GCC will not convert ?: operations into using min/max instructions provided in
this patch unless the user uses -Ofast or similar switches due to issues with
NaNs.  The next patch that adds conditional move instructions will enable the
?: conversion in many cases.

I have done bootstrap builds with this patch on the following 3 systems:
    1)	power9 running LE Linux using --with-cpu=power9
    2)	power8 running BE Linux using --with-cpu=power8, testing both
	32/64-bit.
    3)	power10 prototype running LE Linux using --with-cpu=power10.

There were no regressions to the tests, and the new test added passed.  Can I
check these patches into trunk branch for GCC 12?

I would like to check these patches into GCC 11 after a cooling off period, but
I can also not do the backport if desired.

gcc/
2021-05-18  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
	3.1   IEEE   128-bit   floating  point   xsmaxcqp   and   xsmincqp
	instructions.
	* config/rs6000/rs6000.md (s<minmax><mode>3, IEEE128 iterator):
	New insns.

gcc/testsuite/
2021-05-18  Michael Meissner  <meissner@linux.ibm.com>

	* gcc.target/powerpc/float128-minmax-2.c: New test.
	* gcc.target/powerpc/float128-minmax.c: Turn off power10 code
	generation.
---
 gcc/config/rs6000/rs6000.c                        |  3 ++-
 gcc/config/rs6000/rs6000.md                       | 11 +++++++++++
 .../gcc.target/powerpc/float128-minmax-2.c        | 15 +++++++++++++++
 .../gcc.target/powerpc/float128-minmax.c          |  7 +++++++
 4 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 0d0595dddd6..fdaf12aeda0 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -16111,7 +16111,8 @@ rs6000_emit_minmax (rtx dest, enum rtx_code code, rtx op0, rtx op1)
   /* VSX/altivec have direct min/max insns.  */
   if ((code == SMAX || code == SMIN)
       && (VECTOR_UNIT_ALTIVEC_OR_VSX_P (mode)
-	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))))
+	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))
+	  || (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (mode))))
     {
       emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
       return;
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 0bfeb24d9e8..3a1bc1f8547 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -5196,6 +5196,17 @@ (define_insn "*s<minmax><mode>3_vsx"
 }
   [(set_attr "type" "fp")])
 
+;; Min/max for ISA 3.1 IEEE 128-bit floating point
+(define_insn "s<minmax><mode>3"
+  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
+	(fp_minmax:IEEE128
+	 (match_operand:IEEE128 1 "altivec_register_operand" "v")
+	 (match_operand:IEEE128 2 "altivec_register_operand" "v")))]
+  "TARGET_POWER10"
+  "xs<minmax>cqp %0,%1,%2"
+  [(set_attr "type" "vecfloat")
+   (set_attr "size" "128")])
+
 ;; The conditional move instructions allow us to perform max and min operations
 ;; even when we don't have the appropriate max/min instruction using the FSEL
 ;; instruction.
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
new file mode 100644
index 00000000000..c71ba08c9f8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
@@ -0,0 +1,15 @@
+/* { dg-require-effective-target ppc_float128_hw } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2 -ffast-math" } */
+
+#ifndef TYPE
+#define TYPE _Float128
+#endif
+
+/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
+   call.  */
+TYPE f128_min (TYPE a, TYPE b) { return __builtin_fminf128 (a, b); }
+TYPE f128_max (TYPE a, TYPE b) { return __builtin_fmaxf128 (a, b); }
+
+/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
+/* { dg-final { scan-assembler {\mxsmincqp\M} } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
index fe397518f2f..c3af759c0b9 100644
--- a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
@@ -3,6 +3,13 @@
 /* { dg-require-effective-target float128 } */
 /* { dg-options "-mpower9-vector -O2 -ffast-math" } */
 
+/* If the compiler was configured to automatically generate power10 support with
+   --with-cpu=power10, turn it off.  Otherwise, it will generate XXMAXCQP and
+   XXMINCQP instructions.  */
+#ifdef _ARCH_PWR10
+#pragma GCC target ("cpu=power9")
+#endif
+
 #ifndef TYPE
 #define TYPE _Float128
 #endif
-- 
2.31.1


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

[PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

[Michael Meissner]

[PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

This patch adds the support for power10 IEEE 128-bit floating point conditional
move and for automatically generating min/max.

In this patch, I simplified things compared to previous patches.  Instead of
allowing any four of the modes to be used for the conditional move comparison
and the move itself could use different modes, I restricted the conditional
move to just the same mode.  I.e. you can do:

        _Float128 a, b, c, d, e, r;

        r = (a == b) ? c : d;

But you can't do:

        _Float128 c, d, r;
        double a, b;

        r = (a == b) ? c : d;

or:

        _Float128 a, b;
        double c, d, r;

        r = (a == b) ? c : d;

This eliminates a lot of the complexity of the code, because you don't have to
worry about the sizes being different, and the IEEE 128-bit types being
restricted to Altivec registers, while the SF/DF modes can use any VSX
register.

I did not modify the existing support that allowed conditional moves where
SFmode operands are compared and DFmode operands are moved (and vice versa).

I modified the test cases that I added to reflect this change.  I have also
fixed the test for not equal to use '!=' instead of '=='.

I have done bootstrap builds with this patch on the following 3 systems:
    1)	power9 running LE Linux using --with-cpu=power9
    2)	power8 running BE Linux using --with-cpu=power8, testing both
	32/64-bit.
    3)	power10 prototype running LE Linux using --with-cpu=power10.

There were no regressions to the tests, and the new test added passed.  Can I
check these patches into trunk branch for GCC 12?

I would like to check these patches into GCC 11 after a cooling off period, but
I can also not do the backport if desired.

gcc/
2021-05-18 Michael Meissner  <meissner@linux.ibm.com>

        * config/rs6000/rs6000.c (rs6000_maybe_emit_fp_cmove): Add IEEE
	128-bit floating point conditional move support.
	(have_compare_and_set_mask): Add IEEE 128-bit floating point
	types.
	* config/rs6000/rs6000.md (mov<mode>cc, IEEE128 iterator): New insn.
	(mov<mode>cc_p10, IEEE128 iterator): New insn.
	(mov<mode>cc_invert_p10, IEEE128 iterator): New insn.
	(fpmask<mode>, IEEE128 iterator): New insn.
	(xxsel<mode>, IEEE128 iterator): New insn.

gcc/testsuite/
2021-05-18  Michael Meissner  <meissner@linux.ibm.com>

        * gcc.target/powerpc/float128-cmove.c: New test.
        * gcc.target/powerpc/float128-minmax-3.c: New test.
---
 gcc/config/rs6000/rs6000.c                    |  38 ++++++-
 gcc/config/rs6000/rs6000.md                   | 106 ++++++++++++++++++
 .../gcc.target/powerpc/float128-cmove.c       |  58 ++++++++++
 .../gcc.target/powerpc/float128-minmax-3.c    |  15 +++
 4 files changed, 215 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-cmove.c
 create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index fdaf12aeda0..ef1ebaaee05 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -15706,8 +15706,8 @@ rs6000_emit_vector_cond_expr (rtx dest, rtx op_true, rtx op_false,
   return 1;
 }
 
-/* Possibly emit the xsmaxcdp and xsmincdp instructions to emit a maximum or
-   minimum with "C" semantics.
+/* Possibly emit the xsmaxc{dp,qp} and xsminc{dp,qp} instructions to emit a
+   maximum or minimum with "C" semantics.
 
    Unless you use -ffast-math, you can't use these instructions to replace
    conditions that implicitly reverse the condition because the comparison
@@ -15783,6 +15783,7 @@ rs6000_maybe_emit_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
   enum rtx_code code = GET_CODE (op);
   rtx op0 = XEXP (op, 0);
   rtx op1 = XEXP (op, 1);
+  machine_mode compare_mode = GET_MODE (op0);
   machine_mode result_mode = GET_MODE (dest);
   rtx compare_rtx;
   rtx cmove_rtx;
@@ -15791,6 +15792,35 @@ rs6000_maybe_emit_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
   if (!can_create_pseudo_p ())
     return 0;
 
+  /* We allow the comparison to be either SFmode/DFmode and the true/false
+     condition to be either SFmode/DFmode.  I.e. we allow:
+
+	float a, b;
+	double c, d, r;
+
+	r = (a == b) ? c : d;
+
+    and:
+
+	double a, b;
+	float c, d, r;
+
+	r = (a == b) ? c : d;
+
+    but we don't allow intermixing the IEEE 128-bit floating point types with
+    the 32/64-bit scalar types.
+
+    It gets too messy where SFmode/DFmode can use any register and TFmode/KFmode
+    can only use Altivec registers.  In addtion, we would need to do a XXPERMDI
+    if we compare SFmode/DFmode and move TFmode/KFmode.  */
+
+  if (compare_mode == result_mode
+      || (compare_mode == SFmode && result_mode == DFmode)
+      || (compare_mode == DFmode && result_mode == SFmode))
+    ;
+  else
+    return false;
+
   switch (code)
     {
     case EQ:
@@ -15843,6 +15873,10 @@ have_compare_and_set_mask (machine_mode mode)
     case E_DFmode:
       return TARGET_P9_MINMAX;
 
+    case E_KFmode:
+    case E_TFmode:
+      return TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (mode);
+
     default:
       break;
     }
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 3a1bc1f8547..0c76338c734 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -5431,6 +5431,112 @@ (define_insn "*xxsel<mode>"
   "xxsel %x0,%x4,%x3,%x1"
   [(set_attr "type" "vecmove")])
 
+;; Support for ISA 3.1 IEEE 128-bit conditional move.  The mode used in the
+;; comparison must be the same as used in the conditional move.
+(define_expand "mov<mode>cc"
+   [(set (match_operand:IEEE128 0 "gpc_reg_operand")
+	 (if_then_else:IEEE128 (match_operand 1 "comparison_operator")
+			       (match_operand:IEEE128 2 "gpc_reg_operand")
+			       (match_operand:IEEE128 3 "gpc_reg_operand")))]
+  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
+{
+  if (rs6000_emit_cmove (operands[0], operands[1], operands[2], operands[3]))
+    DONE;
+  else
+    FAIL;
+})
+
+(define_insn_and_split "*mov<mode>cc_p10"
+  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=&v,v")
+	(if_then_else:IEEE128
+	 (match_operator:CCFP 1 "fpmask_comparison_operator"
+		[(match_operand:IEEE128 2 "altivec_register_operand" "v,v")
+		 (match_operand:IEEE128 3 "altivec_register_operand" "v,v")])
+	 (match_operand:IEEE128 4 "altivec_register_operand" "v,v")
+	 (match_operand:IEEE128 5 "altivec_register_operand" "v,v")))
+   (clobber (match_scratch:V2DI 6 "=0,&v"))]
+  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
+  "#"
+  "&& 1"
+  [(set (match_dup 6)
+	(if_then_else:V2DI (match_dup 1)
+			   (match_dup 7)
+			   (match_dup 8)))
+   (set (match_dup 0)
+	(if_then_else:IEEE128 (ne (match_dup 6)
+				  (match_dup 8))
+			      (match_dup 4)
+			      (match_dup 5)))]
+{
+  if (GET_CODE (operands[6]) == SCRATCH)
+    operands[6] = gen_reg_rtx (V2DImode);
+
+  operands[7] = CONSTM1_RTX (V2DImode);
+  operands[8] = CONST0_RTX (V2DImode);
+}
+ [(set_attr "length" "8")
+  (set_attr "type" "vecperm")])
+
+;; Handle inverting the fpmask comparisons.
+(define_insn_and_split "*mov<mode>cc_invert_p10"
+  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=&v,v")
+	(if_then_else:IEEE128
+	 (match_operator:CCFP 1 "invert_fpmask_comparison_operator"
+		[(match_operand:IEEE128 2 "altivec_register_operand" "v,v")
+		 (match_operand:IEEE128 3 "altivec_register_operand" "v,v")])
+	 (match_operand:IEEE128 4 "altivec_register_operand" "v,v")
+	 (match_operand:IEEE128 5 "altivec_register_operand" "v,v")))
+   (clobber (match_scratch:V2DI 6 "=0,&v"))]
+  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
+  "#"
+  "&& 1"
+  [(set (match_dup 6)
+	(if_then_else:V2DI (match_dup 9)
+			   (match_dup 7)
+			   (match_dup 8)))
+   (set (match_dup 0)
+	(if_then_else:IEEE128 (ne (match_dup 6)
+				  (match_dup 8))
+			      (match_dup 5)
+			      (match_dup 4)))]
+{
+  rtx op1 = operands[1];
+  enum rtx_code cond = reverse_condition_maybe_unordered (GET_CODE (op1));
+
+  if (GET_CODE (operands[6]) == SCRATCH)
+    operands[6] = gen_reg_rtx (V2DImode);
+
+  operands[7] = CONSTM1_RTX (V2DImode);
+  operands[8] = CONST0_RTX (V2DImode);
+
+  operands[9] = gen_rtx_fmt_ee (cond, CCFPmode, operands[2], operands[3]);
+}
+ [(set_attr "length" "8")
+  (set_attr "type" "vecperm")])
+
+(define_insn "*fpmask<mode>"
+  [(set (match_operand:V2DI 0 "altivec_register_operand" "=v")
+	(if_then_else:V2DI
+	 (match_operator:CCFP 1 "fpmask_comparison_operator"
+		[(match_operand:IEEE128 2 "altivec_register_operand" "v")
+		 (match_operand:IEEE128 3 "altivec_register_operand" "v")])
+	 (match_operand:V2DI 4 "all_ones_constant" "")
+	 (match_operand:V2DI 5 "zero_constant" "")))]
+  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
+  "xscmp%V1qp %0,%2,%3"
+  [(set_attr "type" "fpcompare")])
+
+(define_insn "*xxsel<mode>"
+  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
+	(if_then_else:IEEE128
+	 (ne (match_operand:V2DI 1 "altivec_register_operand" "v")
+	     (match_operand:V2DI 2 "zero_constant" ""))
+	 (match_operand:IEEE128 3 "altivec_register_operand" "v")
+	 (match_operand:IEEE128 4 "altivec_register_operand" "v")))]
+  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
+  "xxsel %x0,%x4,%x3,%x1"
+  [(set_attr "type" "vecmove")])
+
 \f
 ;; Conversions to and from floating-point.
 
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-cmove.c b/gcc/testsuite/gcc.target/powerpc/float128-cmove.c
new file mode 100644
index 00000000000..2fae8dc23bc
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/float128-cmove.c
@@ -0,0 +1,58 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target ppc_float128_hw } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2" } */
+
+#ifndef TYPE
+#ifdef __LONG_DOUBLE_IEEE128__
+#define TYPE long double
+
+#else
+#define TYPE _Float128
+#endif
+#endif
+
+/* Verify that the ISA 3.1 (power10) IEEE 128-bit conditional move instructions
+   are generated.  */
+
+TYPE
+eq (TYPE a, TYPE b, TYPE c, TYPE d)
+{
+  return (a == b) ? c : d;
+}
+
+TYPE
+ne (TYPE a, TYPE b, TYPE c, TYPE d)
+{
+  return (a != b) ? c : d;
+}
+
+TYPE
+lt (TYPE a, TYPE b, TYPE c, TYPE d)
+{
+  return (a < b) ? c : d;
+}
+
+TYPE
+le (TYPE a, TYPE b, TYPE c, TYPE d)
+{
+  return (a <= b) ? c : d;
+}
+
+TYPE
+gt (TYPE a, TYPE b, TYPE c, TYPE d)
+{
+  return (a > b) ? c : d;
+}
+
+TYPE
+ge (TYPE a, TYPE b, TYPE c, TYPE d)
+{
+  return (a >= b) ? c : d;
+}
+
+/* { dg-final { scan-assembler-times {\mxscmpeqqp\M} 2 } } */
+/* { dg-final { scan-assembler-times {\mxscmpgeqp\M} 2 } } */
+/* { dg-final { scan-assembler-times {\mxscmpgtqp\M} 2 } } */
+/* { dg-final { scan-assembler-times {\mxxsel\M}     6 } } */
+/* { dg-final { scan-assembler-not   {\mxscmpuqp\M}    } } */
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c
new file mode 100644
index 00000000000..6f7627c0f2a
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c
@@ -0,0 +1,15 @@
+/* { dg-require-effective-target ppc_float128_hw } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2" } */
+
+#ifndef TYPE
+#define TYPE _Float128
+#endif
+
+/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
+   call.  */
+TYPE f128_min (TYPE a, TYPE b) { return (a < b) ? a : b; }
+TYPE f128_max (TYPE a, TYPE b) { return (b > a) ? b : a; }
+
+/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
+/* { dg-final { scan-assembler {\mxsmincqp\M} } } */
-- 
2.31.1

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[will schmidt]

On Tue, 2021-05-18 at 16:26 -0400, Michael Meissner wrote:
> [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.
> 

Hi,


> This patch adds the support for the IEEE 128-bit floating point C minimum and
> maximum instructions.  The next patch will add the support for using the
> compare and set mask instruction to implement conditional moves.
> 
> This patch does not try to re-use the code used for SF/DF min/max
> support.  It defines a separate insn for the IEEE 128-bit support.  It
> uses the code iterator <minmax> to simplify adding both operations.
> 
> GCC will not convert ?: operations into using min/max instructions provided in

I'd throw the ternary term in there, easier to search for later. 
s/?: operations/ternary (?:) operations /

> this patch unless the user uses -Ofast or similar switches due to issues with
> NaNs.  The next patch that adds conditional move instructions will enable the
> ?: conversion in many cases.
> 
> I have done bootstrap builds with this patch on the following 3 systems:
>     1)	power9 running LE Linux using --with-cpu=power9
>     2)	power8 running BE Linux using --with-cpu=power8, testing both
> 	32/64-bit.
>     3)	power10 prototype running LE Linux using --with-cpu=power10.
> 
> There were no regressions to the tests, and the new test added passed.  Can I
> check these patches into trunk branch for GCC 12?
> 
> I would like to check these patches into GCC 11 after a cooling off period, but
> I can also not do the backport if desired.
> 
> gcc/
> 2021-05-18  Michael Meissner  <meissner@linux.ibm.com>
> 
> 	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
> 	3.1   IEEE   128-bit   floating  point   xsmaxcqp   and   xsmincqp
> 	instructions.
> 	* config/rs6000/rs6000.md (s<minmax><mode>3, IEEE128 iterator):
> 	New insns.

ok

> 
> gcc/testsuite/
> 2021-05-18  Michael Meissner  <meissner@linux.ibm.com>
> 
> 	* gcc.target/powerpc/float128-minmax-2.c: New test.
> 	* gcc.target/powerpc/float128-minmax.c: Turn off power10 code
> 	generation.

So, presumably the float128-minmax-2.c test adds/replaces the power10
code gen tests that were removed or disabled from float128-minmax.c. 



> ---
>  gcc/config/rs6000/rs6000.c                        |  3 ++-
>  gcc/config/rs6000/rs6000.md                       | 11 +++++++++++
>  .../gcc.target/powerpc/float128-minmax-2.c        | 15 +++++++++++++++
>  .../gcc.target/powerpc/float128-minmax.c          |  7 +++++++
>  4 files changed, 35 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
> 
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 0d0595dddd6..fdaf12aeda0 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -16111,7 +16111,8 @@ rs6000_emit_minmax (rtx dest, enum rtx_code code, rtx op0, rtx op1)
>    /* VSX/altivec have direct min/max insns.  */
>    if ((code == SMAX || code == SMIN)
>        && (VECTOR_UNIT_ALTIVEC_OR_VSX_P (mode)
> -	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))))
> +	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))
> +	  || (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (mode))))
>      {
>        emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
>        return;
> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
> index 0bfeb24d9e8..3a1bc1f8547 100644
> --- a/gcc/config/rs6000/rs6000.md
> +++ b/gcc/config/rs6000/rs6000.md
> @@ -5196,6 +5196,17 @@ (define_insn "*s<minmax><mode>3_vsx"
>  }
>    [(set_attr "type" "fp")])
> 
> +;; Min/max for ISA 3.1 IEEE 128-bit floating point
> +(define_insn "s<minmax><mode>3"
> +  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
> +	(fp_minmax:IEEE128
> +	 (match_operand:IEEE128 1 "altivec_register_operand" "v")
> +	 (match_operand:IEEE128 2 "altivec_register_operand" "v")))]
> +  "TARGET_POWER10"
> +  "xs<minmax>cqp %0,%1,%2"
> +  [(set_attr "type" "vecfloat")
> +   (set_attr "size" "128")])
> +
>  ;; The conditional move instructions allow us to perform max and min operations
>  ;; even when we don't have the appropriate max/min instruction using the FSEL
>  ;; instruction.

ok


> diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
> new file mode 100644
> index 00000000000..c71ba08c9f8
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
> @@ -0,0 +1,15 @@
> +/* { dg-require-effective-target ppc_float128_hw } */
> +/* { dg-require-effective-target power10_ok } */
> +/* { dg-options "-mdejagnu-cpu=power10 -O2 -ffast-math" } */
> +
> +#ifndef TYPE
> +#define TYPE _Float128
> +#endif
> +
> +/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
> +   call.  */
> +TYPE f128_min (TYPE a, TYPE b) { return __builtin_fminf128 (a, b); }
> +TYPE f128_max (TYPE a, TYPE b) { return __builtin_fmaxf128 (a, b); }
> +
> +/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
> +/* { dg-final { scan-assembler {\mxsmincqp\M} } } */

ok

> diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
> index fe397518f2f..c3af759c0b9 100644
> --- a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
> +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
> @@ -3,6 +3,13 @@
>  /* { dg-require-effective-target float128 } */
>  /* { dg-options "-mpower9-vector -O2 -ffast-math" } */
> 
> +/* If the compiler was configured to automatically generate power10 support with
> +   --with-cpu=power10, turn it off.  Otherwise, it will generate XXMAXCQP and
> +   XXMINCQP instructions.  */
> +#ifdef _ARCH_PWR10
> +#pragma GCC target ("cpu=power9")
> +#endif

Probably fine..  It's good to exercise the pragma target stuff, thoguh
I wonder if it would be better to just specify -mcpu=power9 in the
options since we are already specifying (redundant?) -mpower9-vector. 

I see similar changes in a later patch, probably OK there since those
tests do not appear to be specifying -mcpu=foo options that are already
pointed at power9 features...


> +
>  #ifndef TYPE
>  #define TYPE _Float128
>  #endif
> -- 
> 2.31.1

lgtm, 
thanks
-Will

> 
> 

Re: [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

[will schmidt]

On Tue, 2021-05-18 at 16:28 -0400, Michael Meissner wrote:
> [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.
> 

Hi,


> This patch adds the support for power10 IEEE 128-bit floating point conditional
> move and for automatically generating min/max.
> 
> In this patch, I simplified things compared to previous patches.  Instead of
> allowing any four of the modes to be used for the conditional move comparison
> and the move itself could use different modes, I restricted the conditional
> move to just the same mode.  I.e. you can do:

ok.

> 
>         _Float128 a, b, c, d, e, r;
> 
>         r = (a == b) ? c : d;
> 
> But you can't do:
> 
>         _Float128 c, d, r;
>         double a, b;
> 
>         r = (a == b) ? c : d;
> 
> or:
> 
>         _Float128 a, b;
>         double c, d, r;
> 
>         r = (a == b) ? c : d;
> 
> This eliminates a lot of the complexity of the code, because you don't have to
> worry about the sizes being different, and the IEEE 128-bit types being
> restricted to Altivec registers, while the SF/DF modes can use any VSX
> register.
> 
> I did not modify the existing support that allowed conditional moves where
> SFmode operands are compared and DFmode operands are moved (and vice versa).
> 
> I modified the test cases that I added to reflect this change.  I have also
> fixed the test for not equal to use '!=' instead of '=='.
> 
> I have done bootstrap builds with this patch on the following 3 systems:
>     1)	power9 running LE Linux using --with-cpu=power9
>     2)	power8 running BE Linux using --with-cpu=power8, testing both
> 	32/64-bit.
>     3)	power10 prototype running LE Linux using --with-cpu=power10.
> 
> There were no regressions to the tests, and the new test added passed.  Can I
> check these patches into trunk branch for GCC 12?
> 
> I would like to check these patches into GCC 11 after a cooling off period, but
> I can also not do the backport if desired.
> 
> gcc/
> 2021-05-18 Michael Meissner  <meissner@linux.ibm.com>
> 
>         * config/rs6000/rs6000.c (rs6000_maybe_emit_fp_cmove): Add IEEE
> 	128-bit floating point conditional move support.
> 	(have_compare_and_set_mask): Add IEEE 128-bit floating point
> 	types.
> 	* config/rs6000/rs6000.md (mov<mode>cc, IEEE128 iterator): New insn.
> 	(mov<mode>cc_p10, IEEE128 iterator): New insn.
> 	(mov<mode>cc_invert_p10, IEEE128 iterator): New insn.
> 	(fpmask<mode>, IEEE128 iterator): New insn.
> 	(xxsel<mode>, IEEE128 iterator): New insn.
> 
> gcc/testsuite/
> 2021-05-18  Michael Meissner  <meissner@linux.ibm.com>
> 
>         * gcc.target/powerpc/float128-cmove.c: New test.
>         * gcc.target/powerpc/float128-minmax-3.c: New test.

ok


> ---
>  gcc/config/rs6000/rs6000.c                    |  38 ++++++-
>  gcc/config/rs6000/rs6000.md                   | 106 ++++++++++++++++++
>  .../gcc.target/powerpc/float128-cmove.c       |  58 ++++++++++
>  .../gcc.target/powerpc/float128-minmax-3.c    |  15 +++
>  4 files changed, 215 insertions(+), 2 deletions(-)
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-cmove.c
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c
> 
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index fdaf12aeda0..ef1ebaaee05 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -15706,8 +15706,8 @@ rs6000_emit_vector_cond_expr (rtx dest, rtx op_true, rtx op_false,
>    return 1;
>  }
> 
> -/* Possibly emit the xsmaxcdp and xsmincdp instructions to emit a maximum or
> -   minimum with "C" semantics.
> +/* Possibly emit the xsmaxc{dp,qp} and xsminc{dp,qp} instructions to emit a
> +   maximum or minimum with "C" semantics.
> 
>     Unless you use -ffast-math, you can't use these instructions to replace
>     conditions that implicitly reverse the condition because the comparison
> @@ -15783,6 +15783,7 @@ rs6000_maybe_emit_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
>    enum rtx_code code = GET_CODE (op);
>    rtx op0 = XEXP (op, 0);
>    rtx op1 = XEXP (op, 1);
> +  machine_mode compare_mode = GET_MODE (op0);
>    machine_mode result_mode = GET_MODE (dest);
>    rtx compare_rtx;
>    rtx cmove_rtx;
> @@ -15791,6 +15792,35 @@ rs6000_maybe_emit_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
>    if (!can_create_pseudo_p ())
>      return 0;
> 
> +  /* We allow the comparison to be either SFmode/DFmode and the true/false
> +     condition to be either SFmode/DFmode.  I.e. we allow:
> +
> +	float a, b;
> +	double c, d, r;
> +
> +	r = (a == b) ? c : d;
> +
> +    and:
> +
> +	double a, b;
> +	float c, d, r;
> +
> +	r = (a == b) ? c : d;


This new comment does not seem to align with the comments in the
description, which statee "But you can't do ..." 


> +
> +    but we don't allow intermixing the IEEE 128-bit floating point types with
> +    the 32/64-bit scalar types.
> +
> +    It gets too messy where SFmode/DFmode can use any register and TFmode/KFmode
> +    can only use Altivec registers.  In addtion, we would need to do a XXPERMDI
> +    if we compare SFmode/DFmode and move TFmode/KFmode.  */
> +
> +  if (compare_mode == result_mode
> +      || (compare_mode == SFmode && result_mode == DFmode)
> +      || (compare_mode == DFmode && result_mode == SFmode))
> +    ;
> +  else
> +    return false;

Interesting if/else block.  May want to reverse the logic. I defer if
this way is notably simpler than inverting it.


> +
>    switch (code)
>      {
>      case EQ:
> @@ -15843,6 +15873,10 @@ have_compare_and_set_mask (machine_mode mode)
>      case E_DFmode:
>        return TARGET_P9_MINMAX;
> 
> +    case E_KFmode:
> +    case E_TFmode:
> +      return TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (mode);
> +
>      default:
>        break;
>      }

ok

> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
> index 3a1bc1f8547..0c76338c734 100644
> --- a/gcc/config/rs6000/rs6000.md
> +++ b/gcc/config/rs6000/rs6000.md
> @@ -5431,6 +5431,112 @@ (define_insn "*xxsel<mode>"
>    "xxsel %x0,%x4,%x3,%x1"
>    [(set_attr "type" "vecmove")])
> 
> +;; Support for ISA 3.1 IEEE 128-bit conditional move.  The mode used in the
> +;; comparison must be the same as used in the conditional move.
> +(define_expand "mov<mode>cc"
> +   [(set (match_operand:IEEE128 0 "gpc_reg_operand")
> +	 (if_then_else:IEEE128 (match_operand 1 "comparison_operator")
> +			       (match_operand:IEEE128 2 "gpc_reg_operand")
> +			       (match_operand:IEEE128 3 "gpc_reg_operand")))]
> +  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
> +{
> +  if (rs6000_emit_cmove (operands[0], operands[1], operands[2], operands[3]))
> +    DONE;
> +  else
> +    FAIL;
> +})
> +
> +(define_insn_and_split "*mov<mode>cc_p10"
> +  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=&v,v")
> +	(if_then_else:IEEE128
> +	 (match_operator:CCFP 1 "fpmask_comparison_operator"
> +		[(match_operand:IEEE128 2 "altivec_register_operand" "v,v")
> +		 (match_operand:IEEE128 3 "altivec_register_operand" "v,v")])
> +	 (match_operand:IEEE128 4 "altivec_register_operand" "v,v")
> +	 (match_operand:IEEE128 5 "altivec_register_operand" "v,v")))
> +   (clobber (match_scratch:V2DI 6 "=0,&v"))]
> +  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
> +  "#"
> +  "&& 1"
> +  [(set (match_dup 6)
> +	(if_then_else:V2DI (match_dup 1)
> +			   (match_dup 7)
> +			   (match_dup 8)))
> +   (set (match_dup 0)
> +	(if_then_else:IEEE128 (ne (match_dup 6)
> +				  (match_dup 8))
> +			      (match_dup 4)
> +			      (match_dup 5)))]
> +{
> +  if (GET_CODE (operands[6]) == SCRATCH)
> +    operands[6] = gen_reg_rtx (V2DImode);
> +
> +  operands[7] = CONSTM1_RTX (V2DImode);
> +  operands[8] = CONST0_RTX (V2DImode);
> +}
> + [(set_attr "length" "8")
> +  (set_attr "type" "vecperm")])
> +
> +;; Handle inverting the fpmask comparisons.
> +(define_insn_and_split "*mov<mode>cc_invert_p10"
> +  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=&v,v")
> +	(if_then_else:IEEE128
> +	 (match_operator:CCFP 1 "invert_fpmask_comparison_operator"
> +		[(match_operand:IEEE128 2 "altivec_register_operand" "v,v")
> +		 (match_operand:IEEE128 3 "altivec_register_operand" "v,v")])
> +	 (match_operand:IEEE128 4 "altivec_register_operand" "v,v")
> +	 (match_operand:IEEE128 5 "altivec_register_operand" "v,v")))
> +   (clobber (match_scratch:V2DI 6 "=0,&v"))]
> +  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
> +  "#"
> +  "&& 1"
> +  [(set (match_dup 6)
> +	(if_then_else:V2DI (match_dup 9)
> +			   (match_dup 7)
> +			   (match_dup 8)))
> +   (set (match_dup 0)
> +	(if_then_else:IEEE128 (ne (match_dup 6)
> +				  (match_dup 8))
> +			      (match_dup 5)
> +			      (match_dup 4)))]
> +{
> +  rtx op1 = operands[1];
> +  enum rtx_code cond = reverse_condition_maybe_unordered (GET_CODE (op1));
> +
> +  if (GET_CODE (operands[6]) == SCRATCH)
> +    operands[6] = gen_reg_rtx (V2DImode);
> +
> +  operands[7] = CONSTM1_RTX (V2DImode);
> +  operands[8] = CONST0_RTX (V2DImode);
> +
> +  operands[9] = gen_rtx_fmt_ee (cond, CCFPmode, operands[2], operands[3]);
> +}
> + [(set_attr "length" "8")
> +  (set_attr "type" "vecperm")])
> +
> +(define_insn "*fpmask<mode>"
> +  [(set (match_operand:V2DI 0 "altivec_register_operand" "=v")
> +	(if_then_else:V2DI
> +	 (match_operator:CCFP 1 "fpmask_comparison_operator"
> +		[(match_operand:IEEE128 2 "altivec_register_operand" "v")
> +		 (match_operand:IEEE128 3 "altivec_register_operand" "v")])
> +	 (match_operand:V2DI 4 "all_ones_constant" "")
> +	 (match_operand:V2DI 5 "zero_constant" "")))]
> +  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
> +  "xscmp%V1qp %0,%2,%3"
> +  [(set_attr "type" "fpcompare")])
> +
> +(define_insn "*xxsel<mode>"
> +  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
> +	(if_then_else:IEEE128
> +	 (ne (match_operand:V2DI 1 "altivec_register_operand" "v")
> +	     (match_operand:V2DI 2 "zero_constant" ""))
> +	 (match_operand:IEEE128 3 "altivec_register_operand" "v")
> +	 (match_operand:IEEE128 4 "altivec_register_operand" "v")))]
> +  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
> +  "xxsel %x0,%x4,%x3,%x1"
> +  [(set_attr "type" "vecmove")])
> +

skimmed this part, nothing jumped out at me.

>  
>  ;; Conversions to and from floating-point.
> 
> diff --git a/gcc/testsuite/gcc.target/powerpc/float128-cmove.c b/gcc/testsuite/gcc.target/powerpc/float128-cmove.c
> new file mode 100644
> index 00000000000..2fae8dc23bc
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/float128-cmove.c
> @@ -0,0 +1,58 @@
> +/* { dg-do compile } */
> +/* { dg-require-effective-target ppc_float128_hw } */
> +/* { dg-require-effective-target power10_ok } */
> +/* { dg-options "-mdejagnu-cpu=power10 -O2" } */
> +
> +#ifndef TYPE
> +#ifdef __LONG_DOUBLE_IEEE128__
> +#define TYPE long double
> +
> +#else
> +#define TYPE _Float128
> +#endif
> +#endif
> +
> +/* Verify that the ISA 3.1 (power10) IEEE 128-bit conditional move instructions
> +   are generated.  */
> +
> +TYPE
> +eq (TYPE a, TYPE b, TYPE c, TYPE d)
> +{
> +  return (a == b) ? c : d;
> +}
> +
> +TYPE
> +ne (TYPE a, TYPE b, TYPE c, TYPE d)
> +{
> +  return (a != b) ? c : d;
> +}
> +
> +TYPE
> +lt (TYPE a, TYPE b, TYPE c, TYPE d)
> +{
> +  return (a < b) ? c : d;
> +}
> +
> +TYPE
> +le (TYPE a, TYPE b, TYPE c, TYPE d)
> +{
> +  return (a <= b) ? c : d;
> +}
> +
> +TYPE
> +gt (TYPE a, TYPE b, TYPE c, TYPE d)
> +{
> +  return (a > b) ? c : d;
> +}
> +
> +TYPE
> +ge (TYPE a, TYPE b, TYPE c, TYPE d)
> +{
> +  return (a >= b) ? c : d;
> +}
> +
> +/* { dg-final { scan-assembler-times {\mxscmpeqqp\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mxscmpgeqp\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mxscmpgtqp\M} 2 } } */
> +/* { dg-final { scan-assembler-times {\mxxsel\M}     6 } } */
> +/* { dg-final { scan-assembler-not   {\mxscmpuqp\M}    } } */

ok.

> diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c
> new file mode 100644
> index 00000000000..6f7627c0f2a
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c
> @@ -0,0 +1,15 @@
> +/* { dg-require-effective-target ppc_float128_hw } */
> +/* { dg-require-effective-target power10_ok } */
> +/* { dg-options "-mdejagnu-cpu=power10 -O2" } */
> +
> +#ifndef TYPE
> +#define TYPE _Float128
> +#endif
> +
> +/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
> +   call.  */

s/"if/then/else"/"minmax"/  ?

> +TYPE f128_min (TYPE a, TYPE b) { return (a < b) ? a : b; }
> +TYPE f128_max (TYPE a, TYPE b) { return (b > a) ? b : a; }
> +
> +/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
> +/* { dg-final { scan-assembler {\mxsmincqp\M} } } */


ok
thanks
-Will

> -- 
> 2.31.1
> 

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[Michael Meissner]

On Thu, May 20, 2021 at 02:25:58PM -0500, will schmidt wrote:
> I'd throw the ternary term in there, easier to search for later. 
> s/?: operations/ternary (?:) operations /

Thanks.

> So, presumably the float128-minmax-2.c test adds/replaces the power10
> code gen tests that were removed or disabled from float128-minmax.c. 

Yes.

> Probably fine..  It's good to exercise the pragma target stuff, thoguh
> I wonder if it would be better to just specify -mcpu=power9 in the
> options since we are already specifying (redundant?) -mpower9-vector. 
> 
> I see similar changes in a later patch, probably OK there since those
> tests do not appear to be specifying -mcpu=foo options that are already
> pointed at power9 features...

I think we really want a better solution than #pragma, since some systems (AIX
if memory serves) might not support #pragma to change code generation models,
because they don't have the assembler/linker support for it.

Basically for code generation tests, I see the following cases:

1) Test code targetting precisley power8 (or power9, power10), etc.  Hopefully
these are rare.

2) Test code targetting at least power8.  But as these tests show, that a lot
of the code won't generate the appropriate instructions on power10.  This is
what we have now.  It relies on undocumented switches like -mpower9-vector to
add the necessary support.

3) Test code targetting at least power8 but go to power9 at the maximum.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

[Michael Meissner]

On Thu, May 20, 2021 at 02:27:06PM -0500, will schmidt wrote:
> > diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> > index fdaf12aeda0..ef1ebaaee05 100644
> > --- a/gcc/config/rs6000/rs6000.c
> > +++ b/gcc/config/rs6000/rs6000.c
> > @@ -15706,8 +15706,8 @@ rs6000_emit_vector_cond_expr (rtx dest, rtx op_true, rtx op_false,
> >    return 1;
> >  }
> > 
> > -/* Possibly emit the xsmaxcdp and xsmincdp instructions to emit a maximum or
> > -   minimum with "C" semantics.
> > +/* Possibly emit the xsmaxc{dp,qp} and xsminc{dp,qp} instructions to emit a
> > +   maximum or minimum with "C" semantics.
> > 
> >     Unless you use -ffast-math, you can't use these instructions to replace
> >     conditions that implicitly reverse the condition because the comparison
> > @@ -15783,6 +15783,7 @@ rs6000_maybe_emit_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
> >    enum rtx_code code = GET_CODE (op);
> >    rtx op0 = XEXP (op, 0);
> >    rtx op1 = XEXP (op, 1);
> > +  machine_mode compare_mode = GET_MODE (op0);
> >    machine_mode result_mode = GET_MODE (dest);
> >    rtx compare_rtx;
> >    rtx cmove_rtx;
> > @@ -15791,6 +15792,35 @@ rs6000_maybe_emit_fp_cmove (rtx dest, rtx op, rtx true_cond, rtx false_cond)
> >    if (!can_create_pseudo_p ())
> >      return 0;
> > 
> > +  /* We allow the comparison to be either SFmode/DFmode and the true/false
> > +     condition to be either SFmode/DFmode.  I.e. we allow:
> > +
> > +	float a, b;
> > +	double c, d, r;
> > +
> > +	r = (a == b) ? c : d;
> > +
> > +    and:
> > +
> > +	double a, b;
> > +	float c, d, r;
> > +
> > +	r = (a == b) ? c : d;
> 
> 
> This new comment does not seem to align with the comments in the
> description, which statee "But you can't do ..." 

Yes, the comment is perhaps a little unclear.

> > +
> > +    but we don't allow intermixing the IEEE 128-bit floating point types with
> > +    the 32/64-bit scalar types.
> > +
> > +    It gets too messy where SFmode/DFmode can use any register and TFmode/KFmode
> > +    can only use Altivec registers.  In addtion, we would need to do a XXPERMDI
> > +    if we compare SFmode/DFmode and move TFmode/KFmode.  */
> > +
> > +  if (compare_mode == result_mode
> > +      || (compare_mode == SFmode && result_mode == DFmode)
> > +      || (compare_mode == DFmode && result_mode == SFmode))
> > +    ;
> > +  else
> > +    return false;
> 
> Interesting if/else block.  May want to reverse the logic. I defer if
> this way is notably simpler than inverting it.

I originally tried inverting it, and it just got messy.

> > +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-3.c
> > @@ -0,0 +1,15 @@
> > +/* { dg-require-effective-target ppc_float128_hw } */
> > +/* { dg-require-effective-target power10_ok } */
> > +/* { dg-options "-mdejagnu-cpu=power10 -O2" } */
> > +
> > +#ifndef TYPE
> > +#define TYPE _Float128
> > +#endif
> > +
> > +/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
> > +   call.  */
> 
> s/"if/then/else"/"minmax"/  ?

Thanks.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Ping [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[Michael Meissner]

Ping patch:

| Subject: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.
| Message-ID: <20210518202606.GA14382@ibm-toto.the-meissners.org>

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Ping [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

[Michael Meissner]

Ping patch.

| Subject: [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.
| Message-ID: <20210518202827.GB14382@ibm-toto.the-meissners.org>

Note this patch needs the following patch before it can be applied.

| Subject: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.
| Message-ID: <20210518202606.GA14382@ibm-toto.the-meissners.org>

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Ping #2: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[Michael Meissner]

Ping again.

Original patch (Add IEEE 128-bit min/max support on PowerPC):

| Date: Tue, 18 May 2021 16:26:06 -0400
| Subject: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.
| Message-ID: <20210518202606.GA14382@ibm-toto.the-meissners.org>
| https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570675.html

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Ping #2: [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

[Michael Meissner]

Ping patch again.

Original patch (Add IEEE 128-bit fp conditional move on PowerPC):

| Date: Tue, 18 May 2021 16:28:27 -0400
| Subject: [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.
| Message-ID: <20210518202827.GB14382@ibm-toto.the-meissners.org>

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[Segher Boessenkool]

Hi!

On Thu, May 20, 2021 at 09:38:49PM -0400, Michael Meissner wrote:
> Basically for code generation tests, I see the following cases:
> 
> 1) Test code targetting precisley power8 (or power9, power10), etc.  Hopefully
> these are rare.

-mdejagnu-cpu= works perfectly for this.  You may need a *_ok or a *_hw
as well (and/or other selectors).

> 2) Test code targetting at least power8.  But as these tests show, that a lot
> of the code won't generate the appropriate instructions on power10.  This is
> what we have now.  It relies on undocumented switches like -mpower9-vector to
> add the necessary support.

You should simply not run this test on too new systems.  You can use
dg-skip-if or similar.

> 3) Test code targetting at least power8 but go to power9 at the maximum.

But why?  We will keep testing all interesting CPU / OS combos as long
as they are interesting.


Segher

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[Segher Boessenkool]

On Tue, May 18, 2021 at 04:26:06PM -0400, Michael Meissner wrote:
> This patch adds the support for the IEEE 128-bit floating point C minimum and
> maximum instructions.

> gcc/
> 2021-05-18  Michael Meissner  <meissner@linux.ibm.com>
> 
> 	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
> 	3.1   IEEE   128-bit   floating  point   xsmaxcqp   and   xsmincqp
> 	instructions.

3.1 fits on the previous line (it is better to not split numbers to a
new line).  What is up with the weird multiple spaces?  We don't align
the right border in changelogs :-)

> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
> @@ -0,0 +1,15 @@
> +/* { dg-require-effective-target ppc_float128_hw } */
> +/* { dg-require-effective-target power10_ok } */

Is this needed?  And, why is ppc_float128_hw needed?  That combination
does not seem to make sense.

> --- a/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
> +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax.c
> @@ -3,6 +3,13 @@
>  /* { dg-require-effective-target float128 } */
>  /* { dg-options "-mpower9-vector -O2 -ffast-math" } */
>  
> +/* If the compiler was configured to automatically generate power10 support with
> +   --with-cpu=power10, turn it off.  Otherwise, it will generate XXMAXCQP and
> +   XXMINCQP instructions.  */
> +#ifdef _ARCH_PWR10
> +#pragma GCC target ("cpu=power9")
> +#endif

Yeah, don't.  Add a dg-skip-if if that is what you want.  That
-mpower9-vector shouldn't be there either.


Segher

Re: [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

[Segher Boessenkool]

On Thu, May 20, 2021 at 02:27:06PM -0500, will schmidt wrote:
> On Tue, 2021-05-18 at 16:28 -0400, Michael Meissner wrote:
> > +  if (compare_mode == result_mode
> > +      || (compare_mode == SFmode && result_mode == DFmode)
> > +      || (compare_mode == DFmode && result_mode == SFmode))
> > +    ;
> > +  else
> > +    return false;
> 
> Interesting if/else block.  May want to reverse the logic. I defer if
> this way is notably simpler than inverting it.

This is not simpler, no.  You want to do something that just returns
*first*, and then not have an "else".  *That* is simpler.

And just write !(...) around the condition, don't try to manually invert
it please.  You want both correct code and readable code, not neither of
these, they are not extremes you need to balance, each helps the other!


Segher

Re: [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

[Segher Boessenkool]

On Tue, May 18, 2021 at 04:28:27PM -0400, Michael Meissner wrote:
> In this patch, I simplified things compared to previous patches.  Instead of
> allowing any four of the modes to be used for the conditional move comparison
> and the move itself could use different modes, I restricted the conditional
> move to just the same mode.  I.e. you can do:
> 
>         _Float128 a, b, c, d, e, r;
> 
>         r = (a == b) ? c : d;
> 
> But you can't do:
> 
>         _Float128 c, d, r;
>         double a, b;
> 
>         r = (a == b) ? c : d;
> 
> or:
> 
>         _Float128 a, b;
>         double c, d, r;
> 
>         r = (a == b) ? c : d;
> 
> This eliminates a lot of the complexity of the code, because you don't have to
> worry about the sizes being different, and the IEEE 128-bit types being
> restricted to Altivec registers, while the SF/DF modes can use any VSX
> register.

You do not have to worry about that anyway.  You can just reuse the
existing rs6000_maybe_emit_fp_cmove.  Or why not?  The IF_THEN_ELSE we
generate there should work fine?

> +(define_expand "mov<mode>cc"
> +   [(set (match_operand:IEEE128 0 "gpc_reg_operand")
> +	 (if_then_else:IEEE128 (match_operand 1 "comparison_operator")
> +			       (match_operand:IEEE128 2 "gpc_reg_operand")
> +			       (match_operand:IEEE128 3 "gpc_reg_operand")))]
> +  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
> +{
> +  if (rs6000_emit_cmove (operands[0], operands[1], operands[2], operands[3]))
> +    DONE;
> +  else
> +    FAIL;
> +})

Why is this a special pattern anyway?  Why can you not do
  d = cond ? x : y;
with cond any comparison, not even including any floating point
possibly?


Segher

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[Michael Meissner]

On Mon, Jun 07, 2021 at 03:25:06PM -0500, Segher Boessenkool wrote:
> On Tue, May 18, 2021 at 04:26:06PM -0400, Michael Meissner wrote:
> > This patch adds the support for the IEEE 128-bit floating point C minimum and
> > maximum instructions.
> 
> > gcc/
> > 2021-05-18  Michael Meissner  <meissner@linux.ibm.com>
> > 
> > 	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
> > 	3.1   IEEE   128-bit   floating  point   xsmaxcqp   and   xsmincqp
> > 	instructions.
> 
> 3.1 fits on the previous line (it is better to not split numbers to a
> new line).  What is up with the weird multiple spaces?  We don't align
> the right border in changelogs :-)
> 
> > --- /dev/null
> > +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
> > @@ -0,0 +1,15 @@
> > +/* { dg-require-effective-target ppc_float128_hw } */
> > +/* { dg-require-effective-target power10_ok } */
> 
> Is this needed?  And, why is ppc_float128_hw needed?  That combination
> does not seem to make sense.

Basically it is there to make sure that we are actually generating IEEE 128-bit
instructions.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH 2/2] Add IEEE 128-bit fp conditional move on PowerPC.

[Michael Meissner]

On Mon, Jun 07, 2021 at 05:31:50PM -0500, Segher Boessenkool wrote:
> On Tue, May 18, 2021 at 04:28:27PM -0400, Michael Meissner wrote:
> > In this patch, I simplified things compared to previous patches.  Instead of
> > allowing any four of the modes to be used for the conditional move comparison
> > and the move itself could use different modes, I restricted the conditional
> > move to just the same mode.  I.e. you can do:
> > 
> >         _Float128 a, b, c, d, e, r;
> > 
> >         r = (a == b) ? c : d;
> > 
> > But you can't do:
> > 
> >         _Float128 c, d, r;
> >         double a, b;
> > 
> >         r = (a == b) ? c : d;
> > 
> > or:
> > 
> >         _Float128 a, b;
> >         double c, d, r;
> > 
> >         r = (a == b) ? c : d;
> > 
> > This eliminates a lot of the complexity of the code, because you don't have to
> > worry about the sizes being different, and the IEEE 128-bit types being
> > restricted to Altivec registers, while the SF/DF modes can use any VSX
> > register.
> 
> You do not have to worry about that anyway.  You can just reuse the
> existing rs6000_maybe_emit_fp_cmove.  Or why not?  The IF_THEN_ELSE we
> generate there should work fine?
> 
> > +(define_expand "mov<mode>cc"
> > +   [(set (match_operand:IEEE128 0 "gpc_reg_operand")
> > +	 (if_then_else:IEEE128 (match_operand 1 "comparison_operator")
> > +			       (match_operand:IEEE128 2 "gpc_reg_operand")
> > +			       (match_operand:IEEE128 3 "gpc_reg_operand")))]
> > +  "TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (<MODE>mode)"
> > +{
> > +  if (rs6000_emit_cmove (operands[0], operands[1], operands[2], operands[3]))
> > +    DONE;
> > +  else
> > +    FAIL;
> > +})
> 
> Why is this a special pattern anyway?  Why can you not do
>   d = cond ? x : y;
> with cond any comparison, not even including any floating point
> possibly?

Well in theory you can certainly do this, we just need to add the necessary
code to implement it.  It quickly becomes an exponential cascading pattern,
where you have one set of modes for the comparison and a different set of modes
for the movement.

I've certainly seen instances where the code has an integer comparison and then
a FP move.  We can do this via a SETBC type instruction, direct move, and then
XXSEL.  But that is beyond the scope of this patch.

If you remember, the original form of this patch allowed the comparison to be
SF, DF, KF, and possibly TF, along with the move.  It becomes complicated when
you have to consider that SF/DF comparisons only fill the upper 64 bits of the
vector register with the comparison, and the IEEE 128-bit types need to be in
Altivec registers.

So I scaled back the patch to just allow 128-bit conditional move.  I left in
the existing 64/34-bit mixture because there was at least one benchmark it was
used in the past.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

[PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

[Michael Meissner]

[PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC.

This patch adds the support for the IEEE 128-bit floating point C minimum and
maximum instructions.  The next patch will add the support for using the
compare and set mask instruction to implement conditional moves.

I removed the FLOAT128_MIN_MAX_FPMASK_P macro that was in the last iteration of
the patch.

I have built bootstrap compilers on both a little endian power9 Linux system
and a big endian power8 Linux system.  There were no regressions in either
build in the test suites.  Can I check these changes into the trunk for gcc 11?

gcc/
2021-04-14  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
	3.1 IEEE 128-bit floating point xsmaxcqp and xsmincqp instructions.
	* config/rs6000/rs6000.md (s<minmax><mode>3, IEEE128 iterator):
	New insns.

gcc/testsuite/
2021-04-14  Michael Meissner  <meissner@linux.ibm.com>

	* gcc.target/powerpc/float128-minmax-2.c: New test.
---
 gcc/config/rs6000/rs6000.c                        |  3 ++-
 gcc/config/rs6000/rs6000.md                       | 11 +++++++++++
 .../gcc.target/powerpc/float128-minmax-2.c        | 15 +++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 48b8efd732b..8d00f99e9fd 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -16111,7 +16111,8 @@ rs6000_emit_minmax (rtx dest, enum rtx_code code, rtx op0, rtx op1)
   /* VSX/altivec have direct min/max insns.  */
   if ((code == SMAX || code == SMIN)
       && (VECTOR_UNIT_ALTIVEC_OR_VSX_P (mode)
-	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))))
+	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))
+	  || (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (mode))))
     {
       emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
       return;
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index c8cdc42533c..17b2fdc1cdd 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -5194,6 +5194,17 @@ (define_insn "*s<minmax><mode>3_vsx"
 }
   [(set_attr "type" "fp")])
 
+;; Min/max for ISA 3.1 IEEE 128-bit floating point
+(define_insn "s<minmax><mode>3"
+  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
+	(fp_minmax:IEEE128
+	 (match_operand:IEEE128 1 "altivec_register_operand" "v")
+	 (match_operand:IEEE128 2 "altivec_register_operand" "v")))]
+  "TARGET_POWER10"
+  "xs<minmax>cqp %0,%1,%2"
+  [(set_attr "type" "vecfloat")
+   (set_attr "size" "128")])
+
 ;; The conditional move instructions allow us to perform max and min operations
 ;; even when we don't have the appropriate max/min instruction using the FSEL
 ;; instruction.
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
new file mode 100644
index 00000000000..c71ba08c9f8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
@@ -0,0 +1,15 @@
+/* { dg-require-effective-target ppc_float128_hw } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2 -ffast-math" } */
+
+#ifndef TYPE
+#define TYPE _Float128
+#endif
+
+/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
+   call.  */
+TYPE f128_min (TYPE a, TYPE b) { return __builtin_fminf128 (a, b); }
+TYPE f128_max (TYPE a, TYPE b) { return __builtin_fmaxf128 (a, b); }
+
+/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
+/* { dg-final { scan-assembler {\mxsmincqp\M} } } */
-- 
2.22.0


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC

[Michael Meissner]

On Wed, Apr 14, 2021 at 02:15:47PM -0500, Segher Boessenkool wrote:
> On Wed, Apr 14, 2021 at 03:09:13PM -0400, Michael Meissner wrote:
> > On Tue, Apr 13, 2021 at 05:19:12PM -0500, Segher Boessenkool wrote:
> > > > 	* config/rs6000/rs60000.h (FLOAT128_MIN_MAX_FPMASK_P): New macro.
> > > 
> > > As said in the other mail, don't do the macro; just write its expansion
> > > in the single place it is used.
> > 
> > Note, in the first patch it is only used 1 time, but in the second patch it is
> > used 5 times (4 times in mode iterators in rs6000.md, 1 other use in rs6000.c).
> > But I will eliminate it, and replicate it in each of the 6 places it is used.
> 
> The alternative is to come up with a much better name :-/

I dunno, given the what the macro is used for (i.e. whether we have the IEEE
128-bit minimum, maximum, and floating point compare mask)
FLOAT128_MIN_MAX_FPMASK_P meets the definition.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC

[Segher Boessenkool]

On Wed, Apr 14, 2021 at 03:09:13PM -0400, Michael Meissner wrote:
> On Tue, Apr 13, 2021 at 05:19:12PM -0500, Segher Boessenkool wrote:
> > > 	* config/rs6000/rs60000.h (FLOAT128_MIN_MAX_FPMASK_P): New macro.
> > 
> > As said in the other mail, don't do the macro; just write its expansion
> > in the single place it is used.
> 
> Note, in the first patch it is only used 1 time, but in the second patch it is
> used 5 times (4 times in mode iterators in rs6000.md, 1 other use in rs6000.c).
> But I will eliminate it, and replicate it in each of the 6 places it is used.

The alternative is to come up with a much better name :-/


Segher

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC

[Michael Meissner]

On Tue, Apr 13, 2021 at 05:19:12PM -0500, Segher Boessenkool wrote:
> Hi!
> 
> On Fri, Apr 09, 2021 at 10:42:50AM -0400, Michael Meissner wrote:
> > Since then the patch seems to have gone into a limbo state.
> 
> Patches I cannot immediately handle take time, and if they aren't
> pinged, they can fall off the map.  So a) ping your patches, once a week
> for example; and b) write patches that are simpler to review (do not
> cost many hours each).
> 
> > gcc/
> > 2021-04-09  Michael Meissner  <meissner@linux.ibm.com>
> > 
> > 	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
> > 	3.1 IEEE 128-bit floating point xsmaxcqp and xsmincqp instructions.
> > 	* config/rs6000/rs60000.h (FLOAT128_MIN_MAX_FPMASK_P): New macro.
> 
> As said in the other mail, don't do the macro; just write its expansion
> in the single place it is used.

Note, in the first patch it is only used 1 time, but in the second patch it is
used 5 times (4 times in mode iterators in rs6000.md, 1 other use in rs6000.c).
But I will eliminate it, and replicate it in each of the 6 places it is used.

-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC

[Segher Boessenkool]

Hi!

On Fri, Apr 09, 2021 at 10:42:50AM -0400, Michael Meissner wrote:
> Since then the patch seems to have gone into a limbo state.

Patches I cannot immediately handle take time, and if they aren't
pinged, they can fall off the map.  So a) ping your patches, once a week
for example; and b) write patches that are simpler to review (do not
cost many hours each).

> gcc/
> 2021-04-09  Michael Meissner  <meissner@linux.ibm.com>
> 
> 	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
> 	3.1 IEEE 128-bit floating point xsmaxcqp and xsmincqp instructions.
> 	* config/rs6000/rs60000.h (FLOAT128_MIN_MAX_FPMASK_P): New macro.

As said in the other mail, don't do the macro; just write its expansion
in the single place it is used.

> 	* config/rs6000/rs6000.md (s<minmax><mode>3): Add support for the
> 	ISA 3.1 IEEE 128-bit minimum and maximum instructions.

And rephrase this, just "New" something.

So please resend, taking into account all comments.


Segher

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC

[Segher Boessenkool]

Hi!

On Fri, Apr 09, 2021 at 11:54:57AM -0500, will schmidt wrote:
> On Fri, 2021-04-09 at 10:42 -0400, Michael Meissner wrote:
> > 	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
> > 	3.1 IEEE 128-bit floating point xsmaxcqp and xsmincqp instructions.
> 
> I don't see any direct reference to xsmaxcqp or xsmincqp with respect
> to this change below. 
> 
> It looks like this change adds the FLOAT128_MIN_MAX_FPMASK_P (mode)
> check
> as criteria for emitting some form of a SET instruction. 
>        emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
> 
> Ok, I see it now,  the instructions are mildly obfuscated by
> "xs<minmax>cqp" as part of the rs6000.md change below.

Yeah, that is the downside of using iterators and the like in the
machine description.  But the upsides of that far outweigh these
downsides :-)

> > 	* config/rs6000/rs60000.h (FLOAT128_MIN_MAX_FPMASK_P): New macro.
> 
> which is
> #define FLOAT128_MIN_MAX_FPMASK_P(MODE)	\
>   (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (MODE))
> 
> Are there any non MIN_MAX scenarios that will require the combination
> of POWER10,FLOAT128_HW,FLOAT128_IEEE(mode)?  I'd wonder if there is a name
> not specific to *_MIN_MAX_* that would be a better naming choice.
> But, naming is hard. :-)

Yes, and for every new macro, the reader will have to understand what it
does, what it is for.  If you cannot come up with a good name for it
(one for which it is immediately obvious to the reader what it *means*),
often a good tradeoff is to not make a macro at all, just write out the
few words where you need them.

> > 	* config/rs6000/rs6000.md (s<minmax><mode>3): Add support for the
> > 	ISA 3.1 IEEE 128-bit minimum and maximum instructions.
> 
> I'd move the "xsmaxcqp,xsmincqp" instruction references from the rs6000.c changelog blurb to this changelog blurb.

It should say "New." or "New define_insns." or "New instructions." or
similar.  The changelog says *what*, not *why*.  And it is important
that you can find stuff in it using grep or similar.

Here it should say "s<minmax><mode>3 for IEEE128".  We actually have
some patterns that just say "<code><mode>3", not too useful in a
changelog if you do not say what code and mode are!  (In this case, it
does not help to say what "minmax" is from, it stand for just "min" and
"max" after all :-) )


Segher

Re: [PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC

[will schmidt]

On Fri, 2021-04-09 at 10:42 -0400, Michael Meissner wrote:
> Add IEEE 128-bit min/max support on PowerPC.
> 
> This patch has been posted various times in the past.  My memory is the last
> time I changed the patch, I addressed the concerns posted at that time.  Since
> then the patch seems to have gone into a limbo state.

Hi,

I'll throw some comments at this below, and see if it will trigger more
follow-up. 

> 
> This patch adds the support for the IEEE 128-bit floating point C minimum and
> maximum instructions.  The next patch will add the support for using the
> compare and set mask instruction to implement conditional moves.
> 
> Rather than trying to overload the current SF/DF min/max support, it was
> simpler to just provide the new instructions as a separate insn.
> 
> I have tested this patch in various little endian and big endian PowerPC builds
> since I've posted.  It has no regressions, and it adds the instructions  if
> -mcpu=power10 is used.
> 
> gcc/
> 2021-04-09  Michael Meissner  <meissner@linux.ibm.com>
> 
> 	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
> 	3.1 IEEE 128-bit floating point xsmaxcqp and xsmincqp instructions.

I don't see any direct reference to xsmaxcqp or xsmincqp with respect
to this change below. 

It looks like this change adds the FLOAT128_MIN_MAX_FPMASK_P (mode)
check
as criteria for emitting some form of a SET instruction. 
       emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));

Ok, I see it now,  the instructions are mildly obfuscated by
"xs<minmax>cqp" as part of the rs6000.md change below.




> 	* config/rs6000/rs60000.h (FLOAT128_MIN_MAX_FPMASK_P): New macro.

which is
#define FLOAT128_MIN_MAX_FPMASK_P(MODE)	\
  (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (MODE))

Are there any non MIN_MAX scenarios that will require the combination
of POWER10,FLOAT128_HW,FLOAT128_IEEE(mode)?  I'd wonder if there is a name
not specific to *_MIN_MAX_* that would be a better naming choice.
But, naming is hard. :-)


> 	* config/rs6000/rs6000.md (s<minmax><mode>3): Add support for the
> 	ISA 3.1 IEEE 128-bit minimum and maximum instructions.

I'd move the "xsmaxcqp,xsmincqp" instruction references from the rs6000.c changelog blurb to this changelog blurb.

I've looked over the rest, no further relevant comments below.
thanks
-Will

> 
> gcc/testsuite/
> 2021-04-09  Michael Meissner  <meissner@linux.ibm.com>
> 
> 	* gcc.target/powerpc/float128-minmax-2.c: New test.
> ---
>  gcc/config/rs6000/rs6000.c                        |  3 ++-
>  gcc/config/rs6000/rs6000.h                        |  5 +++++
>  gcc/config/rs6000/rs6000.md                       | 11 +++++++++++
>  .../gcc.target/powerpc/float128-minmax-2.c        | 15 +++++++++++++++
>  4 files changed, 33 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
> 
> diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
> index 35f5c332c41..e87686c1c4d 100644
> --- a/gcc/config/rs6000/rs6000.c
> +++ b/gcc/config/rs6000/rs6000.c
> @@ -16111,7 +16111,8 @@ rs6000_emit_minmax (rtx dest, enum rtx_code code, rtx op0, rtx op1)
>    /* VSX/altivec have direct min/max insns.  */
>    if ((code == SMAX || code == SMIN)
>        && (VECTOR_UNIT_ALTIVEC_OR_VSX_P (mode)
> -	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))))
> +	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))
> +	  || FLOAT128_MIN_MAX_FPMASK_P (mode)))
>      {
>        emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
>        return;

ok


> diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
> index 233a92baf3c..e3fb0798622 100644
> --- a/gcc/config/rs6000/rs6000.h
> +++ b/gcc/config/rs6000/rs6000.h
> @@ -345,6 +345,11 @@ extern const char *host_detect_local_cpu (int argc, const char **argv);
>     || ((MODE) == TDmode)						\
>     || (!TARGET_FLOAT128_TYPE && FLOAT128_IEEE_P (MODE)))
> 
> +/* Macro whether the float128 minimum, maximum, and set compare mask
> +   instructions are enabled.  */
> +#define FLOAT128_MIN_MAX_FPMASK_P(MODE)					\
> +  (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (MODE))
> +
>  /* Return true for floating point that does not use a vector register.  */
>  #define SCALAR_FLOAT_MODE_NOT_VECTOR_P(MODE)				\
>    (SCALAR_FLOAT_MODE_P (MODE) && !FLOAT128_VECTOR_P (MODE))


ok

> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
> index c8cdc42533c..17b2fdc1cdd 100644
> --- a/gcc/config/rs6000/rs6000.md
> +++ b/gcc/config/rs6000/rs6000.md
> @@ -5194,6 +5194,17 @@ (define_insn "*s<minmax><mode>3_vsx"
>  }
>    [(set_attr "type" "fp")])
> 
> +;; Min/max for ISA 3.1 IEEE 128-bit floating point
> +(define_insn "s<minmax><mode>3"
> +  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
> +	(fp_minmax:IEEE128
> +	 (match_operand:IEEE128 1 "altivec_register_operand" "v")
> +	 (match_operand:IEEE128 2 "altivec_register_operand" "v")))]
> +  "TARGET_POWER10"
> +  "xs<minmax>cqp %0,%1,%2"
> +  [(set_attr "type" "vecfloat")
> +   (set_attr "size" "128")])
> +
>  ;; The conditional move instructions allow us to perform max and min operations
>  ;; even when we don't have the appropriate max/min instruction using the FSEL
>  ;; instruction.

ok

> diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
> new file mode 100644
> index 00000000000..c71ba08c9f8
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
> @@ -0,0 +1,15 @@
> +/* { dg-require-effective-target ppc_float128_hw } */
> +/* { dg-require-effective-target power10_ok } */
> +/* { dg-options "-mdejagnu-cpu=power10 -O2 -ffast-math" } */
> +
> +#ifndef TYPE
> +#define TYPE _Float128
> +#endif
> +
> +/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
> +   call.  */
> +TYPE f128_min (TYPE a, TYPE b) { return __builtin_fminf128 (a, b); }
> +TYPE f128_max (TYPE a, TYPE b) { return __builtin_fmaxf128 (a, b); }
> +
> +/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
> +/* { dg-final { scan-assembler {\mxsmincqp\M} } } */

ok

> -- 
> 2.22.0
> 
> 

[PATCH 1/2] Add IEEE 128-bit min/max support on PowerPC

[Michael Meissner]

Add IEEE 128-bit min/max support on PowerPC.

This patch has been posted various times in the past.  My memory is the last
time I changed the patch, I addressed the concerns posted at that time.  Since
then the patch seems to have gone into a limbo state.

This patch adds the support for the IEEE 128-bit floating point C minimum and
maximum instructions.  The next patch will add the support for using the
compare and set mask instruction to implement conditional moves.

Rather than trying to overload the current SF/DF min/max support, it was
simpler to just provide the new instructions as a separate insn.

I have tested this patch in various little endian and big endian PowerPC builds
since I've posted.  It has no regressions, and it adds the instructions  if
-mcpu=power10 is used.

gcc/
2021-04-09  Michael Meissner  <meissner@linux.ibm.com>

	* config/rs6000/rs6000.c (rs6000_emit_minmax): Add support for ISA
	3.1 IEEE 128-bit floating point xsmaxcqp and xsmincqp instructions.
	* config/rs6000/rs60000.h (FLOAT128_MIN_MAX_FPMASK_P): New macro.
	* config/rs6000/rs6000.md (s<minmax><mode>3): Add support for the
	ISA 3.1 IEEE 128-bit minimum and maximum instructions.

gcc/testsuite/
2021-04-09  Michael Meissner  <meissner@linux.ibm.com>

	* gcc.target/powerpc/float128-minmax-2.c: New test.
---
 gcc/config/rs6000/rs6000.c                        |  3 ++-
 gcc/config/rs6000/rs6000.h                        |  5 +++++
 gcc/config/rs6000/rs6000.md                       | 11 +++++++++++
 .../gcc.target/powerpc/float128-minmax-2.c        | 15 +++++++++++++++
 4 files changed, 33 insertions(+), 1 deletion(-)
 create mode 100644 gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index 35f5c332c41..e87686c1c4d 100644
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -16111,7 +16111,8 @@ rs6000_emit_minmax (rtx dest, enum rtx_code code, rtx op0, rtx op1)
   /* VSX/altivec have direct min/max insns.  */
   if ((code == SMAX || code == SMIN)
       && (VECTOR_UNIT_ALTIVEC_OR_VSX_P (mode)
-	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))))
+	  || (mode == SFmode && VECTOR_UNIT_VSX_P (DFmode))
+	  || FLOAT128_MIN_MAX_FPMASK_P (mode)))
     {
       emit_insn (gen_rtx_SET (dest, gen_rtx_fmt_ee (code, mode, op0, op1)));
       return;
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index 233a92baf3c..e3fb0798622 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -345,6 +345,11 @@ extern const char *host_detect_local_cpu (int argc, const char **argv);
    || ((MODE) == TDmode)						\
    || (!TARGET_FLOAT128_TYPE && FLOAT128_IEEE_P (MODE)))
 
+/* Macro whether the float128 minimum, maximum, and set compare mask
+   instructions are enabled.  */
+#define FLOAT128_MIN_MAX_FPMASK_P(MODE)					\
+  (TARGET_POWER10 && TARGET_FLOAT128_HW && FLOAT128_IEEE_P (MODE))
+
 /* Return true for floating point that does not use a vector register.  */
 #define SCALAR_FLOAT_MODE_NOT_VECTOR_P(MODE)				\
   (SCALAR_FLOAT_MODE_P (MODE) && !FLOAT128_VECTOR_P (MODE))
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index c8cdc42533c..17b2fdc1cdd 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -5194,6 +5194,17 @@ (define_insn "*s<minmax><mode>3_vsx"
 }
   [(set_attr "type" "fp")])
 
+;; Min/max for ISA 3.1 IEEE 128-bit floating point
+(define_insn "s<minmax><mode>3"
+  [(set (match_operand:IEEE128 0 "altivec_register_operand" "=v")
+	(fp_minmax:IEEE128
+	 (match_operand:IEEE128 1 "altivec_register_operand" "v")
+	 (match_operand:IEEE128 2 "altivec_register_operand" "v")))]
+  "TARGET_POWER10"
+  "xs<minmax>cqp %0,%1,%2"
+  [(set_attr "type" "vecfloat")
+   (set_attr "size" "128")])
+
 ;; The conditional move instructions allow us to perform max and min operations
 ;; even when we don't have the appropriate max/min instruction using the FSEL
 ;; instruction.
diff --git a/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
new file mode 100644
index 00000000000..c71ba08c9f8
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/float128-minmax-2.c
@@ -0,0 +1,15 @@
+/* { dg-require-effective-target ppc_float128_hw } */
+/* { dg-require-effective-target power10_ok } */
+/* { dg-options "-mdejagnu-cpu=power10 -O2 -ffast-math" } */
+
+#ifndef TYPE
+#define TYPE _Float128
+#endif
+
+/* Test that the fminf128/fmaxf128 functions generate if/then/else and not a
+   call.  */
+TYPE f128_min (TYPE a, TYPE b) { return __builtin_fminf128 (a, b); }
+TYPE f128_max (TYPE a, TYPE b) { return __builtin_fmaxf128 (a, b); }
+
+/* { dg-final { scan-assembler {\mxsmaxcqp\M} } } */
+/* { dg-final { scan-assembler {\mxsmincqp\M} } } */
-- 
2.22.0


-- 
Michael Meissner, IBM
IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA
email: meissner@linux.ibm.com, phone: +1 (978) 899-4797