[patch-1, rs6000] enable fctiw on old archs [PR112707]

[HAO CHEN GUI <guihaoc@linux.ibm.com>]

Hi,
  SImode in float register is supported on P7 above. It causes "fctiw"
can be generated on old 32-bit processors as the output operand of
fctiw insn is a SImode in float/double register. This patch fixes the
problem by adding an expand and an insn pattern for fctiw. The output
of new pattern is SFmode. When the target doesn't support SImode in
float register, it calls the new pattern and convert the SFmode to
SImode via stack.

  Bootstrapped and tested on x86 and powerpc64-linux BE and LE with
no regressions. Is this OK for trunk?

Thanks
Gui Haochen

ChangeLog
rs6000: enable fctiw on old archs

The powerpc 32-bit processors (e.g. 5470) supports "fctiw" instruction,
but the instruction can't be generated on such platforms as the insn is
guard by TARGET_POPCNTD.  The root cause is SImode in float register is
supported from Power7.  Actually implementation of "fctiw" only needs
stfiwx which is supported by the old 320-bit processors.  This patch
enables "fctiw" expand for these processors.

gcc/
	PR target/112707
	* config/rs6000/rs6000.md (UNSPEC_STFIWX_SF, UNSPEC_FCTIW_SF): New.
	(expand lrint<mode>si2): New.
	(insn lrint<mode>si2): Rename to...
	(lrint<mode>si_internal): ...this, and remove guard TARGET_POPCNTD.
	(lrint<mode>si_internal2): New.
	(stfiwx_sf): New.

gcc/testsuite/
	PR target/112707
	* gcc.target/powerpc/pr112707-1.c: New.

patch.diff
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index d4337ce42a9..1b207522ad5 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -90,6 +90,7 @@ (define_c_enum "unspec"
    UNSPEC_TLSTLS_PCREL
    UNSPEC_FIX_TRUNC_TF		; fadd, rounding towards zero
    UNSPEC_STFIWX
+   UNSPEC_STFIWX_SF
    UNSPEC_POPCNTB
    UNSPEC_FRES
    UNSPEC_SP_SET
@@ -111,6 +112,7 @@ (define_c_enum "unspec"
    UNSPEC_PARITY
    UNSPEC_CMPB
    UNSPEC_FCTIW
+   UNSPEC_FCTIW_SF
    UNSPEC_FCTID
    UNSPEC_LFIWAX
    UNSPEC_LFIWZX
@@ -6722,11 +6724,39 @@ (define_insn "lrint<mode>di2"
   "fctid %0,%1"
   [(set_attr "type" "fp")])

-(define_insn "lrint<mode>si2"
+(define_expand "lrint<mode>si2"
   [(set (match_operand:SI 0 "gpc_reg_operand" "=d")
 	(unspec:SI [(match_operand:SFDF 1 "gpc_reg_operand" "<rreg2>")]
 		   UNSPEC_FCTIW))]
-  "TARGET_HARD_FLOAT && TARGET_POPCNTD"
+  "TARGET_HARD_FLOAT && TARGET_STFIWX"
+{
+  /* For those old archs in which SImode can't be hold in float registers,
+     call lrint<mode>si_internal2 to put the result in SFmode then
+     convert it via stack.  */
+  if (!TARGET_POPCNTD)
+    {
+      rtx tmp = gen_reg_rtx (SFmode);
+      emit_insn (gen_lrint<mode>si_internal2 (tmp, operands[1]));
+      rtx stack = rs6000_allocate_stack_temp (SImode, false, true);
+      emit_insn (gen_stfiwx_sf (stack, tmp));
+      emit_move_insn (operands[0], stack);
+      DONE;
+    }
+})
+
+(define_insn "lrint<mode>si_internal"
+  [(set (match_operand:SI 0 "gpc_reg_operand" "=d")
+	(unspec:SI [(match_operand:SFDF 1 "gpc_reg_operand" "<rreg2>")]
+		   UNSPEC_FCTIW))]
+  "TARGET_HARD_FLOAT"
+  "fctiw %0,%1"
+  [(set_attr "type" "fp")])
+
+(define_insn "lrint<mode>si_internal2"
+  [(set (match_operand:SF 0 "gpc_reg_operand" "=d")
+	(unspec:SF [(match_operand:SFDF 1 "gpc_reg_operand" "<rreg2>")]
+		   UNSPEC_FCTIW_SF))]
+  "TARGET_HARD_FLOAT"
   "fctiw %0,%1"
   [(set_attr "type" "fp")])

@@ -6801,6 +6831,14 @@ (define_insn "stfiwx"
   [(set_attr "type" "fpstore")
    (set_attr "isa" "*,p8v")])

+(define_insn "stfiwx_sf"
+  [(set (match_operand:SI 0 "memory_operand" "=Z")
+	(unspec:SI [(match_operand:SF 1 "gpc_reg_operand" "d")]
+		   UNSPEC_STFIWX_SF))]
+  "TARGET_STFIWX"
+  "stfiwx %1,%y0"
+  [(set_attr "type" "fpstore")])
+
 ;; If we don't have a direct conversion to single precision, don't enable this
 ;; conversion for 32-bit without fast math, because we don't have the insn to
 ;; generate the fixup swizzle to avoid double rounding problems.
diff --git a/gcc/testsuite/gcc.target/powerpc/pr112707-1.c b/gcc/testsuite/gcc.target/powerpc/pr112707-1.c
new file mode 100644
index 00000000000..32f708c5402
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr112707-1.c
@@ -0,0 +1,15 @@
+/* { dg-do compile { target { powerpc*-*-* && be } } } */
+/* { dg-options "-O2 -mdejagnu-cpu=7450 -m32 -fno-math-errno" } */
+/* { dg-require-effective-target ilp32 } */
+/* { dg-final { scan-assembler-times {\mfctiw\M} 2 } }  */
+/* { dg-final { scan-assembler-times {\mstfiwx\M} 2 } }  */
+
+int test1 (double a)
+{
+  return __builtin_irint (a);
+}
+
+int test2 (float a)
+{
+  return __builtin_irint (a);
+}