[PATCH v3] x86: make VPTERNLOG* usable on less than 512-bit operands with just AVX512F

[Jan Beulich <jbeulich@suse.com>]

There's no reason to constrain this to AVX512VL, unless instructed so by
-mprefer-vector-width=, as the wider operation is unusable for more
narrow operands only when the possible memory source is a non-broadcast
one. This way even the scalar copysign<mode>3 can benefit from the
operation being a single-insn one (leaving aside moves which the
compiler decides to insert for unclear reasons, and leaving aside the
fact that bcst_mem_operand() is too restrictive for broadcast to be
embedded right into VPTERNLOG*).

While there also bring *<avx512>_vternlog<mode>_all's in sync with that
of the three splitters.

Along with this also request value duplication in
ix86_expand_copysign()'s call to ix86_build_signbit_mask(), eliminating
excess space allocation in .rodata.*, filled with zeros which are never
read.

gcc/

	* config/i386/i386-expand.cc (ix86_expand_copysign): Request
	value duplication by ix86_build_signbit_mask() when AVX512F and
	not HFmode.
	* config/i386/sse.md (*<avx512>_vternlog<mode>_all): Convert to
	2-alternative form. Adjust "mode" attribute. Add "enabled"
	attribute.
	(*<avx512>_vpternlog<mode>_1): Also permit when TARGET_AVX512F
	&& !TARGET_PREFER_AVX256.
	(*<avx512>_vpternlog<mode>_2): Likewise.
	(*<avx512>_vpternlog<mode>_3): Likewise.

gcc/testsuite/
	* gcc.target/i386/avx512f-copysign.c: New test.
---
I haven't been able to find documentation on the dejagnu(?) regex syntax
(?:...). With ordinary (...) failing (producing twice as many matches),
I could only derive this from other scan-assembler patterns.

I guess the underlying pattern, going along the lines of what
<mask_codefor>one_cmpl<mode>2<mask_name> uses, can be applied elsewhere
as well.

HFmode could use embedded broadcast too for copysign and alike, but that
would need to be V2HF -> V8HF (for which I don't think there are any
existing patterns).
---
v3: Adjust insn conditional as well. Add testcase.
v2: Respect -mprefer-vector-width=.

--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -2266,7 +2266,7 @@ ix86_expand_copysign (rtx operands[])
   else
     dest = NULL_RTX;
   op1 = lowpart_subreg (vmode, force_reg (mode, operands[2]), mode);
-  mask = ix86_build_signbit_mask (vmode, 0, 0);
+  mask = ix86_build_signbit_mask (vmode, TARGET_AVX512F && mode != HFmode, 0);
 
   if (CONST_DOUBLE_P (operands[1]))
     {
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -12399,22 +12399,35 @@
    (set_attr "mode" "<sseinsnmode>")])
 
 (define_insn "*<avx512>_vternlog<mode>_all"
-  [(set (match_operand:V 0 "register_operand" "=v")
+  [(set (match_operand:V 0 "register_operand" "=v,v")
 	(unspec:V
-	  [(match_operand:V 1 "register_operand" "0")
-	   (match_operand:V 2 "register_operand" "v")
-	   (match_operand:V 3 "bcst_vector_operand" "vmBr")
+	  [(match_operand:V 1 "register_operand" "0,0")
+	   (match_operand:V 2 "register_operand" "v,v")
+	   (match_operand:V 3 "bcst_vector_operand" "vBr,m")
 	   (match_operand:SI 4 "const_0_to_255_operand")]
 	  UNSPEC_VTERNLOG))]
-  "TARGET_AVX512F
+  "(<MODE_SIZE> == 64 || TARGET_AVX512VL
+    || (TARGET_AVX512F && !TARGET_PREFER_AVX256))
 /* Disallow embeded broadcast for vector HFmode since
    it's not real AVX512FP16 instruction.  */
   && (GET_MODE_SIZE (GET_MODE_INNER (<MODE>mode)) >= 4
      || GET_CODE (operands[3]) != VEC_DUPLICATE)"
-  "vpternlog<ternlogsuffix>\t{%4, %3, %2, %0|%0, %2, %3, %4}"
+{
+  if (TARGET_AVX512VL)
+    return "vpternlog<ternlogsuffix>\t{%4, %3, %2, %0|%0, %2, %3, %4}";
+  else
+    return "vpternlog<ternlogsuffix>\t{%4, %g3, %g2, %g0|%g0, %g2, %g3, %4}";
+}
   [(set_attr "type" "sselog")
    (set_attr "prefix" "evex")
-   (set_attr "mode" "<sseinsnmode>")])
+   (set (attr "mode")
+        (if_then_else (match_test "TARGET_AVX512VL")
+		      (const_string "<sseinsnmode>")
+		      (const_string "XI")))
+   (set (attr "enabled")
+	(if_then_else (eq_attr "alternative" "1")
+		      (symbol_ref "<MODE_SIZE> == 64 || TARGET_AVX512VL")
+		      (const_string "*")))])
 
 ;; There must be lots of other combinations like
 ;;
@@ -12443,7 +12456,8 @@
 	  (any_logic2:V
 	    (match_operand:V 3 "regmem_or_bitnot_regmem_operand")
 	    (match_operand:V 4 "regmem_or_bitnot_regmem_operand"))))]
-  "(<MODE_SIZE> == 64 || TARGET_AVX512VL)
+  "(<MODE_SIZE> == 64 || TARGET_AVX512VL
+    || (TARGET_AVX512F && !TARGET_PREFER_AVX256))
    && ix86_pre_reload_split ()
    && (rtx_equal_p (STRIP_UNARY (operands[1]),
 		    STRIP_UNARY (operands[4]))
@@ -12527,7 +12541,8 @@
 	      (match_operand:V 2 "regmem_or_bitnot_regmem_operand"))
 	    (match_operand:V 3 "regmem_or_bitnot_regmem_operand"))
 	  (match_operand:V 4 "regmem_or_bitnot_regmem_operand")))]
-  "(<MODE_SIZE> == 64 || TARGET_AVX512VL)
+  "(<MODE_SIZE> == 64 || TARGET_AVX512VL
+    || (TARGET_AVX512F && !TARGET_PREFER_AVX256))
    && ix86_pre_reload_split ()
    && (rtx_equal_p (STRIP_UNARY (operands[1]),
 		    STRIP_UNARY (operands[4]))
@@ -12610,7 +12625,8 @@
 	    (match_operand:V 1 "regmem_or_bitnot_regmem_operand")
 	    (match_operand:V 2 "regmem_or_bitnot_regmem_operand"))
 	  (match_operand:V 3 "regmem_or_bitnot_regmem_operand")))]
-  "(<MODE_SIZE> == 64 || TARGET_AVX512VL)
+  "(<MODE_SIZE> == 64 || TARGET_AVX512VL
+    || (TARGET_AVX512F && !TARGET_PREFER_AVX256))
    && ix86_pre_reload_split ()"
   "#"
   "&& 1"
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/avx512f-copysign.c
@@ -0,0 +1,32 @@
+/* { dg-do compile } */
+/* { dg-options "-mavx512f -mno-avx512vl -O2" } */
+/* { dg-final { scan-assembler-times "vpternlog\[dq\]\[ \\t\]+\\\$(?:216|228|0xd8|0xe4)," 5 } } */
+
+double cs_df (double x, double y)
+{
+  return __builtin_copysign (x, y);
+}
+
+float cs_sf (float x, float y)
+{
+  return __builtin_copysignf (x, y);
+}
+
+typedef double __attribute__ ((vector_size (16))) v2df;
+typedef double __attribute__ ((vector_size (32))) v4df;
+typedef double __attribute__ ((vector_size (64))) v8df;
+
+v2df cs_v2df (v2df x, v2df y)
+{
+  return __builtin_ia32_copysignpd (x, y);
+}
+
+v4df cs_v4df (v4df x, v4df y)
+{
+  return __builtin_ia32_copysignpd256 (x, y);
+}
+
+v8df cs_v8df (v8df x, v8df y)
+{
+  return __builtin_ia32_copysignpd512 (x, y);
+}