Re: [PATCH] Extend ldexp{s, d}f3 to vscalefs{s, d} when TARGET_AVX512F and TARGET_SSE_MATH.

[Uros Bizjak via Gcc-patches]

On Wed, Aug 11, 2021 at 8:36 AM Uros Bizjak <ubiz...@gmail.com> wrote:
>
> On Tue, Aug 10, 2021 at 2:13 PM liuhongt <hongtao....@intel.com> wrote:
> >
> > Hi:
> >   AVX512F supported vscalefs{s,d} which is the same as ldexp except the 
> > second operand should be floating point.
> >   Bootstrapped and regtested on x86_64-linux-gnu{-m32,}.
> >
> > gcc/ChangeLog:
> >
> >         PR target/98309
> >         * config/i386/i386.md (ldexp<mode>3): Extend to vscalefs[sd]
> >         when TARGET_AVX512F and TARGET_SSE_MATH.
> >
> > gcc/testsuite/ChangeLog:
> >
> >         PR target/98309
> >         * gcc.target/i386/pr98309-1.c: New test.
> >         * gcc.target/i386/pr98309-2.c: New test.
>
> OK.

Actually, we should introduce a scalar version of avx512f_vmscalef, so
we can avoid all subreg conversions with the vector-merge (VM)
version, and will also allow memory in operand 2.

Please test the attached incremental patch.

Uros.

diff --git a/gcc/config/i386/i386.md b/gcc/config/i386/i386.md
index 56b09c566ed..4a8e8fea290 100644
--- a/gcc/config/i386/i386.md
+++ b/gcc/config/i386/i386.md
@@ -125,6 +125,9 @@
   UNSPEC_RSQRT
   UNSPEC_PSADBW
 
+  ;; For AVX512F support
+  UNSPEC_SCALEF
+
   ;; Generic math support
   UNSPEC_COPYSIGN
   UNSPEC_XORSIGN
@@ -17894,6 +17897,17 @@
   DONE;
 })
 
+(define_insn "avx512f_scalef<mode>2"
+  [(set (match_operand:MODEF 0 "register_operand" "=v")
+       (unspec:MODEF
+         [(match_operand:MODEF 1 "register_operand" "v")
+          (match_operand:MODEF 2 "nonimmediate_operand" "vm")]
+         UNSPEC_SCALEF))]
+  "TARGET_AVX512F"
+  "vscalef<ssemodesuffix>\t{%2, %1, %0|%0, %1, %2}"
+  [(set_attr "prefix" "evex")
+   (set_attr "mode"  "<MODE>")])
+
 (define_expand "ldexpxf3"
   [(match_operand:XF 0 "register_operand")
    (match_operand:XF 1 "register_operand")
@@ -17924,15 +17938,12 @@
   if (TARGET_AVX512F && TARGET_SSE_MATH)
    {
      rtx op2 = gen_reg_rtx (<MODE>mode);
-     emit_insn (gen_floatsi<mode>2 (op2, operands[2]));
-     operands[0] = lowpart_subreg (<ssevecmodef>mode, operands[0], <MODE>mode);
-     if (MEM_P (operands[1]))
+
+     if (!nonimmediate_operand (operands[1], <MODE>mode))
        operands[1] = force_reg (<MODE>mode, operands[1]);
-     operands[1] = lowpart_subreg (<ssevecmodef>mode, operands[1], <MODE>mode);
-     op2 = lowpart_subreg (<ssevecmodef>mode, op2, <MODE>mode);
-     emit_insn (gen_avx512f_vmscalef<ssevecmodelower> (operands[0],
-                                                      operands[1],
-                                                      op2));
+
+     emit_insn (gen_floatsi<mode>2 (op2, operands[2]));
+     emit_insn (gen_avx512f_scalef<mode>2 (operands[0], operands[1], op2));
    }
   else
     {
diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md
index 3957c86c3df..9233dfc6150 100644
--- a/gcc/config/i386/sse.md
+++ b/gcc/config/i386/sse.md
@@ -92,7 +92,6 @@
   UNSPEC_RCP14
   UNSPEC_RSQRT14
   UNSPEC_FIXUPIMM
-  UNSPEC_SCALEF
   UNSPEC_VTERNLOG
   UNSPEC_GETEXP
   UNSPEC_GETMANT