[gcc r17-3196] i386: Don't use VCOMX for XFmode compares [PR126676]

https://gcc.gnu.org/g:121691a8f8b29fd0cc8bf538b5a24424607a59f6

commit r17-3196-g121691a8f8b29fd0cc8bf538b5a24424607a59f6
Author: Hu, Lin1 <[email protected]>
Date:   Fri Aug 7 16:07:45 2026 +0800

    i386: Don't use VCOMX for XFmode compares [PR126676]
    
    gcc/ChangeLog:
    
            PR target/126676
            * config/i386/i386-expand.cc (ix86_expand_fp_compare): Only use
            UNSPEC_OPTCOMX for the modes VCOMX exists for.
    
    gcc/testsuite/ChangeLog:
    
            PR target/126676
            * gcc.target/i386/pr126676.c: New test.

Diff:
---
 gcc/config/i386/i386-expand.cc           | 15 ++++++++-------
 gcc/testsuite/gcc.target/i386/pr126676.c |  7 +++++++
 2 files changed, 15 insertions(+), 7 deletions(-)

diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index d0b92efc48b6..fb4224af0da3 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -2922,6 +2922,7 @@ ix86_expand_fp_compare (enum rtx_code code, rtx op0, rtx op1)
   rtx tmp, scratch;
 
   code = ix86_prepare_fp_compare_args (code, &op0, &op1);
+  machine_mode op_mode = GET_MODE (op0);
 
   tmp = gen_rtx_COMPARE (CCFPmode, op0, op1);
   if (unordered_compare)
@@ -2932,14 +2933,14 @@ ix86_expand_fp_compare (enum rtx_code code, rtx op0, rtx op1)
     {
     case IX86_FPCMP_COMI:
       tmp = gen_rtx_COMPARE (CCFPmode, op0, op1);
+      /* VCOMX/VUCOMX only have DF/SF/HF mode instructions.  */
+      if (TARGET_AVX10_2
+	  && (code == EQ || code == NE)
+	  && (op_mode == HFmode || op_mode == SFmode || op_mode == DFmode))
+	tmp = gen_rtx_UNSPEC (CCFPmode, gen_rtvec (1, tmp), UNSPEC_OPTCOMX);
       /* We only have vcomisbf16, No vcomubf16 nor vcomxbf16 */
-      if (GET_MODE (op0) != E_BFmode)
-	{
-	  if (TARGET_AVX10_2 && (code == EQ || code == NE))
-	    tmp = gen_rtx_UNSPEC (CCFPmode, gen_rtvec (1, tmp), UNSPEC_OPTCOMX);
-	  if (unordered_compare)
-	    tmp = gen_rtx_UNSPEC (CCFPmode, gen_rtvec (1, tmp), UNSPEC_NOTRAP);
-	}
+      if (op_mode != BFmode && unordered_compare)
+	tmp = gen_rtx_UNSPEC (CCFPmode, gen_rtvec (1, tmp), UNSPEC_NOTRAP);
       cmp_mode = CCFPmode;
       emit_insn (gen_rtx_SET (gen_rtx_REG (CCFPmode, FLAGS_REG), tmp));
       break;
diff --git a/gcc/testsuite/gcc.target/i386/pr126676.c b/gcc/testsuite/gcc.target/i386/pr126676.c
new file mode 100644
index 000000000000..219a6133790c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr126676.c
@@ -0,0 +1,7 @@
+/* { dg-do compile { target { ! ia32 } } } */
+/* { dg-options "-O2 -march=x86-64 -mavx10.2 -mapxf" } */
+/* { dg-final { scan-assembler-times "fucomip" 2 } } */
+/* { dg-final { scan-assembler-not "comx" } } */
+
+int f1 (long double a, long double b, int x) { return x > 0 && a == b; }
+int f2 (long double a, long double b, int x) { return x > 0 && a != b; }