[gcc r14-2085] Don't use intermiediate type for FIX_TRUNC_EXPR when ftrapping-math.

[gcc r14-2085] Don't use intermiediate type for FIX_TRUNC_EXPR when ftrapping-math.

[hongtao Liu]

https://gcc.gnu.org/g:77a50c772771f681085922b493922516c3c03e9a

commit r14-2085-g77a50c772771f681085922b493922516c3c03e9a
Author: liuhongt <hongtao.liu@intel.com>
Date:   Sun Jun 25 11:35:09 2023 +0800

    Don't use intermiediate type for FIX_TRUNC_EXPR when ftrapping-math.
    
    > > Hmm, good question.  GENERIC has a direct truncation to unsigned char
    > > for example, the C standard generally says if the integral part cannot
    > > be represented then the behavior is undefined.  So I think we should be
    > > safe here (0x1.0p32 doesn't fit an int).
    >
    > We should be following Annex F (unspecified value plus "invalid" exception
    > for out-of-range floating-to-integer conversions rather than undefined
    > behavior).  But we don't achieve that very well at present (see bug 93806
    > comments 27-29 for examples of how such conversions produce wobbly
    > values).
    
    That would mean guarding this with !flag_trapping_math would be the appropriate
    thing to do.
    
    gcc/ChangeLog:
    
            PR tree-optimization/110371
            PR tree-optimization/110018
            * tree-vect-stmts.cc (vectorizable_conversion): Don't use
            intermiediate type for FIX_TRUNC_EXPR when ftrapping-math.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/i386/pr110018-1.c: Add -fno-trapping-math to dg-options.
            * gcc.target/i386/pr110018-2.c: Ditto.

Diff:
---
 gcc/testsuite/gcc.target/i386/pr110018-1.c | 2 +-
 gcc/testsuite/gcc.target/i386/pr110018-2.c | 2 +-
 gcc/tree-vect-stmts.cc                     | 3 ++-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/gcc/testsuite/gcc.target/i386/pr110018-1.c b/gcc/testsuite/gcc.target/i386/pr110018-1.c
index b6a3be7b7a2..24eeca60f6f 100644
--- a/gcc/testsuite/gcc.target/i386/pr110018-1.c
+++ b/gcc/testsuite/gcc.target/i386/pr110018-1.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-mavx512fp16 -mavx512vl -O2 -mavx512dq" } */
+/* { dg-options "-mavx512fp16 -mavx512vl -O2 -mavx512dq -fno-trapping-math" } */
 /* { dg-final { scan-assembler-times {(?n)vcvttp[dsh]2[dqw]} 5 } } */
 /* { dg-final { scan-assembler-times {(?n)vcvt[dqw]*2p[dsh]} 5 } } */
 
diff --git a/gcc/testsuite/gcc.target/i386/pr110018-2.c b/gcc/testsuite/gcc.target/i386/pr110018-2.c
index a663e074698..9a2d9e17894 100644
--- a/gcc/testsuite/gcc.target/i386/pr110018-2.c
+++ b/gcc/testsuite/gcc.target/i386/pr110018-2.c
@@ -1,5 +1,5 @@
 /* { dg-do compile } */
-/* { dg-options "-mavx512fp16 -mavx512vl -O2 -mavx512dq" } */
+/* { dg-options "-mavx512fp16 -mavx512vl -O2 -mavx512dq -fno-trapping-math" } */
 /* { dg-final { scan-assembler-times {(?n)vcvttp[dsh]2[dqw]} 5 } } */
 /* { dg-final { scan-assembler-times {(?n)vcvt[dqw]*2p[dsh]} 5 } } */
 
diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
index 85d1f3ae52c..7d24bbee152 100644
--- a/gcc/tree-vect-stmts.cc
+++ b/gcc/tree-vect-stmts.cc
@@ -5263,7 +5263,8 @@ vectorizable_conversion (vec_info *vinfo,
       if ((code == FLOAT_EXPR
 	   && GET_MODE_SIZE (lhs_mode) > GET_MODE_SIZE (rhs_mode))
 	  || (code == FIX_TRUNC_EXPR
-	      && GET_MODE_SIZE (rhs_mode) > GET_MODE_SIZE (lhs_mode)))
+	      && GET_MODE_SIZE (rhs_mode) > GET_MODE_SIZE (lhs_mode)
+	      && !flag_trapping_math))
 	{
 	  bool float_expr_p = code == FLOAT_EXPR;
 	  scalar_mode imode = float_expr_p ? rhs_mode : lhs_mode;