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 --git a/gcc/testsuite/gcc.target/i386/pr110018-1.c b/gcc/testsuite/gcc.target/i386/pr110018-1.c
index b6a3be7b7a233f0b580289bf90c0b8758a7169c6..24eeca60f6f2e1280daee6a4d45ec9de6fcdb37e 100644 (file)
--- 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 a663e0746983c1d0741fd2be17fc94962cc6bab1..9a2d9e1789491c82f7b0e6b64721202950357438 100644 (file)
--- 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 85d1f3ae52cb1f32aed209e09d559e587220e4fb..7d24bbee1525928e2538f9850f9c3e7479c0a385 100644 (file)
--- 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;