> > 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.
Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,} and aarch64-linux-gnu.
Ok for trunk?
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.
---
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 1748555a625..bf61461939b 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;
--
2.39.1.388.g2fc9e9ca3c
