On Mon, Oct 14, 2024 at 08:53:29AM +0200, Jakub Jelinek wrote:
> > PR middle-end/116891
> > * match.pd ((negate (IFN_FNMS@3 @0 @1 @2)) -> (IFN_FMA @0 @1 @2)):
> > Only enable for !HONOR_SIGN_DEPENDENT_ROUNDING.
>
> Guess it would be nice to have a testcase which FAILs without the patch and
> PASSes with it, but it can be added later.
I've added such a testcase now, and additionally found the fix only fixed
one of the 4 problematic similar cases.
Here is a patch which fixes the others too and adds the testcases.
fma-pr116891.c FAILed without your patch, FAILs with your patch too (but
only due to the bar/baz/qux checks) and PASSes with the patch.
Ok for trunk if it passes full bootstrap/regtest?
2024-10-15 Jakub Jelinek <ja...@redhat.com>
PR middle-end/116891
* match.pd ((negate (fmas@3 @0 @1 @2)) -> (IFN_FNMS @0 @1 @2)):
Only enable for !HONOR_SIGN_DEPENDENT_ROUNDING.
((negate (IFN_FMS@3 @0 @1 @2)) -> (IFN_FNMA @0 @1 @2)): Likewise.
((negate (IFN_FNMA@3 @0 @1 @2)) -> (IFN_FMS @0 @1 @2)): Likewise.
* gcc.dg/pr116891.c: New test.
* gcc.target/i386/fma-pr116891.c: New test.
--- gcc/match.pd.jj 2024-10-15 12:50:47.699905473 +0200
+++ gcc/match.pd 2024-10-15 12:57:19.547400416 +0200
@@ -9452,7 +9452,7 @@ (define_operator_list SYNC_FETCH_AND_AND
(IFN_FNMS @0 @1 @2))
(simplify
(negate (fmas@3 @0 @1 @2))
- (if (single_use (@3))
+ (if (!HONOR_SIGN_DEPENDENT_ROUNDING (type) && single_use (@3))
(IFN_FNMS @0 @1 @2))))
(simplify
@@ -9466,7 +9466,7 @@ (define_operator_list SYNC_FETCH_AND_AND
(IFN_FNMA @0 @1 @2))
(simplify
(negate (IFN_FMS@3 @0 @1 @2))
- (if (single_use (@3))
+ (if (!HONOR_SIGN_DEPENDENT_ROUNDING (type) && single_use (@3))
(IFN_FNMA @0 @1 @2)))
(simplify
@@ -9480,7 +9480,7 @@ (define_operator_list SYNC_FETCH_AND_AND
(IFN_FMS @0 @1 @2))
(simplify
(negate (IFN_FNMA@3 @0 @1 @2))
- (if (single_use (@3))
+ (if (!HONOR_SIGN_DEPENDENT_ROUNDING (type) && single_use (@3))
(IFN_FMS @0 @1 @2)))
(simplify
--- gcc/testsuite/gcc.dg/pr116891.c.jj 2024-10-15 12:31:57.619723244 +0200
+++ gcc/testsuite/gcc.dg/pr116891.c 2024-10-15 12:56:37.809987933 +0200
@@ -0,0 +1,47 @@
+/* PR middle-end/116891 */
+/* { dg-do run } */
+/* { dg-require-effective-target fenv } */
+/* { dg-require-effective-target hard_float } */
+/* { dg-require-effective-target c99_runtime } */
+/* { dg-options "-O2 -frounding-math" } */
+
+#include <fenv.h>
+
+__attribute__((noipa)) double
+foo (double x, double y, double z)
+{
+ return -__builtin_fma (-x, y, -z);
+}
+
+__attribute__((noipa)) double
+bar (double x, double y, double z)
+{
+ return -__builtin_fma (-x, y, z);
+}
+
+__attribute__((noipa)) double
+baz (double x, double y, double z)
+{
+ return -__builtin_fma (x, y, -z);
+}
+
+__attribute__((noipa)) double
+qux (double x, double y, double z)
+{
+ return -__builtin_fma (x, y, z);
+}
+
+int
+main ()
+{
+#if defined (FE_DOWNWARD) && __DBL_MANT_DIG__ == 53 && __DBL_MAX_EXP__ == 1024
+ fesetround (FE_DOWNWARD);
+ double a = foo (-0x1.p256, 0x1.p256, 0x1.p-256);
+ if (a != -__builtin_nextafter (0x1p256 * 0x1p256, 0.))
+ __builtin_abort ();
+ if (a != bar (-0x1.p256, 0x1.p256, -0x1.p-256)
+ || a != baz (0x1.p256, 0x1.p256, 0x1.p-256)
+ || a != qux (0x1.p256, 0x1.p256, -0x1.p-256))
+ __builtin_abort ();
+#endif
+}
--- gcc/testsuite/gcc.target/i386/fma-pr116891.c.jj 2024-10-15
12:42:39.711719596 +0200
+++ gcc/testsuite/gcc.target/i386/fma-pr116891.c 2024-10-15
12:44:56.692806834 +0200
@@ -0,0 +1,19 @@
+/* PR middle-end/116891 */
+/* { dg-do run } */
+/* { dg-require-effective-target fenv } */
+/* { dg-require-effective-target hard_float } */
+/* { dg-require-effective-target c99_runtime } */
+/* { dg-require-effective-target fma } */
+/* { dg-options "-O2 -mfma -frounding-math" } */
+
+#include <fenv.h>
+#include "fma-check.h"
+
+#define main() do_main ()
+#include "../../gcc.dg/pr116891.c"
+
+static void
+fma_test (void)
+{
+ do_main ();
+}
Jakub
