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| author | Jakub Jelinek <jakub@redhat.com> | 2021-09-06 10:08:16 +0200 |
|---|---|---|
| committer | Jakub Jelinek <jakub@redhat.com> | 2021-09-06 10:08:16 +0200 |
| commit | 8a4602c2e0f81895415ba7ee23bf81dc795d1103 (patch) | |
| tree | d45c41b2fe49e3573b83c74eb9741ac12c7df030 | |
| parent | 564efbf40077c25623cdd6ce2f911c56b5b08f6c (diff) | |
| download | gcc-8a4602c2e0f81895415ba7ee23bf81dc795d1103.zip gcc-8a4602c2e0f81895415ba7ee23bf81dc795d1103.tar.gz gcc-8a4602c2e0f81895415ba7ee23bf81dc795d1103.tar.bz2 | |
match.pd: Fix up __builtin_*_overflow arg demotion [PR102207]
My earlier patch to demote arguments of __builtin_*_overflow unfortunately
caused a wrong-code regression. The builtins operate on infinite precision
arguments, outer_prec > inner_prec signed -> signed, unsigned -> unsigned
promotions there are just repeating the sign or 0s and can be demoted,
similarly unsigned -> signed which also is repeating 0s, but as the
testcase shows, signed -> unsigned promotions need to be preserved (unless
we'd know the inner arguments can't be negative), because for negative
numbers such promotion sets the outer_prec -> inner_prec bits to 1 bit the
bits above that to 0 in the infinite precision.
So, the following patch avoids the demotions for the signed -> unsigned
promotions.
2021-09-06 Jakub Jelinek <jakub@redhat.com>
PR tree-optimization/102207
* match.pd: Don't demote operands of IFN_{ADD,SUB,MUL}_OVERFLOW if they
were promoted from signed to wider unsigned type.
* gcc.dg/pr102207.c: New test.
| -rw-r--r-- | gcc/match.pd | 6 | ||||
| -rw-r--r-- | gcc/testsuite/gcc.dg/pr102207.c | 24 |
2 files changed, 28 insertions, 2 deletions
diff --git a/gcc/match.pd b/gcc/match.pd index cc7809d..008f775 100644 --- a/gcc/match.pd +++ b/gcc/match.pd @@ -5608,13 +5608,15 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (ovf (convert@2 @0) @1) (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) && INTEGRAL_TYPE_P (TREE_TYPE (@2)) - && TYPE_PRECISION (TREE_TYPE (@2)) > TYPE_PRECISION (TREE_TYPE (@0))) + && TYPE_PRECISION (TREE_TYPE (@2)) > TYPE_PRECISION (TREE_TYPE (@0)) + && (!TYPE_UNSIGNED (TREE_TYPE (@2)) || TYPE_UNSIGNED (TREE_TYPE (@0)))) (ovf @0 @1))) (simplify (ovf @1 (convert@2 @0)) (if (INTEGRAL_TYPE_P (TREE_TYPE (@0)) && INTEGRAL_TYPE_P (TREE_TYPE (@2)) - && TYPE_PRECISION (TREE_TYPE (@2)) > TYPE_PRECISION (TREE_TYPE (@0))) + && TYPE_PRECISION (TREE_TYPE (@2)) > TYPE_PRECISION (TREE_TYPE (@0)) + && (!TYPE_UNSIGNED (TREE_TYPE (@2)) || TYPE_UNSIGNED (TREE_TYPE (@0)))) (ovf @1 @0)))) /* Simplification of math builtins. These rules must all be optimizations diff --git a/gcc/testsuite/gcc.dg/pr102207.c b/gcc/testsuite/gcc.dg/pr102207.c new file mode 100644 index 0000000..08540d0 --- /dev/null +++ b/gcc/testsuite/gcc.dg/pr102207.c @@ -0,0 +1,24 @@ +/* PR tree-optimization/102207 */ +/* { dg-do run { target int128 } } */ +/* { dg-options "-O2" } */ + +typedef unsigned __int128 u128; + +u128 +foo (unsigned short a) +{ + u128 g; + __builtin_sub_overflow ((unsigned long long) -a, 1, &g); + return g; +} + +int +main () +{ + if (__SIZEOF_LONG_LONG__ * __CHAR_BIT__ != 64 + || __SIZEOF_SHORT__ * __CHAR_BIT__ != 16) + return 0; + if (foo (1) != 0xfffffffffffffffeULL) + __builtin_abort (); + return 0; +} |