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| author | Marc Glisse <marc.glisse@inria.fr> | 2020-08-10 12:50:42 +0200 |
|---|---|---|
| committer | Giuliano Belinassi <giuliano.belinassi@usp.br> | 2020-08-17 15:07:54 -0300 |
| commit | 429181b1ac18d008cd83da586350ac631e7b5787 (patch) | |
| tree | 3cfb40852b82921ec5aeb8741af1fa8492528f51 /gcc/testsuite | |
| parent | 001a9a3b85b1c103992e2b4d5ce586263c3c5590 (diff) | |
Simplify X * C1 == C2 with wrapping overflow
Odd numbers are invertible in Z / 2^n Z, so X * C1 == C2 can be rewritten
as X == C2 * inv(C1) when overflow wraps.
mod_inv should probably be updated to better match the other wide_int
functions, but that's a separate issue.
2020-08-10 Marc Glisse <marc.glisse@inria.fr>
PR tree-optimization/95433
* match.pd (X * C1 == C2): Handle wrapping overflow.
* expr.c (maybe_optimize_mod_cmp): Qualify call to mod_inv.
(mod_inv): Move...
* wide-int.cc (mod_inv): ... here.
* wide-int.h (mod_inv): Declare it.
* gcc.dg/tree-ssa/pr95433-2.c: New file.
Diffstat (limited to 'gcc/testsuite')
| -rw-r--r-- | gcc/testsuite/gcc.dg/tree-ssa/pr95433-2.c | 15 |
1 files changed, 15 insertions, 0 deletions
diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr95433-2.c b/gcc/testsuite/gcc.dg/tree-ssa/pr95433-2.c new file mode 100644 index 00000000000..c830a3d195f --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/pr95433-2.c @@ -0,0 +1,15 @@ +/* { dg-do compile } */ +/* { dg-options "-O -fwrapv -fdump-tree-gimple" } */ + +typedef __INT32_TYPE__ int32_t; +typedef unsigned __INT32_TYPE__ uint32_t; + +int e(int32_t x){return 3*x==5;} +int f(int32_t x){return 3*x==-5;} +int g(int32_t x){return -3*x==5;} +int h(int32_t x){return 7*x==3;} +int i(uint32_t x){return 7*x==3;} + +/* { dg-final { scan-tree-dump-times "== 1431655767" 1 "gimple" } } */ +/* { dg-final { scan-tree-dump-times "== -1431655767" 2 "gimple" } } */ +/* { dg-final { scan-tree-dump-times "== 613566757" 2 "gimple" } } */ |