diff options
Diffstat (limited to 'gcc/cse.c')
| -rw-r--r-- | gcc/cse.c | 22 |
1 files changed, 16 insertions, 6 deletions
diff --git a/gcc/cse.c b/gcc/cse.c index cfa2b00216c..213b6083e7f 100644 --- a/gcc/cse.c +++ b/gcc/cse.c @@ -2669,16 +2669,26 @@ exp_equiv_p (const_rtx x, const_rtx y, int validate, bool for_gcse) case MEM: if (for_gcse) { - /* Can't merge two expressions in different alias sets, since we - can decide that the expression is transparent in a block when - it isn't, due to it being set with the different alias set. */ - if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y)) - return 0; - /* A volatile mem should not be considered equivalent to any other. */ if (MEM_VOLATILE_P (x) || MEM_VOLATILE_P (y)) return 0; + + /* Can't merge two expressions in different alias sets, since we + can decide that the expression is transparent in a block when + it isn't, due to it being set with the different alias set. + + Also, can't merge two expressions with different MEM_ATTRS. + They could e.g. be two different entities allocated into the + same space on the stack (see e.g. PR25130). In that case, the + MEM addresses can be the same, even though the two MEMs are + absolutely not equivalent. + + But because really all MEM attributes should be the same for + equivalent MEMs, we just use the invariant that MEMs that have + the same attributes share the same mem_attrs data structure. */ + if (MEM_ATTRS (x) != MEM_ATTRS (y)) + return 0; } break; |