diff options
Diffstat (limited to 'gcc/tree-ssa-threadedge.c')
| -rw-r--r-- | gcc/tree-ssa-threadedge.c | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/gcc/tree-ssa-threadedge.c b/gcc/tree-ssa-threadedge.c index c447b72..8a0103b 100644 --- a/gcc/tree-ssa-threadedge.c +++ b/gcc/tree-ssa-threadedge.c @@ -387,7 +387,34 @@ record_temporary_equivalences_from_stmts_at_dest (edge e, && (gimple_code (stmt) != GIMPLE_CALL || gimple_call_lhs (stmt) == NULL_TREE || TREE_CODE (gimple_call_lhs (stmt)) != SSA_NAME)) - continue; + { + /* STMT might still have DEFS and we need to invalidate any known + equivalences for them. + + Consider if STMT is a GIMPLE_ASM with one or more outputs that + feeds a conditional inside a loop. We might derive an equivalence + due to the conditional. */ + tree op; + ssa_op_iter iter; + + if (backedge_seen) + FOR_EACH_SSA_TREE_OPERAND (op, stmt, iter, SSA_OP_ALL_DEFS) + { + /* This call only invalidates equivalences created by + PHI nodes. This is by design to keep the cost of + of invalidation reasonable. */ + invalidate_equivalences (op, stack, src_map, dst_map); + + /* However, conditionals can imply values for real + operands as well. And those won't be recorded in the + maps. In fact, those equivalences may be recorded totally + outside the threading code. We can just create a new + temporary NULL equivalence here. */ + record_temporary_equivalence (op, NULL_TREE, stack); + } + + continue; + } /* The result of __builtin_object_size depends on all the arguments of a phi node. Temporarily using only one edge produces invalid |