diff options
Diffstat (limited to 'gcc/tree-ssa-coalesce.c')
| -rw-r--r-- | gcc/tree-ssa-coalesce.c | 16 |
1 files changed, 12 insertions, 4 deletions
diff --git a/gcc/tree-ssa-coalesce.c b/gcc/tree-ssa-coalesce.c index c445c78626e..252fc33a7f0 100644 --- a/gcc/tree-ssa-coalesce.c +++ b/gcc/tree-ssa-coalesce.c @@ -1256,8 +1256,8 @@ coalesce_ssa_name (void) cl = create_coalesce_list (); map = create_outofssa_var_map (cl, used_in_copies); - /* We need to coalesce all names originating same SSA_NAME_VAR - so debug info remains undisturbed. */ + /* If optimization is disabled, we need to coalesce all the names originating + from the same SSA_NAME_VAR so debug info remains undisturbed. */ if (!optimize) { hash_table <ssa_name_var_hash> ssa_name_hash; @@ -1278,8 +1278,16 @@ coalesce_ssa_name (void) *slot = a; else { - add_coalesce (cl, SSA_NAME_VERSION (a), SSA_NAME_VERSION (*slot), - MUST_COALESCE_COST - 1); + /* If the variable is a PARM_DECL or a RESULT_DECL, we + _require_ that all the names originating from it be + coalesced, because there must be a single partition + containing all the names so that it can be assigned + the canonical RTL location of the DECL safely. */ + const int cost + = TREE_CODE (SSA_NAME_VAR (a)) == VAR_DECL + ? MUST_COALESCE_COST - 1 : MUST_COALESCE_COST; + add_coalesce (cl, SSA_NAME_VERSION (a), + SSA_NAME_VERSION (*slot), cost); bitmap_set_bit (used_in_copies, SSA_NAME_VERSION (a)); bitmap_set_bit (used_in_copies, SSA_NAME_VERSION (*slot)); } |