diff options
Diffstat (limited to 'gcc/tree-ssa-ccp.c')
| -rw-r--r-- | gcc/tree-ssa-ccp.c | 42 |
1 files changed, 33 insertions, 9 deletions
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c index 9dd63fe..2acd62e 100644 --- a/gcc/tree-ssa-ccp.c +++ b/gcc/tree-ssa-ccp.c @@ -293,6 +293,24 @@ ccp_decl_initial_min_invariant (tree t) return true; } +/* If SYM is a constant variable with known value, return the value. + NULL_TREE is returned otherwise. */ + +static tree +get_symbol_constant_value (tree sym) +{ + if (TREE_STATIC (sym) + && TREE_READONLY (sym) + && !MTAG_P (sym)) + { + tree val = DECL_INITIAL (sym); + if (val + && ccp_decl_initial_min_invariant (val)) + return val; + } + + return NULL_TREE; +} /* Compute a default value for variable VAR and store it in the CONST_VAL array. The following rules are used to get default @@ -320,6 +338,7 @@ get_default_value (tree var) { tree sym = SSA_NAME_VAR (var); prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE }; + tree cst_val; if (!do_store_ccp && !is_gimple_reg (var)) { @@ -333,16 +352,12 @@ get_default_value (tree var) val.lattice_val = CONSTANT; val.value = SSA_NAME_VALUE (var); } - else if (TREE_STATIC (sym) - && TREE_READONLY (sym) - && !MTAG_P (sym) - && DECL_INITIAL (sym) - && ccp_decl_initial_min_invariant (DECL_INITIAL (sym))) + else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE) { /* Globals and static variables declared 'const' take their initial value. */ val.lattice_val = CONSTANT; - val.value = DECL_INITIAL (sym); + val.value = cst_val; val.mem_ref = sym; } else @@ -415,9 +430,10 @@ set_lattice_value (tree var, prop_value_t new_val) value. If *OLD_VAL and NEW_VAL are the same, return false to inform the caller that this was a non-transition. */ - gcc_assert (old_val->lattice_val <= new_val.lattice_val + gcc_assert (old_val->lattice_val < new_val.lattice_val || (old_val->lattice_val == new_val.lattice_val - && old_val->value == new_val.value + && ((!old_val->value && !new_val.value) + || operand_equal_p (old_val->value, new_val.value, 0)) && old_val->mem_ref == new_val.mem_ref)); if (old_val->lattice_val != new_val.lattice_val) @@ -1222,7 +1238,15 @@ visit_assignment (tree stmt, tree *output_p) /* Set the value of every VDEF to VAL. */ changed = false; FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS) - changed |= set_lattice_value (vdef, val); + { + /* See PR 29801. We may have VDEFs for read-only variables + (see the handling of unmodifiable variables in + add_virtual_operand); do not attempt to change their value. */ + if (get_symbol_constant_value (SSA_NAME_VAR (vdef)) != NULL_TREE) + continue; + + changed |= set_lattice_value (vdef, val); + } /* Note that for propagation purposes, we are only interested in visiting statements that load the exact same memory reference |