diff options
Diffstat (limited to 'gcc/varpool.c')
| -rw-r--r-- | gcc/varpool.c | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/gcc/varpool.c b/gcc/varpool.c index 817a3197901..eac488fa79b 100644 --- a/gcc/varpool.c +++ b/gcc/varpool.c @@ -359,6 +359,37 @@ decide_is_variable_needed (struct varpool_node *node, tree decl) return true; } +/* Return if NODE is constant and its initial value is known (so we can do + constant folding). The decision depends on whole program decisions + and can not be recomputed at ltrans stage for variables from other + partitions. For this reason the new value should be always combined + with the previous knowledge. */ + +bool +varpool_decide_const_value_known (struct varpool_node *node) +{ + tree decl = node->decl; + + gcc_assert (TREE_STATIC (decl) || DECL_EXTERNAL (decl)); + gcc_assert (TREE_CODE (decl) == VAR_DECL); + if (!TREE_READONLY (decl)) + return false; + /* Variables declared 'const' without an initializer + have zero as the initializer if they may not be + overridden at link or run time. */ + if (!DECL_INITIAL (decl) + && (DECL_EXTERNAL (decl) + || DECL_REPLACEABLE_P (decl))) + return false; + + /* Variables declared `const' with an initializer are considered + to not be overwritable with different initializer by default. + + ??? Previously we behaved so for scalar variables but not for array + accesses. */ + return true; +} + /* Mark DECL as finalized. By finalizing the declaration, frontend instruct the middle end to output the variable to asm file, if needed or externally visible. */ |