diff options
Diffstat (limited to 'gcc/tree-ssa-alias.c')
| -rw-r--r-- | gcc/tree-ssa-alias.c | 33 |
1 files changed, 31 insertions, 2 deletions
diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c index a85858e17af..f97502a606a 100644 --- a/gcc/tree-ssa-alias.c +++ b/gcc/tree-ssa-alias.c @@ -737,7 +737,7 @@ refs_may_alias_p (tree ref1, tree ref2) static bool ref_maybe_used_by_call_p_1 (gimple call, tree ref) { - tree base; + tree base, fndecl; unsigned i; int flags = gimple_call_flags (call); @@ -754,6 +754,20 @@ ref_maybe_used_by_call_p_1 (gimple call, tree ref) || !DECL_P (base)) return true; + /* If the reference is based on a decl that is not aliased the call + cannot possibly use it. */ + if (DECL_P (base) + && !may_be_aliased (base) + /* But local statics can be used through recursion! */ + && (!is_global_var (base) + /* But not via builtins. + ??? We just assume that this is true if we are not a + builtin function ourself. */ + || (!DECL_BUILT_IN (cfun->decl) + && (fndecl = gimple_call_fndecl (call)) + && DECL_BUILT_IN (fndecl)))) + goto process_args; + /* Check if base is a global static variable that is not read by the function. */ if (TREE_CODE (base) == VAR_DECL @@ -851,7 +865,7 @@ ref_maybe_used_by_stmt_p (gimple stmt, tree ref) static bool call_may_clobber_ref_p_1 (gimple call, tree ref) { - tree base; + tree fndecl, base; /* If the call is pure or const it cannot clobber anything. */ if (gimple_call_flags (call) @@ -866,6 +880,21 @@ call_may_clobber_ref_p_1 (gimple call, tree ref) || CONSTANT_CLASS_P (base)) return false; + /* If the reference is based on a decl that is not aliased the call + cannot possibly clobber it. */ + if (DECL_P (base) + && !may_be_aliased (base) + /* But local non-readonly statics can be modified through recursion! */ + && (TREE_READONLY (base) + || !is_global_var (base) + /* But not via builtins. + ??? We just assume that this is true if we are not a + builtin function ourself. */ + || (!DECL_BUILT_IN (cfun->decl) + && (fndecl = gimple_call_fndecl (call)) + && DECL_BUILT_IN (fndecl)))) + return false; + /* Check if base is a global static variable that is not written by the function. */ if (TREE_CODE (base) == VAR_DECL |