From 0609b35537e3c1c5677632064635e24bc257ee25 Mon Sep 17 00:00:00 2001 From: Richard Guenther Date: Tue, 7 Apr 2009 14:19:17 +0000 Subject: [PATCH] tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Non-aliased decls are only used if passes as parameters or if... 2009-04-07 Richard Guenther * tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Non-aliased decls are only used if passes as parameters or if they are local statics and the call is not to a builtin. (call_may_clobber_ref_p_1): Likewise. From-SVN: r145676 --- gcc/ChangeLog | 7 +++++++ gcc/tree-ssa-alias.c | 33 +++++++++++++++++++++++++++++++-- 2 files changed, 38 insertions(+), 2 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index c01b7d96f07c..13c4eb2ffb2f 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,10 @@ +2009-04-07 Richard Guenther + + * tree-ssa-alias.c (ref_maybe_used_by_call_p_1): Non-aliased + decls are only used if passes as parameters or if they are + local statics and the call is not to a builtin. + (call_may_clobber_ref_p_1): Likewise. + 2009-04-07 Paolo Bonzini * expr.c (do_store_flag): Remove last argument. Simplify code diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c index a85858e17af9..f97502a606ae 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 -- 2.47.3