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Re: [PATCH][5/5] Postpone expanding va_arg until pass_stdarg


On 23-02-15 09:26, Michael Matz wrote:
Hi,

On Sun, 22 Feb 2015, Tom de Vries wrote:

Btw, I'm wondering if as run-time optimization we can tentatively set
PROP_gimple_lva at the start of the gimple pass, and unset it in
gimplify_va_arg_expr. That way we would avoid the loop in
expand_ifn_va_arg_1 (over all bbs and gimples) in functions without
va_arg.

That makes sense.


I'll put this follow-up patch through testing.

Thanks,
- Tom

2015-02-23  Tom de Vries  <tom@codesourcery.com>

	* gimplify.c (gimplify_function_tree): Tentatively set PROP_gimple_lva
	in cfun->curr_properties.
	(gimplify_va_arg_expr): Clear PROP_gimple_lva in cfun->curr_properties
	if we generate an IFN_VA_ARG.
	* tree-inline.c (expand_call_inline): Reset PROP_gimple_lva in dest
	function if PROP_gimple_lva is not set in src function.
---
 gcc/gimplify.c    | 10 +++++++++-
 gcc/tree-inline.c |  8 ++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/gcc/gimplify.c b/gcc/gimplify.c
index 8ac6a35..497e2fa 100644
--- a/gcc/gimplify.c
+++ b/gcc/gimplify.c
@@ -9218,6 +9218,10 @@ gimplify_function_tree (tree fndecl)
   else
     push_struct_function (fndecl);
 
+  /* Tentatively set PROP_gimple_lva here, and reset it in gimplify_va_arg_expr
+     if necessary.  */
+  cfun->curr_properties |= PROP_gimple_lva;
+
   for (parm = DECL_ARGUMENTS (fndecl); parm ; parm = DECL_CHAIN (parm))
     {
       /* Preliminarily mark non-addressed complex variables as eligible
@@ -9312,7 +9316,7 @@ gimplify_function_tree (tree fndecl)
     }
 
   DECL_SAVED_TREE (fndecl) = NULL_TREE;
-  cfun->curr_properties = PROP_gimple_any;
+  cfun->curr_properties |= PROP_gimple_any;
 
   pop_cfun ();
 }
@@ -9431,6 +9435,10 @@ gimplify_va_arg_expr (tree *expr_p, gimple_seq *pre_p,
   tag = build_int_cst (build_pointer_type (type), 0);
   *expr_p = build_call_expr_internal_loc (loc, IFN_VA_ARG, type, 2, ap, tag);
 
+  /* Clear the tentatively set PROP_gimple_lva, to indicate that IFN_VA_ARG
+     needs to be expanded.  */
+  cfun->curr_properties &= ~PROP_gimple_lva;
+
   return GS_OK;
 }
 
diff --git a/gcc/tree-inline.c b/gcc/tree-inline.c
index d8abe03..7dfef4f 100644
--- a/gcc/tree-inline.c
+++ b/gcc/tree-inline.c
@@ -4524,6 +4524,14 @@ expand_call_inline (basic_block bb, gimple stmt, copy_body_data *id)
   id->src_cfun = DECL_STRUCT_FUNCTION (fn);
   id->call_stmt = stmt;
 
+  /* If the the src function contains an IFN_VA_ARG, then so will the dst
+     function after inlining.  */
+  if ((id->src_cfun->curr_properties & PROP_gimple_lva) == 0)
+    {
+      struct function *dst_cfun = DECL_STRUCT_FUNCTION (id->dst_fn);
+      dst_cfun->curr_properties &= ~PROP_gimple_lva;
+    }
+
   gcc_assert (!id->src_cfun->after_inlining);
 
   id->entry_bb = bb;
-- 
1.9.1


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