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[patch] Improve code generation for assigned goto statements
- From: Steven Bosscher <stevenb at suse dot de>
- To: gcc-patches at gcc dot gnu dot org, fortran at gcc dot gnu dot org
- Date: Sun, 31 Jul 2005 22:35:27 +0200
- Subject: [patch] Improve code generation for assigned goto statements
Hi,
This simple patch implements an idea from Roger Sayle. We currently
produce e.g.
if (&__label_000020 == next.1) goto next.1; else (void) 0;
but this is probably better written with
if (&__label_000020 == next.1) goto goto __label__000020; else (void) 0;
to avoid computed jumps and abnormal edges.
Bootstrapped and tested on x86_64-pc-linux-gnu.
Gr.
Steven
* trans-stmt.c (gfc_trans_goto): Jump to the known label instead
of the assigned goto variable.
Index: trans-stmt.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/fortran/trans-stmt.c,v
retrieving revision 1.39
diff -u -3 -p -r1.39 trans-stmt.c
--- trans-stmt.c 20 Jul 2005 01:19:33 -0000 1.39
+++ trans-stmt.c 31 Jul 2005 20:33:42 -0000
@@ -163,11 +163,11 @@ gfc_trans_goto (gfc_code * code)
gfc_trans_runtime_check (tmp, assign_error, &se.pre);
assigned_goto = GFC_DECL_ASSIGN_ADDR (se.expr);
- target = build1 (GOTO_EXPR, void_type_node, assigned_goto);
code = code->block;
if (code == NULL)
{
+ target = build1 (GOTO_EXPR, void_type_node, assigned_goto);
gfc_add_expr_to_block (&se.pre, target);
return gfc_finish_block (&se.pre);
}
@@ -177,10 +177,12 @@ gfc_trans_goto (gfc_code * code)
do
{
- tmp = gfc_get_label_decl (code->label);
- tmp = gfc_build_addr_expr (pvoid_type_node, tmp);
+ target = gfc_get_label_decl (code->label);
+ tmp = gfc_build_addr_expr (pvoid_type_node, target);
tmp = build2 (EQ_EXPR, boolean_type_node, tmp, assigned_goto);
- tmp = build3_v (COND_EXPR, tmp, target, build_empty_stmt ());
+ tmp = build3_v (COND_EXPR, tmp,
+ build1 (GOTO_EXPR, void_type_node, target),
+ build_empty_stmt ());
gfc_add_expr_to_block (&se.pre, tmp);
code = code->block;
}