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Put constant compound initializers in .rodata
- From: Ian Lance Taylor <iant at google dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Tue, 01 May 2012 13:05:38 -0700
- Subject: Put constant compound initializers in .rodata
This patch to the C frontend and the middle-end puts constant compound
initializers in the readonly data section where possible. This is for
PR 37303. Bootstrapped and ran full testsuite on
x86_64-unknown-linux-gnu.
OK for mainline?
Ian
gcc/:
2012-05-01 Ian Lance Taylor <iant@google.com>
PR c/37303
* c-decl.c (build_compound_literal): Make the decl readonly if it
an array of a readonly type.
* gimplify.c (gimplify_compound_literal_expr): Add fallback
parameter. Change all callers. If the decl is not addressable
and is not an l-value, make it readonly.
gcc/testsuite/:
2012-05-01 Ian Lance Taylor <iant@google.com>
PR c/37303
* gcc.dg/pr37303.c: New test.
Index: gimplify.c
===================================================================
--- gimplify.c (revision 187020)
+++ gimplify.c (working copy)
@@ -3756,7 +3756,8 @@ rhs_predicate_for (tree lhs)
decl instead. */
static enum gimplify_status
-gimplify_compound_literal_expr (tree *expr_p, gimple_seq *pre_p)
+gimplify_compound_literal_expr (tree *expr_p, gimple_seq *pre_p,
+ fallback_t fallback)
{
tree decl_s = COMPOUND_LITERAL_EXPR_DECL_EXPR (*expr_p);
tree decl = DECL_EXPR_DECL (decl_s);
@@ -3775,6 +3776,12 @@ gimplify_compound_literal_expr (tree *ex
&& !needs_to_live_in_memory (decl))
DECL_GIMPLE_REG_P (decl) = 1;
+ /* If the decl is not addressable, then it is being used in some
+ expression or on the right hand side of a statement, and it can
+ be put into a readonly data section. */
+ if (!TREE_ADDRESSABLE (decl) && (fallback & fb_lvalue) == 0)
+ TREE_READONLY (decl) = 1;
+
/* This decl isn't mentioned in the enclosing block, so add it to the
list of temps. FIXME it seems a bit of a kludge to say that
anonymous artificial vars aren't pushed, but everything else is. */
@@ -7071,7 +7078,7 @@ gimplify_expr (tree *expr_p, gimple_seq
break;
case COMPOUND_LITERAL_EXPR:
- ret = gimplify_compound_literal_expr (expr_p, pre_p);
+ ret = gimplify_compound_literal_expr (expr_p, pre_p, fallback);
break;
case MODIFY_EXPR:
Index: c-decl.c
===================================================================
--- c-decl.c (revision 187020)
+++ c-decl.c (working copy)
@@ -4622,7 +4622,9 @@ build_compound_literal (location_t loc,
TREE_USED (decl) = 1;
DECL_READ_P (decl) = 1;
TREE_TYPE (decl) = type;
- TREE_READONLY (decl) = TYPE_READONLY (type);
+ TREE_READONLY (decl) = (TYPE_READONLY (type)
+ || (TREE_CODE (type) == ARRAY_TYPE
+ && TYPE_READONLY (TREE_TYPE (type))));
store_init_value (loc, decl, init, NULL_TREE);
if (TREE_CODE (type) == ARRAY_TYPE && !COMPLETE_TYPE_P (type))
Index: testsuite/gcc.dg/pr37303.c
===================================================================
--- testsuite/gcc.dg/pr37303.c (revision 0)
+++ testsuite/gcc.dg/pr37303.c (revision 0)
@@ -0,0 +1,5 @@
+/* { dg-do compile { target *-*-elf* *-*-linux-gnu* } } */
+/* { dg-options "-std=c99" }
+/* { dg-final { scan-assembler "rodata" } } */
+
+struct S { const int *x; } s = { (const int[]){1, 2, 3} };