In http://gcc.gnu.org/ml/gcc-patches/2010-08/msg02019.html I added code
to call init_varasm_once again if a package imports unsafe. As that
message explains, this is to avoid an assert in
mems_in_disjoint_alias_sets_p if it sees a non-zero alias set when
flag_strict_aliasing is false. However, I tested removing the call to
init_varasm_once in the current compiler, and the assert never triggers.
This appears to be because the alias set allocate in init_varasm_once is
only used for constant memory addresses (MEM_READONLY_P). The patch
http://gcc.gnu.org/ml/gcc-patches/2010-07/msg01758.html fixed
canon_true_dependence so that it gets out quickly for a MEM_READONLY_P
address. So as far as I can tell const_alias_set is no longer used for
anything, so it is no longer necessary to reinitialize it to avoid the
assert.
This patch avoids the call to init_varasm_once and lets me remove the
#include of the backend-only rtl.h from the frontend go-backend.c.
Bootstrapped and ran Go testsuite on x86_64-unknown-linux-gnu.
Committed to mainline.
Ian
2013-07-23 Ian Lance Taylor <i...@google.com>
* go-backend.c: Don't #include "rtl.h".
(go_imported_unsafe): Don't call init_varasm_once.
* Make-lang.in (go/go-backend.o): Don't depend on $(RTL_H).
Index: Make-lang.in
===================================================================
--- Make-lang.in (revision 201171)
+++ Make-lang.in (working copy)
@@ -240,7 +240,7 @@ GO_RUNTIME_H = go/gofrontend/runtime.h g
GO_AST_DUMP_H = go/gofrontend/ast-dump.h go/gofrontend/string-dump.h
go/go-backend.o: go/go-backend.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
- $(TM_H) $(RTL_H) $(TREE_H) $(TM_P_H) output.h $(TARGET_H) \
+ $(TM_H) $(TREE_H) $(TM_P_H) output.h $(TARGET_H) \
$(COMMON_TARGET_H)
CFLAGS-go/go-lang.o += -DDEFAULT_TARGET_VERSION=\"$(version)\" \
Index: go-backend.c
===================================================================
--- go-backend.c (revision 200210)
+++ go-backend.c (working copy)
@@ -22,7 +22,6 @@ along with GCC; see the file COPYING3.
#include "coretypes.h"
#include "simple-object.h"
#include "tm.h"
-#include "rtl.h"
#include "tree.h"
#include "tm_p.h"
#include "intl.h"
@@ -91,12 +90,6 @@ go_imported_unsafe (void)
{
flag_strict_aliasing = false;
- /* This is a real hack. init_varasm_once has already grabbed an
- alias set, which we don't want when we aren't doing strict
- aliasing. We reinitialize to make it do it again. This should
- be OK in practice since we haven't really done anything yet. */
- init_varasm_once ();
-
/* Let the backend know that the options have changed. */
targetm.override_options_after_change ();
}
