The following patch adds the --param(eters) needed to tweak the
optimizers into allowing or disallowing data races in cross-thread
visible data.
There will be additional flags added later to make these parameters
available to the common user. It has been suggested to use
-fmemory-model=xxx, but I will implement this later.
The next step will be to find out where we introduce the data races in
the testsuite, and fix the optimizers accordingly.
Committed to branch.
* params.h (ALLOW_LOAD_DATA_RACES): New.
(ALLOW_STORE_DATA_RACES): New.
(ALLOW_PACKED_LOAD_DATA_RACES): New.
(ALLOW_PACKED_STORE_DATA_RACES): New.
* params.def (PARAM_ALLOW_LOAD_DATA_RACES): New.
(PARAM_ALLOW_STORE_DATA_RACES): New.
(PARAM_ALLOW_PACKED_LOAD_DATA_RACES): New.
(PARAM_ALLOW_PACKED_STORE_DATA_RACES): New.
* doc/invoke.texi (Optimize Options): Document above parameters.
Index: doc/invoke.texi
===================================================================
--- doc/invoke.texi (revision 170745)
+++ doc/invoke.texi (working copy)
@@ -8897,6 +8897,26 @@ partitions.
The maximum number of namespaces to consult for suggestions when C++
name lookup fails for an identifier. The default is 1000.
+@item allow-load-data-races
+Allow optimizers to introduce new data races on loads.
+Set to 1 to allow, otherwise to 0. This option is enabled by default
+unless implicitly set by the @option{-fmemory-model=} option.
+
+@item allow-store-data-races
+Allow optimizers to introduce new data races on stores.
+Set to 1 to allow, otherwise to 0. This option is enabled by default
+unless implicitly set by the @option{-fmemory-model=} option.
+
+@item allow-packed-load-data-races
+Allow optimizers to introduce new data races on packed data loads.
+Set to 1 to allow, otherwise to 0. This option is enabled by default
+unless implicitly set by the @option{-fmemory-model=} option.
+
+@item allow-packed-store-data-races
+Allow optimizers to introduce new data races on packed data stores.
+Set to 1 to allow, otherwise to 0. This option is enabled by default
+unless implicitly set by the @option{-fmemory-model=} option.
+
@end table
@end table
Index: params.h
===================================================================
--- params.h (revision 170745)
+++ params.h (working copy)
@@ -206,4 +206,13 @@ extern void init_param_values (int *para
PARAM_VALUE (PARAM_PREFETCH_MIN_INSN_TO_MEM_RATIO)
#define MIN_NONDEBUG_INSN_UID \
PARAM_VALUE (PARAM_MIN_NONDEBUG_INSN_UID)
+#define ALLOW_LOAD_DATA_RACES \
+ PARAM_VALUE (PARAM_ALLOW_LOAD_DATA_RACES)
+#define ALLOW_STORE_DATA_RACES \
+ PARAM_VALUE (PARAM_ALLOW_STORE_DATA_RACES)
+#define ALLOW_PACKED_LOAD_DATA_RACES \
+ PARAM_VALUE (PARAM_ALLOW_PACKED_LOAD_DATA_RACES)
+#define ALLOW_PACKED_STORE_DATA_RACES \
+ PARAM_VALUE (PARAM_ALLOW_PACKED_STORE_DATA_RACES)
+
#endif /* ! GCC_PARAMS_H */
Index: testsuite/gcc.dg/memmodel/speculative-store.c
===================================================================
--- testsuite/gcc.dg/memmodel/speculative-store.c (revision 170852)
+++ testsuite/gcc.dg/memmodel/speculative-store.c (working copy)
@@ -1,14 +1,12 @@
/* { dg-do link } */
-/* { dg-options "-O2" } */
+/* { dg-options "-O2 --param allow-store-data-races=0" } */
/* { dg-final { memmodel-gdb-test } } */
-/* FIXME: I can't get this to fail. */
-
#include <stdio.h>
#include "memmodel.h"
/* This file tests that speculative store movement out of a loop doesn't
- happen. This is disallowed when -fno-allow-store-data-races is on. */
+ happen. This is disallowed when --param allow-store-data-races is 0. */
int global = 100;
Index: testsuite/gcc.dg/memmodel/subfields.c
===================================================================
--- testsuite/gcc.dg/memmodel/subfields.c (revision 170852)
+++ testsuite/gcc.dg/memmodel/subfields.c (working copy)
@@ -1,9 +1,7 @@
/* { dg-do link } */
-/* { dg-options "-O2" } */
+/* { dg-options "-O2 --param allow-packed-store-data-races=0" } */
/* { dg-final { memmodel-gdb-test } } */
-/* FIXME: I can't get this to fail. */
-
#include <stdio.h>
#include "memmodel.h"
Index: testsuite/gcc.dg/memmodel/global-hoist.c
===================================================================
--- testsuite/gcc.dg/memmodel/global-hoist.c (revision 170852)
+++ testsuite/gcc.dg/memmodel/global-hoist.c (working copy)
@@ -1,10 +1,10 @@
/* { dg-do link } */
-/* { dg-options "-O2" } */
+/* { dg-options "-O2 --param allow-load-data-races=0" } */
/* { dg-final { memmodel-gdb-test } } */
/* Verify that a load of a global is not hoisted out of a loop. This
can introduce a data race, and is dissallowed if
- -fno-allow-load-data-races is enabled. */
+ --param allow-load-data-races is 0. */
#include <stdio.h>
#include <stdlib.h>
Index: testsuite/gcc.dg/memmodel/d2.c
===================================================================
--- testsuite/gcc.dg/memmodel/d2.c (revision 170852)
+++ testsuite/gcc.dg/memmodel/d2.c (working copy)
@@ -1,5 +1,5 @@
/* { dg-do link } */
-/* { dg-options "-O2" } */
+/* { dg-options "-O2 --param allow-load-data-races=0" } */
/* { dg-final { memmodel-gdb-test } } */
#include <stdio.h>
@@ -8,7 +8,7 @@
/* This is a variation on global-hoist.c where instead of a loop, we
store global into different elements of an array in straightline
code with an if condition. This will catch cases where commoning
- should be disabled when -fno-allow-load-data-races is on. */
+ should be disabled when --param allow-load-data-races is 0. */
/* Test the FALSE path in test. */
Index: testsuite/gcc.dg/memmodel/d3.c
===================================================================
--- testsuite/gcc.dg/memmodel/d3.c (revision 170852)
+++ testsuite/gcc.dg/memmodel/d3.c (working copy)
@@ -1,5 +1,5 @@
/* { dg-do link } */
-/* { dg-options "-O2" } */
+/* { dg-options "-O2 --param allow-load-data-races=0" } */
/* { dg-final { memmodel-gdb-test } } */
#include <stdio.h>
@@ -8,7 +8,7 @@
/* A variation on global-hoist.c where instead of a loop, we store
global into different elements of an array in straightline code
with an if condition. This will catch cases where commoning should
- be disabled when -fno-allow-load-data-races is on. */
+ be disabled when --param allow-load-data-races is 0. */
/* Test the TRUE path in test. */
Index: params.def
===================================================================
--- params.def (revision 170745)
+++ params.def (working copy)
@@ -877,6 +877,28 @@ DEFPARAM (CXX_MAX_NAMESPACES_FOR_DIAGNOS
"name lookup fails",
1000, 0, 0)
+ /* Data race flags for C++0x memory model compliance. */
+
+ DEFPARAM (PARAM_ALLOW_LOAD_DATA_RACES,
+ "allow-load-data-races",
+ "Allow new data races on loads to be introduced",
+ 1, 0, 1)
+
+ DEFPARAM (PARAM_ALLOW_STORE_DATA_RACES,
+ "allow-store-data-races",
+ "Allow new data races on stores to be introduced",
+ 1, 0, 1)
+
+ DEFPARAM (PARAM_ALLOW_PACKED_LOAD_DATA_RACES,
+ "allow-packed-load-data-races",
+ "Allow new data races on packed data loads to be introduced",
+ 1, 0, 1)
+
+ DEFPARAM (PARAM_ALLOW_PACKED_STORE_DATA_RACES,
+ "allow-packed-store-data-races",
+ "Allow new data races on packed data stores to be introduced",
+ 1, 0, 1)
+
/*
Local variables:
mode:c
