On 01/18/12 03:09, Richard Guenther wrote:
On Tue, 17 Jan 2012, Aldy Hernandez wrote:
What I have in mind is to abstract out the initialization of TM builtins
from
gtm-builtins.def (through its inclusion in builtins.def) into a separate
function that we can call either in c_define_builtins() from the C-ish
front-ends, or from lto_define_builtins (once we encounter a TM builtin
and
enable flag_tm appropriately).
Hm? They are included in builtins.def, that looks appropriate for
middle-end builtins. Thus they should be initialized by lto1, too.
Are they not?
Since flag_tm is NULL, when lto_define_builtins runs, the TM builtins do not
get initialized. This is because DEF_TM_BUILTIN is predicated on flag_tm.
Ok, so arrange that -fgnu-tm is enabled at link-time as soon as it was
enabled in one TU. You can do that alongside handling of OPT_fPIC, etc.
in lto-wrapper.c:merge_and_complain.
The following patch fixes the problem.
OK?
It isn't until streamer_get_builtin_tree() that we realize the object file has
a TM builtin.
I see. Probably similar issues exist with -fopenmp and the GOMP
builtins.
It is my understanding that openmp is lowered before LTO streaming, so
this isn't a problem for it. I manually tested something similar to the
testcase in the patch below (but for openmp) and verified that openmp
does not suffer from this problem.
Thanks for the suggestion.
PR lto/51280
* lto-wrapper.c (run_gcc): Pass -fgnu_tm on.
(merge_and_complain): Same.
Index: testsuite/gcc.dg/lto/trans-mem-3_0.c
===================================================================
--- testsuite/gcc.dg/lto/trans-mem-3_0.c (revision 0)
+++ testsuite/gcc.dg/lto/trans-mem-3_0.c (revision 0)
@@ -0,0 +1,8 @@
+/* { dg-lto-options {{-flto}} } */
+/* { dg-lto-do link } */
+
+/* Test that we can build one object file with -fgnu-tm
+ (trans-mem-3_1.c), but do the final link of all objects without
+ -fgnu-tm. */
+
+int i;
Index: testsuite/gcc.dg/lto/trans-mem-3_1.c
===================================================================
--- testsuite/gcc.dg/lto/trans-mem-3_1.c (revision 0)
+++ testsuite/gcc.dg/lto/trans-mem-3_1.c (revision 0)
@@ -0,0 +1,18 @@
+/* { dg-options "-fgnu-tm" } */
+
+extern int i;
+
+main()
+{
+ __transaction_atomic { i = 0; }
+}
+
+#define dummy(func) \
+ __attribute__((noinline,noclone,used)) void func() { asm (""); }
+
+dummy(_ITM_beginTransaction)
+dummy(_ITM_commitTransaction)
+dummy(_ITM_WU4)
+dummy(_ITM_WU8)
+dummy(_ITM_registerTMCloneTable)
+dummy(_ITM_deregisterTMCloneTable)
Index: lto-wrapper.c
===================================================================
--- lto-wrapper.c (revision 183244)
+++ lto-wrapper.c (working copy)
@@ -403,6 +403,7 @@ merge_and_complain (struct cl_decoded_op
case OPT_fpie:
case OPT_fcommon:
case OPT_fexceptions:
+ case OPT_fgnu_tm:
/* Do what the old LTO code did - collect exactly one option
setting per OPT code, we pick the first we encounter.
??? This doesn't make too much sense, but when it doesn't
@@ -555,6 +556,7 @@ run_gcc (unsigned argc, char *argv[])
case OPT_fpie:
case OPT_fcommon:
case OPT_fexceptions:
+ case OPT_fgnu_tm:
break;
default:
