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* [gcc(refs/vendors/siemens/heads/gcc-10-lto-fixes)] lto: Don't run ipa-comdats pass during LTO
@ 2021-12-06 23:10 Sandra Loosemore
0 siblings, 0 replies; only message in thread
From: Sandra Loosemore @ 2021-12-06 23:10 UTC (permalink / raw)
To: gcc-cvs
https://gcc.gnu.org/g:3d0c0ba4f49d9cfc5cb7b92b62014d16fcb6996d
commit 3d0c0ba4f49d9cfc5cb7b92b62014d16fcb6996d
Author: Sandra Loosemore <sandra@codesourcery.com>
Date: Sun Dec 5 17:59:19 2021 -0800
lto: Don't run ipa-comdats pass during LTO
When the ipa-visibility pass is invoked during LTO, it attempts to
localize comdat symbols and destroy their comdat group. The
ipa-comdats pass subsequently attempts to do the opposite and move
symbols into comdats, but without marking them as DECL_COMDAT or
restoring appropriate visibility flags. This confuses the
lto-partition pass and leads to ICEs. Running the ipa-comdats pass at
link time seems counterproductive in terms of optimization, so the
simplest fix is not to do that.
2021-12-05 Sandra Loosemore <sandra@codesourcery.com>
gcc/
* ipa-comdats.c (pass_ipa_comdats::gate): Skip this pass if it
would un-do the comdat localization already performed at LTO
time in ipa-visibility.c.
Diff:
---
gcc/ipa-comdats.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/gcc/ipa-comdats.c b/gcc/ipa-comdats.c
index feea458ca3f..fe56a6f470b 100644
--- a/gcc/ipa-comdats.c
+++ b/gcc/ipa-comdats.c
@@ -428,6 +428,13 @@ public:
bool
pass_ipa_comdats::gate (function *)
{
+ if ((in_lto_p || flag_whole_program) && !flag_incremental_link)
+ /* This is the combination of flags cgraph_externally_visible_p in
+ ipa-visibility.c uses to enable localization of comdat symbols.
+ Do not attempt to undo that by trying to re-insert symbols into
+ comdats without their original visibility information, as it
+ causes assertion failures in lto-partition. */
+ return false;
return HAVE_COMDAT_GROUP;
}
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