[PATCH] D15156: [ThinLTO] Appending linkage fixes
Teresa Johnson via llvm-commits
llvm-commits at lists.llvm.org
Thu Dec 3 06:44:49 PST 2015
tejohnson updated this revision to Diff 41750.
tejohnson added a comment.
- Handle case where dest module already has an appending linkage variable with the same name. Cleanup old handling.
http://reviews.llvm.org/D15156
Files:
lib/Linker/LinkModules.cpp
test/Linker/Inputs/funcimport_appending_global.ll
test/Linker/funcimport_appending_global.ll
Index: test/Linker/funcimport_appending_global.ll
===================================================================
--- /dev/null
+++ test/Linker/funcimport_appending_global.ll
@@ -0,0 +1,20 @@
+; RUN: llvm-as -function-summary %s -o %t.bc
+; RUN: llvm-as -function-summary %p/Inputs/funcimport_appending_global.ll -o %t2.bc
+; RUN: llvm-lto -thinlto -o %t3 %t.bc %t2.bc
+
+; Do the import now
+; RUN: llvm-link %t.bc -functionindex=%t3.thinlto.bc -import=foo:%t2.bc -S | FileCheck %s
+
+; Ensure that global constructor (appending linkage) is not imported
+; CHECK-NOT: @llvm.global_ctors = {{.*}}@foo
+
+declare void @f()
+ at llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @f, i8* null}]
+
+define i32 @main() {
+entry:
+ call void @foo()
+ ret i32 0
+}
+
+declare void @foo()
Index: test/Linker/Inputs/funcimport_appending_global.ll
===================================================================
--- /dev/null
+++ test/Linker/Inputs/funcimport_appending_global.ll
@@ -0,0 +1,6 @@
+ at v = weak global i8 1
+ at llvm.global_ctors = appending global [1 x { i32, void ()*, i8* }] [{ i32, void ()*, i8* } { i32 65535, void ()* @foo, i8* @v}]
+
+define void @foo() {
+ ret void
+}
Index: lib/Linker/LinkModules.cpp
===================================================================
--- lib/Linker/LinkModules.cpp
+++ lib/Linker/LinkModules.cpp
@@ -762,8 +762,10 @@
// It would be incorrect to import an appending linkage variable,
// since it would cause global constructors/destructors to be
// executed multiple times. This should have already been handled
- // by linkGlobalValueProto.
- llvm_unreachable("Cannot import appending linkage variable");
+ // by linkIfNeeded, and we will assert in shouldLinkFromSource
+ // if we try to import, so we simply return AppendingLinkage here
+ // as this helper is called more widely in getLinkedToGlobal.
+ return GlobalValue::AppendingLinkage;
case GlobalValue::InternalLinkage:
case GlobalValue::PrivateLinkage:
@@ -1067,8 +1069,7 @@
// We always have to add Src if it has appending linkage.
if (Src.hasAppendingLinkage()) {
- // Caller should have already determined that we can't link from source
- // when importing (see comments in linkGlobalValueProto).
+ // Should have prevented importing for appending linkage in linkIfNeeded.
assert(!isPerformingImport());
LinkFromSrc = true;
return false;
@@ -1396,17 +1397,12 @@
// Handle the ultra special appending linkage case first.
assert(!DGV || SGV->hasAppendingLinkage() == DGV->hasAppendingLinkage());
- if (SGV->hasAppendingLinkage() && isPerformingImport()) {
- // Don't want to append to global_ctors list, for example, when we
- // are importing for ThinLTO, otherwise the global ctors and dtors
- // get executed multiple times for local variables (the latter causing
- // double frees).
- DoNotLinkFromSource.insert(SGV);
- return false;
- }
- if (SGV->hasAppendingLinkage())
+ if (SGV->hasAppendingLinkage()) {
+ // Should have prevented importing for appending linkage in linkIfNeeded.
+ assert(!isPerformingImport());
return linkAppendingVarProto(cast_or_null<GlobalVariable>(DGV),
cast<GlobalVariable>(SGV));
+ }
bool LinkFromSrc = true;
Comdat *C = nullptr;
@@ -1864,6 +1860,12 @@
GV.hasAvailableExternallyLinkage())) {
return false;
}
+ // Don't want to append to global_ctors list, for example, when we
+ // are importing for ThinLTO, otherwise the global ctors and dtors
+ // get executed multiple times for local variables (the latter causing
+ // double frees).
+ if (GV.hasAppendingLinkage() && isPerformingImport())
+ return false;
MapValue(&GV, ValueMap, RF_MoveDistinctMDs, &TypeMap, &ValMaterializer);
return HasError;
}
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