Linker: Don't double-schedule appending variables

Add an assertion to ValueMapper that prevents double-scheduling of
GlobalValues to remap, and fix the one place it happened.  There are
tons of tests that fail with this assertion in place and without the
code change, so I'm not adding another.

Although it looks related, r266563 was, indeed, removing dead code.
AFAICT, this cross-file double-scheduling started in r266510 when the
cross-file recursion was removed.

llvm-svn: 266569

2 files changed, 10 insertions, 1 deletions

diff --git a/llvm/lib/Linker/IRMover.cpp b/llvm/lib/Linker/IRMover.cpp
index 272dfcf6dc4..02fe58d2cc5 100644
--- a/llvm/lib/Linker/IRMover.cpp
+++ b/llvm/lib/Linker/IRMover.cpp
@@ -540,7 +540,7 @@ void IRLinker::materializeInitFor(GlobalValue *New, GlobalValue *Old,
     if (!F->isDeclaration())
       return;
   } else if (auto *V = dyn_cast<GlobalVariable>(New)) {
-    if (V->hasInitializer())
+    if (V->hasInitializer() || V->hasAppendingLinkage())
       return;
   } else {
     auto *A = cast<GlobalAlias>(New);
diff --git a/llvm/lib/Transforms/Utils/ValueMapper.cpp b/llvm/lib/Transforms/Utils/ValueMapper.cpp
index 84dcb42a749..8ab6626202c 100644
--- a/llvm/lib/Transforms/Utils/ValueMapper.cpp
+++ b/llvm/lib/Transforms/Utils/ValueMapper.cpp
@@ -13,6 +13,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Utils/ValueMapper.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/IR/CallSite.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DebugInfoMetadata.h"
@@ -99,6 +100,10 @@ class MDNodeMapper;
 class Mapper {
   friend class MDNodeMapper;
 
+#ifndef NDEBUG
+  DenseSet<GlobalValue *> AlreadyScheduled;
+#endif
+
   RemapFlags Flags;
   ValueMapTypeRemapper *TypeMapper;
   unsigned CurrentMCID = 0;
@@ -965,6 +970,7 @@ void Mapper::mapAppendingVariable(GlobalVariable &GV, Constant *InitPrefix,
 
 void Mapper::scheduleMapGlobalInitializer(GlobalVariable &GV, Constant &Init,
                                           unsigned MCID) {
+  assert(AlreadyScheduled.insert(&GV).second && "Should not reschedule");
   assert(MCID < MCs.size() && "Invalid mapping context");
 
   WorklistEntry WE;
@@ -980,6 +986,7 @@ void Mapper::scheduleMapAppendingVariable(GlobalVariable &GV,
                                           bool IsOldCtorDtor,
                                           ArrayRef<Constant *> NewMembers,
                                           unsigned MCID) {
+  assert(AlreadyScheduled.insert(&GV).second && "Should not reschedule");
   assert(MCID < MCs.size() && "Invalid mapping context");
 
   WorklistEntry WE;
@@ -995,6 +1002,7 @@ void Mapper::scheduleMapAppendingVariable(GlobalVariable &GV,
 
 void Mapper::scheduleMapGlobalAliasee(GlobalAlias &GA, Constant &Aliasee,
                                       unsigned MCID) {
+  assert(AlreadyScheduled.insert(&GA).second && "Should not reschedule");
   assert(MCID < MCs.size() && "Invalid mapping context");
 
   WorklistEntry WE;
@@ -1006,6 +1014,7 @@ void Mapper::scheduleMapGlobalAliasee(GlobalAlias &GA, Constant &Aliasee,
 }
 
 void Mapper::scheduleRemapFunction(Function &F, unsigned MCID) {
+  assert(AlreadyScheduled.insert(&F).second && "Should not reschedule");
   assert(MCID < MCs.size() && "Invalid mapping context");
 
   WorklistEntry WE;