diff options
| -rw-r--r-- | include/llvm/GlobalValue.h | 10 | ||||
| -rw-r--r-- | lib/Transforms/IPO/ConstantMerge.cpp | 16 | ||||
| -rw-r--r-- | test/Transforms/ConstantMerge/linker-private.ll | 23 |
3 files changed, 43 insertions, 6 deletions
diff --git a/include/llvm/GlobalValue.h b/include/llvm/GlobalValue.h index 81a11a4..d43a2fa 100644 --- a/include/llvm/GlobalValue.h +++ b/include/llvm/GlobalValue.h @@ -192,6 +192,14 @@ public: Linkage == LinkerPrivateWeakDefAutoLinkage; } + /// mayBeRemovedByLinker - Whether the definition of this global may be + /// removed at link time. + static bool mayBeRemovedByLinker(LinkageTypes Linkage) { + return isLinkerPrivateLinkage(Linkage) || + isLinkerPrivateWeakLinkage(Linkage) || + isLinkerPrivateWeakDefAutoLinkage(Linkage); + } + bool hasExternalLinkage() const { return isExternalLinkage(Linkage); } bool hasAvailableExternallyLinkage() const { return isAvailableExternallyLinkage(Linkage); @@ -225,6 +233,8 @@ public: bool isWeakForLinker() const { return isWeakForLinker(Linkage); } + bool mayBeRemovedByLinker() const { return mayBeRemovedByLinker(Linkage); } + /// copyAttributesFrom - copy all additional attributes (those not needed to /// create a GlobalValue) from the GlobalValue Src to this one. virtual void copyAttributesFrom(const GlobalValue *Src); diff --git a/lib/Transforms/IPO/ConstantMerge.cpp b/lib/Transforms/IPO/ConstantMerge.cpp index c3ecb7a..268a281 100644 --- a/lib/Transforms/IPO/ConstantMerge.cpp +++ b/lib/Transforms/IPO/ConstantMerge.cpp @@ -140,18 +140,21 @@ bool ConstantMerge::runOnModule(Module &M) { UsedGlobals.count(GV)) continue; + // Ignore any constants which may be removed by the linker. + if (GV->mayBeRemovedByLinker()) + continue; + Constant *Init = GV->getInitializer(); // Check to see if the initializer is already known. PointerIntPair<Constant*, 1, bool> Pair(Init, hasKnownAlignment(GV)); GlobalVariable *&Slot = CMap[Pair]; - // If this is the first constant we find or if the old on is local, - // replace with the current one. It the current is externally visible + // If this is the first constant we find or if the old one is local, + // replace with the current one. If the current is externally visible // it cannot be replace, but can be the canonical constant we merge with. - if (Slot == 0 || IsBetterCannonical(*GV, *Slot)) { + if (Slot == 0 || IsBetterCannonical(*GV, *Slot)) Slot = GV; - } } // Second: identify all globals that can be merged together, filling in @@ -169,8 +172,9 @@ bool ConstantMerge::runOnModule(Module &M) { UsedGlobals.count(GV)) continue; - // We can only replace constant with local linkage. - if (!GV->hasLocalLinkage()) + // We can only replace constants with local linkage and which aren't + // removed by the linker. + if (!GV->hasLocalLinkage() || GV->mayBeRemovedByLinker()) continue; Constant *Init = GV->getInitializer(); diff --git a/test/Transforms/ConstantMerge/linker-private.ll b/test/Transforms/ConstantMerge/linker-private.ll new file mode 100644 index 0000000..eba7880 --- /dev/null +++ b/test/Transforms/ConstantMerge/linker-private.ll @@ -0,0 +1,23 @@ +; RUN: opt < %s -constmerge -S | FileCheck %s +; <rdar://problem/10564621> + +%0 = type opaque +%struct.NSConstantString = type { i32*, i32, i8*, i32 } + +; CHECK: @.str3 = linker_private unnamed_addr constant [1 x i8] zeroinitializer, align 1 + +@isLogVisible = global i8 0, align 1 +@__CFConstantStringClassReference = external global [0 x i32] +@.str3 = linker_private unnamed_addr constant [1 x i8] zeroinitializer, align 1 +@_unnamed_cfstring_4 = private constant %struct.NSConstantString { i32* getelementptr inbounds ([0 x i32]* @__CFConstantStringClassReference, i32 0, i32 0), i32 1992, i8* getelementptr inbounds ([1 x i8]* @.str3, i32 0, i32 0), i32 0 }, section "__DATA,__cfstring" +@null.array = weak_odr constant [1 x i8] zeroinitializer, align 1 + +define linkonce_odr void @bar() nounwind ssp align 2 { +entry: + %stack = alloca i8*, align 4 + %call = call %0* bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to %0* (i8*, i8*, %0*)*)(i8* null, i8* null, %0* bitcast (%struct.NSConstantString* @_unnamed_cfstring_4 to %0*)) + store i8* getelementptr inbounds ([1 x i8]* @null.array, i32 0, i32 0), i8** %stack, align 4 + ret void +} + +declare i8* @objc_msgSend(i8*, i8*, ...) nonlazybind |