LowerBitSets: Do not export symbols for bit set referenced globals on Darwin.

The linker on that platform may re-order symbols or strip dead symbols, which
will break bit set checks. Avoid this by hiding the symbols from the linker.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@232235 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/IPO/LowerBitSets.cpp b/lib/Transforms/IPO/LowerBitSets.cpp
index 9eb5cdba0e5ab94f9eb5b421541af9d986b1df2b..8602642103cf75ebd6955adf8163257ce2a846dc 100644 (file)
--- a/lib/Transforms/IPO/LowerBitSets.cpp
+++ b/lib/Transforms/IPO/LowerBitSets.cpp
@@ -16,6 +16,7 @@
 #include "llvm/Transforms/IPO.h"
 #include "llvm/ADT/EquivalenceClasses.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/Triple.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/GlobalVariable.h"
@@ -186,6 +187,7 @@ struct LowerBitSets : public ModulePass {
 
   Module *M;
 
+  bool LinkerSubsectionsViaSymbols;
   IntegerType *Int1Ty;
   IntegerType *Int8Ty;
   IntegerType *Int32Ty;
@@ -235,6 +237,9 @@ bool LowerBitSets::doInitialization(Module &Mod) {
   M = &Mod;
   const DataLayout &DL = Mod.getDataLayout();
 
+  Triple TargetTriple(M->getTargetTriple());
+  LinkerSubsectionsViaSymbols = TargetTriple.isMacOSX();
+
   Int1Ty = Type::getInt1Ty(M->getContext());
   Int8Ty = Type::getInt8Ty(M->getContext());
   Int32Ty = Type::getInt32Ty(M->getContext());
@@ -524,9 +529,12 @@ void LowerBitSets::buildBitSetsFromGlobals(
                                       ConstantInt::get(Int32Ty, I * 2)};
     Constant *CombinedGlobalElemPtr =
         ConstantExpr::getGetElementPtr(CombinedGlobal, CombinedGlobalIdxs);
+    GlobalValue::LinkageTypes GAliasLinkage = LinkerSubsectionsViaSymbols
+                                                  ? GlobalValue::PrivateLinkage
+                                                  : Globals[I]->getLinkage();
     GlobalAlias *GAlias = GlobalAlias::create(
         Globals[I]->getType()->getElementType(),
-        Globals[I]->getType()->getAddressSpace(), Globals[I]->getLinkage(),
+        Globals[I]->getType()->getAddressSpace(), GAliasLinkage,
         "", CombinedGlobalElemPtr, M);
     GAlias->takeName(Globals[I]);
     Globals[I]->replaceAllUsesWith(GAlias);

diff --git a/test/Transforms/LowerBitSets/simple.ll b/test/Transforms/LowerBitSets/simple.ll
index 7a7808b86ed726e049ec3c58cce2ea1db2206421..b3b7eb38aea5cb08386bddbbbe0e738f3f6918da 100644 (file)
--- a/test/Transforms/LowerBitSets/simple.ll
+++ b/test/Transforms/LowerBitSets/simple.ll
@@ -1,4 +1,5 @@
 ; RUN: opt -S -lowerbitsets < %s | FileCheck %s
+; RUN: opt -S -lowerbitsets -mtriple=x86_64-apple-macosx10.8.0 < %s | FileCheck -check-prefix=CHECK-DARWIN %s
 ; RUN: opt -S -O3 < %s | FileCheck -check-prefix=CHECK-NODISCARD %s
 
 target datalayout = "e-p:32:32"
@@ -41,6 +42,10 @@ target datalayout = "e-p:32:32"
 ; CHECK: @b = alias getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 2)
 ; CHECK: @c = alias getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 4)
 ; CHECK: @d = alias getelementptr inbounds ({ i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }, { i32, [0 x i8], [63 x i32], [4 x i8], i32, [0 x i8], [2 x i32] }* [[G]], i32 0, i32 6)
+; CHECK-DARWIN: @a = private alias
+; CHECK-DARWIN: @b = private alias
+; CHECK-DARWIN: @c = private alias
+; CHECK-DARWIN: @d = private alias
 
 ; CHECK: @bits = private alias getelementptr inbounds ([68 x i8], [68 x i8]* [[BA]], i32 0, i32 0)
 ; CHECK: @bits1 = private alias getelementptr inbounds ([68 x i8], [68 x i8]* [[BA]], i32 0, i32 0)