From b35cc691ea93d9408f76736170359fd7ce604b53 Mon Sep 17 00:00:00 2001 From: Teresa Johnson Date: Wed, 20 Apr 2016 14:39:45 +0000 Subject: [ThinLTO] Prevent importing of "llvm.used" values Summary: This patch prevents importing from (and therefore exporting from) any module with a "llvm.used" local value. Local values need to be promoted and renamed when importing, and their presense on the llvm.used variable indicates that there are opaque uses that won't see the rename. One such example is a use in inline assembly. See also the discussion at: http://lists.llvm.org/pipermail/llvm-dev/2016-April/098047.html As part of this, move collectUsedGlobalVariables out of Transforms/Utils and into IR/Module so that it can be used more widely. There are several other places in LLVM that used copies of this code that can be cleaned up as a follow on NFC patch. Reviewers: joker.eph Subscribers: pcc, llvm-commits, joker.eph Differential Revision: http://reviews.llvm.org/D18986 llvm-svn: 266877 --- llvm/lib/IR/Module.cpp | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) (limited to 'llvm/lib/IR/Module.cpp') diff --git a/llvm/lib/IR/Module.cpp b/llvm/lib/IR/Module.cpp index 64528d2815a..10110367841 100644 --- a/llvm/lib/IR/Module.cpp +++ b/llvm/lib/IR/Module.cpp @@ -14,6 +14,7 @@ #include "llvm/IR/Module.h" #include "SymbolTableListTraitsImpl.h" #include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/SmallString.h" #include "llvm/ADT/StringExtras.h" #include "llvm/IR/Constants.h" @@ -515,3 +516,18 @@ void Module::setProfileSummary(Metadata *M) { Metadata *Module::getProfileSummary() { return getModuleFlag("ProfileSummary"); } + +GlobalVariable *llvm::collectUsedGlobalVariables( + const Module &M, SmallPtrSetImpl &Set, bool CompilerUsed) { + const char *Name = CompilerUsed ? "llvm.compiler.used" : "llvm.used"; + GlobalVariable *GV = M.getGlobalVariable(Name); + if (!GV || !GV->hasInitializer()) + return GV; + + const ConstantArray *Init = cast(GV->getInitializer()); + for (Value *Op : Init->operands()) { + GlobalValue *G = cast(Op->stripPointerCastsNoFollowAliases()); + Set.insert(G); + } + return GV; +} -- cgit v1.2.3