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Unified Diff: lib/Transforms/NaCl/StripMetadata.cpp

Issue 939073008: Rebased PNaCl localmods in LLVM to 223109 (Closed)
Patch Set: undo localmod Created 5 years, 10 months ago
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Index: lib/Transforms/NaCl/StripMetadata.cpp
diff --git a/lib/Transforms/NaCl/StripMetadata.cpp b/lib/Transforms/NaCl/StripMetadata.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..7e576a981172395c48e922b7361a95d75e1c9444
--- /dev/null
+++ b/lib/Transforms/NaCl/StripMetadata.cpp
@@ -0,0 +1,115 @@
+//===- StripMetadata.cpp - Strip non-stable non-debug metadata ------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// The StripMetadata transformation strips instruction attachment
+// metadata, such as !tbaa and !prof metadata.
+// TODO: Strip NamedMetadata too.
+//
+// It does not strip debug metadata. Debug metadata is used by debug
+// intrinsic functions and calls to those intrinsic functions. Use the
+// -strip-debug or -strip pass to strip that instead.
+//
+// The goal of this pass is to reduce bitcode ABI surface area.
+// We don't know yet which kind of metadata is considered stable.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/NaCl.h"
+
+using namespace llvm;
+
+namespace {
+ class StripMetadata : public ModulePass {
+ public:
+ static char ID;
+ StripMetadata() : ModulePass(ID), ShouldStripModuleFlags(false) {
+ initializeStripMetadataPass(*PassRegistry::getPassRegistry());
+ }
+
+ virtual bool runOnModule(Module &M);
+
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+ AU.setPreservesCFG();
+ }
+
+ protected:
+ bool ShouldStripModuleFlags;
+ };
+
+ class StripModuleFlags : public StripMetadata {
+ public:
+ static char ID;
+ StripModuleFlags() : StripMetadata() {
+ initializeStripModuleFlagsPass(*PassRegistry::getPassRegistry());
+ ShouldStripModuleFlags = true;
+ }
+ };
+}
+
+char StripMetadata::ID = 0;
+INITIALIZE_PASS(StripMetadata, "strip-metadata",
+ "Strip all non-stable non-debug metadata from a module.",
+ false, false)
+
+char StripModuleFlags::ID = 0;
+INITIALIZE_PASS(StripModuleFlags, "strip-module-flags",
+ "Strip all non-stable non-debug metadata from a module, "
+ "including the llvm.module.flags metadata.",
+ false, false)
+
+ModulePass *llvm::createStripMetadataPass() {
+ return new StripMetadata();
+}
+
+ModulePass *llvm::createStripModuleFlagsPass() {
+ return new StripModuleFlags();
+}
+
+static bool IsWhitelistedMetadata(const NamedMDNode *node,
+ bool StripModuleFlags) {
+ // Leave debug metadata to the -strip-debug pass.
+ return (node->getName().startswith("llvm.dbg.") ||
+ // "Debug Info Version" is in llvm.module.flags.
+ (!StripModuleFlags && node->getName().equals("llvm.module.flags")));
+}
+
+static bool DoStripMetadata(Module &M, bool StripModuleFlags) {
+ bool Changed = false;
+
+ if (!StripModuleFlags)
+ for (Function &F : M)
+ for (BasicBlock &B : F)
+ for (Instruction &I : B) {
+ SmallVector<std::pair<unsigned, MDNode *>, 8> InstMeta;
+ // Let the debug metadata be stripped by the -strip-debug pass.
+ I.getAllMetadataOtherThanDebugLoc(InstMeta);
+ for (size_t i = 0; i < InstMeta.size(); ++i) {
+ I.setMetadata(InstMeta[i].first, NULL);
+ Changed = true;
+ }
+ }
+
+ // Strip unsupported named metadata.
+ SmallVector<NamedMDNode*, 8> ToErase;
+ for (Module::NamedMDListType::iterator I = M.named_metadata_begin(),
+ E = M.named_metadata_end(); I != E; ++I) {
+ if (!IsWhitelistedMetadata(I, StripModuleFlags))
+ ToErase.push_back(I);
+ }
+ for (size_t i = 0; i < ToErase.size(); ++i)
+ M.eraseNamedMetadata(ToErase[i]);
+
+ return Changed;
+}
+
+bool StripMetadata::runOnModule(Module &M) {
+ return DoStripMetadata(M, ShouldStripModuleFlags);
+}
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