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Unified Diff: lib/Transforms/NaCl/CanonicalizeMemIntrinsics.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/CanonicalizeMemIntrinsics.cpp
diff --git a/lib/Transforms/NaCl/CanonicalizeMemIntrinsics.cpp b/lib/Transforms/NaCl/CanonicalizeMemIntrinsics.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..1acde98d322a3f50d44c35ecd75492a4498a0e1b
--- /dev/null
+++ b/lib/Transforms/NaCl/CanonicalizeMemIntrinsics.cpp
@@ -0,0 +1,100 @@
+//===- CanonicalizeMemIntrinsics.cpp - Make memcpy's "len" arg consistent--===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass canonicalizes uses of the llvm.memset, llvm.memcpy and
+// llvm.memmove intrinsics so that the variants with 64-bit "len"
+// arguments aren't used, and the 32-bit variants are used instead.
+//
+// This means the PNaCl translator won't need to handle two versions
+// of each of these intrinsics, and it won't need to do any implicit
+// truncations from 64-bit to 32-bit.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/NaCl.h"
+
+using namespace llvm;
+
+namespace {
+ // This is a ModulePass because that makes it easier to find all
+ // uses of intrinsics efficiently.
+ class CanonicalizeMemIntrinsics : public ModulePass {
+ public:
+ static char ID; // Pass identification, replacement for typeid
+ CanonicalizeMemIntrinsics() : ModulePass(ID) {
+ initializeCanonicalizeMemIntrinsicsPass(*PassRegistry::getPassRegistry());
+ }
+
+ virtual bool runOnModule(Module &M);
+ };
+}
+
+char CanonicalizeMemIntrinsics::ID = 0;
+INITIALIZE_PASS(CanonicalizeMemIntrinsics, "canonicalize-mem-intrinsics",
+ "Make memcpy() et al's \"len\" argument consistent",
+ false, false)
+
+static bool expandIntrinsic(Module *M, Intrinsic::ID ID) {
+ SmallVector<Type *, 3> Types;
+ Types.push_back(Type::getInt8PtrTy(M->getContext()));
+ if (ID != Intrinsic::memset)
+ Types.push_back(Type::getInt8PtrTy(M->getContext()));
+ unsigned LengthTypePos = Types.size();
+ Types.push_back(Type::getInt64Ty(M->getContext()));
+
+ std::string OldName = Intrinsic::getName(ID, Types);
+ Function *OldIntrinsic = M->getFunction(OldName);
+ if (!OldIntrinsic)
+ return false;
+
+ Types[LengthTypePos] = Type::getInt32Ty(M->getContext());
+ Function *NewIntrinsic = Intrinsic::getDeclaration(M, ID, Types);
+
+ SmallVector<CallInst *, 64> Calls;
+ for (User *U : OldIntrinsic->users()) {
+ if (CallInst *Call = dyn_cast<CallInst>(U))
+ Calls.push_back(Call);
+ else
+ report_fatal_error("CanonicalizeMemIntrinsics: Taking the address of an "
+ "intrinsic is not allowed: " +
+ OldName);
+ }
+
+ for (CallInst *Call : Calls) {
+ // This temporarily leaves Call non-well-typed.
+ Call->setCalledFunction(NewIntrinsic);
+ // Truncate the "len" argument. No overflow check.
+ IRBuilder<> Builder(Call);
+ Value *Length = Builder.CreateTrunc(Call->getArgOperand(2),
+ Type::getInt32Ty(M->getContext()),
+ "mem_len_truncate");
+ Call->setArgOperand(2, Length);
+ }
+
+ OldIntrinsic->eraseFromParent();
+ return true;
+}
+
+bool CanonicalizeMemIntrinsics::runOnModule(Module &M) {
+ bool Changed = false;
+ Changed |= expandIntrinsic(&M, Intrinsic::memset);
+ Changed |= expandIntrinsic(&M, Intrinsic::memcpy);
+ Changed |= expandIntrinsic(&M, Intrinsic::memmove);
+ return Changed;
+}
+
+ModulePass *llvm::createCanonicalizeMemIntrinsicsPass() {
+ return new CanonicalizeMemIntrinsics();
+}
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