From b256cb88a716dfd270745af1bb98b49c22521a99 Mon Sep 17 00:00:00 2001
From: Vitaly Buka <vitalybuka@google.com>
Date: Thu, 30 Jul 2020 18:48:34 -0700
Subject: [PATCH] [ValueTracking] Remove AllocaForValue parameter

findAllocaForValue uses AllocaForValue to cache resolved values.
The function is used only to resolve arguments of lifetime
intrinsic which usually are not fare for allocas. So result reuse
is likely unnoticeable.

In followup patches I'd like to replace the function with
GetUnderlyingObjects.

Depends on D84616.

Differential Revision: https://reviews.llvm.org/D84617
---
 llvm/include/llvm/Analysis/ValueTracking.h             |  6 ++++--
 llvm/lib/Analysis/ValueTracking.cpp                    | 10 +++++++---
 llvm/lib/Target/AArch64/AArch64StackTagging.cpp        |  4 +---
 .../Transforms/Instrumentation/AddressSanitizer.cpp    |  7 +------
 .../lib/Transforms/Instrumentation/MemorySanitizer.cpp |  4 +---
 5 files changed, 14 insertions(+), 17 deletions(-)

diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index 8008e6003e7d..92dc7c01e83b 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -415,8 +415,10 @@ class Value;
                             const DataLayout &DL);
 
   /// Finds alloca where the value comes from.
-  AllocaInst *
-  findAllocaForValue(Value *V, DenseMap<Value *, AllocaInst *> &AllocaForValue);
+  AllocaInst *findAllocaForValue(Value *V);
+  inline const AllocaInst *findAllocaForValue(const Value *V) {
+    return findAllocaForValue(const_cast<Value *>(V));
+  }
 
   /// Return true if the only users of this pointer are lifetime markers.
   bool onlyUsedByLifetimeMarkers(const Value *V);
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 6fb36fa826d0..9dfe8fdcb1a5 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -4313,9 +4313,8 @@ bool llvm::getUnderlyingObjectsForCodeGen(const Value *V,
   return true;
 }
 
-AllocaInst *
-llvm::findAllocaForValue(Value *V,
-                         DenseMap<Value *, AllocaInst *> &AllocaForValue) {
+static AllocaInst *
+findAllocaForValue(Value *V, DenseMap<Value *, AllocaInst *> &AllocaForValue) {
   if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
     return AI;
   // See if we've already calculated (or started to calculate) alloca for a
@@ -4348,6 +4347,11 @@ llvm::findAllocaForValue(Value *V,
   return Res;
 }
 
+AllocaInst *llvm::findAllocaForValue(Value *V) {
+  DenseMap<Value *, AllocaInst *> AllocaForValue;
+  return ::findAllocaForValue(V, AllocaForValue);
+}
+
 static bool onlyUsedByLifetimeMarkersOrDroppableInstsHelper(
     const Value *V, bool AllowLifetime, bool AllowDroppable) {
   for (const User *U : V->users()) {
diff --git a/llvm/lib/Target/AArch64/AArch64StackTagging.cpp b/llvm/lib/Target/AArch64/AArch64StackTagging.cpp
index 0ed576fbc75f..1b8c6417be38 100644
--- a/llvm/lib/Target/AArch64/AArch64StackTagging.cpp
+++ b/llvm/lib/Target/AArch64/AArch64StackTagging.cpp
@@ -544,7 +544,6 @@ bool AArch64StackTagging::runOnFunction(Function &Fn) {
 
   MapVector<AllocaInst *, AllocaInfo> Allocas; // need stable iteration order
   SmallVector<Instruction *, 8> RetVec;
-  DenseMap<Value *, AllocaInst *> AllocaForValue;
   SmallVector<Instruction *, 4> UnrecognizedLifetimes;
 
   for (auto &BB : *F) {
@@ -566,8 +565,7 @@ bool AArch64StackTagging::runOnFunction(Function &Fn) {
       auto *II = dyn_cast<IntrinsicInst>(I);
       if (II && (II->getIntrinsicID() == Intrinsic::lifetime_start ||
                  II->getIntrinsicID() == Intrinsic::lifetime_end)) {
-        AllocaInst *AI =
-            llvm::findAllocaForValue(II->getArgOperand(1), AllocaForValue);
+        AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
         if (!AI) {
           UnrecognizedLifetimes.push_back(I);
           continue;
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 647d25e6a24e..053b9aa812bf 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -911,10 +911,6 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
   AllocaInst *DynamicAllocaLayout = nullptr;
   IntrinsicInst *LocalEscapeCall = nullptr;
 
-  // Maps Value to an AllocaInst from which the Value is originated.
-  using AllocaForValueMapTy = DenseMap<Value *, AllocaInst *>;
-  AllocaForValueMapTy AllocaForValue;
-
   bool HasInlineAsm = false;
   bool HasReturnsTwiceCall = false;
 
@@ -1065,8 +1061,7 @@ struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
         !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
       return;
     // Find alloca instruction that corresponds to llvm.lifetime argument.
-    AllocaInst *AI =
-        llvm::findAllocaForValue(II.getArgOperand(1), AllocaForValue);
+    AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
     if (!AI) {
       HasUntracedLifetimeIntrinsic = true;
       return;
diff --git a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
index f31d88a633b9..edde80ce0ee8 100644
--- a/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp
@@ -2693,9 +2693,7 @@ struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> {
   void handleLifetimeStart(IntrinsicInst &I) {
     if (!PoisonStack)
       return;
-    DenseMap<Value *, AllocaInst *> AllocaForValue;
-    AllocaInst *AI =
-        llvm::findAllocaForValue(I.getArgOperand(1), AllocaForValue);
+    AllocaInst *AI = llvm::findAllocaForValue(I.getArgOperand(1));
     if (!AI)
       InstrumentLifetimeStart = false;
     LifetimeStartList.push_back(std::make_pair(&I, AI));
-- 
2.34.1