jmciver updated this revision to Diff 545294.
jmciver edited the summary of this revision.
jmciver added a comment.
Herald added subscribers: foad, kerbowa, jvesely, arsenm.
Refactor AMDGPUPromoteAlloca to use getInitialValueOfAllocation.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D155773/new/
https://reviews.llvm.org/D155773
Files:
llvm/include/llvm/Analysis/MemoryBuiltins.h
llvm/lib/Analysis/MemoryBuiltins.cpp
llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
llvm/lib/Transforms/Scalar/GVN.cpp
llvm/lib/Transforms/Scalar/NewGVN.cpp
llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
Index: llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
===================================================================
--- llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
+++ llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -24,6 +24,7 @@
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/Analysis/IteratedDominanceFrontier.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/BasicBlock.h"
#include "llvm/IR/CFG.h"
@@ -600,7 +601,7 @@
if (I == StoresByIndex.begin()) {
if (StoresByIndex.empty())
// If there are no stores, the load takes the undef value.
- ReplVal = UndefValue::get(LI->getType());
+ ReplVal = getInitialValueOfAllocation(AI, nullptr, LI->getType());
else
// There is no store before this load, bail out (load may be affected
// by the following stores - see main comment).
Index: llvm/lib/Transforms/Scalar/NewGVN.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/NewGVN.cpp
+++ llvm/lib/Transforms/Scalar/NewGVN.cpp
@@ -1496,21 +1496,18 @@
if (LoadPtr != lookupOperandLeader(DepInst) &&
!AA->isMustAlias(LoadPtr, DepInst))
return nullptr;
- // If this load really doesn't depend on anything, then we must be loading an
- // undef value. This can happen when loading for a fresh allocation with no
- // intervening stores, for example. Note that this is only true in the case
- // that the result of the allocation is pointer equal to the load ptr.
- if (isa<AllocaInst>(DepInst)) {
- return createConstantExpression(UndefValue::get(LoadType));
- }
// If this load occurs either right after a lifetime begin,
// then the loaded value is undefined.
- else if (auto *II = dyn_cast<IntrinsicInst>(DepInst)) {
+ if (auto *II = dyn_cast<IntrinsicInst>(DepInst)) {
if (II->getIntrinsicID() == Intrinsic::lifetime_start)
return createConstantExpression(UndefValue::get(LoadType));
- } else if (auto *InitVal =
- getInitialValueOfAllocation(DepInst, TLI, LoadType))
- return createConstantExpression(InitVal);
+ }
+ // If this load really doesn't depend on anything, then we must be loading an
+ // undef value. This can happen when loading for a fresh allocation with no
+ // intervening stores, for example. Note that this is only true in the case
+ // that the result of the allocation is pointer equal to the load ptr.
+ else if (auto *InitVal = getInitialValueOfAllocation(DepInst, TLI, LoadType))
+ return createConstantExpression(InitVal);
return nullptr;
}
Index: llvm/lib/Transforms/Scalar/GVN.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/GVN.cpp
+++ llvm/lib/Transforms/Scalar/GVN.cpp
@@ -1239,11 +1239,12 @@
}
assert(DepInfo.isDef() && "follows from above");
- // Loading the alloca -> undef.
// Loading immediately after lifetime begin -> undef.
- if (isa<AllocaInst>(DepInst) || isLifetimeStart(DepInst))
+ if (isLifetimeStart(DepInst))
return AvailableValue::get(UndefValue::get(Load->getType()));
+ // In addition to allocator function calls this includes loading the alloca ->
+ // undef.
if (Constant *InitVal =
getInitialValueOfAllocation(DepInst, TLI, Load->getType()))
return AvailableValue::get(InitVal);
Index: llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp
@@ -32,6 +32,7 @@
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/InstSimplifyFolder.h"
#include "llvm/Analysis/InstructionSimplify.h"
+#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/IRBuilder.h"
@@ -805,7 +806,9 @@
// undef.
SSAUpdater Updater;
Updater.Initialize(VectorTy, "promotealloca");
- Updater.AddAvailableValue(Alloca.getParent(), UndefValue::get(VectorTy));
+ Updater.AddAvailableValue(
+ Alloca.getParent(),
+ getInitialValueOfAllocation(&Alloca, nullptr, VectorTy));
// First handle the initial worklist.
SmallVector<LoadInst *, 4> DeferredLoads;
Index: llvm/lib/Analysis/MemoryBuiltins.cpp
===================================================================
--- llvm/lib/Analysis/MemoryBuiltins.cpp
+++ llvm/lib/Analysis/MemoryBuiltins.cpp
@@ -436,6 +436,9 @@
Constant *llvm::getInitialValueOfAllocation(const Value *V,
const TargetLibraryInfo *TLI,
Type *Ty) {
+ if (isa<AllocaInst>(V))
+ return UndefValue::get(Ty);
+
auto *Alloc = dyn_cast<CallBase>(V);
if (!Alloc)
return nullptr;
Index: llvm/include/llvm/Analysis/MemoryBuiltins.h
===================================================================
--- llvm/include/llvm/Analysis/MemoryBuiltins.h
+++ llvm/include/llvm/Analysis/MemoryBuiltins.h
@@ -119,8 +119,8 @@
});
/// If this is a call to an allocation function that initializes memory to a
-/// fixed value, return said value in the requested type. Otherwise, return
-/// nullptr.
+/// fixed value, return said value in the requested type. If this is a call to
+/// alloca instruction the returned value is undef. Otherwise, return nullptr.
Constant *getInitialValueOfAllocation(const Value *V,
const TargetLibraryInfo *TLI,
Type *Ty);
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