[llvm] r294453 - [InstCombineCalls] Unfold element atomic memcpy instruction
Igor Laevsky via llvm-commits
llvm-commits at lists.llvm.org
Wed Feb 8 06:32:05 PST 2017
Author: igor.laevsky
Date: Wed Feb 8 08:32:04 2017
New Revision: 294453
URL: http://llvm.org/viewvc/llvm-project?rev=294453&view=rev
Log:
[InstCombineCalls] Unfold element atomic memcpy instruction
Differential Revision: https://reviews.llvm.org/D28909
Added:
llvm/trunk/test/Transforms/InstCombine/element-atomic-memcpy-to-loads.ll
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp?rev=294453&r1=294452&r2=294453&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCalls.cpp Wed Feb 8 08:32:04 2017
@@ -60,6 +60,12 @@ using namespace PatternMatch;
STATISTIC(NumSimplified, "Number of library calls simplified");
+static cl::opt<uint64_t> UnfoldElementAtomicMemcpyMaxElements(
+ "unfold-element-atomic-memcpy-max-elements",
+ cl::init(16),
+ cl::desc("Maximum number of elements in atomic memcpy the optimizer is "
+ "allowed to unfold"));
+
/// Return the specified type promoted as it would be to pass though a va_arg
/// area.
static Type *getPromotedType(Type *Ty) {
@@ -108,6 +114,78 @@ static Constant *getNegativeIsTrueBoolVe
return ConstantVector::get(BoolVec);
}
+Instruction *
+InstCombiner::SimplifyElementAtomicMemCpy(ElementAtomicMemCpyInst *AMI) {
+ // Try to unfold this intrinsic into sequence of explicit atomic loads and
+ // stores.
+ // First check that number of elements is compile time constant.
+ auto *NumElementsCI = dyn_cast<ConstantInt>(AMI->getNumElements());
+ if (!NumElementsCI)
+ return nullptr;
+
+ // Check that there are not too many elements.
+ uint64_t NumElements = NumElementsCI->getZExtValue();
+ if (NumElements >= UnfoldElementAtomicMemcpyMaxElements)
+ return nullptr;
+
+ // Don't unfold into illegal integers
+ uint64_t ElementSizeInBytes = AMI->getElementSizeInBytes() * 8;
+ if (!getDataLayout().isLegalInteger(ElementSizeInBytes))
+ return nullptr;
+
+ // Cast source and destination to the correct type. Intrinsic input arguments
+ // are usually represented as i8*.
+ // Often operands will be explicitly casted to i8* and we can just strip
+ // those casts instead of inserting new ones. However it's easier to rely on
+ // other InstCombine rules which will cover trivial cases anyway.
+ Value *Src = AMI->getRawSource();
+ Value *Dst = AMI->getRawDest();
+ Type *ElementPointerType = Type::getIntNPtrTy(
+ AMI->getContext(), ElementSizeInBytes, Src->getType()->getPointerAddressSpace());
+
+ Value *SrcCasted = Builder->CreatePointerCast(Src, ElementPointerType,
+ "memcpy_unfold.src_casted");
+ Value *DstCasted = Builder->CreatePointerCast(Dst, ElementPointerType,
+ "memcpy_unfold.dst_casted");
+
+ for (uint64_t i = 0; i < NumElements; ++i) {
+ // Get current element addresses
+ ConstantInt *ElementIdxCI =
+ ConstantInt::get(AMI->getContext(), APInt(64, i));
+ Value *SrcElementAddr =
+ Builder->CreateGEP(SrcCasted, ElementIdxCI, "memcpy_unfold.src_addr");
+ Value *DstElementAddr =
+ Builder->CreateGEP(DstCasted, ElementIdxCI, "memcpy_unfold.dst_addr");
+
+ // Load from the source. Transfer alignment information and mark load as
+ // unordered atomic.
+ LoadInst *Load = Builder->CreateLoad(SrcElementAddr, "memcpy_unfold.val");
+ Load->setOrdering(AtomicOrdering::Unordered);
+ // We know alignment of the first element. It is also guaranteed by the
+ // verifier that element size is less or equal than first element alignment
+ // and both of this values are powers of two.
+ // This means that all subsequent accesses are at least element size
+ // aligned.
+ // TODO: We can infer better alignment but there is no evidence that this
+ // will matter.
+ Load->setAlignment(i == 0 ? AMI->getSrcAlignment()
+ : AMI->getElementSizeInBytes());
+ Load->setDebugLoc(AMI->getDebugLoc());
+
+ // Store loaded value via unordered atomic store.
+ StoreInst *Store = Builder->CreateStore(Load, DstElementAddr);
+ Store->setOrdering(AtomicOrdering::Unordered);
+ Store->setAlignment(i == 0 ? AMI->getDstAlignment()
+ : AMI->getElementSizeInBytes());
+ Store->setDebugLoc(AMI->getDebugLoc());
+ }
+
+ // Set the number of elements of the copy to 0, it will be deleted on the
+ // next iteration.
+ AMI->setNumElements(Constant::getNullValue(NumElementsCI->getType()));
+ return AMI;
+}
+
Instruction *InstCombiner::SimplifyMemTransfer(MemIntrinsic *MI) {
unsigned DstAlign = getKnownAlignment(MI->getArgOperand(0), DL, MI, &AC, &DT);
unsigned SrcAlign = getKnownAlignment(MI->getArgOperand(1), DL, MI, &AC, &DT);
@@ -1839,6 +1917,9 @@ Instruction *InstCombiner::visitCallInst
if (Constant *C = dyn_cast<Constant>(AMI->getNumElements()))
if (C->isNullValue())
return eraseInstFromFunction(*AMI);
+
+ if (Instruction *I = SimplifyElementAtomicMemCpy(AMI))
+ return I;
}
if (Instruction *I = SimplifyNVVMIntrinsic(II, *this))
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h?rev=294453&r1=294452&r2=294453&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h Wed Feb 8 08:32:04 2017
@@ -650,6 +650,8 @@ private:
Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
Instruction *MatchBSwap(BinaryOperator &I);
bool SimplifyStoreAtEndOfBlock(StoreInst &SI);
+
+ Instruction *SimplifyElementAtomicMemCpy(ElementAtomicMemCpyInst *AMI);
Instruction *SimplifyMemTransfer(MemIntrinsic *MI);
Instruction *SimplifyMemSet(MemSetInst *MI);
Added: llvm/trunk/test/Transforms/InstCombine/element-atomic-memcpy-to-loads.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/element-atomic-memcpy-to-loads.ll?rev=294453&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/element-atomic-memcpy-to-loads.ll (added)
+++ llvm/trunk/test/Transforms/InstCombine/element-atomic-memcpy-to-loads.ll Wed Feb 8 08:32:04 2017
@@ -0,0 +1,92 @@
+; RUN: opt -instcombine -unfold-element-atomic-memcpy-max-elements=8 -S < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+
+; Test basic unfolding
+define void @test1(i8* %Src, i8* %Dst) {
+; CHECK-LABEL: test1
+; CHECK-NOT: llvm.memcpy.element.atomic
+
+; CHECK-DAG: %memcpy_unfold.src_casted = bitcast i8* %Src to i32*
+; CHECK-DAG: %memcpy_unfold.dst_casted = bitcast i8* %Dst to i32*
+
+; CHECK-DAG: [[VAL1:%[^\s]+]] = load atomic i32, i32* %memcpy_unfold.src_casted unordered, align 4
+; CHECK-DAG: store atomic i32 [[VAL1]], i32* %memcpy_unfold.dst_casted unordered, align 8
+
+; CHECK-DAG: [[VAL2:%[^\s]+]] = load atomic i32, i32* %{{[^\s]+}} unordered, align 4
+; CHECK-DAG: store atomic i32 [[VAL2]], i32* %{{[^\s]+}} unordered, align 4
+
+; CHECK-DAG: [[VAL3:%[^\s]+]] = load atomic i32, i32* %{{[^\s]+}} unordered, align 4
+; CHECK-DAG: store atomic i32 [[VAL3]], i32* %{{[^\s]+}} unordered, align 4
+
+; CHECK-DAG: [[VAL4:%[^\s]+]] = load atomic i32, i32* %{{[^\s]+}} unordered, align 4
+; CHECK-DAG: store atomic i32 [[VAL4]], i32* %{{[^\s]+}} unordered, align 4
+entry:
+ call void @llvm.memcpy.element.atomic.p0i8.p0i8(i8* align 4 %Dst, i8* align 8 %Src, i64 4, i32 4)
+ ret void
+}
+
+; Test that we don't unfold too much
+define void @test2(i8* %Src, i8* %Dst) {
+; CHECK-LABEL: test2
+
+; CHECK-NOT: load
+; CHECK-NOT: store
+; CHECK: llvm.memcpy.element.atomic
+entry:
+ call void @llvm.memcpy.element.atomic.p0i8.p0i8(i8* align 4 %Dst, i8* align 4 %Src, i64 1000, i32 4)
+ ret void
+}
+
+; Test that we will not unfold into non native integers
+define void @test3(i8* %Src, i8* %Dst) {
+; CHECK-LABEL: test3
+
+; CHECK-NOT: load
+; CHECK-NOT: store
+; CHECK: llvm.memcpy.element.atomic
+entry:
+ call void @llvm.memcpy.element.atomic.p0i8.p0i8(i8* align 64 %Dst, i8* align 64 %Src, i64 4, i32 64)
+ ret void
+}
+
+; Test that we will eliminate redundant bitcasts
+define void @test4(i64* %Src, i64* %Dst) {
+; CHECK-LABEL: test4
+; CHECK-NOT: llvm.memcpy.element.atomic
+
+; CHECK-NOT: bitcast
+
+; CHECK-DAG: [[VAL1:%[^\s]+]] = load atomic i64, i64* %Src unordered, align 16
+; CHECK-DAG: store atomic i64 [[VAL1]], i64* %Dst unordered, align 16
+
+; CHECK-DAG: [[SRC_ADDR2:%[^ ]+]] = getelementptr i64, i64* %Src, i64 1
+; CHECK-DAG: [[DST_ADDR2:%[^ ]+]] = getelementptr i64, i64* %Dst, i64 1
+; CHECK-DAG: [[VAL2:%[^\s]+]] = load atomic i64, i64* [[SRC_ADDR2]] unordered, align 8
+; CHECK-DAG: store atomic i64 [[VAL2]], i64* [[DST_ADDR2]] unordered, align 8
+
+; CHECK-DAG: [[SRC_ADDR3:%[^ ]+]] = getelementptr i64, i64* %Src, i64 2
+; CHECK-DAG: [[DST_ADDR3:%[^ ]+]] = getelementptr i64, i64* %Dst, i64 2
+; CHECK-DAG: [[VAL3:%[^ ]+]] = load atomic i64, i64* [[SRC_ADDR3]] unordered, align 8
+; CHECK-DAG: store atomic i64 [[VAL3]], i64* [[DST_ADDR3]] unordered, align 8
+
+; CHECK-DAG: [[SRC_ADDR4:%[^ ]+]] = getelementptr i64, i64* %Src, i64 3
+; CHECK-DAG: [[DST_ADDR4:%[^ ]+]] = getelementptr i64, i64* %Dst, i64 3
+; CHECK-DAG: [[VAL4:%[^ ]+]] = load atomic i64, i64* [[SRC_ADDR4]] unordered, align 8
+; CHECK-DAG: store atomic i64 [[VAL4]], i64* [[DST_ADDR4]] unordered, align 8
+entry:
+ %Src.casted = bitcast i64* %Src to i8*
+ %Dst.casted = bitcast i64* %Dst to i8*
+ call void @llvm.memcpy.element.atomic.p0i8.p0i8(i8* align 16 %Dst.casted, i8* align 16 %Src.casted, i64 4, i32 8)
+ ret void
+}
+
+define void @test5(i8* %Src, i8* %Dst) {
+; CHECK-LABEL: test5
+
+; CHECK-NOT: llvm.memcpy.element.atomic.p0i8.p0i8(i8* align 64 %Dst, i8* align 64 %Src, i64 0, i32 64)
+entry:
+ call void @llvm.memcpy.element.atomic.p0i8.p0i8(i8* align 64 %Dst, i8* align 64 %Src, i64 0, i32 64)
+ ret void
+}
+
+declare void @llvm.memcpy.element.atomic.p0i8.p0i8(i8* nocapture, i8* nocapture, i64, i32)
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