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[InstCombine][SVE] Fix visitGetElementPtrInst for scalable type.

Summary:
This patch fix the following issues in InstCombiner::visitGetElementPtrInst

    1. Skip for scalable type if transformation requires fixed size number of
    vector element.
    2. Skip for scalable type if transformation relies on compile-time known type
    alloc size.
    3. Use VectorType::getElementCount when scalable property is used to construct
    new VectorType.
    4. Use TypeSize::getKnownMinSize when minimal size of a scalable type is valid to determine GEP 'inbounds'.
    5. Explicitly call TypeSize::getFixedSize to avoid implicit type conversion to uint64_t.

Reviewers: sdesmalen, efriedma, spatel, ctetreau

Reviewed By: efriedma

Subscribers: tschuett, hiraditya, rkruppe, psnobl, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D78081
This commit is contained in:
Huihui Zhang 2020-04-14 12:38:03 -07:00
parent 7beb37bd0a
commit e95004d091
2 changed files with 93 additions and 14 deletions

View File

@ -1854,12 +1854,16 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
SmallVector<Value*, 8> Ops(GEP.op_begin(), GEP.op_end());
Type *GEPType = GEP.getType();
Type *GEPEltType = GEP.getSourceElementType();
bool IsGEPSrcEleScalable =
GEPEltType->isVectorTy() && cast<VectorType>(GEPEltType)->isScalable();
if (Value *V = SimplifyGEPInst(GEPEltType, Ops, SQ.getWithInstruction(&GEP)))
return replaceInstUsesWith(GEP, V);
// For vector geps, use the generic demanded vector support.
if (auto *GEPVTy = dyn_cast<VectorType>(GEP.getType())) {
auto VWidth = GEPVTy->getNumElements();
// Skip if GEP return type is scalable. The number of elements is unknown at
// compile-time.
if (GEPType->isVectorTy() && !cast<VectorType>(GEPType)->isScalable()) {
auto VWidth = cast<VectorType>(GEPType)->getNumElements();
APInt UndefElts(VWidth, 0);
APInt AllOnesEltMask(APInt::getAllOnesValue(VWidth));
if (Value *V = SimplifyDemandedVectorElts(&GEP, AllOnesEltMask,
@ -1896,7 +1900,7 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
Type *NewIndexType =
IndexTy->isVectorTy()
? VectorType::get(NewScalarIndexTy,
cast<VectorType>(IndexTy)->getNumElements())
cast<VectorType>(IndexTy)->getElementCount())
: NewScalarIndexTy;
// If the element type has zero size then any index over it is equivalent
@ -2146,11 +2150,13 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
GEP.getName());
}
if (GEP.getNumIndices() == 1) {
// Skip if GEP source element type is scalable. The type alloc size is unknown
// at compile-time.
if (GEP.getNumIndices() == 1 && !IsGEPSrcEleScalable) {
unsigned AS = GEP.getPointerAddressSpace();
if (GEP.getOperand(1)->getType()->getScalarSizeInBits() ==
DL.getIndexSizeInBits(AS)) {
uint64_t TyAllocSize = DL.getTypeAllocSize(GEPEltType);
uint64_t TyAllocSize = DL.getTypeAllocSize(GEPEltType).getFixedSize();
bool Matched = false;
uint64_t C;
@ -2263,10 +2269,12 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
}
}
}
} else if (GEP.getNumOperands() == 2) {
// Transform things like:
// %t = getelementptr i32* bitcast ([2 x i32]* %str to i32*), i32 %V
// into: %t1 = getelementptr [2 x i32]* %str, i32 0, i32 %V; bitcast
} else if (GEP.getNumOperands() == 2 && !IsGEPSrcEleScalable) {
// Skip if GEP source element type is scalable. The type alloc size is
// unknown at compile-time.
// Transform things like: %t = getelementptr i32*
// bitcast ([2 x i32]* %str to i32*), i32 %V into: %t1 = getelementptr [2
// x i32]* %str, i32 0, i32 %V; bitcast
if (StrippedPtrEltTy->isArrayTy() &&
DL.getTypeAllocSize(StrippedPtrEltTy->getArrayElementType()) ==
DL.getTypeAllocSize(GEPEltType)) {
@ -2290,8 +2298,8 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
if (GEPEltType->isSized() && StrippedPtrEltTy->isSized()) {
// Check that changing the type amounts to dividing the index by a scale
// factor.
uint64_t ResSize = DL.getTypeAllocSize(GEPEltType);
uint64_t SrcSize = DL.getTypeAllocSize(StrippedPtrEltTy);
uint64_t ResSize = DL.getTypeAllocSize(GEPEltType).getFixedSize();
uint64_t SrcSize = DL.getTypeAllocSize(StrippedPtrEltTy).getFixedSize();
if (ResSize && SrcSize % ResSize == 0) {
Value *Idx = GEP.getOperand(1);
unsigned BitWidth = Idx->getType()->getPrimitiveSizeInBits();
@ -2330,9 +2338,10 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
StrippedPtrEltTy->isArrayTy()) {
// Check that changing to the array element type amounts to dividing the
// index by a scale factor.
uint64_t ResSize = DL.getTypeAllocSize(GEPEltType);
uint64_t ResSize = DL.getTypeAllocSize(GEPEltType).getFixedSize();
uint64_t ArrayEltSize =
DL.getTypeAllocSize(StrippedPtrEltTy->getArrayElementType());
DL.getTypeAllocSize(StrippedPtrEltTy->getArrayElementType())
.getFixedSize();
if (ResSize && ArrayEltSize % ResSize == 0) {
Value *Idx = GEP.getOperand(1);
unsigned BitWidth = Idx->getType()->getPrimitiveSizeInBits();
@ -2480,7 +2489,9 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
if (auto *AI = dyn_cast<AllocaInst>(UnderlyingPtrOp)) {
if (GEP.accumulateConstantOffset(DL, BasePtrOffset) &&
BasePtrOffset.isNonNegative()) {
APInt AllocSize(IdxWidth, DL.getTypeAllocSize(AI->getAllocatedType()));
APInt AllocSize(
IdxWidth,
DL.getTypeAllocSize(AI->getAllocatedType()).getKnownMinSize());
if (BasePtrOffset.ule(AllocSize)) {
return GetElementPtrInst::CreateInBounds(
GEP.getSourceElementType(), PtrOp, makeArrayRef(Ops).slice(1),

View File

@ -0,0 +1,68 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -S -instcombine < %s | FileCheck %s
; This test is used to verify we are not crashing at Assertion `CastInst::castIsValid(opc, C, Ty) && "Invalid constantexpr cast!".
define <vscale x 2 x i8*> @gep_index_type_is_scalable(i8* %p) {
; CHECK-LABEL: @gep_index_type_is_scalable(
; CHECK-NEXT: [[GEP:%.*]] = getelementptr i8, i8* [[P:%.*]], <vscale x 2 x i64> undef
; CHECK-NEXT: ret <vscale x 2 x i8*> [[GEP]]
;
%gep = getelementptr i8, i8* %p, <vscale x 2 x i64> undef
ret <vscale x 2 x i8*> %gep
}
; This test serves to verify code changes for "GEP.getNumIndices() == 1".
define <vscale x 4 x i32>* @gep_num_of_indices_1(<vscale x 4 x i32>* %p) {
; CHECK-LABEL: @gep_num_of_indices_1(
; CHECK-NEXT: [[GEP:%.*]] = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* [[P:%.*]], i64 1
; CHECK-NEXT: ret <vscale x 4 x i32>* [[GEP]]
;
%gep = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* %p, i64 1
ret <vscale x 4 x i32>* %gep
}
; This test serves to verify code changes for "GEP.getNumOperands() == 2".
define void @gep_bitcast(i8* %p) {
; CHECK-LABEL: @gep_bitcast(
; CHECK-NEXT: [[CAST:%.*]] = bitcast i8* [[P:%.*]] to <vscale x 16 x i8>*
; CHECK-NEXT: store <vscale x 16 x i8> zeroinitializer, <vscale x 16 x i8>* [[CAST]], align 16
; CHECK-NEXT: [[GEP2:%.*]] = getelementptr <vscale x 16 x i8>, <vscale x 16 x i8>* [[CAST]], i64 1
; CHECK-NEXT: store <vscale x 16 x i8> zeroinitializer, <vscale x 16 x i8>* [[GEP2]], align 16
; CHECK-NEXT: ret void
;
%cast = bitcast i8* %p to <vscale x 16 x i8>*
%gep1 = getelementptr <vscale x 16 x i8>, <vscale x 16 x i8>* %cast, i64 0
store <vscale x 16 x i8> zeroinitializer, <vscale x 16 x i8>* %gep1
%gep2 = getelementptr <vscale x 16 x i8>, <vscale x 16 x i8>* %cast, i64 1
store <vscale x 16 x i8> zeroinitializer, <vscale x 16 x i8>* %gep2
ret void
}
; These tests serve to verify code changes when underlying gep ptr is alloca.
; This test is to verify 'inbounds' is added when it's valid to accumulate constant offset.
define i32 @gep_alloca_inbounds_vscale_zero() {
; CHECK-LABEL: @gep_alloca_inbounds_vscale_zero(
; CHECK-NEXT: [[A:%.*]] = alloca <vscale x 4 x i32>, align 16
; CHECK-NEXT: [[TMP:%.*]] = getelementptr inbounds <vscale x 4 x i32>, <vscale x 4 x i32>* [[A]], i64 0, i64 2
; CHECK-NEXT: [[LOAD:%.*]] = load i32, i32* [[TMP]], align 8
; CHECK-NEXT: ret i32 [[LOAD]]
;
%a = alloca <vscale x 4 x i32>
%tmp = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* %a, i32 0, i32 2
%load = load i32, i32* %tmp
ret i32 %load
}
; This test is to verify 'inbounds' is not added when a constant offset can not be determined at compile-time.
define i32 @gep_alloca_inbounds_vscale_nonzero() {
; CHECK-LABEL: @gep_alloca_inbounds_vscale_nonzero(
; CHECK-NEXT: [[A:%.*]] = alloca <vscale x 4 x i32>, align 16
; CHECK-NEXT: [[TMP:%.*]] = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* [[A]], i64 1, i64 2
; CHECK-NEXT: [[LOAD:%.*]] = load i32, i32* [[TMP]], align 8
; CHECK-NEXT: ret i32 [[LOAD]]
;
%a = alloca <vscale x 4 x i32>
%tmp = getelementptr <vscale x 4 x i32>, <vscale x 4 x i32>* %a, i32 1, i32 2
%load = load i32, i32* %tmp
ret i32 %load
}