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[InstCombine] Handle scalable geps in EmitGEPOffset #71565

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Merged
merged 1 commit into from
Nov 8, 2023
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[InstCombine] Handle scalable geps in EmitGEPOffset #71565

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11 changes: 7 additions & 4 deletions llvm/lib/Analysis/Local.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -45,7 +45,8 @@ Value *llvm::emitGEPOffset(IRBuilderBase *Builder, const DataLayout &DL,
for (User::op_iterator i = GEP->op_begin() + 1, e = GEP->op_end(); i != e;
++i, ++GTI) {
Value *Op = *i;
uint64_t Size = DL.getTypeAllocSize(GTI.getIndexedType()) & PtrSizeMask;
TypeSize TSize = DL.getTypeAllocSize(GTI.getIndexedType());
uint64_t Size = TSize.getKnownMinValue() & PtrSizeMask;
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I'm not entirely clear on the role of PtrSizeMask, but it seems odd to be applying this to the known min value for a scalable vector and not the full dynamic type size. Doesn't seem to match the fixed vector semantics.

if (Constant *OpC = dyn_cast<Constant>(Op)) {
if (OpC->isZeroValue())
continue;
Expand All @@ -70,10 +71,12 @@ Value *llvm::emitGEPOffset(IRBuilderBase *Builder, const DataLayout &DL,
// Convert to correct type.
if (Op->getType() != IntIdxTy)
Op = Builder->CreateIntCast(Op, IntIdxTy, true, Op->getName() + ".c");
if (Size != 1) {
if (Size != 1 || TSize.isScalable()) {
// We'll let instcombine(mul) convert this to a shl if possible.
Op = Builder->CreateMul(Op, ConstantInt::get(IntIdxTy, Size),
GEP->getName() + ".idx", false /*NUW*/,
auto *ScaleC = ConstantInt::get(IntIdxTy, Size);
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This expression should just be IRBuilder::getTypeSize(IntIdxTy, TSize).

Value *Scale =
!TSize.isScalable() ? ScaleC : Builder->CreateVScale(ScaleC);
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It looks like ScaleC could possibly be a VectorType judging from the CreateVectorSplat call above. Do we need a test for this?

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Thanks for the suggestion. It looks like the above CreateVectorSplat wouldn't handle scalable vectors either. That is actually a different form of scalable vector, but I'll try and address that in a separate patch.

Op = Builder->CreateMul(Op, Scale, GEP->getName() + ".idx", false /*NUW*/,
isInBounds /*NSW*/);
}
AddOffset(Op);
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70 changes: 70 additions & 0 deletions llvm/test/Transforms/InstCombine/icmp-gep.ll
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Expand Up @@ -396,3 +396,73 @@ define i1 @test61_as1(ptr addrspace(1) %foo, i16 %i, i16 %j) {
ret i1 %cmp
; Don't transform non-inbounds GEPs.
}

define i1 @test_scalable_same(ptr %x) {
; CHECK-LABEL: @test_scalable_same(
; CHECK-NEXT: ret i1 false
;
%a = getelementptr <vscale x 4 x i8>, ptr %x, i64 8
%b = getelementptr inbounds <vscale x 4 x i8>, ptr %x, i64 8
%c = icmp ugt ptr %a, %b
ret i1 %c
}

define i1 @test_scalable_x(ptr %x) {
; CHECK-LABEL: @test_scalable_x(
; CHECK-NEXT: [[TMP1:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[A_IDX_MASK:%.*]] = and i64 [[TMP1]], 576460752303423487
; CHECK-NEXT: [[C:%.*]] = icmp eq i64 [[A_IDX_MASK]], 0
; CHECK-NEXT: ret i1 [[C]]
;
%a = getelementptr <vscale x 4 x i8>, ptr %x, i64 8
%c = icmp eq ptr %a, %x
ret i1 %c
}

define i1 @test_scalable_xc(ptr %x) {
; CHECK-LABEL: @test_scalable_xc(
; CHECK-NEXT: [[TMP1:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[A_IDX_MASK:%.*]] = and i64 [[TMP1]], 576460752303423487
; CHECK-NEXT: [[C:%.*]] = icmp eq i64 [[A_IDX_MASK]], 0
; CHECK-NEXT: ret i1 [[C]]
;
%a = getelementptr <vscale x 4 x i8>, ptr %x, i64 8
%c = icmp eq ptr %x, %a
ret i1 %c
}

define i1 @test_scalable_xy(ptr %foo, i64 %i, i64 %j) {
; CHECK-LABEL: @test_scalable_xy(
; CHECK-NEXT: [[TMP1:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP2:%.*]] = shl i64 [[TMP1]], 2
; CHECK-NEXT: [[GEP2_IDX:%.*]] = mul nsw i64 [[TMP2]], [[J:%.*]]
; CHECK-NEXT: [[TMP3:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP4:%.*]] = shl i64 [[TMP3]], 4
; CHECK-NEXT: [[GEP1_IDX:%.*]] = mul nsw i64 [[TMP4]], [[I:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp sgt i64 [[GEP2_IDX]], [[GEP1_IDX]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%bit = addrspacecast ptr %foo to ptr addrspace(3)
%gep1 = getelementptr inbounds <vscale x 4 x i32>, ptr addrspace(3) %bit, i64 %i
%gep2 = getelementptr inbounds <vscale x 4 x i8>, ptr %foo, i64 %j
%cast1 = addrspacecast ptr addrspace(3) %gep1 to ptr
%cmp = icmp ult ptr %cast1, %gep2
ret i1 %cmp
}

define i1 @test_scalable_ij(ptr %foo, i64 %i, i64 %j) {
; CHECK-LABEL: @test_scalable_ij(
; CHECK-NEXT: [[TMP1:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP2:%.*]] = shl i64 [[TMP1]], 4
; CHECK-NEXT: [[GEP1_IDX:%.*]] = mul nsw i64 [[TMP2]], [[I:%.*]]
; CHECK-NEXT: [[TMP3:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP4:%.*]] = shl i64 [[TMP3]], 2
; CHECK-NEXT: [[GEP2_IDX:%.*]] = mul nsw i64 [[TMP4]], [[J:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i64 [[GEP1_IDX]], [[GEP2_IDX]]
; CHECK-NEXT: ret i1 [[CMP]]
;
%gep1 = getelementptr inbounds <vscale x 4 x i32>, ptr %foo, i64 %i
%gep2 = getelementptr inbounds <vscale x 4 x i8>, ptr %foo, i64 %j
%cmp = icmp ult ptr %gep1, %gep2
ret i1 %cmp
}
61 changes: 61 additions & 0 deletions llvm/test/Transforms/InstCombine/sub-gep.ll
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Expand Up @@ -370,6 +370,67 @@ define i64 @gep_diff_with_bitcast(ptr %p, i64 %idx) {
ret i64 %i6
}

define i64 @sub_scalable(ptr noundef %val1) {
; CHECK-LABEL: @sub_scalable(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP1:%.*]] = shl i64 [[TMP0]], 4
; CHECK-NEXT: ret i64 [[TMP1]]
;
entry:
%gep1 = getelementptr <vscale x 4 x i32>, ptr %val1, i64 1
%sub.ptr.lhs.cast.i = ptrtoint ptr %gep1 to i64
%sub.ptr.rhs.cast.i = ptrtoint ptr %val1 to i64
%sub.ptr.sub.i = sub i64 %sub.ptr.lhs.cast.i, %sub.ptr.rhs.cast.i
ret i64 %sub.ptr.sub.i
}

define i64 @sub_scalable2(ptr noundef %val1) {
; CHECK-LABEL: @sub_scalable2(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP1:%.*]] = shl i64 [[TMP0]], 4
; CHECK-NEXT: [[TMP2:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[GEP2_IDX:%.*]] = shl i64 [[TMP2]], 5
; CHECK-NEXT: [[GEPDIFF:%.*]] = sub i64 [[TMP1]], [[GEP2_IDX]]
; CHECK-NEXT: ret i64 [[GEPDIFF]]
;
entry:
%gep1 = getelementptr <vscale x 4 x i32>, ptr %val1, i64 1
%sub.ptr.lhs.cast.i = ptrtoint ptr %gep1 to i64
%gep2 = getelementptr <vscale x 4 x i32>, ptr %val1, i64 2
%sub.ptr.rhs.cast.i = ptrtoint ptr %gep2 to i64
%sub.ptr.sub.i = sub i64 %sub.ptr.lhs.cast.i, %sub.ptr.rhs.cast.i
ret i64 %sub.ptr.sub.i
}

define i64 @nullptrtoint_scalable_c() {
; CHECK-LABEL: @nullptrtoint_scalable_c(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[PTR_IDX:%.*]] = shl i64 [[TMP0]], 7
; CHECK-NEXT: ret i64 [[PTR_IDX]]
;
entry:
%ptr = getelementptr inbounds <vscale x 4 x i32>, ptr null, i64 8
%ret = ptrtoint ptr %ptr to i64
ret i64 %ret
}

define i64 @nullptrtoint_scalable_x(i64 %x) {
; CHECK-LABEL: @nullptrtoint_scalable_x(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = call i64 @llvm.vscale.i64()
; CHECK-NEXT: [[TMP1:%.*]] = shl i64 [[TMP0]], 4
; CHECK-NEXT: [[PTR_IDX:%.*]] = mul nsw i64 [[TMP1]], [[X:%.*]]
; CHECK-NEXT: ret i64 [[PTR_IDX]]
;
entry:
%ptr = getelementptr inbounds <vscale x 4 x i32>, ptr null, i64 %x
%ret = ptrtoint ptr %ptr to i64
ret i64 %ret
}

define i1 @_gep_phi1(ptr noundef %str1) {
; CHECK-LABEL: @_gep_phi1(
; CHECK-NEXT: entry:
Expand Down