Skip to content

release/18.x: [InstCombine] Fold gep of exact unsigned division (#82334) #82347

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 2 commits into from
Feb 20, 2024
Merged

release/18.x: [InstCombine] Fold gep of exact unsigned division (#82334) #82347

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
c74afe6
[InstCombine] Add unsigned variants of gep exact div tests (NFC)
nikic Feb 20, 2024
ebc589e
[InstCombine] Fold gep of exact unsigned division (#82334)
nikic Feb 20, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
6 changes: 3 additions & 3 deletions llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2594,10 +2594,10 @@ Instruction *InstCombinerImpl::visitGetElementPtrInst(GetElementPtrInst &GEP) {
Value *V;
if ((has_single_bit(TyAllocSize) &&
match(GEP.getOperand(1),
m_Exact(m_AShr(m_Value(V),
m_SpecificInt(countr_zero(TyAllocSize)))))) ||
m_Exact(m_Shr(m_Value(V),
m_SpecificInt(countr_zero(TyAllocSize)))))) ||
match(GEP.getOperand(1),
m_Exact(m_SDiv(m_Value(V), m_SpecificInt(TyAllocSize))))) {
m_Exact(m_IDiv(m_Value(V), m_SpecificInt(TyAllocSize))))) {
GetElementPtrInst *NewGEP = GetElementPtrInst::Create(
Builder.getInt8Ty(), GEP.getPointerOperand(), V);
NewGEP->setIsInBounds(GEP.isInBounds());
Expand Down
54 changes: 54 additions & 0 deletions llvm/test/Transforms/InstCombine/getelementptr.ll
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,7 @@ define void @test_overaligned_vec(i8 %B) {
; CHECK-LABEL: @test_overaligned_vec(
; CHECK-NEXT: store i8 [[B:%.*]], ptr getelementptr inbounds ([10 x i8], ptr @Global, i64 0, i64 2), align 1
; CHECK-NEXT: ret void
;
%A = getelementptr <2 x half>, ptr @Global, i64 0, i64 1
store i8 %B, ptr %A
ret void
Expand Down Expand Up @@ -1473,6 +1474,16 @@ define ptr @gep_sdiv(ptr %p, i64 %off) {
ret ptr %ptr
}

define ptr @gep_udiv(ptr %p, i64 %off) {
; CHECK-LABEL: @gep_udiv(
; CHECK-NEXT: [[PTR:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 [[OFF:%.*]]
; CHECK-NEXT: ret ptr [[PTR]]
;
%index = udiv exact i64 %off, 7
%ptr = getelementptr %struct.C, ptr %p, i64 %index
ret ptr %ptr
}

define <2 x ptr> @gep_sdiv_vec(<2 x ptr> %p, <2 x i64> %off) {
; CHECK-LABEL: @gep_sdiv_vec(
; CHECK-NEXT: [[PTR:%.*]] = getelementptr i8, <2 x ptr> [[P:%.*]], <2 x i64> [[OFF:%.*]]
Expand Down Expand Up @@ -1503,6 +1514,16 @@ define ptr @gep_ashr(ptr %p, i64 %off) {
ret ptr %ptr
}

define ptr @gep_lshr(ptr %p, i64 %off) {
; CHECK-LABEL: @gep_lshr(
; CHECK-NEXT: [[PTR:%.*]] = getelementptr i8, ptr [[P:%.*]], i64 [[OFF:%.*]]
; CHECK-NEXT: ret ptr [[PTR]]
;
%index = lshr exact i64 %off, 2
%ptr = getelementptr i32, ptr %p, i64 %index
ret ptr %ptr
}

; Negative tests

define ptr @gep_i8(ptr %p, i64 %off) {
Expand All @@ -1525,6 +1546,17 @@ define ptr @gep_sdiv_mismatched_size(ptr %p, i64 %off) {
ret ptr %ptr
}

define ptr @gep_udiv_mismatched_size(ptr %p, i64 %off) {
; CHECK-LABEL: @gep_udiv_mismatched_size(
; CHECK-NEXT: [[INDEX:%.*]] = udiv exact i64 [[OFF:%.*]], 20
; CHECK-NEXT: [[PTR:%.*]] = getelementptr [[STRUCT_C:%.*]], ptr [[P:%.*]], i64 [[INDEX]]
; CHECK-NEXT: ret ptr [[PTR]]
;
%index = udiv exact i64 %off, 20
%ptr = getelementptr %struct.C, ptr %p, i64 %index
ret ptr %ptr
}

define ptr @gep_sdiv_without_exact(ptr %p, i64 %off) {
; CHECK-LABEL: @gep_sdiv_without_exact(
; CHECK-NEXT: [[INDEX:%.*]] = sdiv i64 [[OFF:%.*]], 7
Expand All @@ -1536,6 +1568,17 @@ define ptr @gep_sdiv_without_exact(ptr %p, i64 %off) {
ret ptr %ptr
}

define ptr @gep_udiv_without_exact(ptr %p, i64 %off) {
; CHECK-LABEL: @gep_udiv_without_exact(
; CHECK-NEXT: [[INDEX:%.*]] = udiv i64 [[OFF:%.*]], 7
; CHECK-NEXT: [[PTR:%.*]] = getelementptr [[STRUCT_C:%.*]], ptr [[P:%.*]], i64 [[INDEX]]
; CHECK-NEXT: ret ptr [[PTR]]
;
%index = udiv i64 %off, 7
%ptr = getelementptr %struct.C, ptr %p, i64 %index
ret ptr %ptr
}

define ptr @gep_ashr_without_exact(ptr %p, i64 %off) {
; CHECK-LABEL: @gep_ashr_without_exact(
; CHECK-NEXT: [[INDEX:%.*]] = ashr i64 [[OFF:%.*]], 2
Expand All @@ -1547,6 +1590,17 @@ define ptr @gep_ashr_without_exact(ptr %p, i64 %off) {
ret ptr %ptr
}

define ptr @gep_lshr_without_exact(ptr %p, i64 %off) {
; CHECK-LABEL: @gep_lshr_without_exact(
; CHECK-NEXT: [[INDEX:%.*]] = lshr i64 [[OFF:%.*]], 2
; CHECK-NEXT: [[PTR:%.*]] = getelementptr i32, ptr [[P:%.*]], i64 [[INDEX]]
; CHECK-NEXT: ret ptr [[PTR]]
;
%index = lshr i64 %off, 2
%ptr = getelementptr i32, ptr %p, i64 %index
ret ptr %ptr
}

define i1 @test_only_used_by_icmp(ptr %a, ptr %b, ptr %c) {
; CHECK-LABEL: @test_only_used_by_icmp(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq ptr [[B:%.*]], [[C:%.*]]
Expand Down