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[ConstantFold] Remove non-trivial gep-of-gep fold #93823

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merged 2 commits into from
May 31, 2024
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[ConstantFold] Remove non-trivial gep-of-gep fold #93823

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7fbc036
[ConstantFold] Remove non-trivial gep-of-gep fold
nikic May 30, 2024
7299a3b
Update one more test
nikic May 31, 2024
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4 changes: 2 additions & 2 deletions clang/test/CodeGenCXX/2011-12-19-init-list-ctor.cpp
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Expand Up @@ -22,5 +22,5 @@ struct S {
// CHECK: call void @_ZN1AC1EPKc(ptr {{[^,]*}} getelementptr inbounds (%struct.S, ptr @arr, i32 0, i32 1), ptr noundef @.str)
// CHECK: store i32 1, ptr getelementptr inbounds (%struct.S, ptr @arr, i64 1)
// CHECK: call void @_ZN1AC1EPKc(ptr {{[^,]*}} getelementptr inbounds (%struct.S, ptr @arr, i64 1, i32 1), ptr noundef @.str.1)
// CHECK: store i32 2, ptr getelementptr inbounds (%struct.S, ptr @arr, i64 2)
// CHECK: call void @_ZN1AC1EPKc(ptr {{[^,]*}} getelementptr inbounds (%struct.S, ptr @arr, i64 2, i32 1), ptr noundef @.str.2)
// CHECK: store i32 2, ptr getelementptr inbounds (%struct.S, ptr getelementptr inbounds (%struct.S, ptr @arr, i64 1), i64 1)
// CHECK: call void @_ZN1AC1EPKc(ptr {{[^,]*}} getelementptr inbounds (%struct.S, ptr getelementptr inbounds (%struct.S, ptr @arr, i64 1), i64 1, i32 1), ptr noundef @.str.2)
8 changes: 4 additions & 4 deletions clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist-pr12086.cpp
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Expand Up @@ -83,8 +83,8 @@ std::initializer_list<std::initializer_list<int>> nested = {
// CHECK-DYNAMIC-BL: store i32 5, ptr @_ZGR6nested2_
// CHECK-DYNAMIC-BL: store i32 {{.*}}, ptr getelementptr inbounds (i32, ptr @_ZGR6nested2_, i64 1)
// CHECK-DYNAMIC-BL: store ptr @_ZGR6nested2_,
// CHECK-DYNAMIC-BL: ptr getelementptr inbounds ({{.*}}, ptr @_ZGR6nested_, i64 2), align 8
// CHECK-DYNAMIC-BL: store i64 2, ptr getelementptr inbounds ({{.*}}, ptr @_ZGR6nested_, i64 2, i32 1), align 8
// CHECK-DYNAMIC-BL: ptr getelementptr inbounds ({{.*}}, ptr getelementptr inbounds ({{.*}}, ptr @_ZGR6nested_, i64 1), i64 1), align 8
// CHECK-DYNAMIC-BL: store i64 2, ptr getelementptr inbounds ({{.*}}, ptr getelementptr inbounds ({{.*}}, ptr @_ZGR6nested_, i64 1), i64 1, i32 1), align 8
// CHECK-DYNAMIC-BL: store ptr @_ZGR6nested_,
// CHECK-DYNAMIC-BL: ptr @nested, align 8
// CHECK-DYNAMIC-BL: store i64 3, ptr getelementptr inbounds ({{.*}}, ptr @nested, i32 0, i32 1), align 8
Expand Down Expand Up @@ -123,9 +123,9 @@ std::initializer_list<std::initializer_list<int>> nested = {
// CHECK-DYNAMIC-BE: store i32 5, ptr @_ZGR6nested2_
// CHECK-DYNAMIC-BE: store i32 {{.*}}, ptr getelementptr inbounds (i32, ptr @_ZGR6nested2_, i64 1)
// CHECK-DYNAMIC-BE: store ptr @_ZGR6nested2_,
// CHECK-DYNAMIC-BE: ptr getelementptr inbounds ({{.*}}, ptr @_ZGR6nested_, i64 2), align 8
// CHECK-DYNAMIC-BE: ptr getelementptr inbounds ({{.*}}, ptr getelementptr inbounds ({{.*}}, ptr @_ZGR6nested_, i64 1), i64 1), align 8
// CHECK-DYNAMIC-BE: store ptr getelementptr inbounds ([2 x i32], ptr @_ZGR6nested2_, i64 0, i64 2),
// CHECK-DYNAMIC-BE: ptr getelementptr inbounds ({{.*}}, ptr @_ZGR6nested_, i64 2, i32 1), align 8
// CHECK-DYNAMIC-BE: ptr getelementptr inbounds ({{.*}}, ptr getelementptr inbounds ({{.*}}, ptr @_ZGR6nested_, i64 1), i64 1, i32 1), align 8
// CHECK-DYNAMIC-BE: store ptr @_ZGR6nested_,
// CHECK-DYNAMIC-BE: ptr @nested, align 8
// CHECK-DYNAMIC-BE: store ptr getelementptr inbounds ([3 x {{.*}}], ptr @_ZGR6nested_, i64 0, i64 3),
Expand Down
4 changes: 2 additions & 2 deletions clang/test/CodeGenCXX/cxx0x-initializer-stdinitializerlist.cpp
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Expand Up @@ -370,8 +370,8 @@ namespace partly_constant {
//
// Third init list.
// CHECK-NOT: @[[PARTLY_CONSTANT_THIRD]],
// CHECK: store ptr {{.*}}@[[PARTLY_CONSTANT_THIRD]]{{.*}}, ptr getelementptr inbounds ({{.*}}, ptr {{.*}}@[[PARTLY_CONSTANT_INNER]]{{.*}}, i64 2)
// CHECK: store i64 4, ptr getelementptr inbounds ({{.*}}, ptr {{.*}}@[[PARTLY_CONSTANT_INNER]]{{.*}}, i64 2, i32 1)
// CHECK: store ptr {{.*}}@[[PARTLY_CONSTANT_THIRD]]{{.*}}, ptr getelementptr inbounds ({{.*}}, ptr getelementptr inbounds ({{.*}}, ptr {{.*}}@[[PARTLY_CONSTANT_INNER]]{{.*}}, i64 1), i64 1)
// CHECK: store i64 4, ptr getelementptr inbounds ({{.*}}, ptr getelementptr inbounds ({{.*}}, ptr {{.*}}@[[PARTLY_CONSTANT_INNER]]{{.*}}, i64 1), i64 1, i32 1)
// CHECK-NOT: @[[PARTLY_CONSTANT_THIRD]],
//
// Outer init list.
Expand Down
96 changes: 48 additions & 48 deletions clang/test/OpenMP/threadprivate_codegen.cpp
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56 changes: 4 additions & 52 deletions llvm/lib/IR/ConstantFold.cpp
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Expand Up @@ -1429,64 +1429,16 @@ static Constant *foldGEPOfGEP(GEPOperator *GEP, Type *PointeeTy, bool InBounds,
if (GEP->getInRange())
return nullptr;

// Only handle simple case with leading zero index. We cannot perform an
// actual addition as we don't know the correct index type size to use.
Constant *Idx0 = cast<Constant>(Idxs[0]);
if (Idx0->isNullValue()) {
// Handle the simple case of a zero index.
SmallVector<Value*, 16> NewIndices;
NewIndices.reserve(Idxs.size() + GEP->getNumIndices());
NewIndices.append(GEP->idx_begin(), GEP->idx_end());
NewIndices.append(Idxs.begin() + 1, Idxs.end());
return ConstantExpr::getGetElementPtr(
GEP->getSourceElementType(), cast<Constant>(GEP->getPointerOperand()),
NewIndices, InBounds && GEP->isInBounds());
}

gep_type_iterator LastI = gep_type_end(GEP);
for (gep_type_iterator I = gep_type_begin(GEP), E = gep_type_end(GEP);
I != E; ++I)
LastI = I;

// We can't combine GEPs if the last index is a struct type.
if (!LastI.isSequential())
return nullptr;
// We could perform the transform with non-constant index, but prefer leaving
// it as GEP of GEP rather than GEP of add for now.
ConstantInt *CI = dyn_cast<ConstantInt>(Idx0);
if (!CI)
return nullptr;

// TODO: This code may be extended to handle vectors as well.
auto *LastIdx = cast<Constant>(GEP->getOperand(GEP->getNumOperands()-1));
Type *LastIdxTy = LastIdx->getType();
if (LastIdxTy->isVectorTy())
if (!Idx0->isNullValue())
return nullptr;

SmallVector<Value*, 16> NewIndices;
NewIndices.reserve(Idxs.size() + GEP->getNumIndices());
NewIndices.append(GEP->idx_begin(), GEP->idx_end() - 1);

// Add the last index of the source with the first index of the new GEP.
// Make sure to handle the case when they are actually different types.
if (LastIdxTy != Idx0->getType()) {
unsigned CommonExtendedWidth =
std::max(LastIdxTy->getIntegerBitWidth(),
Idx0->getType()->getIntegerBitWidth());
CommonExtendedWidth = std::max(CommonExtendedWidth, 64U);

Type *CommonTy =
Type::getIntNTy(LastIdxTy->getContext(), CommonExtendedWidth);
if (Idx0->getType() != CommonTy)
Idx0 = ConstantFoldCastInstruction(Instruction::SExt, Idx0, CommonTy);
if (LastIdx->getType() != CommonTy)
LastIdx =
ConstantFoldCastInstruction(Instruction::SExt, LastIdx, CommonTy);
if (!Idx0 || !LastIdx)
return nullptr;
}

NewIndices.push_back(ConstantExpr::get(Instruction::Add, Idx0, LastIdx));
NewIndices.append(GEP->idx_begin(), GEP->idx_end());
NewIndices.append(Idxs.begin() + 1, Idxs.end());

return ConstantExpr::getGetElementPtr(
GEP->getSourceElementType(), cast<Constant>(GEP->getPointerOperand()),
NewIndices, InBounds && GEP->isInBounds());
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/Other/constant-fold-gep.ll
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Expand Up @@ -104,7 +104,7 @@

; Fold GEP of a GEP. Very simple cases are folded without targetdata.

; PLAIN: @Y = global ptr getelementptr inbounds ([3 x { i32, i32 }], ptr @ext, i64 2)
; PLAIN: @Y = global ptr getelementptr inbounds ([3 x { i32, i32 }], ptr getelementptr inbounds ([3 x { i32, i32 }], ptr @ext, i64 1), i64 1)
; PLAIN: @Z = global ptr getelementptr inbounds (i32, ptr getelementptr inbounds ([3 x { i32, i32 }], ptr @ext, i64 0, i64 1, i32 0), i64 1)
; OPT: @Y = local_unnamed_addr global ptr getelementptr inbounds (i8, ptr @ext, i64 48)
; OPT: @Z = local_unnamed_addr global ptr getelementptr inbounds (i8, ptr @ext, i64 12)
Expand Down
2 changes: 1 addition & 1 deletion llvm/test/Transforms/InstCombine/gepgep.ll
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Expand Up @@ -10,7 +10,7 @@ declare void @use(ptr)

define void @f() {
; CHECK-LABEL: define void @f() {
; CHECK-NEXT: call void @use(ptr getelementptr (i8, ptr @buffer, i64 add (i64 sub (i64 0, i64 ptrtoint (ptr @buffer to i64)), i64 127)))
; CHECK-NEXT: call void @use(ptr getelementptr (i8, ptr getelementptr (i8, ptr @buffer, i64 add (i64 sub (i64 0, i64 ptrtoint (ptr @buffer to i64)), i64 63)), i64 64))
; CHECK-NEXT: ret void
;
call void @use(ptr getelementptr (i8, ptr getelementptr (i8, ptr @buffer, i64 add (i64 sub (i64 0, i64 ptrtoint (ptr @buffer to i64)), i64 63)), i64 64))
Expand Down
3 changes: 1 addition & 2 deletions llvm/test/Transforms/InstCombine/getelementptr.ll
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Expand Up @@ -1683,10 +1683,9 @@ if.else:

@g = external global i8

; FIXME: This is a miscompile
define ptr @constexpr_gep_of_gep_with_narrow_type() {
; CHECK-LABEL: @constexpr_gep_of_gep_with_narrow_type(
; CHECK-NEXT: ret ptr getelementptr (i8, ptr @g, i64 -2)
; CHECK-NEXT: ret ptr getelementptr (i8, ptr @g, i64 254)
;
ret ptr getelementptr (i8, ptr getelementptr (i8, ptr @g, i8 127), i8 127)
}
Expand Down
16 changes: 8 additions & 8 deletions llvm/test/Transforms/InstCombine/ptrtoint-nullgep.ll
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Expand Up @@ -68,10 +68,10 @@ define void @constant_fold_ptrtoint_of_gep_of_nullgep() {
; LLPARSER-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) null, i64 1234) to i64))
; LLPARSER-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) null, i64 1234) to i64))
; LLPARSER-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) null, i64 1234) to i64))
; LLPARSER-NEXT: call void @use_i64(i64 0)
; LLPARSER-NEXT: call void @use_i64(i64 0)
; LLPARSER-NEXT: call void @use_i64(i64 0)
; LLPARSER-NEXT: call void @use_i64(i64 0)
; LLPARSER-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) null, i64 -1), i64 1) to i64))
; LLPARSER-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) null, i64 -1), i64 1) to i64))
; LLPARSER-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) getelementptr (i8, ptr addrspace(1) null, i64 -1), i64 1) to i64))
; LLPARSER-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) getelementptr (i8, ptr addrspace(1) null, i64 -1), i64 1) to i64))
; LLPARSER-NEXT: ret void
;
; INSTSIMPLIFY-LABEL: define {{[^@]+}}@constant_fold_ptrtoint_of_gep_of_nullgep() {
Expand All @@ -83,10 +83,10 @@ define void @constant_fold_ptrtoint_of_gep_of_nullgep() {
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) null, i64 1234) to i64))
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) null, i64 1234) to i64))
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) null, i64 1234) to i64))
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 0)
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 0)
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 0)
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 0)
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) null, i64 -1), i64 1) to i64))
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) null, i64 -1), i64 1) to i64))
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr inbounds (i8, ptr addrspace(1) getelementptr (i8, ptr addrspace(1) null, i64 -1), i64 1) to i64))
; INSTSIMPLIFY-NEXT: call void @use_i64(i64 ptrtoint (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) getelementptr (i8, ptr addrspace(1) null, i64 -1), i64 1) to i64))
; INSTSIMPLIFY-NEXT: ret void
;
; INSTCOMBINE-LABEL: define {{[^@]+}}@constant_fold_ptrtoint_of_gep_of_nullgep() {
Expand Down
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