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[InstCombine] fold sub(zext(ptrtoint),zext(ptrtoint)) #115369

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Merged
merged 6 commits into from
Nov 15, 2024
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[InstCombine] fold sub(zext(ptrtoint),zext(ptrtoint)) #115369

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e360e21
[InstCombine] fold `sub(zext(ptrtoint),zext(ptrtoint))`
npanchen Nov 7, 2024
5c692fd
Changed pattern matching
npanchen Nov 8, 2024
a2b3e03
Addressed comments
npanchen Nov 13, 2024
fa83e47
Addressed comments
npanchen Nov 14, 2024
11090ab
Updated test
npanchen Nov 14, 2024
987bfd9
Added identical test that use non-global ptr
npanchen Nov 15, 2024
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4 changes: 2 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2618,8 +2618,8 @@ Instruction *InstCombinerImpl::visitSub(BinaryOperator &I) {
// Optimize pointer differences into the same array into a size. Consider:
// &A[10] - &A[0]: we should compile this to "10".
Value *LHSOp, *RHSOp;
if (match(Op0, m_PtrToInt(m_Value(LHSOp))) &&
match(Op1, m_PtrToInt(m_Value(RHSOp))))
if (match(Op0, m_ZExtOrSelf(m_PtrToInt(m_Value(LHSOp)))) &&
match(Op1, m_ZExtOrSelf(m_PtrToInt(m_Value(RHSOp)))))
if (Value *Res = OptimizePointerDifference(LHSOp, RHSOp, I.getType(),
I.hasNoUnsignedWrap()))
return replaceInstUsesWith(I, Res);
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56 changes: 56 additions & 0 deletions llvm/test/Transforms/InstCombine/sub-gep.ll
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Expand Up @@ -270,6 +270,36 @@ define i64 @test25(ptr %P, i64 %A){
ret i64 %G
}

define i64 @zext_ptrtoint_sub_ptrtoint(ptr %p, i32 %offset) {
; CHECK-LABLE: @zext_ptrtoint_sub_ptrtoint(
; CHECK-NEXT: %1 = sext i32 %offset to i64
; CHECK-NEXT: %A = getelementptr bfloat, ptr @Arr, i64 %1
; CHECK-NEXT: %2 = ptrtoint ptr %A to i64
; CHECK-NEXT: %C = and i64 %2, 4294967294
; CHECK-NEXT: %D = sub i64 %C, ptrtoint (ptr @Arr to i64)
; CHECK-NEXT: ret i64 %D
%A = getelementptr bfloat, ptr @Arr, i32 %offset
%B = ptrtoint ptr %A to i32
%C = zext i32 %B to i64
%D = sub i64 %C, ptrtoint (ptr @Arr to i64)
ret i64 %D
}

define i64 @ptrtoint_sub_zext_ptrtoint(ptr %p, i32 %offset) {
; CHECK-LABLE: @ptrtoint_sub_zext_ptrtoint(
; CHECK-NEXT: %1 = sext i32 %offset to i64
; CHECK-NEXT: %A = getelementptr bfloat, ptr @Arr, i64 %1
; CHECK-NEXT: %2 = ptrtoint ptr %A to i64
; CHECK-NEXT: %C = and i64 %2, 4294967294
; CHECK-NEXT: %D = sub i64 ptrtoint (ptr @Arr to i64), %C
; CHECK-NEXT: ret i64 %D
%A = getelementptr bfloat, ptr @Arr, i32 %offset
%B = ptrtoint ptr %A to i32
%C = zext i32 %B to i64
%D = sub i64 ptrtoint (ptr @Arr to i64), %C
ret i64 %D
}

@Arr_as1 = external addrspace(1) global [42 x i16]

define i16 @test25_as1(ptr addrspace(1) %P, i64 %A) {
Expand All @@ -285,6 +315,32 @@ define i16 @test25_as1(ptr addrspace(1) %P, i64 %A) {
ret i16 %G
}

define i64 @zext_ptrtoint_sub_ptrtoint_as1(ptr addrspace(1) %p, i32 %offset) {
; CHECK-LABLE: @zext_ptrtoint_sub_ptrtoint_as1(
; CHECK-NEXT: %1 = trunc i32 %offset to i16
; CHECK-NEXT: %A.idx = shl i16 %1, 1
; CHECK-NEXT: %D = sext i16 %A.idx to i64
; CHECK-NEXT: ret i64 %D
%A = getelementptr bfloat, ptr addrspace(1) @Arr_as1, i32 %offset
%B = ptrtoint ptr addrspace(1) %A to i32
%C = zext i32 %B to i64
%D = sub i64 %C, ptrtoint (ptr addrspace(1) @Arr_as1 to i64)
ret i64 %D
}

define i64 @ptrtoint_sub_zext_ptrtoint_as1(ptr addrspace(1) %p, i32 %offset) {
; CHECK-LABLE: @ptrtoint_sub_zext_ptrtoint_as1(
; CHECK-NEXT: %1 = trunc i32 %offset to i16
; CHECK-NEXT: %A.idx.neg = mul i16 %1, -2
; CHECK-NEXT: %D = sext i16 %A.idx.neg to i64
; CHECK-NEXT: ret i64 %D
%A = getelementptr bfloat, ptr addrspace(1) @Arr_as1, i32 %offset
%B = ptrtoint ptr addrspace(1) %A to i32
%C = zext i32 %B to i64
%D = sub i64 ptrtoint (ptr addrspace(1) @Arr_as1 to i64), %C
ret i64 %D
}

define i64 @test30(ptr %foo, i64 %i, i64 %j) {
; CHECK-LABEL: @test30(
; CHECK-NEXT: [[GEP1_IDX:%.*]] = shl nsw i64 [[I:%.*]], 2
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