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[InstSimplify] Support ptrtoaddr in pointer subtraction fold #162672

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Merged
merged 1 commit into from
Oct 10, 2025
Merged

[InstSimplify] Support ptrtoaddr in pointer subtraction fold #162672

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12 changes: 12 additions & 0 deletions llvm/include/llvm/IR/PatternMatch.h
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Original file line number Diff line number Diff line change
Expand Up @@ -2184,6 +2184,18 @@ inline PtrToIntSameSize_match<OpTy> m_PtrToIntSameSize(const DataLayout &DL,
return PtrToIntSameSize_match<OpTy>(DL, Op);
}

/// Matches PtrToAddr.
template <typename OpTy>
inline CastOperator_match<OpTy, Instruction::PtrToAddr>
m_PtrToAddr(const OpTy &Op) {
return CastOperator_match<OpTy, Instruction::PtrToAddr>(Op);
}

/// Matches PtrToInt or PtrToAddr.
template <typename OpTy> inline auto m_PtrToIntOrAddr(const OpTy &Op) {
return m_CombineOr(m_PtrToInt(Op), m_PtrToAddr(Op));
}

/// Matches IntToPtr.
template <typename OpTy>
inline CastOperator_match<OpTy, Instruction::IntToPtr>
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4 changes: 3 additions & 1 deletion llvm/lib/Analysis/InstructionSimplify.cpp
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Expand Up @@ -853,10 +853,12 @@ static Value *simplifySubInst(Value *Op0, Value *Op1, bool IsNSW, bool IsNUW,
return W;

// Variations on GEP(base, I, ...) - GEP(base, i, ...) -> GEP(null, I-i, ...).
if (match(Op0, m_PtrToInt(m_Value(X))) && match(Op1, m_PtrToInt(m_Value(Y))))
if (match(Op0, m_PtrToIntOrAddr(m_Value(X))) &&
match(Op1, m_PtrToIntOrAddr(m_Value(Y)))) {
if (Constant *Result = computePointerDifference(Q.DL, X, Y))
return ConstantFoldIntegerCast(Result, Op0->getType(), /*IsSigned*/ true,
Q.DL);
}

// i1 sub -> xor.
if (MaxRecurse && Op0->getType()->isIntOrIntVectorTy(1))
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24 changes: 24 additions & 0 deletions llvm/test/Transforms/InstCombine/ptrtoaddr.ll
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Expand Up @@ -130,3 +130,27 @@ define i32 @ptrtoaddr_sub_consts_offset_addrsize() {
;
ret i32 sub (i32 ptrtoaddr (ptr addrspace(1) getelementptr (i8, ptr addrspace(1) @g.as1, i32 42) to i32), i32 ptrtoaddr (ptr addrspace(1) @g.as1 to i32))
}

define i64 @ptrtoaddr_sub_known_offset(ptr %p) {
; CHECK-LABEL: define i64 @ptrtoaddr_sub_known_offset(
; CHECK-SAME: ptr [[P:%.*]]) {
; CHECK-NEXT: ret i64 42
;
%p2 = getelementptr inbounds i8, ptr %p, i64 42
%p.addr = ptrtoaddr ptr %p to i64
%p2.addr = ptrtoaddr ptr %p2 to i64
%sub = sub i64 %p2.addr, %p.addr
ret i64 %sub
}

define i32 @ptrtoaddr_sub_known_offset_addrsize(ptr addrspace(1) %p) {
; CHECK-LABEL: define i32 @ptrtoaddr_sub_known_offset_addrsize(
; CHECK-SAME: ptr addrspace(1) [[P:%.*]]) {
; CHECK-NEXT: ret i32 42
;
%p2 = getelementptr inbounds i8, ptr addrspace(1) %p, i32 42
%p.addr = ptrtoaddr ptr addrspace(1) %p to i32
%p2.addr = ptrtoaddr ptr addrspace(1) %p2 to i32
%sub = sub i32 %p2.addr, %p.addr
ret i32 %sub
}