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[LVI] Look through pointer operand when evaluating ptrtoints #162627

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[LVI] Look through pointer operand when evaluating ptrtoints #162627

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20 changes: 20 additions & 0 deletions llvm/lib/Analysis/LazyValueInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -966,6 +966,7 @@ LazyValueInfoImpl::solveBlockValueCast(CastInst *CI, BasicBlock *BB) {
// recurse on our operand. This can cut a long search short if we know we're
// not going to be able to get any useful information anways.
switch (CI->getOpcode()) {
case Instruction::PtrToInt:
case Instruction::Trunc:
case Instruction::SExt:
case Instruction::ZExt:
Expand All @@ -977,6 +978,11 @@ LazyValueInfoImpl::solveBlockValueCast(CastInst *CI, BasicBlock *BB) {
return ValueLatticeElement::getOverdefined();
}

// Assumed predicate over the integral value of the pointer are constraints on
// the cast to integer value itself.
if (auto *PTI = dyn_cast<PtrToIntInst>(CI))
return getBlockValue(PTI->getPointerOperand(), BB, PTI);

// Figure out the range of the LHS. If that fails, we still apply the
// transfer rule on the full set since we may be able to locally infer
// interesting facts.
Expand Down Expand Up @@ -1350,6 +1356,20 @@ std::optional<ValueLatticeElement> LazyValueInfoImpl::getValueFromICmpCondition(
}

Type *Ty = Val->getType();

// On the off-chance we may compute a range over the address of a pointer.
ConstantInt *CI = nullptr;
if (Ty->isPointerTy() && LHS == Val &&
match(RHS, m_IntToPtr(m_ConstantInt(CI)))) {
if (Ty->getPointerAddressSpace() ==
RHS->getType()->getPointerAddressSpace()) {
ConstantRange RHSRange(CI->getValue());
ConstantRange AllowedR =
ConstantRange::makeAllowedICmpRegion(EdgePred, RHSRange);
return ValueLatticeElement::getRange(AllowedR);
}
}

if (!Ty->isIntegerTy())
return ValueLatticeElement::getOverdefined();

Expand Down
55 changes: 55 additions & 0 deletions llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll
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Expand Up @@ -355,3 +355,58 @@ define i8 @test_umax_nneg(i8 %a, i8 %b) {
%ret = call i8 @llvm.umax.i8(i8 %nneg_a, i8 %nneg_b)
ret i8 %ret
}

define i8 @test_umin_ptr_address(ptr %p) {
; CHECK-LABEL: @test_umin_ptr_address(
; CHECK-NEXT: [[PI:%.*]] = ptrtoint ptr [[P:%.*]] to i64
; CHECK-NEXT: [[PI_SHR:%.*]] = lshr i64 [[PI]], 32
; CHECK-NEXT: [[PI_HI:%.*]] = trunc nuw nsw i64 [[PI_SHR]] to i8
; CHECK-NEXT: [[CMP:%.*]] = icmp ult ptr [[P]], inttoptr (i64 176093659136 to ptr)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret i8 [[PI_HI]]
;
%pi = ptrtoint ptr %p to i64
%pi.shr = lshr i64 %pi, 32
%pi.hi = trunc nuw i64 %pi.shr to i8
%umin = call i8 @llvm.umin.i8(i8 %pi.hi, i8 41)
%cmp = icmp ult ptr %p, inttoptr (i64 176093659136 to ptr)
call void @llvm.assume(i1 %cmp)
ret i8 %umin
}

define i8 @test_umax_ptr_address(ptr %p) {
; CHECK-LABEL: @test_umax_ptr_address(
; CHECK-NEXT: [[PI:%.*]] = ptrtoint ptr [[P:%.*]] to i64
; CHECK-NEXT: [[PI_SHR:%.*]] = lshr i64 [[PI]], 32
; CHECK-NEXT: [[PI_HI:%.*]] = trunc nuw i64 [[PI_SHR]] to i8
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt ptr [[P]], inttoptr (i64 180388626431 to ptr)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret i8 [[PI_HI]]
;
%pi = ptrtoint ptr %p to i64
%pi.shr = lshr i64 %pi, 32
%pi.hi = trunc nuw i64 %pi.shr to i8
%umin = call i8 @llvm.umax.i8(i8 %pi.hi, i8 41)
%cmp = icmp ugt ptr %p, inttoptr (i64 180388626431 to ptr)
call void @llvm.assume(i1 %cmp)
ret i8 %umin
}

define i8 @test_umin_ptr_address_negative(ptr %p) {
; CHECK-LABEL: @test_umin_ptr_address_negative(
; CHECK-NEXT: [[PI:%.*]] = ptrtoint ptr [[P:%.*]] to i64
; CHECK-NEXT: [[PI_SHR:%.*]] = lshr i64 [[PI]], 32
; CHECK-NEXT: [[PI_HI:%.*]] = trunc nuw i64 [[PI_SHR]] to i8
; CHECK-NEXT: [[UMIN:%.*]] = call i8 @llvm.umin.i8(i8 [[PI_HI]], i8 41)
; CHECK-NEXT: [[CMP:%.*]] = icmp ne ptr [[P]], inttoptr (i64 176093659136 to ptr)
; CHECK-NEXT: call void @llvm.assume(i1 [[CMP]])
; CHECK-NEXT: ret i8 [[UMIN]]
;
%pi = ptrtoint ptr %p to i64
%pi.shr = lshr i64 %pi, 32
%pi.hi = trunc nuw i64 %pi.shr to i8
%umin = call i8 @llvm.umin.i8(i8 %pi.hi, i8 41)
%cmp = icmp ne ptr %p, inttoptr (i64 176093659136 to ptr)
call void @llvm.assume(i1 %cmp)
ret i8 %umin
}
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