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[PredicateInfo] Handle trunc nuw i1 condition. #152988

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Merged
andjo403 merged 2 commits into from
Aug 11, 2025
Merged

[PredicateInfo] Handle trunc nuw i1 condition. #152988

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56e2be9
[PredicateInfo] Add test for trunc nuw condition (NFC)
andjo403 Aug 11, 2025
86b1bfc
[PredicateInfo] Handle trunc nuw i1 condition.
andjo403 Aug 11, 2025
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9 changes: 9 additions & 0 deletions llvm/lib/Transforms/Utils/PredicateInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -370,6 +370,8 @@ void PredicateInfoBuilder::processAssume(
Values.push_back(Cond);
if (auto *Cmp = dyn_cast<CmpInst>(Cond))
collectCmpOps(Cmp, Values);
else if (match(Cond, m_NUWTrunc(m_Value(Op0))))
Values.push_back(Op0);

for (Value *V : Values) {
if (shouldRename(V)) {
Expand Down Expand Up @@ -416,6 +418,8 @@ void PredicateInfoBuilder::processBranch(
Values.push_back(Cond);
if (auto *Cmp = dyn_cast<CmpInst>(Cond))
collectCmpOps(Cmp, Values);
else if (match(Cond, m_NUWTrunc(m_Value(Op0))))
Values.push_back(Op0);

for (Value *V : Values) {
if (shouldRename(V)) {
Expand Down Expand Up @@ -709,6 +713,11 @@ std::optional<PredicateConstraint> PredicateBase::getConstraint() const {
: ConstantInt::getFalse(Condition->getType())}};
}

if (match(Condition, m_NUWTrunc(m_Specific(RenamedOp)))) {
return {{TrueEdge ? CmpInst::ICMP_NE : CmpInst::ICMP_EQ,
ConstantInt::getNullValue(RenamedOp->getType())}};
}

CmpInst *Cmp = dyn_cast<CmpInst>(Condition);
if (!Cmp) {
// TODO: Make this an assertion once RenamedOp is fully accurate.
Expand Down
50 changes: 50 additions & 0 deletions llvm/test/Transforms/SCCP/assume.ll
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Expand Up @@ -69,3 +69,53 @@ define void @nonnull(ptr %v) {
call void @use(i1 %c4)
ret void
}

define void @trunc_nuw(i8 %v) {
; CHECK-LABEL: @trunc_nuw(
; CHECK-NEXT: [[A:%.*]] = trunc nuw i8 [[V:%.*]] to i1
; CHECK-NEXT: call void @llvm.assume(i1 [[A]])
; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: call void @use(i1 true)
; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: call void @use(i1 true)
; CHECK-NEXT: ret void
;
%a = trunc nuw i8 %v to i1
call void @llvm.assume(i1 %a)
%c1 = icmp eq i8 %v, 0
call void @use(i1 %c1)
%c2 = icmp ne i8 %v, 0
call void @use(i1 %c2)
%c3 = icmp eq i8 0, %v
call void @use(i1 %c3)
%c4 = icmp ne i8 0, %v
call void @use(i1 %c4)
ret void
}

define void @neg_trunc(i8 %v) {
; CHECK-LABEL: @neg_trunc(
; CHECK-NEXT: [[A:%.*]] = trunc i8 [[V:%.*]] to i1
; CHECK-NEXT: call void @llvm.assume(i1 [[A]])
; CHECK-NEXT: [[C1:%.*]] = icmp eq i8 [[V]], 0
; CHECK-NEXT: call void @use(i1 [[C1]])
; CHECK-NEXT: [[C2:%.*]] = icmp ne i8 [[V]], 0
; CHECK-NEXT: call void @use(i1 [[C2]])
; CHECK-NEXT: [[C3:%.*]] = icmp eq i8 0, [[V]]
; CHECK-NEXT: call void @use(i1 [[C3]])
; CHECK-NEXT: [[C4:%.*]] = icmp ne i8 0, [[V]]
; CHECK-NEXT: call void @use(i1 [[C4]])
; CHECK-NEXT: ret void
;
%a = trunc i8 %v to i1
call void @llvm.assume(i1 %a)
%c1 = icmp eq i8 %v, 0
call void @use(i1 %c1)
%c2 = icmp ne i8 %v, 0
call void @use(i1 %c2)
%c3 = icmp eq i8 0, %v
call void @use(i1 %c3)
%c4 = icmp ne i8 0, %v
call void @use(i1 %c4)
ret void
}
62 changes: 62 additions & 0 deletions llvm/test/Transforms/SCCP/conditions-ranges.ll
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Expand Up @@ -1444,3 +1444,65 @@ define i1 @ptr_icmp_data_layout() {
%cmp = icmp eq ptr %a.end, @A
ret i1 %cmp
}

define void @trunc_nuw_1_dominating_icmp_ne_0(i8 %x) {
; CHECK-LABEL: @trunc_nuw_1_dominating_icmp_ne_0(
; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw i8 [[X:%.*]] to i1
; CHECK-NEXT: br i1 [[TRUNC]], label [[BB1:%.*]], label [[BB2:%.*]]
; CHECK: bb1:
; CHECK-NEXT: call void @use(i1 true)
; CHECK-NEXT: call void @use(i1 true)
; CHECK-NEXT: ret void
; CHECK: bb2:
; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: call void @use(i1 false)
; CHECK-NEXT: ret void
;
%trunc = trunc nuw i8 %x to i1
br i1 %trunc, label %bb1, label %bb2
bb1:
%c1 = icmp ne i8 %x , 0
call void @use(i1 %c1)
%c2 = icmp ne i8 0, %x
call void @use(i1 %c2)
ret void
bb2:
%c3 = icmp ne i8 %x , 0
call void @use(i1 %c3)
%c4 = icmp ne i8 0, %x
call void @use(i1 %c4)
ret void
}

define void @neg_trunc_1_dominating_icmp_ne_0(i8 %x) {
; CHECK-LABEL: @neg_trunc_1_dominating_icmp_ne_0(
; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[X:%.*]] to i1
; CHECK-NEXT: br i1 [[TRUNC]], label [[BB1:%.*]], label [[BB2:%.*]]
; CHECK: bb1:
; CHECK-NEXT: [[C1:%.*]] = icmp ne i8 [[X]], 0
; CHECK-NEXT: call void @use(i1 [[C1]])
; CHECK-NEXT: [[C2:%.*]] = icmp ne i8 0, [[X]]
; CHECK-NEXT: call void @use(i1 [[C2]])
; CHECK-NEXT: ret void
; CHECK: bb2:
; CHECK-NEXT: [[C3:%.*]] = icmp ne i8 [[X]], 0
; CHECK-NEXT: call void @use(i1 [[C3]])
; CHECK-NEXT: [[C4:%.*]] = icmp ne i8 0, [[X]]
; CHECK-NEXT: call void @use(i1 [[C4]])
; CHECK-NEXT: ret void
;
%trunc = trunc i8 %x to i1
br i1 %trunc, label %bb1, label %bb2
bb1:
%c1 = icmp ne i8 %x , 0
call void @use(i1 %c1)
%c2 = icmp ne i8 0, %x
call void @use(i1 %c2)
ret void
bb2:
%c3 = icmp ne i8 %x , 0
call void @use(i1 %c3)
%c4 = icmp ne i8 0, %x
call void @use(i1 %c4)
ret void
}