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[PredicateInfo] Handle trunc nuw i1 condition. (llvm#152988)
proof: https://alive2.llvm.org/ce/z/mxtn4L
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3 files changed

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‎llvm/lib/Transforms/Utils/PredicateInfo.cpp

Lines changed: 9 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -370,6 +370,8 @@ void PredicateInfoBuilder::processAssume(
370370
Values.push_back(Cond);
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if (auto *Cmp = dyn_cast<CmpInst>(Cond))
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collectCmpOps(Cmp, Values);
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else if (match(Cond, m_NUWTrunc(m_Value(Op0))))
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Values.push_back(Op0);
373375

374376
for (Value *V : Values) {
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if (shouldRename(V)) {
@@ -416,6 +418,8 @@ void PredicateInfoBuilder::processBranch(
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Values.push_back(Cond);
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if (auto *Cmp = dyn_cast<CmpInst>(Cond))
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collectCmpOps(Cmp, Values);
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else if (match(Cond, m_NUWTrunc(m_Value(Op0))))
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Values.push_back(Op0);
419423

420424
for (Value *V : Values) {
421425
if (shouldRename(V)) {
@@ -709,6 +713,11 @@ std::optional<PredicateConstraint> PredicateBase::getConstraint() const {
709713
: ConstantInt::getFalse(Condition->getType())}};
710714
}
711715

716+
if (match(Condition, m_NUWTrunc(m_Specific(RenamedOp)))) {
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return {{TrueEdge ? CmpInst::ICMP_NE : CmpInst::ICMP_EQ,
718+
ConstantInt::getNullValue(RenamedOp->getType())}};
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}
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712721
CmpInst *Cmp = dyn_cast<CmpInst>(Condition);
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if (!Cmp) {
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// TODO: Make this an assertion once RenamedOp is fully accurate.

‎llvm/test/Transforms/SCCP/assume.ll

Lines changed: 50 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -69,3 +69,53 @@ define void @nonnull(ptr %v) {
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call void @use(i1 %c4)
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ret void
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}
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define void @trunc_nuw(i8 %v) {
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; CHECK-LABEL: @trunc_nuw(
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; CHECK-NEXT: [[A:%.*]] = trunc nuw i8 [[V:%.*]] to i1
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; CHECK-NEXT: call void @llvm.assume(i1 [[A]])
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; CHECK-NEXT: call void @use(i1 false)
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; CHECK-NEXT: call void @use(i1 true)
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; CHECK-NEXT: call void @use(i1 false)
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; CHECK-NEXT: call void @use(i1 true)
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; CHECK-NEXT: ret void
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;
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%a = trunc nuw i8 %v to i1
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call void @llvm.assume(i1 %a)
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%c1 = icmp eq i8 %v, 0
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call void @use(i1 %c1)
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%c2 = icmp ne i8 %v, 0
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call void @use(i1 %c2)
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%c3 = icmp eq i8 0, %v
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call void @use(i1 %c3)
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%c4 = icmp ne i8 0, %v
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call void @use(i1 %c4)
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ret void
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}
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define void @neg_trunc(i8 %v) {
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; CHECK-LABEL: @neg_trunc(
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; CHECK-NEXT: [[A:%.*]] = trunc i8 [[V:%.*]] to i1
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; CHECK-NEXT: call void @llvm.assume(i1 [[A]])
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; CHECK-NEXT: [[C1:%.*]] = icmp eq i8 [[V]], 0
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; CHECK-NEXT: call void @use(i1 [[C1]])
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; CHECK-NEXT: [[C2:%.*]] = icmp ne i8 [[V]], 0
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; CHECK-NEXT: call void @use(i1 [[C2]])
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; CHECK-NEXT: [[C3:%.*]] = icmp eq i8 0, [[V]]
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; CHECK-NEXT: call void @use(i1 [[C3]])
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; CHECK-NEXT: [[C4:%.*]] = icmp ne i8 0, [[V]]
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; CHECK-NEXT: call void @use(i1 [[C4]])
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; CHECK-NEXT: ret void
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;
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%a = trunc i8 %v to i1
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call void @llvm.assume(i1 %a)
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%c1 = icmp eq i8 %v, 0
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call void @use(i1 %c1)
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%c2 = icmp ne i8 %v, 0
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call void @use(i1 %c2)
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%c3 = icmp eq i8 0, %v
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call void @use(i1 %c3)
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%c4 = icmp ne i8 0, %v
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call void @use(i1 %c4)
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ret void
121+
}

‎llvm/test/Transforms/SCCP/conditions-ranges.ll

Lines changed: 62 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1444,3 +1444,65 @@ define i1 @ptr_icmp_data_layout() {
14441444
%cmp = icmp eq ptr %a.end, @A
14451445
ret i1 %cmp
14461446
}
1447+
1448+
define void @trunc_nuw_1_dominating_icmp_ne_0(i8 %x) {
1449+
; CHECK-LABEL: @trunc_nuw_1_dominating_icmp_ne_0(
1450+
; CHECK-NEXT: [[TRUNC:%.*]] = trunc nuw i8 [[X:%.*]] to i1
1451+
; CHECK-NEXT: br i1 [[TRUNC]], label [[BB1:%.*]], label [[BB2:%.*]]
1452+
; CHECK: bb1:
1453+
; CHECK-NEXT: call void @use(i1 true)
1454+
; CHECK-NEXT: call void @use(i1 true)
1455+
; CHECK-NEXT: ret void
1456+
; CHECK: bb2:
1457+
; CHECK-NEXT: call void @use(i1 false)
1458+
; CHECK-NEXT: call void @use(i1 false)
1459+
; CHECK-NEXT: ret void
1460+
;
1461+
%trunc = trunc nuw i8 %x to i1
1462+
br i1 %trunc, label %bb1, label %bb2
1463+
bb1:
1464+
%c1 = icmp ne i8 %x , 0
1465+
call void @use(i1 %c1)
1466+
%c2 = icmp ne i8 0, %x
1467+
call void @use(i1 %c2)
1468+
ret void
1469+
bb2:
1470+
%c3 = icmp ne i8 %x , 0
1471+
call void @use(i1 %c3)
1472+
%c4 = icmp ne i8 0, %x
1473+
call void @use(i1 %c4)
1474+
ret void
1475+
}
1476+
1477+
define void @neg_trunc_1_dominating_icmp_ne_0(i8 %x) {
1478+
; CHECK-LABEL: @neg_trunc_1_dominating_icmp_ne_0(
1479+
; CHECK-NEXT: [[TRUNC:%.*]] = trunc i8 [[X:%.*]] to i1
1480+
; CHECK-NEXT: br i1 [[TRUNC]], label [[BB1:%.*]], label [[BB2:%.*]]
1481+
; CHECK: bb1:
1482+
; CHECK-NEXT: [[C1:%.*]] = icmp ne i8 [[X]], 0
1483+
; CHECK-NEXT: call void @use(i1 [[C1]])
1484+
; CHECK-NEXT: [[C2:%.*]] = icmp ne i8 0, [[X]]
1485+
; CHECK-NEXT: call void @use(i1 [[C2]])
1486+
; CHECK-NEXT: ret void
1487+
; CHECK: bb2:
1488+
; CHECK-NEXT: [[C3:%.*]] = icmp ne i8 [[X]], 0
1489+
; CHECK-NEXT: call void @use(i1 [[C3]])
1490+
; CHECK-NEXT: [[C4:%.*]] = icmp ne i8 0, [[X]]
1491+
; CHECK-NEXT: call void @use(i1 [[C4]])
1492+
; CHECK-NEXT: ret void
1493+
;
1494+
%trunc = trunc i8 %x to i1
1495+
br i1 %trunc, label %bb1, label %bb2
1496+
bb1:
1497+
%c1 = icmp ne i8 %x , 0
1498+
call void @use(i1 %c1)
1499+
%c2 = icmp ne i8 0, %x
1500+
call void @use(i1 %c2)
1501+
ret void
1502+
bb2:
1503+
%c3 = icmp ne i8 %x , 0
1504+
call void @use(i1 %c3)
1505+
%c4 = icmp ne i8 0, %x
1506+
call void @use(i1 %c4)
1507+
ret void
1508+
}

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