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[LVI] Support no constant range of cast value in getEdgeValueLocal. #157614

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Merged
merged 4 commits into from
Sep 10, 2025
Merged

[LVI] Support no constant range of cast value in getEdgeValueLocal. #157614

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3b6e08d
[LVI] Add test of no constant range of cast and freeze value in getE…
andjo403 Sep 9, 2025
7cce3e7
[LVI] Support no constant range of cast and freeze value in getEdgeV…
andjo403 Sep 9, 2025
d75a408
fixup! [LVI] Support no constant range of cast and freeze value in g…
andjo403 Sep 9, 2025
46b3556
fixup! fixup! [LVI] Support no constant range of cast and freeze val…
andjo403 Sep 9, 2025
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18 changes: 18 additions & 0 deletions llvm/lib/Analysis/LazyValueInfo.cpp
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Expand Up @@ -1493,6 +1493,24 @@ LazyValueInfoImpl::getEdgeValueLocal(Value *Val, BasicBlock *BBFrom,
// br %Condition, label %then, label %else
APInt ConditionVal(1, isTrueDest ? 1 : 0);
Result = constantFoldUser(Usr, Condition, ConditionVal, DL);
} else if (isa<TruncInst, ZExtInst, SExtInst, FreezeInst>(Usr)) {
ValueLatticeElement OpLatticeVal =
*getValueFromCondition(Usr->getOperand(0), Condition,
isTrueDest, /*UseBlockValue*/ false);

if (isa<FreezeInst>(Usr) || !OpLatticeVal.isConstantRange())
return OpLatticeVal;

const unsigned ResultBitWidth =
Usr->getType()->getScalarSizeInBits();
if (auto *Trunc = dyn_cast<TruncInst>(Usr))
return ValueLatticeElement::getRange(
OpLatticeVal.getConstantRange().truncate(
ResultBitWidth, Trunc->getNoWrapKind()));

return ValueLatticeElement::getRange(
OpLatticeVal.getConstantRange().castOp(
cast<CastInst>(Usr)->getOpcode(), ResultBitWidth));
} else {
// If one of Val's operand has an inferred value, we may be able to
// infer the value of Val.
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144 changes: 144 additions & 0 deletions llvm/test/Transforms/CorrelatedValuePropagation/range.ll
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Expand Up @@ -1235,6 +1235,150 @@ define i1 @neg_icmp_eq_range_call() {
ret i1 %cmp
}

define i16 @return_range_for_edge_value_zext(i8 %a) {
; CHECK-LABEL: define range(i16 0, 98) i16 @return_range_for_edge_value_zext(
; CHECK-SAME: i8 [[A:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[B:%.*]] = zext i8 [[A]] to i16
; CHECK-NEXT: br label %[[DISPATCH:.*]]
; CHECK: [[DISPATCH]]:
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[A]], 98
; CHECK-NEXT: br i1 [[CMP]], label %[[TARGET:.*]], label %[[DISPATCH]]
; CHECK: [[TARGET]]:
; CHECK-NEXT: ret i16 [[B]]
;
entry:
%b = zext i8 %a to i16
br label %dispatch

dispatch:
%cmp = icmp ult i8 %a, 98
br i1 %cmp, label %target, label %dispatch

target:
ret i16 %b
}

define i16 @return_range_for_edge_value_sext(i8 %a) {
; CHECK-LABEL: define range(i16 0, 98) i16 @return_range_for_edge_value_sext(
; CHECK-SAME: i8 [[A:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[B:%.*]] = sext i8 [[A]] to i16
; CHECK-NEXT: br label %[[DISPATCH:.*]]
; CHECK: [[DISPATCH]]:
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[A]], 98
; CHECK-NEXT: br i1 [[CMP]], label %[[TARGET:.*]], label %[[DISPATCH]]
; CHECK: [[TARGET]]:
; CHECK-NEXT: ret i16 [[B]]
;
entry:
%b = sext i8 %a to i16
br label %dispatch

dispatch:
%cmp = icmp ult i8 %a, 98
br i1 %cmp, label %target, label %dispatch

target:
ret i16 %b
}

define i8 @return_range_for_edge_value_trunc(i16 %a) {
; CHECK-LABEL: define range(i8 0, 98) i8 @return_range_for_edge_value_trunc(
; CHECK-SAME: i16 [[A:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[B:%.*]] = trunc i16 [[A]] to i8
; CHECK-NEXT: br label %[[DISPATCH:.*]]
; CHECK: [[DISPATCH]]:
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i16 [[A]], 98
; CHECK-NEXT: br i1 [[CMP]], label %[[TARGET:.*]], label %[[DISPATCH]]
; CHECK: [[TARGET]]:
; CHECK-NEXT: ret i8 [[B]]
;
entry:
%b = trunc i16 %a to i8
br label %dispatch

dispatch:
%cmp = icmp ult i16 %a, 98
br i1 %cmp, label %target, label %dispatch

target:
ret i8 %b
}

define i8 @neg_return_range_for_edge_value_trunc(i16 %a) {
; CHECK-LABEL: define i8 @neg_return_range_for_edge_value_trunc(
; CHECK-SAME: i16 [[A:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[B:%.*]] = trunc i16 [[A]] to i8
; CHECK-NEXT: br label %[[DISPATCH:.*]]
; CHECK: [[DISPATCH]]:
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i16 [[A]], 200
; CHECK-NEXT: br i1 [[CMP]], label %[[TARGET:.*]], label %[[DISPATCH]]
; CHECK: [[TARGET]]:
; CHECK-NEXT: ret i8 [[B]]
;
entry:
%b = trunc i16 %a to i8
br label %dispatch

dispatch:
%cmp = icmp ugt i16 %a, 200
br i1 %cmp, label %target, label %dispatch

target:
ret i8 %b
}

define i8 @return_range_for_edge_value_trunc_nuw(i16 %a) {
; CHECK-LABEL: define range(i8 -55, 0) i8 @return_range_for_edge_value_trunc_nuw(
; CHECK-SAME: i16 [[A:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[B:%.*]] = trunc nuw i16 [[A]] to i8
; CHECK-NEXT: br label %[[DISPATCH:.*]]
; CHECK: [[DISPATCH]]:
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i16 [[A]], 200
; CHECK-NEXT: br i1 [[CMP]], label %[[TARGET:.*]], label %[[DISPATCH]]
; CHECK: [[TARGET]]:
; CHECK-NEXT: ret i8 [[B]]
;
entry:
%b = trunc nuw i16 %a to i8
br label %dispatch

dispatch:
%cmp = icmp ugt i16 %a, 200
br i1 %cmp, label %target, label %dispatch

target:
ret i8 %b
}

define i8 @return_range_for_edge_value_freeze(i8 %a) {
; CHECK-LABEL: define range(i8 0, 98) i8 @return_range_for_edge_value_freeze(
; CHECK-SAME: i8 [[A:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[B:%.*]] = freeze i8 [[A]]
; CHECK-NEXT: br label %[[DISPATCH:.*]]
; CHECK: [[DISPATCH]]:
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[A]], 98
; CHECK-NEXT: br i1 [[CMP]], label %[[TARGET:.*]], label %[[DISPATCH]]
; CHECK: [[TARGET]]:
; CHECK-NEXT: ret i8 [[B]]
;
entry:
%b = freeze i8 %a
br label %dispatch

dispatch:
%cmp = icmp ult i8 %a, 98
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InstCombine canonicalizes all uses of %a to %b. Can you put freeze-related changes into a separate PR?

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good catch there was no changes for freeze when I did a benchmark run I only added it as it was listed in isOperationFoldable. but is dropped now

br i1 %cmp, label %target, label %dispatch

target:
ret i8 %b
}

declare i16 @llvm.ctlz.i16(i16, i1)
declare i16 @llvm.cttz.i16(i16, i1)
declare i16 @llvm.ctpop.i16(i16)
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2 changes: 1 addition & 1 deletion llvm/test/Transforms/JumpThreading/branch-debug-info2.ll
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Expand Up @@ -19,7 +19,7 @@ if.end.i60: ; preds = %shadow_to_ptr.exit
; Jump threading is going to fold the select in to the branch. Ensure debug
; info is not lost, and is merged from the select and the branch.
; CHECK-NOT: br i1 %cmp3.i, label %for.inc, label %ptr_to_shadow.exit
; CHECK: br i1 %cmp3.i, label %for.inc, label %ptr_to_shadow.exit, !dbg [[DBG:![0-9]+]]
; CHECK: br i1 %cmp3.i, label %for.inc, label %if.end22, !dbg [[DBG:![0-9]+]]
; CHECK: [[DBG]] = !DILocation(line: 9, column: 1, scope: !{{.*}})

br label %ptr_to_shadow.exit, !dbg !17
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