[InstCombine] Generalize foldAndOrOfICmpsUsingRanges to handle more cases.
#158498
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
@zyw-bot mfuzz |
llvmbot
added
llvm:instcombine
|
@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesCloses #158326. Full diff: https://github.com/llvm/llvm-project/pull/158498.diff 3 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 2d7524e8018b2..7fd2d6a427396 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1320,74 +1320,49 @@ static Value *foldAndOrOfICmpsWithConstEq(ICmpInst *Cmp0, ICmpInst *Cmp1,
Value *InstCombinerImpl::foldAndOrOfICmpsUsingRanges(ICmpInst *ICmp1,
ICmpInst *ICmp2,
bool IsAnd) {
- CmpPredicate Pred1, Pred2;
- Value *V1, *V2;
- const APInt *C1, *C2;
- if (!match(ICmp1, m_ICmp(Pred1, m_Value(V1), m_APInt(C1))) ||
- !match(ICmp2, m_ICmp(Pred2, m_Value(V2), m_APInt(C2))))
- return nullptr;
-
- // Look through add of a constant offset on V1, V2, or both operands. This
- // allows us to interpret the V + C' < C'' range idiom into a proper range.
- const APInt *Offset1 = nullptr, *Offset2 = nullptr;
- if (V1 != V2) {
- Value *X;
- if (match(V1, m_Add(m_Value(X), m_APInt(Offset1))))
- V1 = X;
- if (match(V2, m_Add(m_Value(X), m_APInt(Offset2))))
- V2 = X;
- }
-
- // Look through and with a negative power of 2 mask on V1 or V2. This
- // detects idioms of the form `(x == A) || ((x & Mask) == A + 1)` where A + 1
- // is aligned to the mask and A + 1 >= |Mask|. This pattern corresponds to a
- // contiguous range check, which can be folded into an addition and compare.
- // The same applies for `(x != A) && ((x & Mask) != A + 1)`.
- auto AreContiguousRangePredicates = [](CmpPredicate Pred1, CmpPredicate Pred2,
- bool IsAnd) {
- if (IsAnd)
- return Pred1 == ICmpInst::ICMP_NE && Pred2 == ICmpInst::ICMP_NE;
- return Pred1 == ICmpInst::ICMP_EQ && Pred2 == ICmpInst::ICMP_EQ;
- };
- const APInt *Mask1 = nullptr, *Mask2 = nullptr;
- bool MatchedAnd1 = false, MatchedAnd2 = false;
- if (V1 != V2 && AreContiguousRangePredicates(Pred1, Pred2, IsAnd)) {
+ auto MatchRangeCheck =
+ [](ICmpInst *ICmp) -> std::optional<std::pair<Value *, ConstantRange>> {
+ const APInt *C;
+ if (!match(ICmp->getOperand(1), m_APInt(C)))
+ return std::nullopt;
+ Value *LHS = ICmp->getOperand(0);
+ CmpPredicate Pred = ICmp->getPredicate();
Value *X;
- if (match(V1, m_OneUse(m_And(m_Value(X), m_NegatedPower2(Mask1)))) &&
- C1->getBitWidth() == C2->getBitWidth() && *C1 == *C2 + 1 &&
- C1->uge(Mask1->abs()) && C1->isPowerOf2()) {
- MatchedAnd1 = true;
- V1 = X;
- }
- if (match(V2, m_OneUse(m_And(m_Value(X), m_NegatedPower2(Mask2)))) &&
- C1->getBitWidth() == C2->getBitWidth() && *C2 == *C1 + 1 &&
- C2->uge(Mask2->abs()) && C2->isPowerOf2()) {
- MatchedAnd2 = true;
- V2 = X;
+ // Match (x & NegPow2) ==/!= C
+ const APInt *Mask;
+ if (ICmpInst::isEquality(Pred) &&
+ match(LHS, m_OneUse(m_And(m_Value(X), m_NegatedPower2(Mask)))) &&
+ C->countr_zero() >= Mask->countr_zero()) {
+ ConstantRange CR{*C, *C - *Mask};
+ if (Pred == ICmpInst::ICMP_NE)
+ CR = CR.inverse();
+ return std::make_pair(X, CR);
}
- }
+ ConstantRange CR = ConstantRange::makeExactICmpRegion(Pred, *C);
+ // Match (add X, C1) pred C
+ const APInt *C1;
+ if (match(LHS, m_AddLike(m_Value(X), m_APInt(C1))))
+ return std::make_pair(X, CR.subtract(*C1));
+ return std::make_pair(LHS, CR);
+ };
+
+ auto RC1 = MatchRangeCheck(ICmp1);
+ if (!RC1)
+ return nullptr;
- if (V1 != V2)
+ auto RC2 = MatchRangeCheck(ICmp2);
+ if (!RC2)
return nullptr;
- ConstantRange CR1 =
- MatchedAnd1
- ? ConstantRange(*C1, *C1 - *Mask1)
- : ConstantRange::makeExactICmpRegion(
- IsAnd ? ICmpInst::getInverseCmpPredicate(Pred1) : Pred1, *C1);
- if (Offset1)
- CR1 = CR1.subtract(*Offset1);
-
- ConstantRange CR2 =
- MatchedAnd2
- ? ConstantRange(*C2, *C2 - *Mask2)
- : ConstantRange::makeExactICmpRegion(
- IsAnd ? ICmpInst::getInverseCmpPredicate(Pred2) : Pred2, *C2);
- if (Offset2)
- CR2 = CR2.subtract(*Offset2);
-
- Type *Ty = V1->getType();
- Value *NewV = V1;
+ if (RC1->first != RC2->first)
+ return nullptr;
+
+ Value *V = RC1->first;
+ auto CR1 = IsAnd ? RC1->second.inverse() : RC1->second;
+ auto CR2 = IsAnd ? RC2->second.inverse() : RC2->second;
+
+ Type *Ty = V->getType();
+ Value *NewV = V;
std::optional<ConstantRange> CR = CR1.exactUnionWith(CR2);
if (!CR) {
if (!(ICmp1->hasOneUse() && ICmp2->hasOneUse()) || CR1.isWrappedSet() ||
diff --git a/llvm/test/Transforms/InstCombine/and-or-icmps.ll b/llvm/test/Transforms/InstCombine/and-or-icmps.ll
index 553c7ac5af0e9..290e344acb980 100644
--- a/llvm/test/Transforms/InstCombine/and-or-icmps.ll
+++ b/llvm/test/Transforms/InstCombine/and-or-icmps.ll
@@ -3672,13 +3672,11 @@ define i1 @neg_or_icmp_eq_double_and_pow2(i32 %x) {
ret i1 %ret
}
-define i1 @neg_select_icmp_eq_and_pow2(i32 %x) {
-; CHECK-LABEL: @neg_select_icmp_eq_and_pow2(
-; CHECK-NEXT: [[ICMP1:%.*]] = icmp sgt i32 [[X:%.*]], 127
-; CHECK-NEXT: [[AND:%.*]] = and i32 [[X]], -32
-; CHECK-NEXT: [[ICMP2:%.*]] = icmp eq i32 [[AND]], 128
-; CHECK-NEXT: [[TMP1:%.*]] = and i1 [[ICMP1]], [[ICMP2]]
-; CHECK-NEXT: ret i1 [[TMP1]]
+define i1 @implied_select_icmp_eq_and_pow2(i32 %x) {
+; CHECK-LABEL: @implied_select_icmp_eq_and_pow2(
+; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[X:%.*]], -32
+; CHECK-NEXT: [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 128
+; CHECK-NEXT: ret i1 [[TMP2]]
;
%icmp1 = icmp sgt i32 %x, 127
%and = and i32 %x, -32
@@ -3686,3 +3684,40 @@ define i1 @neg_select_icmp_eq_and_pow2(i32 %x) {
%1 = select i1 %icmp1, i1 %icmp2, i1 false
ret i1 %1
}
+
+define i1 @implied_range_check(i8 %a) {
+; CHECK-LABEL: @implied_range_check(
+; CHECK-NEXT: [[MASKED:%.*]] = and i8 [[A:%.*]], -2
+; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i8 [[MASKED]], 2
+; CHECK-NEXT: ret i1 [[CMP2]]
+;
+ %cmp1 = icmp ult i8 %a, 5
+ %masked = and i8 %a, -2
+ %cmp2 = icmp eq i8 %masked, 2
+ %and = and i1 %cmp1, %cmp2
+ ret i1 %and
+}
+
+define i1 @merge_range_check_and(i8 %a) {
+; CHECK-LABEL: @merge_range_check_and(
+; CHECK-NEXT: [[CMP2:%.*]] = icmp eq i8 [[MASKED:%.*]], 2
+; CHECK-NEXT: ret i1 [[CMP2]]
+;
+ %cmp1 = icmp ult i8 %a, 3
+ %masked = and i8 %a, -2
+ %cmp2 = icmp eq i8 %masked, 2
+ %and = and i1 %cmp1, %cmp2
+ ret i1 %and
+}
+
+define i1 @merge_range_check_or(i8 %a) {
+; CHECK-LABEL: @merge_range_check_or(
+; CHECK-NEXT: [[AND:%.*]] = icmp ult i8 [[A:%.*]], 4
+; CHECK-NEXT: ret i1 [[AND]]
+;
+ %cmp1 = icmp ult i8 %a, 3
+ %masked = and i8 %a, -2
+ %cmp2 = icmp eq i8 %masked, 2
+ %and = or i1 %cmp1, %cmp2
+ ret i1 %and
+}
diff --git a/llvm/test/Transforms/InstCombine/icmp-range.ll b/llvm/test/Transforms/InstCombine/icmp-range.ll
index 97ed552b9a6da..1970694cf9c42 100644
--- a/llvm/test/Transforms/InstCombine/icmp-range.ll
+++ b/llvm/test/Transforms/InstCombine/icmp-range.ll
@@ -1678,10 +1678,7 @@ define i1 @icmp_slt_sext_ne_otherwise_nofold(i32 %a) {
; tests from PR59555
define i1 @isFloat(i64 %0) {
; CHECK-LABEL: @isFloat(
-; CHECK-NEXT: [[TMP2:%.*]] = icmp ugt i64 [[TMP0:%.*]], 281474976710655
-; CHECK-NEXT: [[TMP3:%.*]] = and i64 [[TMP0]], -281474976710656
-; CHECK-NEXT: [[TMP4:%.*]] = icmp ne i64 [[TMP3]], 281474976710656
-; CHECK-NEXT: [[TMP5:%.*]] = and i1 [[TMP2]], [[TMP4]]
+; CHECK-NEXT: [[TMP5:%.*]] = icmp ugt i64 [[TMP0:%.*]], 562949953421311
; CHECK-NEXT: ret i1 [[TMP5]]
;
%2 = icmp ugt i64 %0, 281474976710655
|
| const APInt *Mask1 = nullptr, *Mask2 = nullptr; | ||
| bool MatchedAnd1 = false, MatchedAnd2 = false; | ||
| if (V1 != V2 && AreContiguousRangePredicates(Pred1, Pred2, IsAnd)) { | ||
| auto MatchRangeCheck = |
There was a problem hiding this comment.
Could add a comment for the lambda function? How about s/MatchRangeCheck/MaybeSatisfyingRangeForPred/ instead (or something along these lines)?
There was a problem hiding this comment.
MaybeSatisfyingRangeForPred
The range is exact (ignoring the poison-generating flags). I think "MaybeSatisfying" is more confusing than the original one...
andjo403
reviewed
Sep 15, 2025
| // Match (x & NegPow2) ==/!= C | ||
| const APInt *Mask; | ||
| if (ICmpInst::isEquality(Pred) && | ||
| match(LHS, m_OneUse(m_And(m_Value(X), m_NegatedPower2(Mask)))) && |
There was a problem hiding this comment.
do we need the one use check here? there is non for the add below
There was a problem hiding this comment.
It was added in #153842. Note that this fold may insert two instructions for the new range check. I think the one-use check here is needed. We can investigate this (and m_AddLike below) in the future. But for now, I want to keep the diff small.
andjo403
approved these changes
Sep 16, 2025
|
@zyw-bot csmith-quick-fuzz |
|
LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/10/builds/13723 Here is the relevant piece of the build log for the reference |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Closes #158326.
Closes #59555.
Proof for
(X & -Pow2) == C -> (X - C) < Pow2: https://alive2.llvm.org/ce/z/HMgkuu