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[ValueTracking] If overlap in unsigned and signed range is contiguous, return it #144267

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[ValueTracking] If overlap in unsigned and signed range is contiguous, return it #144267

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161 changes: 126 additions & 35 deletions llvm/lib/Analysis/ValueTracking.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -9585,56 +9585,147 @@ static void setLimitsForBinOp(const BinaryOperator &BO, APInt &Lower,
bool HasNSW = IIQ.hasNoSignedWrap(&BO);
bool HasNUW = IIQ.hasNoUnsignedWrap(&BO);

// If the caller expects a signed compare, then try to use a signed range.
// Otherwise if both no-wraps are set, use the unsigned range because it
// is never larger than the signed range. Example:
// "sub nuw nsw i8 -2, x" is unsigned [0, 254] vs. signed [-128, 126].
// "sub nuw nsw i8 2, x" is unsigned [0, 2] vs. signed [-125, 127].
if (PreferSignedRange && HasNSW && HasNUW)
HasNUW = false;

if (HasNUW) {
// 'sub nuw c, x' produces [0, C].
Upper = *C + 1;
} else if (HasNSW) {
// Build the two candidate ranges as [lo..hi]:
// unsignedRange: NUW ⇒ [0 .. C]
// signedRange: NSW ⇒ either [SINT_MIN .. -C - SINT_MIN] or [C -
// SINT_MAX .. SINT_MAX]
auto makeUnsignedRange = [&]() {
return std::pair<APInt, APInt>(APInt::getZero(Width), *C);
};
auto makeSignedRange = [&]() {
if (C->isNegative()) {
// 'sub nsw -C, x' produces [SINT_MIN, -C - SINT_MIN].
Lower = APInt::getSignedMinValue(Width);
Upper = *C - APInt::getSignedMaxValue(Width);
// sub nsw -C, x
APInt lo = APInt::getSignedMinValue(Width);
APInt hi = *C - APInt::getSignedMinValue(Width);
return std::pair<APInt, APInt>(lo, hi);
} else {
// sub nsw C, x
APInt lo = *C - APInt::getSignedMaxValue(Width);
APInt hi = APInt::getSignedMaxValue(Width);
return std::pair<APInt, APInt>(lo, hi);
}
};

// Split a (possibly wrapping) [lo..hi] into up to two non‑wrapping
// pieces:
auto splitPieces = [&](std::pair<APInt, APInt> rng,
SmallVectorImpl<std::pair<APInt, APInt>> &pieces) {
APInt lo = rng.first, hi = rng.second;
if (lo.ugt(hi)) {
// wraps around 2^n
pieces.emplace_back(lo, APInt::getMaxValue(Width)); // [lo..2^n-1]
pieces.emplace_back(APInt::getZero(Width), hi); // [0..hi]
} else {
// Note that sub 0, INT_MIN is not NSW. It techically is a signed wrap
// 'sub nsw C, x' produces [C - SINT_MAX, SINT_MAX].
Lower = *C - APInt::getSignedMaxValue(Width);
Upper = APInt::getSignedMinValue(Width);
pieces.emplace_back(lo, hi);
}
};

SmallVector<std::pair<APInt, APInt>, 2> piecesU, piecesS;
if (HasNUW)
splitPieces(makeUnsignedRange(), piecesU);
if (HasNSW)
splitPieces(makeSignedRange(), piecesS);

// Intersect piecewise:
SmallVector<std::pair<APInt, APInt>, 2> inters;
for (auto &u : piecesU) {
for (auto &s : piecesS) {
APInt loI = u.first.ugt(s.first) ? u.first : s.first;
APInt hiI = u.second.ult(s.second) ? u.second : s.second;
if (loI.ule(hiI))
inters.emplace_back(loI, hiI);
}
}

if (inters.size() == 1) {
// Exactly one contiguous overlap → use it
Lower = inters[0].first;
Upper = inters[0].second;
} else if (HasNUW && !PreferSignedRange) {
// Fallback to plain NUW result [0..C]
Lower = APInt::getZero(Width);
Upper = *C;
} else if (HasNSW) {
// Fallback to plain NSW result
auto S = makeSignedRange();
Lower = S.first;
Upper = S.second;
}
}
break;
case Instruction::Add:
if (match(BO.getOperand(1), m_APInt(C)) && !C->isZero()) {
bool HasNSW = IIQ.hasNoSignedWrap(&BO);
bool HasNUW = IIQ.hasNoUnsignedWrap(&BO);

// If the caller expects a signed compare, then try to use a signed
// range. Otherwise if both no-wraps are set, use the unsigned range
// because it is never larger than the signed range. Example: "add nuw
// nsw i8 X, -2" is unsigned [254,255] vs. signed [-128, 125].
if (PreferSignedRange && HasNSW && HasNUW)
HasNUW = false;
// Build the two candidate ranges as [lo..hi] in the unsigned 0..2^n-1
// world:
// NUW: 'add nuw x, C' ⇒ [ C .. UINT_MAX ]
auto makeUnsignedRange = [&]() {
APInt lo = *C;
APInt hi = APInt::getMaxValue(Width);
return std::pair<APInt, APInt>(lo, hi);
};

if (HasNUW) {
// 'add nuw x, C' produces [C, UINT_MAX].
Lower = *C;
} else if (HasNSW) {
// NSW: 'add nsw x, C'
// if C<0: [ SINT_MIN .. SINT_MAX + C ]
// else: [ SINT_MIN + C .. SINT_MAX ]
auto makeSignedRange = [&]() {
if (C->isNegative()) {
// 'add nsw x, -C' produces [SINT_MIN, SINT_MAX - C].
Lower = APInt::getSignedMinValue(Width);
Upper = APInt::getSignedMaxValue(Width) + *C + 1;
APInt lo = APInt::getSignedMinValue(Width);
APInt hi = APInt::getSignedMaxValue(Width) + *C;
return std::pair<APInt, APInt>(lo, hi);
} else {
// 'add nsw x, +C' produces [SINT_MIN + C, SINT_MAX].
Lower = APInt::getSignedMinValue(Width) + *C;
Upper = APInt::getSignedMaxValue(Width) + 1;
APInt lo = APInt::getSignedMinValue(Width) + *C;
APInt hi = APInt::getSignedMaxValue(Width);
return std::pair<APInt, APInt>(lo, hi);
}
};

// Split [lo..hi] into up to two non‑wrapping intervals:
auto splitPieces = [&](std::pair<APInt, APInt> rng,
SmallVectorImpl<std::pair<APInt, APInt>> &dst) {
APInt lo = rng.first, hi = rng.second;
if (lo.ugt(hi)) {
// wraps around 2^n
dst.emplace_back(lo, APInt::getMaxValue(Width));
dst.emplace_back(APInt::getZero(Width), hi);
} else {
dst.emplace_back(lo, hi);
}
};

SmallVector<std::pair<APInt, APInt>, 2> piecesU, piecesS;
if (HasNUW)
splitPieces(makeUnsignedRange(), piecesU);
if (HasNSW)
splitPieces(makeSignedRange(), piecesS);

// Intersect piecewise
SmallVector<std::pair<APInt, APInt>, 2> inters;
for (auto &u : piecesU) {
for (auto &s : piecesS) {
APInt loI = u.first.ugt(s.first) ? u.first : s.first;
APInt hiI = u.second.ult(s.second) ? u.second : s.second;
if (loI.ule(hiI))
inters.emplace_back(loI, hiI);
}
}

if (inters.size() == 1) {
// Exactly one contiguous overlap ⇒ use it
Lower = inters[0].first;
Upper = inters[0].second +
1; // make Upper exclusive if you’re following [Lo..Hi)
} else if (HasNUW && !PreferSignedRange) {
// Fallback to plain NUW [C..UINT_MAX]
Lower = *C;
Upper = APInt::getMaxValue(Width) + 1;
} else if (HasNSW) {
// Fallback to plain NSW
auto S = makeSignedRange();
Lower = S.first;
Upper = S.second + 1;
}
}
break;
Expand Down
6 changes: 2 additions & 4 deletions llvm/test/Transforms/LoopVectorize/AArch64/sve-interleaved-accesses.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -1412,8 +1412,7 @@ define void @interleave_deinterleave_factor3(ptr writeonly noalias %dst, ptr rea
; CHECK-NEXT: [[TMP18:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP18]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP41:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[N_MOD_VF]], 0
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; CHECK-NEXT: br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
;
entry:
Expand Down Expand Up @@ -1502,8 +1501,7 @@ define void @interleave_deinterleave(ptr writeonly noalias %dst, ptr readonly %a
; CHECK-NEXT: [[TMP25:%.*]] = icmp eq i64 [[INDEX_NEXT]], [[N_VEC]]
; CHECK-NEXT: br i1 [[TMP25]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP43:![0-9]+]]
; CHECK: middle.block:
; CHECK-NEXT: [[CMP_N:%.*]] = icmp eq i64 [[N_MOD_VF]], 0
; CHECK-NEXT: br i1 [[CMP_N]], label [[FOR_COND_CLEANUP:%.*]], label [[SCALAR_PH]]
; CHECK-NEXT: br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
; CHECK: scalar.ph:
;
entry:
Expand Down
12 changes: 4 additions & 8 deletions llvm/test/Transforms/LoopVectorize/AArch64/sve-interleaved-masked-accesses.ll
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Expand Up @@ -67,8 +67,7 @@ define dso_local void @masked_strided1(ptr noalias nocapture readonly %p, ptr no
; SCALAR_TAIL_FOLDING-NEXT: [[TMP17:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; SCALAR_TAIL_FOLDING-NEXT: br i1 [[TMP17]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; SCALAR_TAIL_FOLDING: middle.block:
; SCALAR_TAIL_FOLDING-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
; SCALAR_TAIL_FOLDING-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_TAIL_FOLDING-NEXT: br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_TAIL_FOLDING: scalar.ph:
;
; PREDICATED_TAIL_FOLDING-LABEL: define dso_local void @masked_strided1
Expand Down Expand Up @@ -205,8 +204,7 @@ define dso_local void @masked_strided2(ptr noalias nocapture readnone %p, ptr no
; SCALAR_TAIL_FOLDING-NEXT: [[TMP14:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; SCALAR_TAIL_FOLDING-NEXT: br i1 [[TMP14]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
; SCALAR_TAIL_FOLDING: middle.block:
; SCALAR_TAIL_FOLDING-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
; SCALAR_TAIL_FOLDING-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_TAIL_FOLDING-NEXT: br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_TAIL_FOLDING: scalar.ph:
;
; PREDICATED_TAIL_FOLDING-LABEL: define dso_local void @masked_strided2
Expand Down Expand Up @@ -335,8 +333,7 @@ define dso_local void @masked_strided3(ptr noalias nocapture readnone %p, ptr no
; SCALAR_TAIL_FOLDING-NEXT: [[TMP15:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; SCALAR_TAIL_FOLDING-NEXT: br i1 [[TMP15]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP6:![0-9]+]]
; SCALAR_TAIL_FOLDING: middle.block:
; SCALAR_TAIL_FOLDING-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
; SCALAR_TAIL_FOLDING-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_TAIL_FOLDING-NEXT: br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_TAIL_FOLDING: scalar.ph:
;
; PREDICATED_TAIL_FOLDING-LABEL: define dso_local void @masked_strided3
Expand Down Expand Up @@ -490,8 +487,7 @@ define dso_local void @masked_strided_factor4(ptr noalias nocapture readonly %p,
; SCALAR_TAIL_FOLDING-NEXT: [[TMP21:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; SCALAR_TAIL_FOLDING-NEXT: br i1 [[TMP21]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP8:![0-9]+]]
; SCALAR_TAIL_FOLDING: middle.block:
; SCALAR_TAIL_FOLDING-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
; SCALAR_TAIL_FOLDING-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_TAIL_FOLDING-NEXT: br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_TAIL_FOLDING: scalar.ph:
;
; PREDICATED_TAIL_FOLDING-LABEL: define dso_local void @masked_strided_factor4
Expand Down
6 changes: 2 additions & 4 deletions llvm/test/Transforms/LoopVectorize/RISCV/interleaved-masked-access.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -52,8 +52,7 @@ define void @masked_strided_factor2(ptr noalias nocapture readonly %p, ptr noali
; SCALAR_EPILOGUE-NEXT: [[TMP20:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; SCALAR_EPILOGUE-NEXT: br i1 [[TMP20]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
; SCALAR_EPILOGUE: middle.block:
; SCALAR_EPILOGUE-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
; SCALAR_EPILOGUE-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_EPILOGUE-NEXT: br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_EPILOGUE: scalar.ph:
;
; PREDICATED_TAIL_FOLDING-LABEL: define void @masked_strided_factor2
Expand Down Expand Up @@ -237,8 +236,7 @@ define void @masked_strided_factor4(ptr noalias nocapture readonly %p, ptr noali
; SCALAR_EPILOGUE-NEXT: [[TMP32:%.*]] = icmp eq i32 [[INDEX_NEXT]], [[N_VEC]]
; SCALAR_EPILOGUE-NEXT: br i1 [[TMP32]], label [[MIDDLE_BLOCK:%.*]], label [[VECTOR_BODY]], !llvm.loop [[LOOP4:![0-9]+]]
; SCALAR_EPILOGUE: middle.block:
; SCALAR_EPILOGUE-NEXT: [[CMP_N:%.*]] = icmp eq i32 [[N_MOD_VF]], 0
; SCALAR_EPILOGUE-NEXT: br i1 [[CMP_N]], label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_EPILOGUE-NEXT: br i1 false, label [[FOR_END:%.*]], label [[SCALAR_PH]]
; SCALAR_EPILOGUE: scalar.ph:
;
; PREDICATED_TAIL_FOLDING-LABEL: define void @masked_strided_factor4
Expand Down