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[SCEV] more accurate range for addrecexpr with nsw flag.

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Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D72436
This commit is contained in:
Zheng Chen 2020-01-10 22:50:39 -05:00
parent 0744d792d5
commit 1c93f5af35
2 changed files with 21 additions and 13 deletions
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26
lib/Analysis/ScalarEvolution.cpp
View File

@ -5678,23 +5678,31 @@ ScalarEvolution::getRangeRef(const SCEV *S,
ConservativeResult = ConservativeResult.intersectWith(
ConstantRange(C->getAPInt(), APInt(BitWidth, 0)), RangeType);
// If there's no signed wrap, and all the operands have the same sign or
// zero, the value won't ever change sign.
// If there's no signed wrap, and all the operands except initial value have
// the same sign or zero, the value won't ever be:
// 1: smaller than initial value if operands are non negative,
// 2: bigger than initial value if operands are non positive.
// For both cases, value can not cross signed min/max boundary.
if (AddRec->hasNoSignedWrap()) {
bool AllNonNeg = true;
bool AllNonPos = true;
for (unsigned i = 0, e = AddRec->getNumOperands(); i != e; ++i) {
if (!isKnownNonNegative(AddRec->getOperand(i))) AllNonNeg = false;
if (!isKnownNonPositive(AddRec->getOperand(i))) AllNonPos = false;
for (unsigned i = 1, e = AddRec->getNumOperands(); i != e; ++i) {
if (!isKnownNonNegative(AddRec->getOperand(i)))
AllNonNeg = false;
if (!isKnownNonPositive(AddRec->getOperand(i)))
AllNonPos = false;
}
if (AllNonNeg)
ConservativeResult = ConservativeResult.intersectWith(
ConstantRange(APInt(BitWidth, 0),
APInt::getSignedMinValue(BitWidth)), RangeType);
ConstantRange::getNonEmpty(getSignedRangeMin(AddRec->getStart()),
APInt::getSignedMinValue(BitWidth)),
RangeType);
else if (AllNonPos)
ConservativeResult = ConservativeResult.intersectWith(
ConstantRange(APInt::getSignedMinValue(BitWidth),
APInt(BitWidth, 1)), RangeType);
ConstantRange::getNonEmpty(
APInt::getSignedMinValue(BitWidth),
getSignedRangeMax(AddRec->getStart()) + 1),
RangeType);
}
// TODO: non-affine addrec

8
test/Analysis/ScalarEvolution/range_nw_flag.ll
View File

@ -40,7 +40,7 @@ exit:
}
; CHECK-LABEL: @test-addrec-nsw-start-neg-strip-neg
; CHECK: --> {(-1 + (-10 smin %offset))<nsw>,+,-1}<nsw><%loop> U: [-2147483648,1) S: [-2147483648,1)
; CHECK: --> {(-1 + (-10 smin %offset))<nsw>,+,-1}<nsw><%loop> U: [-2147483648,-10) S: [-2147483648,-10)
define void @test-addrec-nsw-start-neg-strip-neg(float* %input, i32 %offset, i32 %numIterations) {
entry:
%cmp = icmp slt i32 %offset, -10
@ -60,7 +60,7 @@ exit:
}
; CHECK-LABEL: @test-addrec-nsw-start-pos-strip-neg
; CHECK: --> {(-1 + (10 smin %offset))<nsw>,+,-1}<nsw><%loop> U: full-set S: full-set
; CHECK: --> {(-1 + (10 smin %offset))<nsw>,+,-1}<nsw><%loop> U: [-2147483648,10) S: [-2147483648,10)
define void @test-addrec-nsw-start-pos-strip-neg(float* %input, i32 %offset, i32 %numIterations) {
entry:
%cmp = icmp slt i32 %offset, 10
@ -80,7 +80,7 @@ exit:
}
; CHECK-LABEL: @test-addrec-nsw-start-pos-strip-pos
; CHECK: --> {(1 + (10 smax %offset))<nuw><nsw>,+,1}<nuw><nsw><%loop> U: [0,-2147483648) S: [0,-2147483648)
; CHECK: --> {(1 + (10 smax %offset))<nuw><nsw>,+,1}<nuw><nsw><%loop> U: [11,-2147483648) S: [11,-2147483648)
define void @test-addrec-nsw-start-pos-strip-pos(float* %input, i32 %offset, i32 %numIterations) {
entry:
%cmp = icmp sgt i32 %offset, 10
@ -100,7 +100,7 @@ exit:
}
; CHECK-LABEL: @test-addrec-nsw-start-neg-strip-pos
; CHECK: --> {(1 + (-10 smax %offset))<nsw>,+,1}<nsw><%loop> U: full-set S: full-set
; CHECK: --> {(1 + (-10 smax %offset))<nsw>,+,1}<nsw><%loop> U: [-9,-2147483648) S: [-9,-2147483648)
define void @test-addrec-nsw-start-neg-strip-pos(float* %input, i32 %offset, i32 %numIterations) {
entry:
%cmp = icmp sgt i32 %offset, -10