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[SCEV] Slightly generalize getRangeViaFactoring

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Building on the previous change, this generalizes
ScalarEvolution::getRangeViaFactoring to work with
{Ext(C?A:B)+k0,+,Ext(C?A:B)+k1} where Ext can be a zero extend, sign
extend or truncate operation, and k0 and k1 are constants.

llvm-svn: 262979
This commit is contained in:
Sanjoy Das 2016-03-09 01:51:02 +00:00
parent 29f43f7c7a
commit 337a8c9c46
2 changed files with 76 additions and 13 deletions
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31
lib/Analysis/ScalarEvolution.cpp
View File

@ -4557,17 +4557,6 @@ ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
const SCEV *Step,
const SCEV *MaxBECount,
unsigned BitWidth) {
APInt Offset(BitWidth, 0);
if (auto *SA = dyn_cast<SCEVAddExpr>(Start)) {
// Peel off a constant offset, if possible. In the future we could consider
// being smarter here and handle {Start+Step,+,Step} too.
if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
return ConstantRange(BitWidth, /* isFullSet = */ true);
Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
Start = SA->getOperand(1);
}
// RangeOf({C?A:B,+,C?P:Q}) == RangeOf(C?{A,+,P}:{B,+,Q})
// == RangeOf({A,+,P}) union RangeOf({B,+,Q})
@ -4579,10 +4568,22 @@ ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
explicit SelectPattern(ScalarEvolution &SE, unsigned BitWidth,
const SCEV *S) {
Optional<unsigned> CastOp;
APInt Offset(BitWidth, 0);
assert(SE.getTypeSizeInBits(S->getType()) == BitWidth &&
"Should be!");
// Peel off a constant offset:
if (auto *SA = dyn_cast<SCEVAddExpr>(S)) {
// In the future we could consider being smarter here and handle
// {Start+Step,+,Step} too.
if (SA->getNumOperands() != 2 || !isa<SCEVConstant>(SA->getOperand(0)))
return;
Offset = cast<SCEVConstant>(SA->getOperand(0))->getAPInt();
S = SA->getOperand(1);
}
// Peel off a cast operation
if (auto *SCast = dyn_cast<SCEVCastExpr>(S)) {
CastOp = SCast->getSCEVType();
@ -4622,6 +4623,10 @@ ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
FalseValue = FalseValue.sext(BitWidth);
break;
}
// Re-apply the constant offset we peeled off earlier
TrueValue += Offset;
FalseValue += Offset;
}
bool isRecognized() { return Condition != nullptr; }
@ -4650,9 +4655,9 @@ ConstantRange ScalarEvolution::getRangeViaFactoring(const SCEV *Start,
// FIXME: without the explicit `this` receiver below, MSVC errors out with
// C2352 and C2512 (otherwise it isn't needed).
const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue + Offset);
const SCEV *TrueStart = this->getConstant(StartPattern.TrueValue);
const SCEV *TrueStep = this->getConstant(StepPattern.TrueValue);
const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue + Offset);
const SCEV *FalseStart = this->getConstant(StartPattern.FalseValue);
const SCEV *FalseStep = this->getConstant(StepPattern.FalseValue);
ConstantRange TrueRange =

58
test/Analysis/ScalarEvolution/increasing-or-decreasing-iv.ll
View File

@ -188,3 +188,61 @@ loop:
leave:
ret void
}
define void @f6(i1 %c) {
; CHECK-LABEL: Classifying expressions for: @f6
entry:
%start = select i1 %c, i32 127, i32 0
%step = select i1 %c, i32 -2, i32 0
br label %loop
loop:
%loop.iv = phi i16 [ 0, %entry ], [ %loop.iv.inc, %loop ]
%iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
; CHECK: %iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
; CHECK-NEXT: --> {%start,+,(1 + %step)<nuw><nsw>}<%loop> U: [0,128) S: [0,128)
%step.plus.one = add i32 %step, 1
%iv.next = add i32 %iv, %step.plus.one
%iv.sext = sext i32 %iv to i64
; CHECK: %iv.sext = sext i32 %iv to i64
; CHECK-NEXT: --> {(sext i32 %start to i64),+,(1 + (sext i32 %step to i64))<nsw>}<nsw><%loop> U: [0,128) S: [0,128)
%loop.iv.inc = add i16 %loop.iv, 1
%be.cond = icmp ne i16 %loop.iv.inc, 128
br i1 %be.cond, label %loop, label %leave
leave:
ret void
}
define void @f7(i1 %c) {
; CHECK-LABEL: Classifying expressions for: @f7
entry:
%start = select i1 %c, i32 127, i32 0
%step = select i1 %c, i32 -1, i32 1
br label %loop
loop:
%loop.iv = phi i16 [ 0, %entry ], [ %loop.iv.inc, %loop ]
%iv = phi i32 [ %start, %entry ], [ %iv.next, %loop ]
%iv.trunc = trunc i32 %iv to i16
; CHECK: %iv.trunc = trunc i32 %iv to i16
; CHECK-NEXT: --> {(trunc i32 %start to i16),+,(trunc i32 %step to i16)}<%loop> U: [0,128) S: [0,128)
%iv.next = add i32 %iv, %step
%iv.trunc.plus.one = add i16 %iv.trunc, 1
; CHECK: %iv.trunc.plus.one = add i16 %iv.trunc, 1
; CHECK-NEXT: --> {(1 + (trunc i32 %start to i16))<nuw><nsw>,+,(trunc i32 %step to i16)}<%loop> U: [1,129) S: [1,129)
%iv.trunc.plus.two = add i16 %iv.trunc, 2
; CHECK: %iv.trunc.plus.two = add i16 %iv.trunc, 2
; CHECK-NEXT: --> {(2 + (trunc i32 %start to i16))<nuw><nsw>,+,(trunc i32 %step to i16)}<%loop> U: [2,130) S: [2,130)
%loop.iv.inc = add i16 %loop.iv, 1
%be.cond = icmp ne i16 %loop.iv.inc, 128
br i1 %be.cond, label %loop, label %leave
leave:
ret void
}