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The logic inside getMulExpr to simplify {a,+,b}*{c,+,d} was wrong, which was

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visible given a=b=c=d=1, on iteration #1 (the second iteration). Replace it with
correct math. Fixes PR10383!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@139133 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nick Lewycky
2011-09-06 05:05:14 +00:00
parent b2840fdcd8
commit fa151a79ed
2 changed files with 54 additions and 16 deletions
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33
lib/Analysis/ScalarEvolution.cpp
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@@ -1735,7 +1735,7 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
// Otherwise, add the folded AddRec by the non-liv parts.
// Otherwise, add the folded AddRec by the non-live parts.
for (unsigned i = 0;; ++i)
if (Ops[i] == AddRec) {
Ops[i] = NewRec;
@@ -1960,7 +1960,7 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
// If all of the other operands were loop invariant, we are done.
if (Ops.size() == 1) return NewRec;
// Otherwise, multiply the folded AddRec by the non-liv parts.
// Otherwise, multiply the folded AddRec by the non-live parts.
for (unsigned i = 0;; ++i)
if (Ops[i] == AddRec) {
Ops[i] = NewRec;
@@ -1976,22 +1976,29 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
OtherIdx < Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
++OtherIdx)
if (AddRecLoop == cast<SCEVAddRecExpr>(Ops[OtherIdx])->getLoop()) {
// F * G, where F = {A,+,B}<L> and G = {C,+,D}<L> -->
// {A*C,+,F*D + G*B + B*D}<L>
// {A,+,B}<L> * {C,+,D}<L> --> {A*C,+,A*D + B*C + B*D,+,2*B*D}<L>
for (; OtherIdx != Ops.size() && isa<SCEVAddRecExpr>(Ops[OtherIdx]);
++OtherIdx)
if (const SCEVAddRecExpr *OtherAddRec =
dyn_cast<SCEVAddRecExpr>(Ops[OtherIdx]))
if (OtherAddRec->getLoop() == AddRecLoop) {
const SCEVAddRecExpr *F = AddRec, *G = OtherAddRec;
const SCEV *NewStart = getMulExpr(F->getStart(), G->getStart());
const SCEV *B = F->getStepRecurrence(*this);
const SCEV *D = G->getStepRecurrence(*this);
const SCEV *NewStep = getAddExpr(getMulExpr(F, D),
getMulExpr(G, B),
getMulExpr(B, D));
const SCEV *NewAddRec = getAddRecExpr(NewStart, NewStep,
F->getLoop(),
const SCEV *A = AddRec->getStart();
const SCEV *B = AddRec->getStepRecurrence(*this);
const SCEV *C = OtherAddRec->getStart();
const SCEV *D = OtherAddRec->getStepRecurrence(*this);
const SCEV *NewStart = getMulExpr(A, C);
const SCEV *BD = getMulExpr(B, D);
const SCEV *NewStep = getAddExpr(getMulExpr(A, D),
getMulExpr(B, C), BD);
const SCEV *NewSecondOrderStep =
getMulExpr(BD, getConstant(BD->getType(), 2));
SmallVector<const SCEV *, 3> AddRecOps;
AddRecOps.push_back(NewStart);
AddRecOps.push_back(NewStep);
AddRecOps.push_back(NewSecondOrderStep);
const SCEV *NewAddRec = getAddRecExpr(AddRecOps,
AddRec->getLoop(),
SCEV::FlagAnyWrap);
if (Ops.size() == 2) return NewAddRec;
Ops[Idx] = AddRec = cast<SCEVAddRecExpr>(NewAddRec);