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Instead of having CollectSubexpr's categorize operands as interesting or

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uninteresting, just put all the operands on one list and make
GenerateReassociations make the decision about what's interesting.
This is simpler, and it avoids an extra ScalarEvolution::getAddExpr call.

llvm-svn: 111133
This commit is contained in:
Dan Gohman 2010-08-16 15:50:00 +00:00
parent 38d11cdfe0
commit 7900e1ace3
1 changed files with 14 additions and 19 deletions
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33
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -2230,14 +2230,13 @@ LSRInstance::CollectLoopInvariantFixupsAndFormulae() {
/// separate registers. If C is non-null, multiply each subexpression by C.
static void CollectSubexprs(const SCEV *S, const SCEVConstant *C,
SmallVectorImpl<const SCEV *> &Ops,
SmallVectorImpl<const SCEV *> &UninterestingOps,
const Loop *L,
ScalarEvolution &SE) {
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
// Break out add operands.
for (SCEVAddExpr::op_iterator I = Add->op_begin(), E = Add->op_end();
I != E; ++I)
CollectSubexprs(*I, C, Ops, UninterestingOps, L, SE);
CollectSubexprs(*I, C, Ops, L, SE);
return;
} else if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
// Split a non-zero base out of an addrec.
@ -2245,8 +2244,8 @@ static void CollectSubexprs(const SCEV *S, const SCEVConstant *C,
CollectSubexprs(SE.getAddRecExpr(SE.getConstant(AR->getType(), 0),
AR->getStepRecurrence(SE),
AR->getLoop()),
C, Ops, UninterestingOps, L, SE);
CollectSubexprs(AR->getStart(), C, Ops, UninterestingOps, L, SE);
C, Ops, L, SE);
CollectSubexprs(AR->getStart(), C, Ops, L, SE);
return;
}
} else if (const SCEVMulExpr *Mul = dyn_cast<SCEVMulExpr>(S)) {
@ -2256,17 +2255,13 @@ static void CollectSubexprs(const SCEV *S, const SCEVConstant *C,
dyn_cast<SCEVConstant>(Mul->getOperand(0))) {
CollectSubexprs(Mul->getOperand(1),
C ? cast<SCEVConstant>(SE.getMulExpr(C, Op0)) : Op0,
Ops, UninterestingOps, L, SE);
Ops, L, SE);
return;
}
}
// Otherwise use the value itself. Loop-variant "unknown" values are
// uninteresting; we won't be able to do anything meaningful with them.
if (!C && isa<SCEVUnknown>(S) && !S->isLoopInvariant(L))
UninterestingOps.push_back(S);
else
Ops.push_back(C ? SE.getMulExpr(C, S) : S);
// Otherwise use the value itself, optionally with a scale applied.
Ops.push_back(C ? SE.getMulExpr(C, S) : S);
}
/// GenerateReassociations - Split out subexpressions from adds and the bases of
@ -2280,19 +2275,19 @@ void LSRInstance::GenerateReassociations(LSRUse &LU, unsigned LUIdx,
for (size_t i = 0, e = Base.BaseRegs.size(); i != e; ++i) {
const SCEV *BaseReg = Base.BaseRegs[i];
SmallVector<const SCEV *, 8> AddOps, UninterestingAddOps;
CollectSubexprs(BaseReg, 0, AddOps, UninterestingAddOps, L, SE);
// Add any uninteresting values as one register, as we won't be able to
// form any interesting reassociation opportunities with them. They'll
// just have to be added inside the loop no matter what we do.
if (!UninterestingAddOps.empty())
AddOps.push_back(SE.getAddExpr(UninterestingAddOps));
SmallVector<const SCEV *, 8> AddOps;
CollectSubexprs(BaseReg, 0, AddOps, L, SE);
if (AddOps.size() == 1) continue;
for (SmallVectorImpl<const SCEV *>::const_iterator J = AddOps.begin(),
JE = AddOps.end(); J != JE; ++J) {
// Loop-variant "unknown" values are uninteresting; we won't be able to
// do anything meaningful with them.
if (isa<SCEVUnknown>(*J) && !(*J)->isLoopInvariant(L))
continue;
// Don't pull a constant into a register if the constant could be folded
// into an immediate field.
if (isAlwaysFoldable(*J, LU.MinOffset, LU.MaxOffset,