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Instead of having CollectSubexpr's categorize operands as interesting or 

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 9b7632df26
commit 89fdbaf99a
1 changed files with 14 additions and 19 deletions
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33
llvm/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,