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Passing unroll parameters (unroll-count, threshold, and partial unroll) via LoopUnroll class's ctor. Doing so

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will allow multiple context with different loop unroll parameters to run.  This is a minor change and no effect 
on existing application.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129449 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Junjie Gu 2011-04-13 16:15:29 +00:00
parent 4f9f41f2f9
commit 32644d9bfd
2 changed files with 24 additions and 13 deletions
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2
include/llvm/Transforms/Scalar.h
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@ -128,7 +128,7 @@ Pass *createLoopInstSimplifyPass();
//
// LoopUnroll - This pass is a simple loop unrolling pass.
//
Pass *createLoopUnrollPass();
Pass *createLoopUnrollPass(int Threshold = -1, int Count = -1, int AllowPartial = -1);
//===----------------------------------------------------------------------===//
//

35
lib/Transforms/Scalar/LoopUnrollPass.cpp
View File

@ -43,7 +43,13 @@ namespace {
class LoopUnroll : public LoopPass {
public:
static char ID; // Pass ID, replacement for typeid
LoopUnroll() : LoopPass(ID) {
LoopUnroll(int T = -1, int C = -1, int P = -1) : LoopPass(ID) {
CurrentThreshold = (T == -1) ? UnrollThreshold : T;
CurrentCount = (C == -1) ? UnrollCount : C;
CurrentAllowPartial = (P == -1) ? UnrollAllowPartial : (bool)P;
UserThreshold = (T != -1) || (UnrollThreshold.getNumOccurrences() > 0);
initializeLoopUnrollPass(*PassRegistry::getPassRegistry());
}
@ -56,7 +62,10 @@ namespace {
// explicit -unroll-threshold).
static const unsigned OptSizeUnrollThreshold = 50;
unsigned CurrentCount;
unsigned CurrentThreshold;
bool CurrentAllowPartial;
bool UserThreshold; // CurrentThreshold is user-specified.
bool runOnLoop(Loop *L, LPPassManager &LPM);
@ -87,7 +96,9 @@ INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
INITIALIZE_PASS_DEPENDENCY(LCSSA)
INITIALIZE_PASS_END(LoopUnroll, "loop-unroll", "Unroll loops", false, false)
Pass *llvm::createLoopUnrollPass() { return new LoopUnroll(); }
Pass *llvm::createLoopUnrollPass(int Threshold, int Count, int AllowPartial) {
return new LoopUnroll();
}
/// ApproximateLoopSize - Approximate the size of the loop.
static unsigned ApproximateLoopSize(const Loop *L, unsigned &NumCalls) {
@ -119,14 +130,14 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
// from UnrollThreshold, it is overridden to a smaller value if the current
// function is marked as optimize-for-size, and the unroll threshold was
// not user specified.
CurrentThreshold = UnrollThreshold;
if (Header->getParent()->hasFnAttr(Attribute::OptimizeForSize) &&
UnrollThreshold.getNumOccurrences() == 0)
CurrentThreshold = OptSizeUnrollThreshold;
unsigned Threshold = CurrentThreshold;
if (!UserThreshold &&
Header->getParent()->hasFnAttr(Attribute::OptimizeForSize))
Threshold = OptSizeUnrollThreshold;
// Find trip count
unsigned TripCount = L->getSmallConstantTripCount();
unsigned Count = UnrollCount;
unsigned Count = CurrentCount;
// Automatically select an unroll count.
if (Count == 0) {
@ -140,7 +151,7 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
}
// Enforce the threshold.
if (CurrentThreshold != NoThreshold) {
if (Threshold != NoThreshold) {
unsigned NumInlineCandidates;
unsigned LoopSize = ApproximateLoopSize(L, NumInlineCandidates);
DEBUG(dbgs() << " Loop Size = " << LoopSize << "\n");
@ -149,16 +160,16 @@ bool LoopUnroll::runOnLoop(Loop *L, LPPassManager &LPM) {
return false;
}
uint64_t Size = (uint64_t)LoopSize*Count;
if (TripCount != 1 && Size > CurrentThreshold) {
if (TripCount != 1 && Size > Threshold) {
DEBUG(dbgs() << " Too large to fully unroll with count: " << Count
<< " because size: " << Size << ">" << CurrentThreshold << "\n");
if (!UnrollAllowPartial) {
<< " because size: " << Size << ">" << Threshold << "\n");
if (!CurrentAllowPartial) {
DEBUG(dbgs() << " will not try to unroll partially because "
<< "-unroll-allow-partial not given\n");
return false;
}
// Reduce unroll count to be modulo of TripCount for partial unrolling
Count = CurrentThreshold / LoopSize;
Count = Threshold / LoopSize;
while (Count != 0 && TripCount%Count != 0) {
Count--;
}