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Disable unrolling in the loop vectorizer when disabled in the pass manager

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When unrolling is disabled in the pass manager, the loop vectorizer should also
not unroll loops. This will allow the -fno-unroll-loops option in Clang to
behave as expected (even for vectorizable loops). The loop vectorizer's
-force-vector-unroll option will (continue to) override the pass-manager
setting (including -force-vector-unroll=0 to force use of the internal
auto-selection logic).

In order to test this, I added a flag to opt (-disable-loop-unrolling) to force
disable unrolling through opt (the analog of -fno-unroll-loops in Clang). Also,
this fixes a small bug in opt where the loop vectorizer was enabled only after
the pass manager populated the queue of passes (the global_alias.ll test needed
a slight update to the RUN line as a result of this fix).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189499 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Hal Finkel
2013-08-28 18:33:10 +00:00
parent 4f066b6db8
commit 435798e96a
6 changed files with 55 additions and 13 deletions
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17
lib/Transforms/Vectorize/LoopVectorize.cpp
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@ -761,9 +761,9 @@ struct LoopVectorizeHints {
/// Vectorization unroll factor.
unsigned Unroll;
LoopVectorizeHints(const Loop *L)
LoopVectorizeHints(const Loop *L, bool DisableUnrolling)
: Width(VectorizationFactor)
, Unroll(VectorizationUnroll)
, Unroll(DisableUnrolling ? 1 : VectorizationUnroll)
, LoopID(L->getLoopID()) {
getHints(L);
// The command line options override any loop metadata except for when
@ -772,6 +772,9 @@ struct LoopVectorizeHints {
Width = VectorizationFactor;
if (VectorizationUnroll.getNumOccurrences() > 0)
Unroll = VectorizationUnroll;
DEBUG(if (DisableUnrolling && Unroll == 1)
dbgs() << "LV: Unrolling disabled by the pass manager\n");
}
/// Return the loop vectorizer metadata prefix.
@ -878,7 +881,8 @@ struct LoopVectorize : public LoopPass {
/// Pass identification, replacement for typeid
static char ID;
explicit LoopVectorize() : LoopPass(ID) {
explicit LoopVectorize(bool NoUnrolling = false)
: LoopPass(ID), DisableUnrolling(NoUnrolling) {
initializeLoopVectorizePass(*PassRegistry::getPassRegistry());
}
@ -888,6 +892,7 @@ struct LoopVectorize : public LoopPass {
TargetTransformInfo *TTI;
DominatorTree *DT;
TargetLibraryInfo *TLI;
bool DisableUnrolling;
virtual bool runOnLoop(Loop *L, LPPassManager &LPM) {
// We only vectorize innermost loops.
@ -909,7 +914,7 @@ struct LoopVectorize : public LoopPass {
DEBUG(dbgs() << "LV: Checking a loop in \"" <<
L->getHeader()->getParent()->getName() << "\"\n");
LoopVectorizeHints Hints(L);
LoopVectorizeHints Hints(L, DisableUnrolling);
if (Hints.Width == 1 && Hints.Unroll == 1) {
DEBUG(dbgs() << "LV: Not vectorizing.\n");
@ -4786,8 +4791,8 @@ INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
INITIALIZE_PASS_END(LoopVectorize, LV_NAME, lv_name, false, false)
namespace llvm {
Pass *createLoopVectorizePass() {
return new LoopVectorize();
Pass *createLoopVectorizePass(bool NoUnrolling) {
return new LoopVectorize(NoUnrolling);
}
}