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-rw-r--r--lib/Transforms/Scalar/LoopRotation.cpp36
1 files changed, 28 insertions, 8 deletions
diff --git a/lib/Transforms/Scalar/LoopRotation.cpp b/lib/Transforms/Scalar/LoopRotation.cpp
index fde6bacb49..2ce58314f8 100644
--- a/lib/Transforms/Scalar/LoopRotation.cpp
+++ b/lib/Transforms/Scalar/LoopRotation.cpp
@@ -11,7 +11,6 @@
//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "loop-rotate"
#include "llvm/Transforms/Scalar.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/CodeMetrics.h"
@@ -24,6 +23,7 @@
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
@@ -31,7 +31,11 @@
#include "llvm/Transforms/Utils/ValueMapper.h"
using namespace llvm;
-#define MAX_HEADER_SIZE 16
+#define DEBUG_TYPE "loop-rotate"
+
+static cl::opt<unsigned>
+DefaultRotationThreshold("rotation-max-header-size", cl::init(16), cl::Hidden,
+ cl::desc("The default maximum header size for automatic loop rotation"));
STATISTIC(NumRotated, "Number of loops rotated");
namespace {
@@ -39,8 +43,12 @@ namespace {
class LoopRotate : public LoopPass {
public:
static char ID; // Pass ID, replacement for typeid
- LoopRotate() : LoopPass(ID) {
+ LoopRotate(int SpecifiedMaxHeaderSize = -1) : LoopPass(ID) {
initializeLoopRotatePass(*PassRegistry::getPassRegistry());
+ if (SpecifiedMaxHeaderSize == -1)
+ MaxHeaderSize = DefaultRotationThreshold;
+ else
+ MaxHeaderSize = unsigned(SpecifiedMaxHeaderSize);
}
// LCSSA form makes instruction renaming easier.
@@ -61,6 +69,7 @@ namespace {
bool rotateLoop(Loop *L, bool SimplifiedLatch);
private:
+ unsigned MaxHeaderSize;
LoopInfo *LI;
const TargetTransformInfo *TTI;
};
@@ -74,7 +83,9 @@ INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
INITIALIZE_PASS_DEPENDENCY(LCSSA)
INITIALIZE_PASS_END(LoopRotate, "loop-rotate", "Rotate Loops", false, false)
-Pass *llvm::createLoopRotatePass() { return new LoopRotate(); }
+Pass *llvm::createLoopRotatePass(int MaxHeaderSize) {
+ return new LoopRotate(MaxHeaderSize);
+}
/// Rotate Loop L as many times as possible. Return true if
/// the loop is rotated at least once.
@@ -82,6 +93,9 @@ bool LoopRotate::runOnLoop(Loop *L, LPPassManager &LPM) {
if (skipOptnoneFunction(L))
return false;
+ // Save the loop metadata.
+ MDNode *LoopMD = L->getLoopID();
+
LI = &getAnalysis<LoopInfo>();
TTI = &getAnalysis<TargetTransformInfo>();
@@ -96,6 +110,12 @@ bool LoopRotate::runOnLoop(Loop *L, LPPassManager &LPM) {
MadeChange = true;
SimplifiedLatch = false;
}
+
+ // Restore the loop metadata.
+ // NB! We presume LoopRotation DOESN'T ADD its own metadata.
+ if ((MadeChange || SimplifiedLatch) && LoopMD)
+ L->setLoopID(LoopMD);
+
return MadeChange;
}
@@ -281,7 +301,7 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
BasicBlock *OrigLatch = L->getLoopLatch();
BranchInst *BI = dyn_cast<BranchInst>(OrigHeader->getTerminator());
- if (BI == 0 || BI->isUnconditional())
+ if (!BI || BI->isUnconditional())
return false;
// If the loop header is not one of the loop exiting blocks then
@@ -292,7 +312,7 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
// If the loop latch already contains a branch that leaves the loop then the
// loop is already rotated.
- if (OrigLatch == 0)
+ if (!OrigLatch)
return false;
// Rotate if either the loop latch does *not* exit the loop, or if the loop
@@ -310,7 +330,7 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
<< " instructions: "; L->dump());
return false;
}
- if (Metrics.NumInsts > MAX_HEADER_SIZE)
+ if (Metrics.NumInsts > MaxHeaderSize)
return false;
}
@@ -319,7 +339,7 @@ bool LoopRotate::rotateLoop(Loop *L, bool SimplifiedLatch) {
// If the loop could not be converted to canonical form, it must have an
// indirectbr in it, just give up.
- if (OrigPreheader == 0)
+ if (!OrigPreheader)
return false;
// Anything ScalarEvolution may know about this loop or the PHI nodes