#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"
#define DEBUG_TYPE "loop-rotate"
-#define MAX_HEADER_SIZE 16
+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 {
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.
bool rotateLoop(Loop *L, bool SimplifiedLatch);
private:
+ unsigned MaxHeaderSize;
LoopInfo *LI;
const TargetTransformInfo *TTI;
};
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.
}
}
-/// Determine whether the instructions in this range my be safely and cheaply
+/// Determine whether the instructions in this range may be safely and cheaply
/// speculated. This is not an important enough situation to develop complex
/// heuristics. We handle a single arithmetic instruction along with any type
/// conversions.
/// Fold the loop tail into the loop exit by speculating the loop tail
/// instructions. Typically, this is a single post-increment. In the case of a
/// simple 2-block loop, hoisting the increment can be much better than
-/// duplicating the entire loop header. In the cast of loops with early exits,
+/// duplicating the entire loop header. In the case of loops with early exits,
/// rotation will not work anyway, but simplifyLoopLatch will put the loop in
/// canonical form so downstream passes can handle it.
///
<< " instructions: "; L->dump());
return false;
}
- if (Metrics.NumInsts > MAX_HEADER_SIZE)
+ if (Metrics.NumInsts > MaxHeaderSize)
return false;
}