#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetSubtargetInfo.h"
#include <algorithm>
using namespace llvm;
cl::Hidden, cl::desc("Split all critical edges during "
"PHI elimination"));
+static cl::opt<bool> NoPhiElimLiveOutEarlyExit(
+ "no-phi-elim-live-out-early-exit", cl::init(false), cl::Hidden,
+ cl::desc("Do not use an early exit if isLiveOutPastPHIs returns true."));
+
namespace {
class PHIElimination : public MachineFunctionPass {
MachineRegisterInfo *MRI; // Machine register information
Changed |= EliminatePHINodes(MF, *I);
// Remove dead IMPLICIT_DEF instructions.
- for (SmallPtrSet<MachineInstr*, 4>::iterator I = ImpDefs.begin(),
- E = ImpDefs.end(); I != E; ++I) {
- MachineInstr *DefMI = *I;
+ for (MachineInstr *DefMI : ImpDefs) {
unsigned DefReg = DefMI->getOperand(0).getReg();
if (MRI->use_nodbg_empty(DefReg)) {
if (LIS)
// Check to make sure we haven't already emitted the copy for this block.
// This can happen because PHI nodes may have multiple entries for the same
// basic block.
- if (!MBBsInsertedInto.insert(&opBlock))
+ if (!MBBsInsertedInto.insert(&opBlock).second)
continue; // If the copy has already been emitted, we're done.
// Find a safe location to insert the copy, this may be the first terminator
// there is a risk it may not be coalesced away.
//
// If the copy would be a kill, there is no need to split the edge.
- if (!isLiveOutPastPHIs(Reg, PreMBB) && !SplitAllCriticalEdges)
+ bool ShouldSplit = isLiveOutPastPHIs(Reg, PreMBB);
+ if (!ShouldSplit && !NoPhiElimLiveOutEarlyExit)
continue;
-
- DEBUG(dbgs() << PrintReg(Reg) << " live-out before critical edge BB#"
- << PreMBB->getNumber() << " -> BB#" << MBB.getNumber()
- << ": " << *BBI);
+ if (ShouldSplit) {
+ DEBUG(dbgs() << PrintReg(Reg) << " live-out before critical edge BB#"
+ << PreMBB->getNumber() << " -> BB#" << MBB.getNumber()
+ << ": " << *BBI);
+ }
// If Reg is not live-in to MBB, it means it must be live-in to some
// other PreMBB successor, and we can avoid the interference by splitting
// is likely to be left after coalescing. If we are looking at a loop
// exiting edge, split it so we won't insert code in the loop, otherwise
// don't bother.
- bool ShouldSplit = !isLiveIn(Reg, &MBB) || SplitAllCriticalEdges;
+ ShouldSplit = ShouldSplit && !isLiveIn(Reg, &MBB);
// Check for a loop exiting edge.
if (!ShouldSplit && CurLoop != PreLoop) {
// Split unless this edge is entering CurLoop from an outer loop.
ShouldSplit = PreLoop && !PreLoop->contains(CurLoop);
}
- if (!ShouldSplit)
+ if (!ShouldSplit && !SplitAllCriticalEdges)
continue;
if (!PreMBB->SplitCriticalEdge(&MBB, this)) {
DEBUG(dbgs() << "Failed to split critical edge.\n");