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-rw-r--r--lib/CodeGen/PHIElimination.cpp13
1 files changed, 9 insertions, 4 deletions
diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp
index aa84a60..6d8f207 100644
--- a/lib/CodeGen/PHIElimination.cpp
+++ b/lib/CodeGen/PHIElimination.cpp
@@ -40,6 +40,11 @@ DisableEdgeSplitting("disable-phi-elim-edge-splitting", cl::init(false),
cl::Hidden, cl::desc("Disable critical edge splitting "
"during PHI elimination"));
+static cl::opt<bool>
+SplitAllCriticalEdges("phi-elim-split-all-critical-edges", cl::init(false),
+ cl::Hidden, cl::desc("Split all critical edges during "
+ "PHI elimination"));
+
namespace {
class PHIElimination : public MachineFunctionPass {
MachineRegisterInfo *MRI; // Machine register information
@@ -550,10 +555,10 @@ bool PHIElimination::SplitPHIEdges(MachineFunction &MF,
// Avoid splitting backedges of loops. It would introduce small
// out-of-line blocks into the loop which is very bad for code placement.
- if (PreMBB == &MBB)
+ if (PreMBB == &MBB && !SplitAllCriticalEdges)
continue;
const MachineLoop *PreLoop = MLI ? MLI->getLoopFor(PreMBB) : 0;
- if (IsLoopHeader && PreLoop == CurLoop)
+ if (IsLoopHeader && PreLoop == CurLoop && !SplitAllCriticalEdges)
continue;
// LV doesn't consider a phi use live-out, so isLiveOut only returns true
@@ -562,7 +567,7 @@ bool PHIElimination::SplitPHIEdges(MachineFunction &MF,
// 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))
+ if (!isLiveOutPastPHIs(Reg, PreMBB) && !SplitAllCriticalEdges)
continue;
DEBUG(dbgs() << PrintReg(Reg) << " live-out before critical edge BB#"
@@ -577,7 +582,7 @@ bool PHIElimination::SplitPHIEdges(MachineFunction &MF,
// 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);
+ bool ShouldSplit = !isLiveIn(Reg, &MBB) || SplitAllCriticalEdges;
// Check for a loop exiting edge.
if (!ShouldSplit && CurLoop != PreLoop) {