Enable -split-phi-edges by default, except when -regalloc=local.
The local register allocator doesn't like it when LiveVariables is run.
We should also disable edge splitting under -O0, but that has to wait a bit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89125 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/PHIElimination.cpp b/lib/CodeGen/PHIElimination.cpp
index c4f2cc7..fc65742 100644
--- a/lib/CodeGen/PHIElimination.cpp
+++ b/lib/CodeGen/PHIElimination.cpp
@@ -21,6 +21,7 @@
#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RegAllocRegistry.h"
#include "llvm/Function.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/ADT/SmallPtrSet.h"
@@ -39,7 +40,7 @@
static cl::opt<bool>
SplitEdges("split-phi-edges",
cl::desc("Split critical edges during phi elimination"),
- cl::init(false), cl::Hidden);
+ cl::init(true), cl::Hidden);
char PHIElimination::ID = 0;
static RegisterPass<PHIElimination>
@@ -47,10 +48,21 @@
const PassInfo *const llvm::PHIEliminationID = &X;
+namespace llvm { FunctionPass *createLocalRegisterAllocator(); }
+
+// Should we run edge splitting?
+static bool shouldSplitEdges() {
+ // Edge splitting breaks the local register allocator. It cannot tolerate
+ // LiveVariables being run.
+ if (RegisterRegAlloc::getDefault() == createLocalRegisterAllocator)
+ return false;
+ return SplitEdges;
+}
+
void llvm::PHIElimination::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreserved<LiveVariables>();
AU.addPreserved<MachineDominatorTree>();
- if (SplitEdges) {
+ if (shouldSplitEdges()) {
AU.addRequired<LiveVariables>();
} else {
AU.setPreservesCFG();
@@ -67,7 +79,7 @@
bool Changed = false;
// Split critical edges to help the coalescer
- if (SplitEdges)
+ if (shouldSplitEdges())
for (MachineFunction::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
Changed |= SplitPHIEdges(Fn, *I);