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 c4f2cc7a75d382c0ae089b21da07245ab5913ba1..fc6574290b350e4bc918b7400e4198c7495d961c 100644 (file)
--- 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 @@ STATISTIC(NumSplits, "Number of critical edges split on demand");
 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 @@ X("phi-node-elimination", "Eliminate PHI nodes for register allocation");
 
 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 llvm::PHIElimination::runOnMachineFunction(MachineFunction &Fn) {
   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);
 

diff --git a/test/CodeGen/X86/2008-04-15-LiveVariableBug.ll b/test/CodeGen/X86/2008-04-15-LiveVariableBug.ll
index 83eb61aed433cd2fd08ac8729aa270c05ed85b39..2aea9c5ebcc4fdfde8dd27800d53b32eac779df4 100644 (file)
--- a/test/CodeGen/X86/2008-04-15-LiveVariableBug.ll
+++ b/test/CodeGen/X86/2008-04-15-LiveVariableBug.ll
@@ -1,5 +1,6 @@
 ; RUN: llc < %s -mtriple=x86_64-apple-darwin
 ; RUN: llc < %s -mtriple=x86_64-apple-darwin -relocation-model=pic -disable-fp-elim -O0 -regalloc=local
+; PR5534
 
        %struct.CGPoint = type { double, double }
        %struct.NSArray = type { %struct.NSObject }

diff --git a/test/CodeGen/X86/stack-color-with-reg.ll b/test/CodeGen/X86/stack-color-with-reg.ll
index 0f32a50fc5b390266fc6e6c3466e053a1047b47c..61cff05a02315c499445fa74739ab9438477e9e0 100644 (file)
--- a/test/CodeGen/X86/stack-color-with-reg.ll
+++ b/test/CodeGen/X86/stack-color-with-reg.ll
@@ -1,6 +1,6 @@
 ; RUN: llc < %s -mtriple=x86_64-apple-darwin10 -relocation-model=pic -disable-fp-elim -color-ss-with-regs -stats -info-output-file - > %t
 ; RUN:   grep stackcoloring %t | grep "stack slot refs replaced with reg refs"  | grep 6
-; RUN:   grep asm-printer %t   | grep 177
+; RUN:   grep asm-printer %t   | grep 175
 
        type { [62 x %struct.Bitvec*] }         ; type %0
        type { i8* }            ; type %1