Move the FindCopyInsertPoint method of PHIElimination to a new standalone

function so that it can be shared with StrongPHIElimination.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120951 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CMakeLists.txt

@@ -50,6 +50,7 @@ add_llvm_library(LLVMCodeGen
   OcamlGC.cpp
   OptimizePHIs.cpp
   PHIElimination.cpp
+  PHIEliminationUtils.cpp
   Passes.cpp
   PeepholeOptimizer.cpp
   PostRAHazardRecognizer.cpp

lib/CodeGen/PHIElimination.cpp

@@ -15,6 +15,7 @@
 
 #define DEBUG_TYPE "phielim"
 #include "PHIElimination.h"
+#include "PHIEliminationUtils.h"
 #include "llvm/CodeGen/LiveVariables.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/MachineDominators.h"
@@ -121,51 +122,7 @@ static bool isSourceDefinedByImplicitDef(const MachineInstr *MPhi,
   return true;
 }
 
-// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from SrcReg
-// when following the CFG edge to SuccMBB. This needs to be after any def of
-// SrcReg, but before any subsequent point where control flow might jump out of
-// the basic block.
-MachineBasicBlock::iterator
-llvm::PHIElimination::FindCopyInsertPoint(MachineBasicBlock &MBB,
-                                          MachineBasicBlock &SuccMBB,
-                                          unsigned SrcReg) {
-  // Handle the trivial case trivially.
-  if (MBB.empty())
-    return MBB.begin();
 
-  // Usually, we just want to insert the copy before the first terminator
-  // instruction. However, for the edge going to a landing pad, we must insert
-  // the copy before the call/invoke instruction.
-  if (!SuccMBB.isLandingPad())
-    return MBB.getFirstTerminator();
-
-  // Discover any defs/uses in this basic block.
-  SmallPtrSet<MachineInstr*, 8> DefUsesInMBB;
-  for (MachineRegisterInfo::reg_iterator RI = MRI->reg_begin(SrcReg),
-         RE = MRI->reg_end(); RI != RE; ++RI) {
-    MachineInstr *DefUseMI = &*RI;
-    if (DefUseMI->getParent() == &MBB)
-      DefUsesInMBB.insert(DefUseMI);
-  }
-
-  MachineBasicBlock::iterator InsertPoint;
-  if (DefUsesInMBB.empty()) {
-    // No defs.  Insert the copy at the start of the basic block.
-    InsertPoint = MBB.begin();
-  } else if (DefUsesInMBB.size() == 1) {
-    // Insert the copy immediately after the def/use.
-    InsertPoint = *DefUsesInMBB.begin();
-    ++InsertPoint;
-  } else {
-    // Insert the copy immediately after the last def/use.
-    InsertPoint = MBB.end();
-    while (!DefUsesInMBB.count(&*--InsertPoint)) {}
-    ++InsertPoint;
-  }
-
-  // Make sure the copy goes after any phi nodes however.
-  return MBB.SkipPHIsAndLabels(InsertPoint);
-}
 
 /// LowerAtomicPHINode - Lower the PHI node at the top of the specified block,
 /// under the assuption that it needs to be lowered in a way that supports
@@ -294,7 +251,7 @@ void llvm::PHIElimination::LowerAtomicPHINode(
     // Find a safe location to insert the copy, this may be the first terminator
     // in the block (or end()).
     MachineBasicBlock::iterator InsertPos =
-      FindCopyInsertPoint(opBlock, MBB, SrcReg);
+      findPHICopyInsertPoint(&opBlock, &MBB, SrcReg);
 
     // Insert the copy.
     if (!reusedIncoming && IncomingReg)

lib/CodeGen/PHIEliminationUtils.cpp

@@ -0,0 +1,61 @@
+//===-- PHIEliminationUtils.cpp - Helper functions for PHI elimination ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PHIEliminationUtils.h"
+#include "llvm/CodeGen/MachineBasicBlock.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/ADT/SmallPtrSet.h"
+using namespace llvm;
+
+// findCopyInsertPoint - Find a safe place in MBB to insert a copy from SrcReg
+// when following the CFG edge to SuccMBB. This needs to be after any def of
+// SrcReg, but before any subsequent point where control flow might jump out of
+// the basic block.
+MachineBasicBlock::iterator
+llvm::findPHICopyInsertPoint(MachineBasicBlock* MBB, MachineBasicBlock* SuccMBB,
+                             unsigned SrcReg) {
+  // Handle the trivial case trivially.
+  if (MBB->empty())
+    return MBB->begin();
+
+  // Usually, we just want to insert the copy before the first terminator
+  // instruction. However, for the edge going to a landing pad, we must insert
+  // the copy before the call/invoke instruction.
+  if (!SuccMBB->isLandingPad())
+    return MBB->getFirstTerminator();
+
+  // Discover any defs/uses in this basic block.
+  SmallPtrSet<MachineInstr*, 8> DefUsesInMBB;
+  MachineRegisterInfo& MRI = MBB->getParent()->getRegInfo();
+  for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(SrcReg),
+         RE = MRI.reg_end(); RI != RE; ++RI) {
+    MachineInstr* DefUseMI = &*RI;
+    if (DefUseMI->getParent() == MBB)
+      DefUsesInMBB.insert(DefUseMI);
+  }
+
+  MachineBasicBlock::iterator InsertPoint;
+  if (DefUsesInMBB.empty()) {
+    // No defs.  Insert the copy at the start of the basic block.
+    InsertPoint = MBB->begin();
+  } else if (DefUsesInMBB.size() == 1) {
+    // Insert the copy immediately after the def/use.
+    InsertPoint = *DefUsesInMBB.begin();
+    ++InsertPoint;
+  } else {
+    // Insert the copy immediately after the last def/use.
+    InsertPoint = MBB->end();
+    while (!DefUsesInMBB.count(&*--InsertPoint)) {}
+    ++InsertPoint;
+  }
+
+  // Make sure the copy goes after any phi nodes however.
+  return MBB->SkipPHIsAndLabels(InsertPoint);
+}

lib/CodeGen/PHIEliminationUtils.h

@@ -0,0 +1,25 @@
+//=- PHIEliminationUtils.h - Helper functions for PHI elimination *- C++ -*--=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_PHIELIMINATIONUTILS_H
+#define LLVM_CODEGEN_PHIELIMINATIONUTILS_H
+
+#include "llvm/CodeGen/MachineBasicBlock.h"
+
+namespace llvm {
+    /// findPHICopyInsertPoint - Find a safe place in MBB to insert a copy from
+    /// SrcReg when following the CFG edge to SuccMBB. This needs to be after
+    /// any def of SrcReg, but before any subsequent point where control flow
+    /// might jump out of the basic block.
+    MachineBasicBlock::iterator
+    findPHICopyInsertPoint(MachineBasicBlock* MBB, MachineBasicBlock* SuccMBB,
+                           unsigned SrcReg);
+}
+
+#endif