--- Reverse-merging (from foreign repository) r67049 into '.':

U    test/CodeGen/X86/2009-03-13-PHIElimBug.ll
D    test/CodeGen/X86/2009-03-16-PHIElimInLPad.ll
U    lib/CodeGen/PHIElimination.cpp

r67049 was causing this failure:

Running /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/test/CodeGen/X86/dg.exp ...
FAIL: /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/test/CodeGen/X86/2009-03-13-PHIElimBug.ll for PR3784
Failed with exit(1) at line 1
while running:  llvm-as < /Volumes/Sandbox/Buildbot/llvm/full-llvm/build/llvm.src/test/CodeGen/X86/2009-03-13-PHIElimBug.ll |  llc -march=x86 | /usr/bin/grep -A 2 {call f} | /usr/bin/grep movl
child process exited abnormally


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67051 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/PHIElimination.cpp

@@ -14,8 +14,6 @@
 //===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "phielim"
-#include "llvm/BasicBlock.h"
-#include "llvm/Instructions.h"
 #include "llvm/CodeGen/LiveVariables.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/MachineFunctionPass.h"
@@ -33,6 +31,7 @@
 using namespace llvm;
 
 STATISTIC(NumAtomic, "Number of atomic phis lowered");
+STATISTIC(NumEH,     "Number of EH try blocks skipped");
 
 namespace {
   class VISIBILITY_HIDDEN PNE : public MachineFunctionPass {
@@ -67,25 +66,8 @@ namespace {
     ///
     void analyzePHINodes(const MachineFunction& Fn);
 
-    // FindCopyInsertPoint - Find a safe place in MBB to insert a copy from
-    // SrcReg.  This needs to be after any def or uses of SrcReg, but before
-    // any subsequent point where control flow might jump out of the basic
-    // block.
-    MachineBasicBlock::iterator FindCopyInsertPoint(MachineBasicBlock &MBB,
-                                                    unsigned SrcReg);
-
-    // SkipPHIsAndLabels - Copies need to be inserted after phi nodes and
-    // also after any exception handling labels: in landing pads execution
-    // starts at the label, so any copies placed before it won't be executed!
-    MachineBasicBlock::iterator SkipPHIsAndLabels(MachineBasicBlock &MBB,
-                                                MachineBasicBlock::iterator I) {
-      // Rather than assuming that EH labels come before other kinds of labels,
-      // just skip all labels.
-      while (I != MBB.end() &&
-             (I->getOpcode() == TargetInstrInfo::PHI || I->isLabel()))
-        ++I;
-      return I;
-    }
+    void WalkPassEHTryRange(MachineBasicBlock &MBB,
+                            MachineBasicBlock::iterator &I, unsigned SrcReg);
 
     typedef std::pair<const MachineBasicBlock*, unsigned> BBVRegPair;
     typedef std::map<BBVRegPair, unsigned> VRegPHIUse;
@@ -138,7 +120,10 @@ bool PNE::EliminatePHINodes(MachineFunction &MF, MachineBasicBlock &MBB) {
 
   // Get an iterator to the first instruction after the last PHI node (this may
   // also be the end of the basic block).
-  MachineBasicBlock::iterator AfterPHIsIt = SkipPHIsAndLabels(MBB, MBB.begin());
+  MachineBasicBlock::iterator AfterPHIsIt = MBB.begin();
+  while (AfterPHIsIt != MBB.end() &&
+         AfterPHIsIt->getOpcode() == TargetInstrInfo::PHI)
+    ++AfterPHIsIt;    // Skip over all of the PHI nodes...
 
   while (MBB.front().getOpcode() == TargetInstrInfo::PHI)
     LowerAtomicPHINode(MBB, AfterPHIsIt);
@@ -159,47 +144,37 @@ static bool isSourceDefinedByImplicitDef(const MachineInstr *MPhi,
   return true;
 }
 
-// FindCopyInsertPoint - Find a safe place in MBB to insert a copy from SrcReg.
-// This needs to be after any def or uses of SrcReg, but before any subsequent
-// point where control flow might jump out of the basic block.
-MachineBasicBlock::iterator PNE::FindCopyInsertPoint(MachineBasicBlock &MBB,
-                                                     unsigned SrcReg) {
-  // Handle the trivial case trivially.
-  if (MBB.empty())
-    return MBB.begin();
+void PNE::WalkPassEHTryRange(MachineBasicBlock &MBB,
+                             MachineBasicBlock::iterator &I, unsigned SrcReg) {
+  if (I == MBB.begin())
+    return;
+  MachineBasicBlock::iterator PI = prior(I);
+  if (PI->getOpcode() != TargetInstrInfo::EH_LABEL)
+    return;
 
-  // If this basic block does not contain an invoke, then control flow always
-  // reaches the end of it, so place the copy there.  The logic below works in
-  // this case too, but is more expensive.
-  if (!isa<InvokeInst>(MBB.getBasicBlock()->getTerminator()))
-    return MBB.getFirstTerminator();
-
-  // Discover any definition/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);
+  // Trying to walk pass the EH try range. If we run into a use instruction,
+  // we want to insert the copy there.
+  SmallPtrSet<MachineInstr*, 4> UsesInMBB;
+  for (MachineRegisterInfo::use_iterator UI = MRI->use_begin(SrcReg),
+         UE = MRI->use_end(); UI != UE; ++UI) {
+    MachineInstr *UseMI = &*UI;
+    if (UseMI->getParent() == &MBB)
+      UsesInMBB.insert(UseMI);
   }
 
-  MachineBasicBlock::iterator InsertPoint;
-  if (DefUsesInMBB.empty()) {
-    // No def/uses.  Insert the copy at the start of the basic block.
-    InsertPoint = MBB.begin();
-  } else if (DefUsesInMBB.size() == 1) {
-    // Insert the copy immediately after the definition/use.
-    InsertPoint = *DefUsesInMBB.begin();
-    ++InsertPoint;
-  } else {
-    // Insert the copy immediately after the last definition/use.
-    InsertPoint = MBB.end();
-    while (!DefUsesInMBB.count(&*--InsertPoint)) {}
-    ++InsertPoint;
+  while (PI != MBB.begin()) {
+    --PI;
+    if (PI->getOpcode() == TargetInstrInfo::EH_LABEL) {
+      ++NumEH;
+      I = PI;
+      return;
+    } else if (UsesInMBB.count(&*PI)) {
+      ++NumEH;
+      I = next(PI);
+      return;
+    }
   }
-
-  // Make sure the copy goes after any phi nodes however.
-  return SkipPHIsAndLabels(MBB, InsertPoint);
+  return;
 }
 
 /// LowerAtomicPHINode - Lower the PHI node at the top of the specified block,
@@ -298,7 +273,10 @@ void PNE::LowerAtomicPHINode(MachineBasicBlock &MBB,
  
     // Find a safe location to insert the copy, this may be the first terminator
     // in the block (or end()).
-    MachineBasicBlock::iterator InsertPos = FindCopyInsertPoint(opBlock, SrcReg);
+    MachineBasicBlock::iterator InsertPos = opBlock.getFirstTerminator();
+
+    // Walk pass EH try range if needed.
+    WalkPassEHTryRange(opBlock, InsertPos, SrcReg);
 
     // Insert the copy.
     TII->copyRegToReg(opBlock, InsertPos, IncomingReg, SrcReg, RC, RC);