Peephole opt needs optimizeSelect() to keep track of newly created MIs

[oota-llvm.git] / lib / CodeGen / PeepholeOptimizer.cpp

diff --git a/lib/CodeGen/PeepholeOptimizer.cpp b/lib/CodeGen/PeepholeOptimizer.cpp
index 7c195a89bd762f02d607729582ae005a58713f1d..283d1f26198bcf0a15a67cdbdc7e6fe6c34a0a50 100644 (file)
--- a/lib/CodeGen/PeepholeOptimizer.cpp
+++ b/lib/CodeGen/PeepholeOptimizer.cpp
@@ -107,7 +107,6 @@ STATISTIC(NumRewrittenCopies, "Number of copies rewritten");
 
 namespace {
   class PeepholeOptimizer : public MachineFunctionPass {
-    MachineFunction *MF;
     const TargetInstrInfo *TII;
     const TargetRegisterInfo *TRI;
     MachineRegisterInfo   *MRI;
@@ -134,7 +133,9 @@ namespace {
     bool optimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB);
     bool optimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
                           SmallPtrSetImpl<MachineInstr*> &LocalMIs);
-    bool optimizeSelect(MachineInstr *MI);
+    bool optimizeSelect(MachineInstr *MI,
+                        SmallPtrSetImpl<MachineInstr *> &LocalMIs);
+    bool optimizeCondBranch(MachineInstr *MI);
     bool optimizeCopyOrBitcast(MachineInstr *MI);
     bool optimizeCoalescableCopy(MachineInstr *MI);
     bool optimizeUncoalescableCopy(MachineInstr *MI,
@@ -482,7 +483,8 @@ bool PeepholeOptimizer::optimizeCmpInstr(MachineInstr *MI,
 }
 
 /// Optimize a select instruction.
-bool PeepholeOptimizer::optimizeSelect(MachineInstr *MI) {
+bool PeepholeOptimizer::optimizeSelect(MachineInstr *MI,
+                            SmallPtrSetImpl<MachineInstr *> &LocalMIs) {
   unsigned TrueOp = 0;
   unsigned FalseOp = 0;
   bool Optimizable = false;
@@ -491,13 +493,19 @@ bool PeepholeOptimizer::optimizeSelect(MachineInstr *MI) {
     return false;
   if (!Optimizable)
     return false;
-  if (!TII->optimizeSelect(MI))
+  if (!TII->optimizeSelect(MI, LocalMIs))
     return false;
   MI->eraseFromParent();
   ++NumSelects;
   return true;
 }
 
+/// \brief Check if a simpler conditional branch can be
+// generated
+bool PeepholeOptimizer::optimizeCondBranch(MachineInstr *MI) {
+  return TII->optimizeCondBranch(MI);
+}
+
 /// \brief Check if the registers defined by the pair (RegisterClass, SubReg)
 /// share the same register file.
 static bool shareSameRegisterFile(const TargetRegisterInfo &TRI,
@@ -1045,28 +1053,34 @@ bool PeepholeOptimizer::foldImmediate(MachineInstr *MI, MachineBasicBlock *MBB,
   return false;
 }
 
-bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &mf) {
-  if (skipOptnoneFunction(*mf.getFunction()))
+bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &MF) {
+  if (skipOptnoneFunction(*MF.getFunction()))
     return false;
 
   DEBUG(dbgs() << "********** PEEPHOLE OPTIMIZER **********\n");
-  DEBUG(dbgs() << "********** Function: " << mf.getName() << '\n');
+  DEBUG(dbgs() << "********** Function: " << MF.getName() << '\n');
 
   if (DisablePeephole)
     return false;
 
-  MF = &mf;
-  TII = MF->getSubtarget().getInstrInfo();
-  TRI = MF->getSubtarget().getRegisterInfo();
-  MRI = &MF->getRegInfo();
+  TII = MF.getSubtarget().getInstrInfo();
+  TRI = MF.getSubtarget().getRegisterInfo();
+  MRI = &MF.getRegInfo();
   DT  = Aggressive ? &getAnalysis<MachineDominatorTree>() : nullptr;
 
   bool Changed = false;
 
-  for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I) {
+  for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I) {
     MachineBasicBlock *MBB = &*I;
 
     bool SeenMoveImm = false;
+
+    // During this forward scan, at some point it needs to answer the question
+    // "given a pointer to an MI in the current BB, is it located before or
+    // after the current instruction".
+    // To perform this, the following set keeps track of the MIs already seen
+    // during the scan, if a MI is not in the set, it is assumed to be located
+    // after. Newly created MIs have to be inserted in the set as well.
     SmallPtrSet<MachineInstr*, 16> LocalMIs;
     SmallSet<unsigned, 4> ImmDefRegs;
     DenseMap<unsigned, MachineInstr*> ImmDefMIs;
@@ -1097,13 +1111,18 @@ bool PeepholeOptimizer::runOnMachineFunction(MachineFunction &mf) {
       if ((isUncoalescableCopy(*MI) &&
            optimizeUncoalescableCopy(MI, LocalMIs)) ||
           (MI->isCompare() && optimizeCmpInstr(MI, MBB)) ||
-          (MI->isSelect() && optimizeSelect(MI))) {
+          (MI->isSelect() && optimizeSelect(MI, LocalMIs))) {
         // MI is deleted.
         LocalMIs.erase(MI);
         Changed = true;
         continue;
       }
 
+      if (MI->isConditionalBranch() && optimizeCondBranch(MI)) {
+        Changed = true;
+        continue;
+      }
+
       if (isCoalescableCopy(*MI) && optimizeCoalescableCopy(MI)) {
         // MI is just rewritten.
         Changed = true;