[llvm-commits] [llvm] r113640 - in /llvm/trunk: include/llvm/Target/TargetInstrInfo.h lib/CodeGen/PeepholeOptimizer.cpp lib/Target/ARM/ARMBaseInstrInfo.cpp lib/Target/ARM/ARMBaseInstrInfo.h

[Bill Wendling]

Author: void
Date: Fri Sep 10 16:55:43 2010
New Revision: 113640

URL: http://llvm.org/viewvc/llvm-project?rev=113640&view=rev
Log:
Modify the comparison optimizations in the peephole optimizer to update the
iterator when an optimization took place. This allows us to do more insane
things with the code than just remove an instruction or two.

Modified:
    llvm/trunk/include/llvm/Target/TargetInstrInfo.h
    llvm/trunk/lib/CodeGen/PeepholeOptimizer.cpp
    llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp
    llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.h

Modified: llvm/trunk/include/llvm/Target/TargetInstrInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Target/TargetInstrInfo.h?rev=113640&r1=113639&r2=113640&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Target/TargetInstrInfo.h (original)
+++ llvm/trunk/include/llvm/Target/TargetInstrInfo.h Fri Sep 10 16:55:43 2010
@@ -586,9 +586,11 @@
   }
 
   /// ConvertToSetZeroFlag - Convert the instruction to set the zero flag so
-  /// that we can remove a "comparison with zero".
-  virtual bool ConvertToSetZeroFlag(MachineInstr *Instr,
-                                    MachineInstr *CmpInstr) const {
+  /// that we can remove a "comparison with zero".  Update the iterator *only*
+  /// if a transformation took place.
+  virtual bool ConvertToSetZeroFlag(MachineInstr * /*Instr*/,
+                                    MachineInstr * /*CmpInstr*/,
+                                    MachineBasicBlock::iterator &) const {
     return false;
   }
 

Modified: llvm/trunk/lib/CodeGen/PeepholeOptimizer.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/PeepholeOptimizer.cpp?rev=113640&r1=113639&r2=113640&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/PeepholeOptimizer.cpp (original)
+++ llvm/trunk/lib/CodeGen/PeepholeOptimizer.cpp Fri Sep 10 16:55:43 2010
@@ -76,7 +76,8 @@
     }
 
   private:
-    bool OptimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB);
+    bool OptimizeCmpInstr(MachineInstr *MI, MachineBasicBlock *MBB,
+                          MachineBasicBlock::iterator &MII);
     bool OptimizeExtInstr(MachineInstr *MI, MachineBasicBlock *MBB,
                           SmallPtrSet<MachineInstr*, 8> &LocalMIs);
   };
@@ -232,7 +233,8 @@
 /// set) the same flag as the compare, then we can remove the comparison and use
 /// the flag from the previous instruction.
 bool PeepholeOptimizer::OptimizeCmpInstr(MachineInstr *MI,
-                                         MachineBasicBlock *MBB) {
+                                         MachineBasicBlock *MBB,
+                                         MachineBasicBlock::iterator &NextIter){
   // If this instruction is a comparison against zero and isn't comparing a
   // physical register, we can try to optimize it.
   unsigned SrcReg;
@@ -247,7 +249,7 @@
     return false;
 
   // Attempt to convert the defining instruction to set the "zero" flag.
-  if (TII->ConvertToSetZeroFlag(&*DI, MI)) {
+  if (TII->ConvertToSetZeroFlag(&*DI, MI, NextIter)) {
     ++NumEliminated;
     return true;
   }
@@ -269,12 +271,14 @@
     LocalMIs.clear();
 
     for (MachineBasicBlock::iterator
-           MII = I->begin(), ME = I->end(); MII != ME; ) {
+           MII = I->begin(), MIE = I->end(); MII != MIE; ) {
       MachineInstr *MI = &*MII;
 
       if (MI->getDesc().isCompare()) {
-        ++MII; // The iterator may become invalid if the compare is deleted.
-        Changed |= OptimizeCmpInstr(MI, MBB);
+        if (OptimizeCmpInstr(MI, MBB, MII))
+          Changed = true;
+        else
+          ++MII;
       } else {
         Changed |= OptimizeExtInstr(MI, MBB, LocalMIs);
         ++MII;

Modified: llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp?rev=113640&r1=113639&r2=113640&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.cpp Fri Sep 10 16:55:43 2010
@@ -1378,9 +1378,11 @@
 }
 
 /// ConvertToSetZeroFlag - Convert the instruction to set the "zero" flag so
-/// that we can remove a "comparison with zero".
+/// that we can remove a "comparison with zero". Update the iterator *only* if a
+/// transformation took place.
 bool ARMBaseInstrInfo::
-ConvertToSetZeroFlag(MachineInstr *MI, MachineInstr *CmpInstr) const {
+ConvertToSetZeroFlag(MachineInstr *MI, MachineInstr *CmpInstr,
+                     MachineBasicBlock::iterator &MII) const {
   // Conservatively refuse to convert an instruction which isn't in the same BB
   // as the comparison.
   if (MI->getParent() != CmpInstr->getParent())
@@ -1414,6 +1416,7 @@
     MI->RemoveOperand(5);
     MachineInstrBuilder(MI)
       .addReg(ARM::CPSR, RegState::Define | RegState::Implicit);
+    MII = llvm::next(MachineBasicBlock::iterator(CmpInstr));
     CmpInstr->eraseFromParent();
     return true;
   }

Modified: llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.h?rev=113640&r1=113639&r2=113640&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.h (original)
+++ llvm/trunk/lib/Target/ARM/ARMBaseInstrInfo.h Fri Sep 10 16:55:43 2010
@@ -347,7 +347,8 @@
   /// ConvertToSetZeroFlag - Convert the instruction to set the zero flag so
   /// that we can remove a "comparison with zero".
   virtual bool ConvertToSetZeroFlag(MachineInstr *Instr,
-                                    MachineInstr *CmpInstr) const;
+                                    MachineInstr *CmpInstr,
+                                    MachineBasicBlock::iterator &MII) const;
 
   virtual unsigned getNumMicroOps(const MachineInstr *MI,
                                   const InstrItineraryData *ItinData) const;