[llvm-commits] [llvm] r92864 - in /llvm/trunk/lib/CodeGen: CriticalAntiDepBreaker.cpp CriticalAntiDepBreaker.h

[Jim Grosbach]

Author: grosbach
Date: Wed Jan  6 16:21:25 2010
New Revision: 92864

URL: http://llvm.org/viewvc/llvm-project?rev=92864&view=rev
Log:
Anti-dependency breaking needs to be careful regarding instructions with
multiple register definitions.

Modified:
    llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.cpp
    llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.h

Modified: llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.cpp?rev=92864&r1=92863&r2=92864&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.cpp (original)
+++ llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.cpp Wed Jan  6 16:21:25 2010
@@ -288,7 +288,8 @@
 }
 
 unsigned
-CriticalAntiDepBreaker::findSuitableFreeRegister(unsigned AntiDepReg,
+CriticalAntiDepBreaker::findSuitableFreeRegister(MachineInstr *MI,
+                                                 unsigned AntiDepReg,
                                                  unsigned LastNewReg,
                                                  const TargetRegisterClass *RC)
 {
@@ -301,6 +302,10 @@
     // an anti-dependence with this AntiDepReg, because that would
     // re-introduce that anti-dependence.
     if (NewReg == LastNewReg) continue;
+    // If the instruction already has a def of the NewReg, it's not suitable.
+    // For example, Instruction with multiple definitions can result in this
+    // condition.
+    if (MI->modifiesRegister(NewReg, TRI)) continue;
     // If NewReg is dead and NewReg's most recent def is not before
     // AntiDepReg's kill, it's safe to replace AntiDepReg with NewReg.
     assert(((KillIndices[AntiDepReg] == ~0u) != (DefIndices[AntiDepReg] == ~0u))
@@ -496,7 +501,7 @@
     // TODO: Instead of picking the first free register, consider which might
     // be the best.
     if (AntiDepReg != 0) {
-      if (unsigned NewReg = findSuitableFreeRegister(AntiDepReg,
+      if (unsigned NewReg = findSuitableFreeRegister(MI, AntiDepReg,
                                                      LastNewReg[AntiDepReg],
                                                      RC)) {
         DEBUG(dbgs() << "Breaking anti-dependence edge on "

Modified: llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.h?rev=92864&r1=92863&r2=92864&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.h (original)
+++ llvm/trunk/lib/CodeGen/CriticalAntiDepBreaker.h Wed Jan  6 16:21:25 2010
@@ -88,7 +88,8 @@
   private:
     void PrescanInstruction(MachineInstr *MI);
     void ScanInstruction(MachineInstr *MI, unsigned Count);
-    unsigned findSuitableFreeRegister(unsigned AntiDepReg,
+    unsigned findSuitableFreeRegister(MachineInstr *MI,
+                                      unsigned AntiDepReg,
                                       unsigned LastNewReg,
                                       const TargetRegisterClass *);
   };