3 files changed, 18 insertions, 2 deletions
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index f92317c322..c38b89534b 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -1203,7 +1203,8 @@ bool ARMBaseInstrInfo::isProfitableToIfCvt(MachineBasicBlock &MBB,
   
   // Attempt to estimate the relative costs of predication versus branching.
   float UnpredCost = Probability * NumInstrs;
-  UnpredCost += 2.0; // FIXME: Should model a misprediction cost.
+  UnpredCost += 1.0; // The branch itself
+  UnpredCost += 0.1 * Subtarget.getMispredictionPenalty();
   
   float PredCost = NumInstrs;
   
@@ -1220,7 +1221,8 @@ isProfitableToIfCvt(MachineBasicBlock &TMBB, unsigned NumT,
   
   // Attempt to estimate the relative costs of predication versus branching.
   float UnpredCost = Probability * NumT + (1.0 - Probability) * NumF;
-  UnpredCost += 2.0; // FIXME: Should model a misprediction cost.
+  UnpredCost += 1.0; // The branch itself
+  UnpredCost += 0.1 * Subtarget.getMispredictionPenalty();
   
   float PredCost = NumT + NumF;
   
diff --git a/lib/Target/ARM/ARMSubtarget.cpp b/lib/Target/ARM/ARMSubtarget.cpp
index 6ecb512d5b..65bb85f29f 100644
--- a/lib/Target/ARM/ARMSubtarget.cpp
+++ b/lib/Target/ARM/ARMSubtarget.cpp
@@ -185,6 +185,18 @@ ARMSubtarget::GVIsIndirectSymbol(const GlobalValue *GV,
   return false;
 }
 
+unsigned ARMSubtarget::getMispredictionPenalty() const {
+  // If we have a reasonable estimate of the pipeline depth, then we can
+  // estimate the penalty of a misprediction based on that.
+  if (isCortexA8())
+    return 13;
+  else if (isCortexA9())
+    return 8;
+  
+  // Otherwise, just return a sensible default.
+  return 10;
+}
+
 bool ARMSubtarget::enablePostRAScheduler(
            CodeGenOpt::Level OptLevel,
            TargetSubtarget::AntiDepBreakMode& Mode,
diff --git a/lib/Target/ARM/ARMSubtarget.h b/lib/Target/ARM/ARMSubtarget.h
index 3d9f40b4e7..aefd130b9a 100644
--- a/lib/Target/ARM/ARMSubtarget.h
+++ b/lib/Target/ARM/ARMSubtarget.h
@@ -194,6 +194,8 @@ protected:
 
   const std::string & getCPUString() const { return CPUString; }
 
+  unsigned getMispredictionPenalty() const;
+  
   /// enablePostRAScheduler - True at 'More' optimization.
   bool enablePostRAScheduler(CodeGenOpt::Level OptLevel,
                              TargetSubtarget::AntiDepBreakMode& Mode,