3 files changed, 26 insertions, 10 deletions
diff --git a/include/llvm/CodeGen/Passes.h b/include/llvm/CodeGen/Passes.h
index 1746fd4c14..5f710e68fe 100644
--- a/include/llvm/CodeGen/Passes.h
+++ b/include/llvm/CodeGen/Passes.h
@@ -181,6 +181,16 @@ protected:
   /// instructions in SSA form.
   virtual void addMachineSSAOptimization();
 
+  /// Add passes that optimize instruction level parallelism for out-of-order
+  /// targets. These passes are run while the machine code is still in SSA
+  /// form, so they can use MachineTraceMetrics to control their heuristics.
+  ///
+  /// All passes added here should preserve the MachineDominatorTree,
+  /// MachineLoopInfo, and MachineTraceMetrics analyses.
+  virtual bool addILPOpts() {
+    return false;
+  }
+
   /// addPreRegAlloc - This method may be implemented by targets that want to
   /// run passes immediately before register allocation. This should return
   /// true if -print-machineinstrs should print after these passes.
diff --git a/lib/CodeGen/Passes.cpp b/lib/CodeGen/Passes.cpp
index 2a135bcc1e..02a14914f1 100644
--- a/lib/CodeGen/Passes.cpp
+++ b/lib/CodeGen/Passes.cpp
@@ -238,9 +238,6 @@ TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
   substitutePass(&EarlyTailDuplicateID, &TailDuplicateID);
   substitutePass(&PostRAMachineLICMID, &MachineLICMID);
 
-  // Disable early if-conversion. Targets that are ready can enable it.
-  disablePass(&EarlyIfConverterID);
-
   // Temporarily disable experimental passes.
   const TargetSubtargetInfo &ST = TM->getSubtarget<TargetSubtargetInfo>();
   if (!ST.enableMachineScheduler())
@@ -551,7 +548,12 @@ void TargetPassConfig::addMachineSSAOptimization() {
   addPass(&DeadMachineInstructionElimID);
   printAndVerify("After codegen DCE pass");
 
-  addPass(&EarlyIfConverterID);
+  // Allow targets to insert passes that improve instruction level parallelism,
+  // like if-conversion. Such passes will typically need dominator trees and
+  // loop info, just like LICM and CSE below.
+  if (addILPOpts())
+    printAndVerify("After ILP optimizations");
+
   addPass(&MachineLICMID);
   addPass(&MachineCSEID);
   addPass(&MachineSinkingID);
diff --git a/lib/Target/X86/X86TargetMachine.cpp b/lib/Target/X86/X86TargetMachine.cpp
index 706e64a09f..799f140407 100644
--- a/lib/Target/X86/X86TargetMachine.cpp
+++ b/lib/Target/X86/X86TargetMachine.cpp
@@ -151,6 +151,7 @@ public:
   }
 
   virtual bool addInstSelector();
+  virtual bool addILPOpts();
   virtual bool addPreRegAlloc();
   virtual bool addPostRegAlloc();
   virtual bool addPreEmitPass();
@@ -158,12 +159,7 @@ public:
 } // namespace
 
 TargetPassConfig *X86TargetMachine::createPassConfig(PassManagerBase &PM) {
-  X86PassConfig *PC = new X86PassConfig(this, PM);
-
-  if (X86EarlyIfConv && Subtarget.hasCMov())
-    PC->enablePass(&EarlyIfConverterID);
-
-  return PC;
+  return new X86PassConfig(this, PM);
 }
 
 bool X86PassConfig::addInstSelector() {
@@ -181,6 +177,14 @@ bool X86PassConfig::addInstSelector() {
   return false;
 }
 
+bool X86PassConfig::addILPOpts() {
+  if (X86EarlyIfConv && getX86Subtarget().hasCMov()) {
+    addPass(&EarlyIfConverterID);
+    return true;
+  }
+  return false;
+}
+
 bool X86PassConfig::addPreRegAlloc() {
   return false;  // -print-machineinstr shouldn't print after this.
 }