3 files changed, 48 insertions, 12 deletions
diff --git a/lib/CodeGen/Passes.cpp b/lib/CodeGen/Passes.cpp
index 285d5df634..427e4ac327 100644
--- a/lib/CodeGen/Passes.cpp
+++ b/lib/CodeGen/Passes.cpp
@@ -115,16 +115,34 @@ char TargetPassConfig::ID = 0;
 static char NoPassIDAnchor = 0;
 char &llvm::NoPassID = NoPassIDAnchor;
 
+namespace llvm {
+class PassConfigImpl {
+public:
+  // List of passes explicitly substituted by this target. Normally this is
+  // empty, but it is a convenient way to suppress or replace specific passes
+  // that are part of a standard pass pipeline without overridding the entire
+  // pipeline. This mechanism allows target options to inherit a standard pass's
+  // user interface. For example, a target may disable a standard pass by
+  // default by substituting NoPass, and the user may still enable that standard
+  // pass with an explicit command line option.
+  DenseMap<AnalysisID,AnalysisID> TargetPasses;
+};
+} // namespace llvm
+
 // Out of line virtual method.
-TargetPassConfig::~TargetPassConfig() {}
+TargetPassConfig::~TargetPassConfig() {
+  delete Impl;
+}
 
 // Out of line constructor provides default values for pass options and
 // registers all common codegen passes.
 TargetPassConfig::TargetPassConfig(TargetMachine *tm, PassManagerBase &pm)
-  : ImmutablePass(ID), TM(tm), PM(pm), Initialized(false),
+  : ImmutablePass(ID), TM(tm), PM(pm), Impl(0), Initialized(false),
     DisableVerify(false),
     EnableTailMerge(true) {
 
+  Impl = new PassConfigImpl();
+
   // Register all target independent codegen passes to activate their PassIDs,
   // including this pass itself.
   initializeCodeGen(*PassRegistry::getPassRegistry());
@@ -149,15 +167,33 @@ void TargetPassConfig::setOpt(bool &Opt, bool Val) {
   Opt = Val;
 }
 
-void TargetPassConfig::addPass(char &ID) {
-  if (&ID == &NoPassID)
-    return;
+void TargetPassConfig::substitutePass(char &StandardID, char &TargetID) {
+  Impl->TargetPasses[&StandardID] = &TargetID;
+}
 
+AnalysisID TargetPassConfig::getPassSubstitution(AnalysisID ID) const {
+  DenseMap<AnalysisID, AnalysisID>::const_iterator
+    I = Impl->TargetPasses.find(ID);
+  if (I == Impl->TargetPasses.end())
+    return ID;
+  return I->second;
+}
+
+/// Add a CodeGen pass at this point in the pipeline after checking for target
+/// and command line overrides.
+AnalysisID TargetPassConfig::addPass(char &ID) {
+  assert(!Initialized && "PassConfig is immutable");
+
+  AnalysisID FinalID = getPassSubstitution(&ID);
   // FIXME: check user overrides
-  Pass *P = Pass::createPass(ID);
+  if (FinalID == &NoPassID)
+    return FinalID;
+
+  Pass *P = Pass::createPass(FinalID);
   if (!P)
     llvm_unreachable("Pass ID not registered");
   PM.add(P);
+  return FinalID;
 }
 
 void TargetPassConfig::printNoVerify(const char *Banner) const {
diff --git a/lib/Target/PTX/PTXTargetMachine.cpp b/lib/Target/PTX/PTXTargetMachine.cpp
index 056bc07efa..61285b1545 100644
--- a/lib/Target/PTX/PTXTargetMachine.cpp
+++ b/lib/Target/PTX/PTXTargetMachine.cpp
@@ -151,11 +151,11 @@ bool PTXPassConfig::addPostRegAlloc() {
 
 /// Add passes that optimize machine instructions after register allocation.
 void PTXPassConfig::addMachineLateOptimization() {
-  addPass(BranchFolderPassID);
-  printNoVerify("After BranchFolding");
+  if (addPass(BranchFolderPassID) != &NoPassID)
+    printNoVerify("After BranchFolding");
 
-  addPass(TailDuplicateID);
-  printNoVerify("After TailDuplicate");
+  if (addPass(TailDuplicateID) != &NoPassID)
+    printNoVerify("After TailDuplicate");
 }
 
 bool PTXPassConfig::addPreEmitPass() {
diff --git a/lib/VMCore/Pass.cpp b/lib/VMCore/Pass.cpp
index 07ac3c35c1..994a7ffcee 100644
--- a/lib/VMCore/Pass.cpp
+++ b/lib/VMCore/Pass.cpp
@@ -189,8 +189,8 @@ const PassInfo *Pass::lookupPassInfo(StringRef Arg) {
   return PassRegistry::getPassRegistry()->getPassInfo(Arg);
 }
 
-Pass *Pass::createPass(char &TI) {
-  const PassInfo *PI = PassRegistry::getPassRegistry()->getPassInfo(&TI);
+Pass *Pass::createPass(AnalysisID ID) {
+  const PassInfo *PI = PassRegistry::getPassRegistry()->getPassInfo(ID);
   if (!PI)
     return NULL;
   return PI->createPass();