Add a hook for PBQP clients to run a custom pre-alloc pass to run prior to PBQP allocation. Patch by Arnaud Allard de Grandmaison.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133249 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/RegAllocPBQP.cpp b/lib/CodeGen/RegAllocPBQP.cpp
index 605507f..49f8fb4 100644
--- a/lib/CodeGen/RegAllocPBQP.cpp
+++ b/lib/CodeGen/RegAllocPBQP.cpp
@@ -84,8 +84,8 @@
   static char ID;
 
   /// Construct a PBQP register allocator.
-  RegAllocPBQP(std::auto_ptr<PBQPBuilder> b)
-      : MachineFunctionPass(ID), builder(b) {
+  RegAllocPBQP(std::auto_ptr<PBQPBuilder> b, char *cPassID=0)
+      : MachineFunctionPass(ID), builder(b), customPassID(cPassID) {
     initializeSlotIndexesPass(*PassRegistry::getPassRegistry());
     initializeLiveIntervalsPass(*PassRegistry::getPassRegistry());
     initializeRegisterCoalescerAnalysisGroup(*PassRegistry::getPassRegistry());
@@ -122,6 +122,8 @@
 
   std::auto_ptr<PBQPBuilder> builder;
 
+  char *customPassID;
+
   MachineFunction *mf;
   const TargetMachine *tm;
   const TargetRegisterInfo *tri;
@@ -449,6 +451,8 @@
   au.addRequired<LiveIntervals>();
   //au.addRequiredID(SplitCriticalEdgesID);
   au.addRequired<RegisterCoalescer>();
+  if (customPassID)
+    au.addRequiredID(*customPassID);
   au.addRequired<CalculateSpillWeights>();
   au.addRequired<LiveStacks>();
   au.addPreserved<LiveStacks>();
@@ -702,8 +706,9 @@
 }
 
 FunctionPass* llvm::createPBQPRegisterAllocator(
-                                           std::auto_ptr<PBQPBuilder> builder) {
-  return new RegAllocPBQP(builder);
+                                           std::auto_ptr<PBQPBuilder> builder,
+                                           char *customPassID) {
+  return new RegAllocPBQP(builder, customPassID);
 }
 
 FunctionPass* llvm::createDefaultPBQPRegisterAllocator() {