3 files changed, 63 insertions, 1 deletions
diff --git a/lib/CodeGen/RegAllocLinearScan.cpp b/lib/CodeGen/RegAllocLinearScan.cpp
index 6929b91..2859c24 100644
--- a/lib/CodeGen/RegAllocLinearScan.cpp
+++ b/lib/CodeGen/RegAllocLinearScan.cpp
@@ -21,6 +21,7 @@
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/RegAllocRegistry.h"
+#include "llvm/CodeGen/RegisterCoalescer.h"
 #include "llvm/CodeGen/SSARegMap.h"
 #include "llvm/Target/MRegisterInfo.h"
 #include "llvm/Target/TargetMachine.h"
@@ -96,7 +97,9 @@ namespace {
 
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.addRequired<LiveIntervals>();
-      AU.addRequiredID(SimpleRegisterCoalescingID);
+      // Make sure PassManager knows which analyses to make available
+      // to coalescing and which analyses coalescing invalidates.
+      AU.addRequiredTransitive<RegisterCoalescer>();
       MachineFunctionPass::getAnalysisUsage(AU);
     }
 
@@ -194,6 +197,11 @@ bool RALinScan::runOnMachineFunction(MachineFunction &fn) {
   mri_ = tm_->getRegisterInfo();
   li_ = &getAnalysis<LiveIntervals>();
 
+  // We don't run the coalescer here because we have no reason to
+  // interact with it.  If the coalescer requires interaction, it
+  // won't do anything.  If it doesn't require interaction, we assume
+  // it was run as a separate pass.
+
   // If this is the first function compiled, compute the related reg classes.
   if (RelatedRegClasses.empty())
     ComputeRelatedRegClasses();
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
new file mode 100644
index 0000000..cffc2e0
--- /dev/null
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -0,0 +1,43 @@
+//===- RegisterCoalescer.cpp - Generic Register Coalescing Interface -------==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the generic RegisterCoalescer interface which
+// is used as the common interface used by all clients and
+// implementations of register coalescing.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/RegisterCoalescer.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/Target/MRegisterInfo.h"
+#include "llvm/Pass.h"
+
+using namespace llvm;
+
+// Register the RegisterCoalescer interface, providing a nice name to refer to.
+namespace {
+  RegisterAnalysisGroup<RegisterCoalescer> Z("Register Coalescer");
+}
+char RegisterCoalescer::ID = 0;
+
+// RegisterCoalescer destructor: DO NOT move this to the header file
+// for RegisterCoalescer or else clients of the RegisterCoalescer
+// class may not depend on the RegisterCoalescer.o file in the current
+// .a file, causing alias analysis support to not be included in the
+// tool correctly!
+//
+RegisterCoalescer::~RegisterCoalescer() {}
+
+// Because of the way .a files work, we must force the SimpleRC
+// implementation to be pulled in if the RegisterCoalescer classes are
+// pulled in.  Otherwise we run the risk of RegisterCoalescer being
+// used, but the default implementation not being linked into the tool
+// that uses it.
+DEFINING_FILE_FOR(RegisterCoalescer)
diff --git a/lib/CodeGen/SimpleRegisterCoalescing.cpp b/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 4d5c081..779c36a 100644
--- a/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -23,6 +23,7 @@
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/SSARegMap.h"
+#include "llvm/CodeGen/RegisterCoalescer.h"
 #include "llvm/Target/MRegisterInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetMachine.h"
@@ -48,6 +49,9 @@ namespace {
 
   RegisterPass<SimpleRegisterCoalescing> 
   X("simple-register-coalescing", "Simple Register Coalescing");
+
+  // Declare that we implement the RegisterCoalescer interface
+  RegisterAnalysisGroup<RegisterCoalescer, true/*The Default*/> V(X);
 }
 
 const PassInfo *llvm::SimpleRegisterCoalescingID = X.getPassInfo();
@@ -1191,3 +1195,10 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
 void SimpleRegisterCoalescing::print(std::ostream &O, const Module* m) const {
    li_->print(O, m);
 }
+
+RegisterCoalescer* llvm::createSimpleRegisterCoalescer() {
+  return new SimpleRegisterCoalescing();
+}
+
+// Make sure that anything that uses RegisterCoalescer pulls in this file...
+DEFINING_FILE_FOR(SimpleRegisterCoalescing)