Add the PPCCTRLoops pass: a PPC machine-code-level optimization pass to form CTR-based loop branching code.

This pass is derived from the Hexagon HardwareLoops pass. The only significant enhancement over the Hexagon
pass is that PPCCTRLoops will also attempt to delete the replaced add and compare operations if they are
no longer otherwise used. Also, invalid preheader DebugLoc is not used.

llvm-svn: 158204

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
index 50f3db8b27f..6f7fc4bb391 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetMachine.cpp
@@ -17,10 +17,15 @@
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/Target/TargetOptions.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FormattedStream.h"
 #include "llvm/Support/TargetRegistry.h"
 using namespace llvm;
 
+static cl::
+opt<bool> DisableCTRLoops("disable-ppc-ctrloops", cl::Hidden,
+                        cl::desc("Disable CTR loops for PPC"));
+
 extern "C" void LLVMInitializePowerPCTarget() {
   // Register the targets
   RegisterTargetMachine<PPC32TargetMachine> A(ThePPC32Target);
@@ -81,6 +86,7 @@ public:
     return getTM<PPCTargetMachine>();
   }
 
+  virtual bool addPreRegAlloc();
   virtual bool addInstSelector();
   virtual bool addPreEmitPass();
 };
@@ -96,6 +102,14 @@ TargetPassConfig *PPCTargetMachine::createPassConfig(PassManagerBase &PM) {
   return PassConfig;
 }
 
+bool PPCPassConfig::addPreRegAlloc() {
+  if (!DisableCTRLoops && getOptLevel() != CodeGenOpt::None) {
+    PM->add(createPPCCTRLoops());
+  }
+
+  return false;
+}
+
 bool PPCPassConfig::addInstSelector() {
   // Install an instruction selector.
   PM->add(createPPCISelDag(getPPCTargetMachine()));