[NVPTX] Re-enable support for virtual registers in the final output

Now that 3.3 is branched, we are re-enabling virtual registers to help
iron out bugs before the next release. Some of the post-RA passes do
not play well with virtual registers, so we disable them for now. The
needed functionality of the PrologEpilogInserter pass is copied to a
new backend-specific NVPTXPrologEpilog pass.

The test for this commit is not breaking the existing tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182998 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 27 insertions, 0 deletions

diff --git a/lib/Target/NVPTX/NVPTXTargetMachine.cpp b/lib/Target/NVPTX/NVPTXTargetMachine.cpp
index 5b8ea1e..68f9bf7 100644
--- a/lib/Target/NVPTX/NVPTXTargetMachine.cpp
+++ b/lib/Target/NVPTX/NVPTXTargetMachine.cpp
@@ -107,6 +107,10 @@ public:
   virtual void addIRPasses();
   virtual bool addInstSelector();
   virtual bool addPreRegAlloc();
+  virtual bool addPostRegAlloc();
+
+  virtual void addFastRegAlloc(FunctionPass *RegAllocPass);
+  virtual void addOptimizedRegAlloc(FunctionPass *RegAllocPass);
 };
 } // end anonymous namespace
 
@@ -116,6 +120,15 @@ TargetPassConfig *NVPTXTargetMachine::createPassConfig(PassManagerBase &PM) {
 }
 
 void NVPTXPassConfig::addIRPasses() {
+  // The following passes are known to not play well with virtual regs hanging
+  // around after register allocation (which in our case, is *all* registers).
+  // We explicitly disable them here.  We do, however, need some functionality
+  // of the PrologEpilogCodeInserter pass, so we emulate that behavior in the
+  // NVPTXPrologEpilog pass (see NVPTXPrologEpilogPass.cpp).
+  disablePass(&PrologEpilogCodeInserterID);
+  disablePass(&MachineCopyPropagationID);
+  disablePass(&BranchFolderPassID);
+
   TargetPassConfig::addIRPasses();
   addPass(createGenericToNVVMPass());
 }
@@ -129,3 +142,17 @@ bool NVPTXPassConfig::addInstSelector() {
 }
 
 bool NVPTXPassConfig::addPreRegAlloc() { return false; }
+bool NVPTXPassConfig::addPostRegAlloc() {
+  addPass(createNVPTXPrologEpilogPass());
+  return false;
+}
+
+void NVPTXPassConfig::addFastRegAlloc(FunctionPass *RegAllocPass) {
+  // No reg alloc
+  addPass(&StrongPHIEliminationID);
+}
+
+void NVPTXPassConfig::addOptimizedRegAlloc(FunctionPass *RegAllocPass) {
+  // No reg alloc
+  addPass(&StrongPHIEliminationID);
+}