AMDGPU: Add stub custom CodeGenPrepare pass

This will do various things including ones
CodeGenPrepare does, but with knowledge of uniform
values.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@273657 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/AMDGPU/AMDGPU.h

@@ -51,6 +51,7 @@ FunctionPass *createSIFixSGPRCopiesPass();
 FunctionPass *createSICodeEmitterPass(formatted_raw_ostream &OS);
 FunctionPass *createSIDebuggerInsertNopsPass();
 FunctionPass *createSIInsertWaitsPass();
+FunctionPass *createAMDGPUCodeGenPreparePass(const TargetMachine *TM = nullptr);
 
 ScheduleDAGInstrs *createSIMachineScheduler(MachineSchedContext *C);
 
@@ -98,6 +99,9 @@ extern char &SIFixControlFlowLiveIntervalsID;
 void initializeAMDGPUAnnotateUniformValuesPass(PassRegistry&);
 extern char &AMDGPUAnnotateUniformValuesPassID;
 
+void initializeAMDGPUCodeGenPreparePass(PassRegistry&);
+extern char &AMDGPUCodeGenPrepareID;
+
 void initializeSIAnnotateControlFlowPass(PassRegistry&);
 extern char &SIAnnotateControlFlowPassID;
 

lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp

@@ -0,0 +1,82 @@
+//===-- AMDGPUCodeGenPrepare.cpp ------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+/// \file
+/// This pass does misc. AMDGPU optimizations on IR before instruction
+/// selection.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AMDGPU.h"
+#include "AMDGPUSubtarget.h"
+
+#include "llvm/Analysis/DivergenceAnalysis.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/InstVisitor.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+
+#define DEBUG_TYPE "amdgpu-codegenprepare"
+
+using namespace llvm;
+
+namespace {
+
+class AMDGPUCodeGenPrepare : public FunctionPass,
+                             public InstVisitor<AMDGPUCodeGenPrepare> {
+  DivergenceAnalysis *DA;
+  const TargetMachine *TM;
+
+public:
+  static char ID;
+  AMDGPUCodeGenPrepare(const TargetMachine *TM = nullptr) :
+    FunctionPass(ID),
+    TM(TM) { }
+
+  bool doInitialization(Module &M) override;
+  bool runOnFunction(Function &F) override;
+
+  const char *getPassName() const override {
+    return "AMDGPU IR optimizations";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.addRequired<DivergenceAnalysis>();
+    AU.setPreservesAll();
+ }
+};
+
+} // End anonymous namespace
+
+bool AMDGPUCodeGenPrepare::doInitialization(Module &M) {
+  return false;
+}
+
+bool AMDGPUCodeGenPrepare::runOnFunction(Function &F) {
+  if (!TM || skipFunction(F))
+    return false;
+
+  DA = &getAnalysis<DivergenceAnalysis>();
+  visit(F);
+
+  return true;
+}
+
+INITIALIZE_TM_PASS_BEGIN(AMDGPUCodeGenPrepare, DEBUG_TYPE,
+                      "AMDGPU IR optimizations", false, false)
+INITIALIZE_PASS_DEPENDENCY(DivergenceAnalysis)
+INITIALIZE_TM_PASS_END(AMDGPUCodeGenPrepare, DEBUG_TYPE,
+                       "AMDGPU IR optimizations", false, false)
+
+char AMDGPUCodeGenPrepare::ID = 0;
+
+FunctionPass *llvm::createAMDGPUCodeGenPreparePass(const TargetMachine *TM) {
+  return new AMDGPUCodeGenPrepare(TM);
+}

lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

@@ -60,6 +60,7 @@ extern "C" void LLVMInitializeAMDGPUTarget() {
   initializeAMDGPUAnnotateKernelFeaturesPass(*PR);
   initializeAMDGPUAnnotateUniformValuesPass(*PR);
   initializeAMDGPUPromoteAllocaPass(*PR);
+  initializeAMDGPUCodeGenPreparePass(*PR);
   initializeSIAnnotateControlFlowPass(*PR);
   initializeSIDebuggerInsertNopsPass(*PR);
   initializeSIInsertWaitsPass(*PR);

lib/Target/AMDGPU/CMakeLists.txt

@@ -33,6 +33,7 @@ add_llvm_target(AMDGPUCodeGen
   AMDGPUAnnotateKernelFeatures.cpp
   AMDGPUAnnotateUniformValues.cpp
   AMDGPUAsmPrinter.cpp
+  AMDGPUCodeGenPrepare.cpp
   AMDGPUFrameLowering.cpp
   AMDGPUTargetObjectFile.cpp
   AMDGPUIntrinsicInfo.cpp

test/CodeGen/AMDGPU/amdgpu-codegenprepare.ll

@@ -0,0 +1,8 @@
+; RUN: opt -S -mtriple=amdgcn-- -amdgpu-codegenprepare < %s | FileCheck %s
+; RUN: opt -S -amdgpu-codegenprepare < %s
+; Make sure this doesn't crash with no triple
+
+; CHECK-LABEL: @foo(
+define void @foo() {
+  ret void
+}