AMDGPU: Add stub custom CodeGenPrepare pass

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

llvm-svn: 273657

1 files changed, 82 insertions, 0 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp b/llvm/lib/Target/AMDGPU/AMDGPUCodeGenPrepare.cpp
new file mode 100644
index 00000000000..3b415774df4
--- /dev/null
+++ b/llvm/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);
+}