[MIR] MIRNamer pass for improving MIR test authoring experience.

This patch reuses the MIR vreg renamer from the MIRCanonicalizerPass to cleanup
names of vregs in a MIR file for MIR test authors. I found it useful when
writing a regression test for a globalisel failure I encountered recently and
thought it might be useful for other folks as well.

Differential Revision: https://reviews.llvm.org/D67209

llvm-svn: 371121

3 files changed, 79 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/CMakeLists.txt b/llvm/lib/CodeGen/CMakeLists.txt
index 1228a2d1c6c..3cf0c60108e 100644
--- a/llvm/lib/CodeGen/CMakeLists.txt
+++ b/llvm/lib/CodeGen/CMakeLists.txt
@@ -122,6 +122,7 @@ add_llvm_library(LLVMCodeGen
   RegisterScavenging.cpp
   RenameIndependentSubregs.cpp
   MIRVRegNamerUtils.cpp
+  MIRNamerPass.cpp
   MIRCanonicalizerPass.cpp
   RegisterUsageInfo.cpp
   RegUsageInfoCollector.cpp
diff --git a/llvm/lib/CodeGen/CodeGen.cpp b/llvm/lib/CodeGen/CodeGen.cpp
index 51be4e3af01..d369160b299 100644
--- a/llvm/lib/CodeGen/CodeGen.cpp
+++ b/llvm/lib/CodeGen/CodeGen.cpp
@@ -54,6 +54,7 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeLocalStackSlotPassPass(Registry);
   initializeLowerIntrinsicsPass(Registry);
   initializeMIRCanonicalizerPass(Registry);
+  initializeMIRNamerPass(Registry);
   initializeMachineBlockFrequencyInfoPass(Registry);
   initializeMachineBlockPlacementPass(Registry);
   initializeMachineBlockPlacementStatsPass(Registry);
diff --git a/llvm/lib/CodeGen/MIRNamerPass.cpp b/llvm/lib/CodeGen/MIRNamerPass.cpp
new file mode 100644
index 00000000000..9d719f3917c
--- /dev/null
+++ b/llvm/lib/CodeGen/MIRNamerPass.cpp
@@ -0,0 +1,77 @@
+//===----------------------- MIRNamer.cpp - MIR Namer ---------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// The purpose of this pass is to rename virtual register operands with the goal
+// of making it easier to author easier to read tests for MIR. This pass reuses
+// the vreg renamer used by MIRCanonicalizerPass.
+//
+// Basic Usage:
+//
+// llc -o - -run-pass mir-namer example.mir
+//
+//===----------------------------------------------------------------------===//
+
+#include "MIRVRegNamerUtils.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+
+using namespace llvm;
+
+namespace llvm {
+extern char &MIRNamerID;
+} // namespace llvm
+
+#define DEBUG_TYPE "mir-namer"
+
+namespace {
+
+class MIRNamer : public MachineFunctionPass {
+public:
+  static char ID;
+  MIRNamer() : MachineFunctionPass(ID) {}
+
+  StringRef getPassName() const override {
+    return "Rename virtual register operands";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+  bool runOnMachineFunction(MachineFunction &MF) override {
+    bool Changed = false;
+
+    if (MF.empty())
+      return Changed;
+
+    NamedVRegCursor NVC(MF.getRegInfo());
+
+    ReversePostOrderTraversal<MachineBasicBlock *> RPOT(&*MF.begin());
+    for (auto &MBB : RPOT)
+      Changed |= NVC.renameVRegs(MBB);
+
+    return Changed;
+  }
+};
+
+} // end anonymous namespace
+
+char MIRNamer::ID;
+
+char &llvm::MIRNamerID = MIRNamer::ID;
+
+INITIALIZE_PASS_BEGIN(MIRNamer, "mir-namer", "Rename Register Operands", false,
+                      false)
+
+INITIALIZE_PASS_END(MIRNamer, "mir-namer", "Rename Register Operands", false,
+                    false)