[CodeGen] Port gc-empty-basic-blocks to new pass manager

llvm/include/llvm/CodeGen/GCEmptyBasicBlocks.h

@@ -0,0 +1,24 @@
+//===-- GCEmptyBasicBlocks.h ------------------------------------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_GCEMPTYBASICBLOCKS_H
+#define LLVM_CODEGEN_GCEMPTYBASICBLOCKS_H
+
+#include "llvm/CodeGen/MachinePassManager.h"
+
+namespace llvm {
+
+class GCEmptyBasicBlocksPass : public PassInfoMixin<GCEmptyBasicBlocksPass> {
+public:
+  PreservedAnalyses run(MachineFunction &MF,
+                        MachineFunctionAnalysisManager &MFAM);
+};
+
+} // namespace llvm
+
+#endif // LLVM_CODEGEN_GCEMPTYBASICBLOCKS_H

llvm/include/llvm/CodeGen/Passes.h

@@ -59,7 +59,7 @@ namespace llvm {
   /// instructions. These blocks confuscate profile analysis (e.g., basic block
   /// sections) since they will share the address of their fallthrough blocks.
   /// This pass garbage-collects such basic blocks.
-  MachineFunctionPass *createGCEmptyBasicBlocksPass();
+  MachineFunctionPass *createGCEmptyBasicBlocksLegacyPass();
 
   /// createBasicBlockSections Pass - This pass assigns sections to machine
   /// basic blocks and is enabled with -fbasic-block-sections.

llvm/include/llvm/InitializePasses.h

@@ -119,7 +119,7 @@ void initializeFixIrreduciblePass(PassRegistry &);
 void initializeFixupStatepointCallerSavedLegacyPass(PassRegistry &);
 void initializeFlattenCFGLegacyPassPass(PassRegistry &);
 void initializeFuncletLayoutPass(PassRegistry &);
-void initializeGCEmptyBasicBlocksPass(PassRegistry &);
+void initializeGCEmptyBasicBlocksLegacyPass(PassRegistry &);
 void initializeGCMachineCodeAnalysisPass(PassRegistry &);
 void initializeGCModuleInfoPass(PassRegistry &);
 void initializeGVNLegacyPassPass(PassRegistry &);

llvm/include/llvm/Passes/MachinePassRegistry.def

@@ -147,6 +147,7 @@ MACHINE_FUNCTION_PASS("early-tailduplication", EarlyTailDuplicatePass())
 MACHINE_FUNCTION_PASS("fentry-insert", FEntryInserterPass())
 MACHINE_FUNCTION_PASS("finalize-isel", FinalizeISelPass())
 MACHINE_FUNCTION_PASS("fixup-statepoint-caller-saved", FixupStatepointCallerSavedPass())
+MACHINE_FUNCTION_PASS("gc-empty-basic-blocks", GCEmptyBasicBlocksPass())
 MACHINE_FUNCTION_PASS("localstackalloc", LocalStackSlotAllocationPass())
 MACHINE_FUNCTION_PASS("machine-cp", MachineCopyPropagationPass())
 MACHINE_FUNCTION_PASS("machine-cse", MachineCSEPass())
@@ -291,7 +292,6 @@ DUMMY_MACHINE_FUNCTION_PASS("cfi-instr-inserter", CFIInstrInserterPass)
 DUMMY_MACHINE_FUNCTION_PASS("dot-machine-cfg", MachineCFGPrinter)
 DUMMY_MACHINE_FUNCTION_PASS("fs-profile-loader", MIRProfileLoaderNewPass)
 DUMMY_MACHINE_FUNCTION_PASS("funclet-layout", FuncletLayoutPass)
-DUMMY_MACHINE_FUNCTION_PASS("gc-empty-basic-blocks", GCEmptyBasicBlocksPass)
 DUMMY_MACHINE_FUNCTION_PASS("implicit-null-checks", ImplicitNullChecksPass)
 DUMMY_MACHINE_FUNCTION_PASS("init-undef-pass", InitUndefPass)
 DUMMY_MACHINE_FUNCTION_PASS("instruction-select", InstructionSelectPass)

llvm/lib/CodeGen/GCEmptyBasicBlocks.cpp

@@ -11,6 +11,7 @@
 /// pass.
 ///
 //===----------------------------------------------------------------------===//
+#include "llvm/CodeGen/GCEmptyBasicBlocks.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"
@@ -26,22 +27,35 @@ using namespace llvm;
 
 STATISTIC(NumEmptyBlocksRemoved, "Number of empty blocks removed");
 
-class GCEmptyBasicBlocks : public MachineFunctionPass {
+static bool removeEmptyBlocks(MachineFunction &MF);
+
+PreservedAnalyses
+GCEmptyBasicBlocksPass::run(MachineFunction &MF,
+                            MachineFunctionAnalysisManager &MFAM) {
+  bool Changed = removeEmptyBlocks(MF);
+  if (Changed)
+    return getMachineFunctionPassPreservedAnalyses();
+  return PreservedAnalyses::all();
+}
+
+class GCEmptyBasicBlocksLegacy : public MachineFunctionPass {
 public:
   static char ID;
 
-  GCEmptyBasicBlocks() : MachineFunctionPass(ID) {
-    initializeGCEmptyBasicBlocksPass(*PassRegistry::getPassRegistry());
+  GCEmptyBasicBlocksLegacy() : MachineFunctionPass(ID) {
+    initializeGCEmptyBasicBlocksLegacyPass(*PassRegistry::getPassRegistry());
   }
 
   StringRef getPassName() const override {
     return "Remove Empty Basic Blocks.";
   }
 
-  bool runOnMachineFunction(MachineFunction &MF) override;
+  bool runOnMachineFunction(MachineFunction &MF) override {
+    return removeEmptyBlocks(MF);
+  }
 };
 
-bool GCEmptyBasicBlocks::runOnMachineFunction(MachineFunction &MF) {
+bool removeEmptyBlocks(MachineFunction &MF) {
   if (MF.size() < 2)
     return false;
   MachineJumpTableInfo *JTI = MF.getJumpTableInfo();
@@ -88,12 +102,12 @@ bool GCEmptyBasicBlocks::runOnMachineFunction(MachineFunction &MF) {
   return NumRemoved != 0;
 }
 
-char GCEmptyBasicBlocks::ID = 0;
-INITIALIZE_PASS(GCEmptyBasicBlocks, "gc-empty-basic-blocks",
+char GCEmptyBasicBlocksLegacy::ID = 0;
+INITIALIZE_PASS(GCEmptyBasicBlocksLegacy, "gc-empty-basic-blocks",
                 "Removes empty basic blocks and redirects their uses to their "
                 "fallthrough blocks.",
                 false, false)
 
-MachineFunctionPass *llvm::createGCEmptyBasicBlocksPass() {
-  return new GCEmptyBasicBlocks();
+MachineFunctionPass *llvm::createGCEmptyBasicBlocksLegacyPass() {
+  return new GCEmptyBasicBlocksLegacy();
 }

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -1230,7 +1230,7 @@ void TargetPassConfig::addMachinePasses() {
   }
 
   if (GCEmptyBlocks)
-    addPass(llvm::createGCEmptyBasicBlocksPass());
+    addPass(llvm::createGCEmptyBasicBlocksLegacyPass());
 
   if (EnableFSDiscriminator)
     addPass(createMIRAddFSDiscriminatorsPass(

llvm/lib/Passes/PassBuilder.cpp

@@ -98,6 +98,7 @@
 #include "llvm/CodeGen/FEntryInserter.h"
 #include "llvm/CodeGen/FinalizeISel.h"
 #include "llvm/CodeGen/FixupStatepointCallerSaved.h"
+#include "llvm/CodeGen/GCEmptyBasicBlocks.h"
 #include "llvm/CodeGen/GCMetadata.h"
 #include "llvm/CodeGen/GlobalMerge.h"
 #include "llvm/CodeGen/GlobalMergeFunctions.h"

llvm/test/CodeGen/X86/gc-empty-basic-blocks.mir

@@ -0,0 +1,49 @@
+# TODO: Remove this and use gc-empty-basic-blocks.ll directly.
+# RUN: llc %s -mtriple=x86_64 -passes=gc-empty-basic-blocks -o - | FileCheck %s
+--- |
+  define void @foo(i1 zeroext %0) #0 {
+    br i1 %0, label %2, label %empty_block
+
+  2:                                                ; preds = %1
+    %3 = call i32 @baz()
+    br label %4
+
+  empty_block:                                      ; preds = %1
+    unreachable
+
+  4:                                                ; preds = %2
+    ret void
+  }
+
+  declare i32 @baz()
+
+  attributes #0 = { nounwind }
+...
+---
+name:            foo
+alignment:       16
+body:             |
+  bb.0:
+    successors: %bb.1(0x40000000), %bb.2(0x40000000)
+    liveins: $edi
+
+    frame-setup PUSH64r undef $rax, implicit-def $rsp, implicit $rsp
+    $al = MOV8rr $dil, implicit killed $edi
+    TEST8ri killed renamable $al, 1, implicit-def $eflags
+    JCC_1 %bb.1, 5, implicit killed $eflags
+    JMP_1 %bb.2
+
+  bb.1:
+    successors: %bb.3(0x80000000)
+
+    CALL64pcrel32 target-flags(x86-plt) @baz, csr_64, implicit $rsp, implicit $ssp, implicit-def $eax
+    JMP_1 %bb.3
+
+  bb.2.empty_block:
+    successors:
+
+  bb.3:
+    $rax = frame-destroy POP64r implicit-def $rsp, implicit $rsp
+    RET64
+...
+# CHECK-NOT: bb.2.empty_block: