Transforms: Split LowerAtomics into separate Utils and pass

This will allow code sharing from AtomicExpandPass. Not entirely sure
why these exist as separate passes though.

llvm/include/llvm/Transforms/Scalar/LowerAtomicPass.h

+//===- LowerAtomicPass.h - Lower atomic intrinsics --------------*- 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+// This pass lowers atomic intrinsics to non-atomic form for use in a known
+// non-preemptible environment.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_SCALAR_LOWERATOMICPASS_H
+#define LLVM_TRANSFORMS_SCALAR_LOWERATOMICPASS_H
+
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+/// A pass that lowers atomic intrinsic into non-atomic intrinsics.
+class LowerAtomicPass : public PassInfoMixin<LowerAtomicPass> {
+public:
+  PreservedAnalyses run(Function &F, FunctionAnalysisManager &);
+  static bool isRequired() { return true; }
+};
+
+}
+
+#endif // LLVM_TRANSFORMS_SCALAR_LOWERATOMICPASS_H

llvm/include/llvm/Transforms/Scalar/LowerAtomic.h → llvm/include/llvm/Transforms/Utils/LowerAtomic.h

-//===- LowerAtomic.cpp - Lower atomic intrinsics ----------------*- C++ -*-===//
+//===- LowerAtomic.h - Lower atomic intrinsics ------------------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -14,18 +14,13 @@
 #ifndef LLVM_TRANSFORMS_SCALAR_LOWERATOMIC_H
 #define LLVM_TRANSFORMS_SCALAR_LOWERATOMIC_H
 
-#include "llvm/IR/PassManager.h"
-
 namespace llvm {
+class AtomicCmpXchgInst;
+class AtomicRMWInst;
 
-/// A pass that lowers atomic intrinsic into non-atomic intrinsics.
-class LowerAtomicPass : public PassInfoMixin<LowerAtomicPass> {
-public:
-  PreservedAnalyses run(Function &F, FunctionAnalysisManager &);
-  static bool isRequired() { return true; }
-};
+/// Convert the given Cmpxchg into primitive load and compare.
+bool lowerAtomicCmpXchgInst(AtomicCmpXchgInst *CXI);
 
-class AtomicRMWInst;
 /// Convert the given RMWI into primitive load and stores,
 /// assuming that doing so is legal. Return true if the lowering
 /// succeeds.

llvm/lib/Passes/PassBuilder.cpp

@@ -185,7 +185,7 @@
 #include "llvm/Transforms/Scalar/LoopUnrollAndJamPass.h"
 #include "llvm/Transforms/Scalar/LoopUnrollPass.h"
 #include "llvm/Transforms/Scalar/LoopVersioningLICM.h"
-#include "llvm/Transforms/Scalar/LowerAtomic.h"
+#include "llvm/Transforms/Scalar/LowerAtomicPass.h"
 #include "llvm/Transforms/Scalar/LowerConstantIntrinsics.h"
 #include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
 #include "llvm/Transforms/Scalar/LowerGuardIntrinsic.h"

llvm/lib/Target/NVPTX/NVPTXAtomicLower.cpp

@@ -17,7 +17,7 @@
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/Instructions.h"
-#include "llvm/Transforms/Scalar/LowerAtomic.h"
+#include "llvm/Transforms/Utils/LowerAtomic.h"
 
 #include "MCTargetDesc/NVPTXBaseInfo.h"
 using namespace llvm;

llvm/lib/Target/WebAssembly/WebAssemblyTargetMachine.cpp

@@ -30,7 +30,7 @@
 #include "llvm/MC/TargetRegistry.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Scalar/LowerAtomic.h"
+#include "llvm/Transforms/Scalar/LowerAtomicPass.h"
 #include "llvm/Transforms/Utils.h"
 using namespace llvm;
 

llvm/lib/Transforms/Scalar/CMakeLists.txt

@@ -47,7 +47,7 @@ add_llvm_component_library(LLVMScalarOpts
   LoopUnrollAndJamPass.cpp
   LoopUnswitch.cpp
   LoopVersioningLICM.cpp
-  LowerAtomic.cpp
+  LowerAtomicPass.cpp
   LowerConstantIntrinsics.cpp
   LowerExpectIntrinsic.cpp
   LowerGuardIntrinsic.cpp

llvm/lib/Transforms/Scalar/LowerAtomicPass.cpp

+//===- LowerAtomic.cpp - Lower atomic intrinsics --------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass lowers atomic intrinsics to non-atomic form for use in a known
+// non-preemptible environment.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Scalar/LowerAtomicPass.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Pass.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/LowerAtomic.h"
+using namespace llvm;
+
+#define DEBUG_TYPE "loweratomic"
+
+static bool LowerFenceInst(FenceInst *FI) {
+  FI->eraseFromParent();
+  return true;
+}
+
+static bool LowerLoadInst(LoadInst *LI) {
+  LI->setAtomic(AtomicOrdering::NotAtomic);
+  return true;
+}
+
+static bool LowerStoreInst(StoreInst *SI) {
+  SI->setAtomic(AtomicOrdering::NotAtomic);
+  return true;
+}
+
+static bool runOnBasicBlock(BasicBlock &BB) {
+  bool Changed = false;
+  for (Instruction &Inst : make_early_inc_range(BB)) {
+    if (FenceInst *FI = dyn_cast<FenceInst>(&Inst))
+      Changed |= LowerFenceInst(FI);
+    else if (AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(&Inst))
+      Changed |= lowerAtomicCmpXchgInst(CXI);
+    else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(&Inst))
+      Changed |= lowerAtomicRMWInst(RMWI);
+    else if (LoadInst *LI = dyn_cast<LoadInst>(&Inst)) {
+      if (LI->isAtomic())
+        LowerLoadInst(LI);
+    } else if (StoreInst *SI = dyn_cast<StoreInst>(&Inst)) {
+      if (SI->isAtomic())
+        LowerStoreInst(SI);
+    }
+  }
+  return Changed;
+}
+
+static bool lowerAtomics(Function &F) {
+  bool Changed = false;
+  for (BasicBlock &BB : F) {
+    Changed |= runOnBasicBlock(BB);
+  }
+  return Changed;
+}
+
+PreservedAnalyses LowerAtomicPass::run(Function &F, FunctionAnalysisManager &) {
+  if (lowerAtomics(F))
+    return PreservedAnalyses::none();
+  return PreservedAnalyses::all();
+}
+
+namespace {
+class LowerAtomicLegacyPass : public FunctionPass {
+public:
+  static char ID;
+
+  LowerAtomicLegacyPass() : FunctionPass(ID) {
+    initializeLowerAtomicLegacyPassPass(*PassRegistry::getPassRegistry());
+  }
+
+  bool runOnFunction(Function &F) override {
+    // Don't skip optnone functions; atomics still need to be lowered.
+    FunctionAnalysisManager DummyFAM;
+    auto PA = Impl.run(F, DummyFAM);
+    return !PA.areAllPreserved();
+  }
+
+private:
+  LowerAtomicPass Impl;
+  };
+}
+
+char LowerAtomicLegacyPass::ID = 0;
+INITIALIZE_PASS(LowerAtomicLegacyPass, "loweratomic",
+                "Lower atomic intrinsics to non-atomic form", false, false)
+
+Pass *llvm::createLowerAtomicPass() { return new LowerAtomicLegacyPass(); }

llvm/lib/Transforms/Utils/CMakeLists.txt

@@ -44,6 +44,7 @@ add_llvm_component_library(LLVMTransformUtils
   LoopUnrollRuntime.cpp
   LoopUtils.cpp
   LoopVersioning.cpp
+  LowerAtomic.cpp
   LowerGlobalDtors.cpp
   LowerInvoke.cpp
   LowerMemIntrinsics.cpp

llvm/lib/Transforms/Scalar/LowerAtomic.cpp → llvm/lib/Transforms/Utils/LowerAtomic.cpp

@@ -11,7 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/Scalar/LowerAtomic.h"
+#include "llvm/Transforms/Utils/LowerAtomic.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/InitializePasses.h"
@@ -21,7 +21,7 @@ using namespace llvm;
 
 #define DEBUG_TYPE "loweratomic"
 
-static bool LowerAtomicCmpXchgInst(AtomicCmpXchgInst *CXI) {
+bool llvm::lowerAtomicCmpXchgInst(AtomicCmpXchgInst *CXI) {
   IRBuilder<> Builder(CXI);
   Value *Ptr = CXI->getPointerOperand();
   Value *Cmp = CXI->getCompareOperand();
@@ -99,79 +99,3 @@ bool llvm::lowerAtomicRMWInst(AtomicRMWInst *RMWI) {
   RMWI->eraseFromParent();
   return true;
 }
-
-static bool LowerFenceInst(FenceInst *FI) {
-  FI->eraseFromParent();
-  return true;
-}
-
-static bool LowerLoadInst(LoadInst *LI) {
-  LI->setAtomic(AtomicOrdering::NotAtomic);
-  return true;
-}
-
-static bool LowerStoreInst(StoreInst *SI) {
-  SI->setAtomic(AtomicOrdering::NotAtomic);
-  return true;
-}
-
-static bool runOnBasicBlock(BasicBlock &BB) {
-  bool Changed = false;
-  for (Instruction &Inst : make_early_inc_range(BB)) {
-    if (FenceInst *FI = dyn_cast<FenceInst>(&Inst))
-      Changed |= LowerFenceInst(FI);
-    else if (AtomicCmpXchgInst *CXI = dyn_cast<AtomicCmpXchgInst>(&Inst))
-      Changed |= LowerAtomicCmpXchgInst(CXI);
-    else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(&Inst))
-      Changed |= lowerAtomicRMWInst(RMWI);
-    else if (LoadInst *LI = dyn_cast<LoadInst>(&Inst)) {
-      if (LI->isAtomic())
-        LowerLoadInst(LI);
-    } else if (StoreInst *SI = dyn_cast<StoreInst>(&Inst)) {
-      if (SI->isAtomic())
-        LowerStoreInst(SI);
-    }
-  }
-  return Changed;
-}
-
-static bool lowerAtomics(Function &F) {
-  bool Changed = false;
-  for (BasicBlock &BB : F) {
-    Changed |= runOnBasicBlock(BB);
-  }
-  return Changed;
-}
-
-PreservedAnalyses LowerAtomicPass::run(Function &F, FunctionAnalysisManager &) {
-  if (lowerAtomics(F))
-    return PreservedAnalyses::none();
-  return PreservedAnalyses::all();
-}
-
-namespace {
-class LowerAtomicLegacyPass : public FunctionPass {
-public:
-  static char ID;
-
-  LowerAtomicLegacyPass() : FunctionPass(ID) {
-    initializeLowerAtomicLegacyPassPass(*PassRegistry::getPassRegistry());
-  }
-
-  bool runOnFunction(Function &F) override {
-    // Don't skip optnone functions; atomics still need to be lowered.
-    FunctionAnalysisManager DummyFAM;
-    auto PA = Impl.run(F, DummyFAM);
-    return !PA.areAllPreserved();
-  }
-
-private:
-  LowerAtomicPass Impl;
-  };
-}
-
-char LowerAtomicLegacyPass::ID = 0;
-INITIALIZE_PASS(LowerAtomicLegacyPass, "loweratomic",
-                "Lower atomic intrinsics to non-atomic form", false, false)
-
-Pass *llvm::createLowerAtomicPass() { return new LowerAtomicLegacyPass(); }