Delete ObjCARCAPElim, as it is entirely superseded by ObjCARCOpts

Author: AZero13

clang/lib/CodeGen/BackendUtil.cpp

@@ -1022,12 +1022,6 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
               MPM.addPass(
                   createModuleToFunctionPassAdaptor(ObjCARCExpandPass()));
           });
-      PB.registerPipelineEarlySimplificationEPCallback(
-          [](ModulePassManager &MPM, OptimizationLevel Level,
-             ThinOrFullLTOPhase) {
-            if (Level != OptimizationLevel::O0)
-              MPM.addPass(ObjCARCAPElimPass());
-          });
       PB.registerScalarOptimizerLateEPCallback(
           [](FunctionPassManager &FPM, OptimizationLevel Level) {
             if (Level != OptimizationLevel::O0)

llvm/include/llvm/Transforms/ObjCARC.h

@@ -35,10 +35,6 @@ struct ObjCARCContractPass : public PassInfoMixin<ObjCARCContractPass> {
   LLVM_ABI PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
 };
 
-struct ObjCARCAPElimPass : public PassInfoMixin<ObjCARCAPElimPass> {
-  LLVM_ABI PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
-};
-
 struct ObjCARCExpandPass : public PassInfoMixin<ObjCARCExpandPass> {
   LLVM_ABI PreservedAnalyses run(Function &M, FunctionAnalysisManager &AM);
 };

llvm/lib/Passes/PassRegistry.def

@@ -113,7 +113,6 @@ MODULE_PASS("module-inline", ModuleInlinerPass())
 MODULE_PASS("name-anon-globals", NameAnonGlobalPass())
 MODULE_PASS("no-op-module", NoOpModulePass())
 MODULE_PASS("nsan", NumericalStabilitySanitizerPass())
-MODULE_PASS("objc-arc-apelim", ObjCARCAPElimPass())
 MODULE_PASS("openmp-opt", OpenMPOptPass())
 MODULE_PASS("openmp-opt-postlink",
             OpenMPOptPass(ThinOrFullLTOPhase::FullLTOPostLink))

llvm/lib/Transforms/ObjCARC/CMakeLists.txt

@@ -2,7 +2,6 @@ add_llvm_component_library(LLVMObjCARCOpts
   ObjCARC.cpp
   ObjCARCOpts.cpp
   ObjCARCExpand.cpp
-  ObjCARCAPElim.cpp
   ObjCARCContract.cpp
   DependencyAnalysis.cpp
   ProvenanceAnalysis.cpp

llvm/lib/Transforms/ObjCARC/ObjCARCAPElim.cpp

@@ -2490,6 +2490,27 @@ bool ObjCARCOpt::run(Function &F, AAResults &AA) {
   return Changed;
 }
 
+/// Interprocedurally determine if calls made by the given call site can
+/// possibly produce autoreleases.
+bool MayAutorelease(const CallBase &CB, unsigned Depth = 0) {
+  if (const Function *Callee = CB.getCalledFunction()) {
+    if (!Callee->hasExactDefinition())
+      return true;
+    for (const BasicBlock &BB : *Callee) {
+      for (const Instruction &I : BB)
+        if (const CallBase *JCB = dyn_cast<CallBase>(&I))
+          // This recursion depth limit is arbitrary. It's just great
+          // enough to cover known interesting testcases.
+          if (Depth < 10 && !JCB->onlyReadsMemory() &&
+              MayAutorelease(*JCB, Depth + 1))
+            return true;
+    }
+    return false;
+  }
+
+  return true;
+}
+
 /// Optimize autorelease pools by eliminating empty push/pop pairs.
 void ObjCARCOpt::OptimizeAutoreleasePools(Function &F) {
   LLVM_DEBUG(dbgs() << "\n== ObjCARCOpt::OptimizeAutoreleasePools ==\n");
@@ -2558,6 +2579,8 @@ void ObjCARCOpt::OptimizeAutoreleasePools(Function &F) {
       }
       case ARCInstKind::CallOrUser:
       case ARCInstKind::Call:
+        if (MayAutorelease(cast<CallBase>(Inst)))
+          break;
       case ARCInstKind::Autorelease:
       case ARCInstKind::AutoreleaseRV:
       case ARCInstKind::FusedRetainAutorelease:

llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp

@@ -1,4 +1,4 @@
-; RUN: opt -S -passes=objc-arc-apelim < %s | FileCheck %s
+; RUN: opt -S -passes=objc-arc < %s | FileCheck %s
 ; rdar://10227311
 
 @llvm.global_ctors = appending global [2 x { i32, ptr, ptr }] [{ i32, ptr, ptr } { i32 65535, ptr @_GLOBAL__I_x, ptr null }, { i32, ptr, ptr } { i32 65535, ptr @_GLOBAL__I_y, ptr null }]

llvm/test/Transforms/ObjCARC/apelim.ll

@@ -1,4 +1,4 @@
-; RUN: opt -S -passes=objc-arc-apelim < %s | FileCheck %s
+; RUN: opt -S -passes=objc-arc < %s | FileCheck %s
 
 ; See PR26774
 

llvm/test/Transforms/ObjCARC/comdat-ipo.ll

@@ -9,7 +9,6 @@ static_library("ObjCARC") {
   sources = [
     "DependencyAnalysis.cpp",
     "ObjCARC.cpp",
-    "ObjCARCAPElim.cpp",
     "ObjCARCContract.cpp",
     "ObjCARCExpand.cpp",
     "ObjCARCOpts.cpp",