CodeGen: Add LibcallLoweringInfo analysis pass

The libcall lowering decisions should be program dependent,
depending on the current module's RuntimeLibcallInfo. We need
another related analysis derived from that plus the current
function's subtarget to provide concrete lowering decisions.

This takes on a somewhat unusual form. It's a Module analysis,
with a lookup keyed on the subtarget. This is a separate module
analysis from RuntimeLibraryAnalysis to avoid that depending on
codegen. It's not a function pass to avoid depending on any
particular function, to avoid repeated subtarget map lookups in
most of the use passes, and to avoid any recomputation in the
common case of one subtarget (and keeps it reusable across
repeated compilations).

This also switches ExpandFp and PreISelIntrinsicLowering as
a sample function and module pass. Note this is not yet wired
up to SelectionDAG, which is still using the LibcallLoweringInfo
constructed inside of TargetLowering.

Author: arsenm

clang/lib/CodeGen/BackendUtil.cpp

@@ -19,6 +19,7 @@
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/RuntimeLibcallInfo.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/BitcodeReader.h"
@@ -667,6 +668,11 @@ bool EmitAssemblyHelper::AddEmitPasses(legacy::PassManager &CodeGenPasses,
       llvm::driver::createTLII(TargetTriple, CodeGenOpts.getVecLib()));
   CodeGenPasses.add(new TargetLibraryInfoWrapperPass(*TLII));
 
+  const llvm::TargetOptions &Options = TM->Options;
+  CodeGenPasses.add(new RuntimeLibraryInfoWrapper(
+      TargetTriple, Options.ExceptionModel, Options.FloatABIType,
+      Options.EABIVersion, Options.MCOptions.ABIName, Options.VecLib));
+
   // Normal mode, emit a .s or .o file by running the code generator. Note,
   // this also adds codegenerator level optimization passes.
   CodeGenFileType CGFT = getCodeGenFileType(Action);

llvm/include/llvm/Analysis/RuntimeLibcallInfo.h

@@ -22,7 +22,12 @@ class LLVM_ABI RuntimeLibraryAnalysis
   RuntimeLibraryAnalysis() = default;
   RuntimeLibraryAnalysis(RTLIB::RuntimeLibcallsInfo &&BaselineInfoImpl)
       : LibcallsInfo(std::move(BaselineInfoImpl)) {}
-  explicit RuntimeLibraryAnalysis(const Triple &T) : LibcallsInfo(T) {}
+  RuntimeLibraryAnalysis(
+      const Triple &TT,
+      ExceptionHandling ExceptionModel = ExceptionHandling::None,
+      FloatABI::ABIType FloatABI = FloatABI::Default,
+      EABI EABIVersion = EABI::Default, StringRef ABIName = "",
+      VectorLibrary VecLib = VectorLibrary::NoLibrary);
 
   LLVM_ABI RTLIB::RuntimeLibcallsInfo run(const Module &M,
                                           ModuleAnalysisManager &);
@@ -41,8 +46,12 @@ class LLVM_ABI RuntimeLibraryInfoWrapper : public ImmutablePass {
 public:
   static char ID;
   RuntimeLibraryInfoWrapper();
-  explicit RuntimeLibraryInfoWrapper(const Triple &T);
-  explicit RuntimeLibraryInfoWrapper(const RTLIB::RuntimeLibcallsInfo &RTLCI);
+  RuntimeLibraryInfoWrapper(
+      const Triple &TT,
+      ExceptionHandling ExceptionModel = ExceptionHandling::None,
+      FloatABI::ABIType FloatABI = FloatABI::Default,
+      EABI EABIVersion = EABI::Default, StringRef ABIName = "",
+      VectorLibrary VecLib = VectorLibrary::NoLibrary);
 
   const RTLIB::RuntimeLibcallsInfo &getRTLCI(const Module &M) {
     ModuleAnalysisManager DummyMAM;

llvm/include/llvm/CodeGen/LibcallLoweringInfo.h

@@ -9,12 +9,16 @@
 #ifndef LLVM_CODEGEN_LIBCALLLOWERINGINFO_H
 #define LLVM_CODEGEN_LIBCALLLOWERINGINFO_H
 
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/IR/RuntimeLibcalls.h"
+#include "llvm/Pass.h"
 
 namespace llvm {
 
 class TargetSubtargetInfo;
+class TargetMachine;
 
+/// Tracks which library functions to use for a particular subtarget.
 class LibcallLoweringInfo {
 private:
   const RTLIB::RuntimeLibcallsInfo &RTLCI;
@@ -73,6 +77,70 @@ class LibcallLoweringInfo {
   }
 };
 
+/// Record a mapping from subtarget to LibcallLoweringInfo.
+class LibcallLoweringModuleAnalysisResult {
+private:
+  using LibcallLoweringMap =
+      DenseMap<const TargetSubtargetInfo *, LibcallLoweringInfo>;
+  mutable LibcallLoweringMap LoweringMap;
+  const RTLIB::RuntimeLibcallsInfo *RTLCI = nullptr;
+
+public:
+  LibcallLoweringModuleAnalysisResult() = default;
+  LibcallLoweringModuleAnalysisResult(RTLIB::RuntimeLibcallsInfo &RTLCI)
+      : RTLCI(&RTLCI) {}
+
+  void init(const RTLIB::RuntimeLibcallsInfo *RT) { RTLCI = RT; }
+
+  void clear() {
+    RTLCI = nullptr;
+    LoweringMap.clear();
+  }
+
+  LLVM_ABI bool invalidate(Module &, const PreservedAnalyses &,
+                           ModuleAnalysisManager::Invalidator &);
+
+  const LibcallLoweringInfo &
+  getLibcallLowering(const TargetSubtargetInfo &Subtarget) const {
+    return LoweringMap.try_emplace(&Subtarget, *RTLCI, Subtarget).first->second;
+  }
+};
+
+class LibcallLoweringModuleAnalysis
+    : public AnalysisInfoMixin<LibcallLoweringModuleAnalysis> {
+private:
+  friend AnalysisInfoMixin<LibcallLoweringModuleAnalysis>;
+  LLVM_ABI static AnalysisKey Key;
+
+  LibcallLoweringModuleAnalysisResult LibcallLoweringMap;
+
+public:
+  using Result = LibcallLoweringModuleAnalysisResult;
+
+  LLVM_ABI Result run(Module &M, ModuleAnalysisManager &);
+};
+
+class LLVM_ABI LibcallLoweringInfoWrapper : public ImmutablePass {
+  LibcallLoweringModuleAnalysisResult Result;
+
+public:
+  static char ID;
+  LibcallLoweringInfoWrapper();
+
+  const LibcallLoweringInfo &
+  getLibcallLowering(const TargetSubtargetInfo &Subtarget) const {
+    return Result.getLibcallLowering(Subtarget);
+  }
+
+  const LibcallLoweringModuleAnalysisResult &getResult() const {
+    return Result;
+  }
+
+  bool doInitialization(Module &M) override;
+  void getAnalysisUsage(AnalysisUsage &AU) const override;
+  void releaseMemory() override;
+};
+
 } // end namespace llvm
 
 #endif // LLVM_CODEGEN_LIBCALLLOWERINGINFO_H

llvm/include/llvm/InitializePasses.h

@@ -133,6 +133,7 @@ LLVM_ABI void initializeGlobalMergeFuncPassWrapperPass(PassRegistry &);
 LLVM_ABI void initializeGlobalMergePass(PassRegistry &);
 LLVM_ABI void initializeGlobalsAAWrapperPassPass(PassRegistry &);
 LLVM_ABI void initializeHardwareLoopsLegacyPass(PassRegistry &);
+LLVM_ABI void initializeLibcallLoweringInfoWrapperPass(PassRegistry &);
 LLVM_ABI void initializeMIRProfileLoaderPassPass(PassRegistry &);
 LLVM_ABI void initializeIRSimilarityIdentifierWrapperPassPass(PassRegistry &);
 LLVM_ABI void initializeIRTranslatorPass(PassRegistry &);

llvm/lib/Analysis/RuntimeLibcallInfo.cpp

@@ -13,6 +13,15 @@ using namespace llvm;
 
 AnalysisKey RuntimeLibraryAnalysis::Key;
 
+RuntimeLibraryAnalysis::RuntimeLibraryAnalysis(const Triple &TT,
+                                               ExceptionHandling ExceptionModel,
+                                               FloatABI::ABIType FloatABI,
+                                               EABI EABIVersion,
+                                               StringRef ABIName,
+                                               VectorLibrary VecLib)
+    : LibcallsInfo(std::in_place, TT, ExceptionModel, FloatABI, EABIVersion,
+                   ABIName, VecLib) {}
+
 RTLIB::RuntimeLibcallsInfo
 RuntimeLibraryAnalysis::run(const Module &M, ModuleAnalysisManager &) {
   if (!LibcallsInfo)
@@ -26,6 +35,13 @@ INITIALIZE_PASS(RuntimeLibraryInfoWrapper, "runtime-library-info",
 RuntimeLibraryInfoWrapper::RuntimeLibraryInfoWrapper()
     : ImmutablePass(ID), RTLA(RTLIB::RuntimeLibcallsInfo(Triple())) {}
 
+RuntimeLibraryInfoWrapper::RuntimeLibraryInfoWrapper(
+    const Triple &TT, ExceptionHandling ExceptionModel,
+    FloatABI::ABIType FloatABI, EABI EABIVersion, StringRef ABIName,
+    VectorLibrary VecLib)
+    : ImmutablePass(ID), RTLCI(std::in_place, TT, ExceptionModel, FloatABI,
+                               EABIVersion, ABIName, VecLib) {}
+
 char RuntimeLibraryInfoWrapper::ID = 0;
 
 ModulePass *llvm::createRuntimeLibraryInfoWrapperPass() {

llvm/lib/CodeGen/CodeGen.cpp

@@ -57,6 +57,7 @@ void llvm::initializeCodeGen(PassRegistry &Registry) {
   initializeInterleavedLoadCombinePass(Registry);
   initializeInterleavedAccessPass(Registry);
   initializeJMCInstrumenterPass(Registry);
+  initializeLibcallLoweringInfoWrapperPass(Registry);
   initializeLiveDebugValuesLegacyPass(Registry);
   initializeLiveDebugVariablesWrapperLegacyPass(Registry);
   initializeLiveIntervalsWrapperPassPass(Registry);

llvm/lib/CodeGen/ExpandFp.cpp

@@ -991,7 +991,7 @@ static void addToWorklist(Instruction &I,
 }
 
 static bool runImpl(Function &F, const TargetLowering &TLI,
-                    AssumptionCache *AC) {
+                    const LibcallLoweringInfo &Libcalls, AssumptionCache *AC) {
   SmallVector<Instruction *, 4> Worklist;
 
   unsigned MaxLegalFpConvertBitWidth =
@@ -1090,12 +1090,17 @@ class ExpandFpLegacyPass : public FunctionPass {
 
   bool runOnFunction(Function &F) override {
     auto *TM = &getAnalysis<TargetPassConfig>().getTM<TargetMachine>();
-    auto *TLI = TM->getSubtargetImpl(F)->getTargetLowering();
+    const TargetSubtargetInfo *Subtarget = TM->getSubtargetImpl(F);
+    auto *TLI = Subtarget->getTargetLowering();
     AssumptionCache *AC = nullptr;
 
+    const LibcallLoweringInfo &Libcalls =
+        getAnalysis<LibcallLoweringInfoWrapper>().getLibcallLowering(
+            *Subtarget);
+
     if (OptLevel != CodeGenOptLevel::None && !F.hasOptNone())
       AC = &getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F);
-    return runImpl(F, *TLI, AC);
+    return runImpl(F, *TLI, Libcalls, AC);
   }
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
@@ -1104,6 +1109,7 @@ class ExpandFpLegacyPass : public FunctionPass {
       AU.addRequired<AssumptionCacheTracker>();
     AU.addPreserved<AAResultsWrapperPass>();
     AU.addPreserved<GlobalsAAWrapperPass>();
+    AU.addRequired<LibcallLoweringInfoWrapper>();
   }
 };
 } // namespace
@@ -1126,8 +1132,23 @@ PreservedAnalyses ExpandFpPass::run(Function &F, FunctionAnalysisManager &FAM) {
   AssumptionCache *AC = nullptr;
   if (OptLevel != CodeGenOptLevel::None)
     AC = &FAM.getResult<AssumptionAnalysis>(F);
-  return runImpl(F, TLI, AC) ? PreservedAnalyses::none()
-                             : PreservedAnalyses::all();
+
+  auto &MAMProxy = FAM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
+
+  const LibcallLoweringModuleAnalysisResult *LibcallLowering =
+      MAMProxy.getCachedResult<LibcallLoweringModuleAnalysis>(*F.getParent());
+
+  if (!LibcallLowering) {
+    F.getContext().emitError("'" + LibcallLoweringModuleAnalysis::name() +
+                             "' analysis required");
+    return PreservedAnalyses::all();
+  }
+
+  const LibcallLoweringInfo &Libcalls =
+      LibcallLowering->getLibcallLowering(*STI);
+
+  return runImpl(F, TLI, Libcalls, AC) ? PreservedAnalyses::none()
+                                       : PreservedAnalyses::all();
 }
 
 char ExpandFpLegacyPass::ID = 0;

llvm/lib/CodeGen/LibcallLoweringInfo.cpp

@@ -7,7 +7,10 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/LibcallLoweringInfo.h"
+#include "llvm/Analysis/RuntimeLibcallInfo.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
+#include "llvm/InitializePasses.h"
+#include "llvm/Target/TargetMachine.h"
 
 using namespace llvm;
 
@@ -28,3 +31,42 @@ LibcallLoweringInfo::LibcallLoweringInfo(
 
   Subtarget.initLibcallLoweringInfo(*this);
 }
+
+AnalysisKey LibcallLoweringModuleAnalysis::Key;
+
+bool LibcallLoweringModuleAnalysisResult::invalidate(
+    Module &, const PreservedAnalyses &PA,
+    ModuleAnalysisManager::Invalidator &) {
+  // Passes that change the runtime libcall set must explicitly invalidate this
+  // pass.
+  auto PAC = PA.getChecker<LibcallLoweringModuleAnalysis>();
+  return !PAC.preservedWhenStateless();
+}
+
+LibcallLoweringModuleAnalysisResult
+LibcallLoweringModuleAnalysis::run(Module &M, ModuleAnalysisManager &MAM) {
+  LibcallLoweringMap.init(&MAM.getResult<RuntimeLibraryAnalysis>(M));
+  return LibcallLoweringMap;
+}
+
+INITIALIZE_PASS_BEGIN(LibcallLoweringInfoWrapper, "libcall-lowering-info",
+                      "Library Function Lowering Analysis", false, true)
+INITIALIZE_PASS_DEPENDENCY(RuntimeLibraryInfoWrapper)
+INITIALIZE_PASS_END(LibcallLoweringInfoWrapper, "libcall-lowering-info",
+                    "Library Function Lowering Analysis", false, true)
+
+char LibcallLoweringInfoWrapper::ID = 0;
+
+LibcallLoweringInfoWrapper::LibcallLoweringInfoWrapper() : ImmutablePass(ID) {}
+
+bool LibcallLoweringInfoWrapper::doInitialization(Module &M) {
+  Result.init(&getAnalysis<RuntimeLibraryInfoWrapper>().getRTLCI(M));
+  return false;
+}
+
+void LibcallLoweringInfoWrapper::getAnalysisUsage(AnalysisUsage &AU) const {
+  AU.addRequired<RuntimeLibraryInfoWrapper>();
+  AU.setPreservesAll();
+}
+
+void LibcallLoweringInfoWrapper::releaseMemory() { Result.clear(); }