Merge pull request swiftlang#31113 from CodaFi/a-little-less-context-would-be-nice

Excise the Global LLVM Context

Author: CodaFi

include/swift/AST/ASTContext.h

@@ -50,6 +50,10 @@ namespace clang {
   class ObjCInterfaceDecl;
 }
 
+namespace llvm {
+  class LLVMContext;
+}
+
 namespace swift {
   class AbstractFunctionDecl;
   class ASTContext;
@@ -949,6 +953,11 @@ class ASTContext final {
                                        GenericSignatureBuilder &&builder);
   friend class GenericSignatureBuilder;
 
+private:
+  friend class IntrinsicInfo;
+  /// Retrieve an LLVMContext that is used for scratch space for intrinsic lookup.
+  llvm::LLVMContext &getIntrinsicScratchContext() const;
+
 public:
   /// Retrieve or create the stored generic signature builder for the given
   /// canonical generic signature and module.

include/swift/AST/Builtins.h

@@ -126,7 +126,7 @@ class IntrinsicInfo {
 public:
   llvm::Intrinsic::ID ID;
   SmallVector<Type, 4> Types;
-  bool hasAttribute(llvm::Attribute::AttrKind Kind) const;
+  const llvm::AttributeList &getOrCreateAttributes(ASTContext &Ctx) const;
 };
 
 /// Turn a string like "release" into the LLVM enum.

include/swift/Subsystems.h

@@ -21,7 +21,6 @@
 #include "swift/Basic/OptionSet.h"
 #include "swift/Basic/PrimarySpecificPaths.h"
 #include "swift/Basic/Version.h"
-#include "llvm/IR/LLVMContext.h"
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"

lib/AST/ASTContext.cpp

@@ -56,6 +56,7 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringSwitch.h"
+#include "llvm/IR/LLVMContext.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/Support/Compiler.h"
 #include <algorithm>
@@ -473,11 +474,15 @@ struct ASTContext::Implementation {
 
   /// The IRGen specific SIL transforms that have been registered.
   SILTransformCtors IRGenSILPasses;
+
+  /// The scratch context used to allocate intrinsic data on behalf of \c swift::IntrinsicInfo
+  std::unique_ptr<llvm::LLVMContext> IntrinsicScratchContext;
 };
 
 ASTContext::Implementation::Implementation()
     : IdentifierTable(Allocator),
-      TheSyntaxArena(new syntax::SyntaxArena()) {}
+      TheSyntaxArena(new syntax::SyntaxArena()),
+      IntrinsicScratchContext(new llvm::LLVMContext()) {}
 ASTContext::Implementation::~Implementation() {
   for (auto &cleanup : Cleanups)
     cleanup();
@@ -4792,3 +4797,8 @@ AutoDiffDerivativeFunctionIdentifier *AutoDiffDerivativeFunctionIdentifier::get(
 
   return newNode;
 }
+
+llvm::LLVMContext &ASTContext::getIntrinsicScratchContext() const {
+  return *getImpl().IntrinsicScratchContext.get();
+}
+

lib/AST/Builtins.cpp

@@ -26,24 +26,11 @@
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
-#include "llvm/IR/LLVMContext.h"
 #include "llvm/Support/ManagedStatic.h"
 #include <tuple>
 
 using namespace swift;
 
-// FIXME: The "Global Context" is a holdover from LLVM's removal of the global
-// context. LLVM's global context was used as scratch space to allocate some
-// attributes for the routines in this file, so we just made our own to work
-// around its removal. Really, it doesn't matter where we allocate these
-// attributes, but it's somewhat convenient for now that they're all in one
-// place instead of requiring a fresh context for every call. If we can
-// sequester ownership of a context (e.g. in SILModule) we could do away with
-// this, but there are callers of \c swift::getSwiftFunctionTypeForIntrinsic
-// all over the compiler.
-static llvm::ManagedStatic<llvm::LLVMContext> GlobalContext;
-static llvm::LLVMContext &getGlobalLLVMContext() { return *GlobalContext; }
-
 struct BuiltinExtraInfoTy {
   const char *Attributes;
 };
@@ -58,13 +45,13 @@ bool BuiltinInfo::isReadNone() const {
   return strchr(BuiltinExtraInfo[(unsigned)ID].Attributes, 'n') != nullptr;
 }
 
-bool IntrinsicInfo::hasAttribute(llvm::Attribute::AttrKind Kind) const {
+const llvm::AttributeList &
+IntrinsicInfo::getOrCreateAttributes(ASTContext &Ctx) const {
   using DenseMapInfo = llvm::DenseMapInfo<llvm::AttributeList>;
   if (DenseMapInfo::isEqual(Attrs, DenseMapInfo::getEmptyKey())) {
-    // FIXME: We should not be relying on the global LLVM context.
-    Attrs = llvm::Intrinsic::getAttributes(getGlobalLLVMContext(), ID);
+    Attrs = llvm::Intrinsic::getAttributes(Ctx.getIntrinsicScratchContext(), ID);
   }
-  return Attrs.hasFnAttribute(Kind);
+  return Attrs;
 }
 
 Type swift::getBuiltinType(ASTContext &Context, StringRef Name) {
@@ -1837,8 +1824,9 @@ getSwiftFunctionTypeForIntrinsic(llvm::Intrinsic::ID ID,
   }
 
   // Translate LLVM function attributes to Swift function attributes.
-  llvm::AttributeList attrs =
-      llvm::Intrinsic::getAttributes(getGlobalLLVMContext(), ID);
+  IntrinsicInfo II;
+  II.ID = ID;
+  auto attrs = II.getOrCreateAttributes(Context);
   if (attrs.hasAttribute(llvm::AttributeList::FunctionIndex,
                          llvm::Attribute::NoReturn)) {
     ResultTy = Context.getNeverType();

lib/LLVMPasses/LLVMMergeFunctions.cpp

@@ -44,7 +44,6 @@
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InlineAsm.h"
 #include "llvm/IR/Instructions.h"
-#include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/ValueHandle.h"

lib/SIL/IR/SILInstruction.cpp

@@ -978,13 +978,14 @@ SILInstruction::MemoryBehavior SILInstruction::getMemoryBehavior() const {
     // Handle LLVM intrinsic functions.
     const IntrinsicInfo &IInfo = BI->getIntrinsicInfo();
     if (IInfo.ID != llvm::Intrinsic::not_intrinsic) {
+      auto IAttrs = IInfo.getOrCreateAttributes(getModule().getASTContext());
       // Read-only.
-      if (IInfo.hasAttribute(llvm::Attribute::ReadOnly) &&
-          IInfo.hasAttribute(llvm::Attribute::NoUnwind))
+      if (IAttrs.hasFnAttribute(llvm::Attribute::ReadOnly) &&
+          IAttrs.hasFnAttribute(llvm::Attribute::NoUnwind))
         return MemoryBehavior::MayRead;
       // Read-none?
-      return IInfo.hasAttribute(llvm::Attribute::ReadNone) &&
-                     IInfo.hasAttribute(llvm::Attribute::NoUnwind)
+      return IAttrs.hasFnAttribute(llvm::Attribute::ReadNone) &&
+                     IAttrs.hasFnAttribute(llvm::Attribute::NoUnwind)
                  ? MemoryBehavior::None
                  : MemoryBehavior::MayHaveSideEffects;
     }

lib/SIL/IR/SILModule.cpp

@@ -646,7 +646,9 @@ void SILModule::notifyDeleteHandlers(SILNode *node) {
 bool SILModule::isNoReturnBuiltinOrIntrinsic(Identifier Name) {
   const auto &IntrinsicInfo = getIntrinsicInfo(Name);
   if (IntrinsicInfo.ID != llvm::Intrinsic::not_intrinsic) {
-    return IntrinsicInfo.hasAttribute(llvm::Attribute::NoReturn);
+    return IntrinsicInfo
+              .getOrCreateAttributes(getASTContext())
+              .hasFnAttribute(llvm::Attribute::NoReturn);
   }
   const auto &BuiltinInfo = getBuiltinInfo(Name);
   switch (BuiltinInfo.ID) {

lib/SILOptimizer/Analysis/ARCAnalysis.cpp

@@ -103,7 +103,8 @@ static bool canApplyOfBuiltinUseNonTrivialValues(BuiltinInst *BInst) {
 
   auto &II = BInst->getIntrinsicInfo();
   if (II.ID != llvm::Intrinsic::not_intrinsic) {
-    if (II.hasAttribute(llvm::Attribute::ReadNone)) {
+    auto attrs = II.getOrCreateAttributes(F->getASTContext());
+    if (attrs.hasFnAttribute(llvm::Attribute::ReadNone)) {
       for (auto &Op : BInst->getAllOperands()) {
         if (!Op.get()->getType().isTrivial(*F)) {
           return true;