[Annotation] Allows annotation to carry some additional constant arguments.

This allows using annotation in a much more contexts than it currently has.
especially when annotation with template or constexpr.

Reviewed By: aaron.ballman

Differential Revision: https://reviews.llvm.org/D88645

1 files changed, 42 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index a1511e0..fd13321 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -2341,13 +2341,48 @@ llvm::Constant *CodeGenModule::EmitAnnotationLineNo(SourceLocation L) {
   return llvm::ConstantInt::get(Int32Ty, LineNo);
 }
 
+llvm::Constant *CodeGenModule::EmitAnnotationArgs(const AnnotateAttr *Attr) {
+  ArrayRef<Expr *> Exprs = {Attr->args_begin(), Attr->args_size()};
+  Exprs = Exprs.drop_front();
+  if (Exprs.empty())
+    return llvm::ConstantPointerNull::get(Int8PtrTy);
+
+  llvm::FoldingSetNodeID ID;
+  for (Expr *E : Exprs) {
+    ID.Add(cast<clang::ConstantExpr>(E)->getAPValueResult());
+  }
+  llvm::Constant *&Lookup = AnnotationArgs[ID.ComputeHash()];
+  if (Lookup)
+    return Lookup;
+
+  llvm::SmallVector<llvm::Constant *, 4> LLVMArgs;
+  LLVMArgs.reserve(Exprs.size());
+  ConstantEmitter ConstEmiter(*this);
+  llvm::transform(Exprs, std::back_inserter(LLVMArgs), [&](const Expr *E) {
+    const auto *CE = cast<clang::ConstantExpr>(E);
+    return ConstEmiter.emitAbstract(CE->getBeginLoc(), CE->getAPValueResult(),
+                                    CE->getType());
+  });
+  auto *Struct = llvm::ConstantStruct::getAnon(LLVMArgs);
+  auto *GV = new llvm::GlobalVariable(getModule(), Struct->getType(), true,
+                                      llvm::GlobalValue::PrivateLinkage, Struct,
+                                      ".args");
+  GV->setSection(AnnotationSection);
+  GV->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
+  auto *Bitcasted = llvm::ConstantExpr::getBitCast(GV, Int8PtrTy);
+
+  Lookup = Bitcasted;
+  return Bitcasted;
+}
+
 llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
                                                 const AnnotateAttr *AA,
                                                 SourceLocation L) {
   // Get the globals for file name, annotation, and the line number.
   llvm::Constant *AnnoGV = EmitAnnotationString(AA->getAnnotation()),
                  *UnitGV = EmitAnnotationUnit(L),
-                 *LineNoCst = EmitAnnotationLineNo(L);
+                 *LineNoCst = EmitAnnotationLineNo(L),
+                 *Args = EmitAnnotationArgs(AA);
 
   llvm::Constant *ASZeroGV = GV;
   if (GV->getAddressSpace() != 0) {
@@ -2356,11 +2391,12 @@ llvm::Constant *CodeGenModule::EmitAnnotateAttr(llvm::GlobalValue *GV,
   }
 
   // Create the ConstantStruct for the global annotation.
-  llvm::Constant *Fields[4] = {
-    llvm::ConstantExpr::getBitCast(ASZeroGV, Int8PtrTy),
-    llvm::ConstantExpr::getBitCast(AnnoGV, Int8PtrTy),
-    llvm::ConstantExpr::getBitCast(UnitGV, Int8PtrTy),
-    LineNoCst
+  llvm::Constant *Fields[] = {
+      llvm::ConstantExpr::getBitCast(ASZeroGV, Int8PtrTy),
+      llvm::ConstantExpr::getBitCast(AnnoGV, Int8PtrTy),
+      llvm::ConstantExpr::getBitCast(UnitGV, Int8PtrTy),
+      LineNoCst,
+      Args,
   };
   return llvm::ConstantStruct::getAnon(Fields);
 }