Debug info: (Bugfix) Make sure artificial functions like _GLOBAL__I_a

are not associated with any source lines.

Previously, if the Location of a Decl was empty, EmitFunctionStart would
just keep using CurLoc, which would sometimes be correct (e.g., thunks)
but in other cases would just point to a hilariously random location.

This patch fixes this by completely eliminating all uses of CurLoc from
EmitFunctionStart and rather have clients explicitly pass in a
SourceLocation for the function header and the function body.

rdar://problem/14985269

llvm-svn: 205999

1 files changed, 19 insertions, 4 deletions

diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index ffaba95..95e4ee4 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -503,6 +503,7 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
                                     llvm::Function *Fn,
                                     const CGFunctionInfo &FnInfo,
                                     const FunctionArgList &Args,
+                                    SourceLocation Loc,
                                     SourceLocation StartLoc) {
   const Decl *D = GD.getDecl();
 
@@ -580,9 +581,7 @@ void CodeGenFunction::StartFunction(GlobalDecl GD,
     QualType FnType =
       getContext().getFunctionType(RetTy, ArgTypes,
                                    FunctionProtoType::ExtProtoInfo());
-
-    DI->setLocation(StartLoc);
-    DI->EmitFunctionStart(GD, FnType, CurFn, Builder);
+    DI->EmitFunctionStart(GD, Loc, StartLoc, FnType, CurFn, Builder);
   }
 
   if (ShouldInstrumentFunction())
@@ -759,8 +758,24 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn,
   if (Stmt *Body = FD->getBody()) BodyRange = Body->getSourceRange();
   CurEHLocation = BodyRange.getEnd();
 
+  // Use the location of the start of the function to determine where
+  // the function definition is located. By default use the location
+  // of the declaration as the location for the subprogram. A function
+  // may lack a declaration in the source code if it is created by code
+  // gen. (examples: _GLOBAL__I_a, __cxx_global_array_dtor, thunk).
+  SourceLocation Loc;
+  if (FD) {
+    Loc = FD->getLocation();
+
+    // If this is a function specialization then use the pattern body
+    // as the location for the function.
+    if (const FunctionDecl *SpecDecl = FD->getTemplateInstantiationPattern())
+      if (SpecDecl->hasBody(SpecDecl))
+        Loc = SpecDecl->getLocation();
+  }
+
   // Emit the standard function prologue.
-  StartFunction(GD, ResTy, Fn, FnInfo, Args, BodyRange.getBegin());
+  StartFunction(GD, ResTy, Fn, FnInfo, Args, Loc, BodyRange.getBegin());
 
   // Generate the body of the function.
   PGO.assignRegionCounters(GD.getDecl(), CurFn);