DebugInfo: Provide a less subtle way to set the debug location of simple ret instructions

un-XFAILing the test XFAIL'd in r225086 after it regressed in r225083.

llvm-svn: 225090

clang/lib/CodeGen/CGDebugInfo.cpp

@@ -75,6 +75,15 @@ ApplyDebugLocation::ApplyDebugLocation(CodeGenFunction &CGF,
   }
 }
 
+ApplyDebugLocation::ApplyDebugLocation(CodeGenFunction &CGF, llvm::DebugLoc Loc)
+    : CGF(CGF) {
+  if (CGF.getDebugInfo()) {
+    OriginalLocation = CGF.Builder.getCurrentDebugLocation();
+    if (!Loc.isUnknown())
+      CGF.Builder.SetCurrentDebugLocation(Loc);
+  }
+}
+
 ApplyDebugLocation::~ApplyDebugLocation() {
   // Query CGF so the location isn't overwritten when location updates are
   // temporarily disabled (for C++ default function arguments)

clang/lib/CodeGen/CGDebugInfo.h

@@ -454,6 +454,7 @@ public:
   ApplyDebugLocation(CodeGenFunction &CGF,
                      SourceLocation TemporaryLocation = SourceLocation(),
                      bool ForceColumnInfo = false);
+  ApplyDebugLocation(CodeGenFunction &CGF, llvm::DebugLoc Loc);
   ~ApplyDebugLocation();
 };
 

clang/lib/CodeGen/CodeGenFunction.cpp

@@ -158,7 +158,7 @@ TypeEvaluationKind CodeGenFunction::getEvaluationKind(QualType type) {
   }
 }
 
-void CodeGenFunction::EmitReturnBlock() {
+llvm::DebugLoc CodeGenFunction::EmitReturnBlock() {
   // For cleanliness, we try to avoid emitting the return block for
   // simple cases.
   llvm::BasicBlock *CurBB = Builder.GetInsertBlock();
@@ -173,7 +173,7 @@ void CodeGenFunction::EmitReturnBlock() {
       delete ReturnBlock.getBlock();
     } else
       EmitBlock(ReturnBlock.getBlock());
-    return;
+    return llvm::DebugLoc();
   }
 
   // Otherwise, if the return block is the target of a single direct
@@ -184,15 +184,13 @@ void CodeGenFunction::EmitReturnBlock() {
       dyn_cast<llvm::BranchInst>(*ReturnBlock.getBlock()->user_begin());
     if (BI && BI->isUnconditional() &&
         BI->getSuccessor(0) == ReturnBlock.getBlock()) {
-      // Reset insertion point, including debug location, and delete the
-      // branch.  This is really subtle and only works because the next change
-      // in location will hit the caching in CGDebugInfo::EmitLocation and not
-      // override this.
-      Builder.SetCurrentDebugLocation(BI->getDebugLoc());
+      // Record/return the DebugLoc of the simple 'return' expression to be used
+      // later by the actual 'ret' instruction.
+      llvm::DebugLoc Loc = BI->getDebugLoc();
       Builder.SetInsertPoint(BI->getParent());
       BI->eraseFromParent();
       delete ReturnBlock.getBlock();
-      return;
+      return Loc;
     }
   }
 
@@ -201,6 +199,7 @@ void CodeGenFunction::EmitReturnBlock() {
   // region.end for now.
 
   EmitBlock(ReturnBlock.getBlock());
+  return llvm::DebugLoc();
 }
 
 static void EmitIfUsed(CodeGenFunction &CGF, llvm::BasicBlock *BB) {
@@ -254,16 +253,18 @@ void CodeGenFunction::FinishFunction(SourceLocation EndLoc) {
   }
 
   // Emit function epilog (to return).
-  EmitReturnBlock();
+  llvm::DebugLoc Loc = EmitReturnBlock();
 
   if (ShouldInstrumentFunction())
     EmitFunctionInstrumentation("__cyg_profile_func_exit");
 
   // Emit debug descriptor for function end.
-  if (CGDebugInfo *DI = getDebugInfo()) {
+  if (CGDebugInfo *DI = getDebugInfo())
     DI->EmitFunctionEnd(Builder);
-  }
 
+  // Reset the debug location to that of the simple 'return' expression, if any
+  // rather than that of the end of the function's scope '}'.
+  ApplyDebugLocation AL(*this, Loc);
   EmitFunctionEpilog(*CurFnInfo, EmitRetDbgLoc, EndLoc);
   EmitEndEHSpec(CurCodeDecl);
 

clang/lib/CodeGen/CodeGenFunction.h

@@ -1262,7 +1262,7 @@ public:
 
   /// EmitReturnBlock - Emit the unified return block, trying to avoid its
   /// emission when possible.
-  void EmitReturnBlock();
+  llvm::DebugLoc EmitReturnBlock();
 
   /// FinishFunction - Complete IR generation of the current function. It is
   /// legal to call this function even if there is no current insertion point.

clang/test/CodeGen/debug-info-line3.c

@@ -1,10 +1,5 @@
 // RUN: %clang_cc1 -g -S -emit-llvm %s -o - | FileCheck %s
 
-// Temporarily XFAIL while investigating regression. (other improvements seem
-// more important to keep rather than reverting them in favor of preserving
-// this)
-// XFAIL: *
-
 void func(char c, char* d)
 {
   *d = c + 1;