[PATCH] D39310: [CGBlocks] Improve line info in backtraces containing *_helper_block

[Vedant Kumar via Phabricator via cfe-commits]

vsk created this revision.

Instead of only setting a non-zero debug location on the return
instruction in *_helper_block functions, set a proper location on all
instructions within these functions. Pick the start location of the
block literal expr for maximum clarity.

The debugger does not step into *_helper_block functions during normal
single-stepping because we mark their parameters as artificial. This is
what we want (the functions are implicitly generated and uninteresting
to most users). The stepping behavior is unchanged by this patch.

rdar://32907581


https://reviews.llvm.org/D39310

Files:
  lib/CodeGen/CGBlocks.cpp
  test/CodeGenObjC/debug-info-blocks.m


Index: test/CodeGenObjC/debug-info-blocks.m
===================================================================
--- test/CodeGenObjC/debug-info-blocks.m
+++ test/CodeGenObjC/debug-info-blocks.m
@@ -10,9 +10,10 @@
 // CHECK-NEXT: call void @llvm.dbg.declare(metadata <{ i8*, i32, i32, i8*, %struct.__block_descriptor*, %0* }>** %[[ALLOCA]], metadata ![[SELF:[0-9]+]], metadata !{{.*}})
 // CHECK-NEXT: call void @llvm.dbg.declare(metadata %1** %d, metadata ![[D:[0-9]+]], metadata !{{.*}})
 
-// rdar://problem/14386148
-// Test that we don't emit bogus line numbers for the helper functions.
-// Test that we do emit scope info for the helper functions.
+// rdar://problem/32907581
+// Test that we do emit scope info for the helper functions, and that the
+// parameters to these functions are marked as artificial (so the debugger
+// doesn't accidentally step into the function).
 // CHECK: define {{.*}} @__copy_helper_block_{{.*}}(i8*, i8*)
 // CHECK-NOT: ret
 // CHECK: call {{.*}}, !dbg ![[DBG_LINE:[0-9]+]]
@@ -23,10 +24,13 @@
 // CHECK: load {{.*}}, !dbg ![[DESTROY_LINE:[0-9]+]]
 
 // CHECK-DAG: [[DBG_LINE]] = !DILocation(line: 0, scope: ![[COPY_SP:[0-9]+]])
-// CHECK-DAG: [[COPY_LINE]] = !DILocation(line: 0, scope: ![[COPY_SP:[0-9]+]])
+// CHECK-DAG: [[COPY_LINE]] = !DILocation(line: 67, scope: ![[COPY_SP:[0-9]+]])
 // CHECK-DAG: [[COPY_SP]] = distinct !DISubprogram(name: "__copy_helper_block_"
-// CHECK-DAG: [[DESTROY_LINE]] = !DILocation(line: 0, scope: ![[DESTROY_SP:[0-9]+]])
+// CHECK-DAG: [[DESTROY_LINE]] = !DILocation(line: 67, scope: ![[DESTROY_SP:[0-9]+]])
 // CHECK-DAG: [[DESTROY_SP]] = distinct !DISubprogram(name: "__destroy_helper_block_"
+// CHECK-DAG: !DILocalVariable(arg: 1, scope: ![[COPY_SP]], {{.*}}, flags: DIFlagArtificial)
+// CHECK-DAG: !DILocalVariable(arg: 2, scope: ![[COPY_SP]], {{.*}}, flags: DIFlagArtificial)
+// CHECK-DAG: !DILocalVariable(arg: 1, scope: ![[DESTROY_SP]], {{.*}}, flags: DIFlagArtificial)
 typedef unsigned int NSUInteger;
 
 @protocol NSObject
Index: lib/CodeGen/CGBlocks.cpp
===================================================================
--- lib/CodeGen/CGBlocks.cpp
+++ lib/CodeGen/CGBlocks.cpp
@@ -1647,10 +1647,8 @@
 
   CGM.SetInternalFunctionAttributes(nullptr, Fn, FI);
 
-  auto NL = ApplyDebugLocation::CreateEmpty(*this);
   StartFunction(FD, C.VoidTy, Fn, FI, args);
-  // Create a scope with an artificial location for the body of this function.
-  auto AL = ApplyDebugLocation::CreateArtificial(*this);
+  ApplyDebugLocation NL{*this, blockInfo.getBlockExpr()->getLocStart()};
   llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
 
   Address src = GetAddrOfLocalVar(&SrcDecl);
@@ -1819,10 +1817,8 @@
 
   CGM.SetInternalFunctionAttributes(nullptr, Fn, FI);
 
-  // Create a scope with an artificial location for the body of this function.
-  auto NL = ApplyDebugLocation::CreateEmpty(*this);
   StartFunction(FD, C.VoidTy, Fn, FI, args);
-  auto AL = ApplyDebugLocation::CreateArtificial(*this);
+  ApplyDebugLocation NL{*this, blockInfo.getBlockExpr()->getLocStart()};
 
   llvm::Type *structPtrTy = blockInfo.StructureType->getPointerTo();
 


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