Remove the obsolete BlockByRefStruct flag from LLVM IR

DIFlagBlockByRefStruct is an unused DIFlag that originally was used by
clang to express (Objective-)C block captures in debug info. For the
last year Clang has been emitting complex DIExpressions to describe
block captures instead, which makes all the code supporting this flag
redundant.

This patch removes the flag and all supporting "dead" code, so we can
reuse the bit for something else in the future.

Since this only affects debug info generated by Clang with the block
extension this mostly affects Apple platforms and I don't have any
bitcode compatibility concerns for removing this. The Verifier will
reject debug info that uses the bit and thus degrade gracefully when
LTO'ing older bitcode with a newer compiler.

rdar://problem/44304813

Differential Revision: https://reviews.llvm.org/D67453

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@372272 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/bindings/go/llvm/dibuilder.go b/bindings/go/llvm/dibuilder.go
index 98c11c151153b86e3ad47259ee61e62e957741d5..2c6bee411c0eca4e8e5c29d8a99c8d2fd8c5ec93 100644 (file)
--- a/bindings/go/llvm/dibuilder.go
+++ b/bindings/go/llvm/dibuilder.go
@@ -44,7 +44,7 @@ const (
        FlagProtected
        FlagFwdDecl
        FlagAppleBlock
-       FlagBlockByrefStruct
+       FlagReserved
        FlagVirtual
        FlagArtificial
        FlagExplicit

diff --git a/include/llvm-c/DebugInfo.h b/include/llvm-c/DebugInfo.h
index 33c8110a863c007b0ed989e21b15210e701ea1bd..c96faa2fbba4efb446ed826731146e1849a65cb4 100644 (file)
--- a/include/llvm-c/DebugInfo.h
+++ b/include/llvm-c/DebugInfo.h
@@ -32,7 +32,7 @@ typedef enum {
   LLVMDIFlagPublic = 3,
   LLVMDIFlagFwdDecl = 1 << 2,
   LLVMDIFlagAppleBlock = 1 << 3,
-  LLVMDIFlagBlockByrefStruct = 1 << 4,
+  LLVMDIFlagReservedBit4 = 1 << 4,
   LLVMDIFlagVirtual = 1 << 5,
   LLVMDIFlagArtificial = 1 << 6,
   LLVMDIFlagExplicit = 1 << 7,

diff --git a/include/llvm/IR/DebugInfoFlags.def b/include/llvm/IR/DebugInfoFlags.def
index c6c696523fbb5faeb18b1149988e1c7487a5ffa6..f90c580f10ef112ae8f9bbcdf4f50b7e14a341f4 100644 (file)
--- a/include/llvm/IR/DebugInfoFlags.def
+++ b/include/llvm/IR/DebugInfoFlags.def
@@ -31,7 +31,8 @@ HANDLE_DI_FLAG(2, Protected)
 HANDLE_DI_FLAG(3, Public)
 HANDLE_DI_FLAG((1 << 2), FwdDecl)
 HANDLE_DI_FLAG((1 << 3), AppleBlock)
-HANDLE_DI_FLAG((1 << 4), BlockByrefStruct)
+// Used to be BlockByRef, can be reused for anything except DICompositeType.
+HANDLE_DI_FLAG((1 << 4), ReservedBit4)
 HANDLE_DI_FLAG((1 << 5), Virtual)
 HANDLE_DI_FLAG((1 << 6), Artificial)
 HANDLE_DI_FLAG((1 << 7), Explicit)

diff --git a/include/llvm/IR/DebugInfoMetadata.h b/include/llvm/IR/DebugInfoMetadata.h
index 1f0533d98f63adad7b05666a5f924e2234b3e1c0..b94640f17712223203ac18ca47a9e9c737e38665 100644 (file)
--- a/include/llvm/IR/DebugInfoMetadata.h
+++ b/include/llvm/IR/DebugInfoMetadata.h
@@ -650,7 +650,6 @@ public:
   }
   bool isForwardDecl() const { return getFlags() & FlagFwdDecl; }
   bool isAppleBlockExtension() const { return getFlags() & FlagAppleBlock; }
-  bool isBlockByrefStruct() const { return getFlags() & FlagBlockByrefStruct; }
   bool isVirtual() const { return getFlags() & FlagVirtual; }
   bool isArtificial() const { return getFlags() & FlagArtificial; }
   bool isObjectPointer() const { return getFlags() & FlagObjectPointer; }

diff --git a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index f859a02033b4ba812e00cd41fe5cd8332acf0c02..edc8cefa3e22febb8275de7d79108c85934ead2a 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -1165,16 +1165,8 @@ void DwarfCompileUnit::addGlobalTypeUnitType(const DIType *Ty,
   GlobalTypes.insert(std::make_pair(std::move(FullName), &getUnitDie()));
 }
 
-/// addVariableAddress - Add DW_AT_location attribute for a
-/// DbgVariable based on provided MachineLocation.
 void DwarfCompileUnit::addVariableAddress(const DbgVariable &DV, DIE &Die,
                                           MachineLocation Location) {
-  // addBlockByrefAddress is obsolete and will be removed soon.
-  // The clang frontend always generates block byref variables with a
-  // complex expression that encodes exactly what addBlockByrefAddress
-  // would do.
-  assert((!DV.isBlockByrefVariable() || DV.hasComplexAddress()) &&
-         "block byref variable without a complex expression");
   if (DV.hasComplexAddress())
     addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
   else

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index 9be64c42f0cd2eb7954f93e58240b798a000d93f..255203740ac7c2fd04e5916cefe1ad41a37e8b4b 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -198,54 +198,8 @@ bool DebugLocDwarfExpression::isFrameRegister(const TargetRegisterInfo &TRI,
   return false;
 }
 
-bool DbgVariable::isBlockByrefVariable() const {
-  assert(getVariable() && "Invalid complex DbgVariable!");
-  return getVariable()->getType()->isBlockByrefStruct();
-}
-
 const DIType *DbgVariable::getType() const {
-  DIType *Ty = getVariable()->getType();
-  // FIXME: isBlockByrefVariable should be reformulated in terms of complex
-  // addresses instead.
-  if (Ty->isBlockByrefStruct()) {
-    /* Byref variables, in Blocks, are declared by the programmer as
-       "SomeType VarName;", but the compiler creates a
-       __Block_byref_x_VarName struct, and gives the variable VarName
-       either the struct, or a pointer to the struct, as its type.  This
-       is necessary for various behind-the-scenes things the compiler
-       needs to do with by-reference variables in blocks.
-
-       However, as far as the original *programmer* is concerned, the
-       variable should still have type 'SomeType', as originally declared.
-
-       The following function dives into the __Block_byref_x_VarName
-       struct to find the original type of the variable.  This will be
-       passed back to the code generating the type for the Debug
-       Information Entry for the variable 'VarName'.  'VarName' will then
-       have the original type 'SomeType' in its debug information.
-
-       The original type 'SomeType' will be the type of the field named
-       'VarName' inside the __Block_byref_x_VarName struct.
-
-       NOTE: In order for this to not completely fail on the debugger
-       side, the Debug Information Entry for the variable VarName needs to
-       have a DW_AT_location that tells the debugger how to unwind through
-       the pointers and __Block_byref_x_VarName struct to find the actual
-       value of the variable.  The function addBlockByrefType does this.  */
-    DIType *subType = Ty;
-    uint16_t tag = Ty->getTag();
-
-    if (tag == dwarf::DW_TAG_pointer_type)
-      subType = cast<DIDerivedType>(Ty)->getBaseType();
-
-    auto Elements = cast<DICompositeType>(subType)->getElements();
-    for (unsigned i = 0, N = Elements.size(); i < N; ++i) {
-      auto *DT = cast<DIDerivedType>(Elements[i]);
-      if (getName() == DT->getName())
-        return DT->getBaseType();
-    }
-  }
-  return Ty;
+  return getVariable()->getType();
 }
 
 /// Get .debug_loc entry for the instruction range starting at MI.

diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h
index 843caf1ab184f4f9d340ef1b41634cbf47b63d69..c8c511f67c2a095d7260b8c5d4f093b7ffa6e601 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -216,7 +216,6 @@ public:
     return !FrameIndexExprs.empty();
   }
 
-  bool isBlockByrefVariable() const;
   const DIType *getType() const;
 
   static bool classof(const DbgEntity *N) {

diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.h b/lib/CodeGen/AsmPrinter/DwarfUnit.h
index a376d5e75f6752396085ad474ced1a8119e85596..a188002722d2f6194b129a6c3072d45e4b4109fa 100644 (file)
--- a/lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ b/lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -216,15 +216,6 @@ public:
   /// Add thrown types.
   void addThrownTypes(DIE &Die, DINodeArray ThrownTypes);
 
-  // FIXME: Should be reformulated in terms of addComplexAddress.
-  /// Start with the address based on the location provided, and generate the
-  /// DWARF information necessary to find the actual Block variable (navigating
-  /// the Block struct) based on the starting location.  Add the DWARF
-  /// information to the die.  Obsolete, please use addComplexAddress instead.
-  void addBlockByrefAddress(const DbgVariable &DV, DIE &Die,
-                            dwarf::Attribute Attribute,
-                            const MachineLocation &Location);
-
   /// Add a new type attribute to the specified entity.
   ///
   /// This takes and attribute parameter because DW_AT_friend attributes are

diff --git a/lib/IR/Verifier.cpp b/lib/IR/Verifier.cpp
index 18bd74baf177a8b21afa09ac0af122e362f73edd..ebd4125f184efb20073606a8f31d55331733fe77 100644 (file)
--- a/lib/IR/Verifier.cpp
+++ b/lib/IR/Verifier.cpp
@@ -982,6 +982,9 @@ void Verifier::visitDICompositeType(const DICompositeType &N) {
            N.getRawVTableHolder());
   AssertDI(!hasConflictingReferenceFlags(N.getFlags()),
            "invalid reference flags", &N);
+  unsigned DIBlockByRefStruct = 1 << 4;
+  AssertDI((N.getFlags() & DIBlockByRefStruct) == 0,
+           "DIBlockByRefStruct on DICompositeType is no longer supported", &N);
 
   if (N.isVector()) {
     const DINodeArray Elements = N.getElements();
@@ -4902,11 +4905,6 @@ void Verifier::visitDbgIntrinsic(StringRef Kind, DbgVariableIntrinsic &DII) {
   // This check is redundant with one in visitLocalVariable().
   AssertDI(isType(Var->getRawType()), "invalid type ref", Var,
            Var->getRawType());
-  if (auto *Type = dyn_cast_or_null<DIType>(Var->getRawType()))
-    if (Type->isBlockByrefStruct())
-      AssertDI(DII.getExpression() && DII.getExpression()->getNumElements(),
-               "BlockByRef variable without complex expression", Var, &DII);
-
   verifyFnArgs(DII);
 }
 

diff --git a/test/CodeGen/ARM/debug-info-blocks.ll b/test/CodeGen/ARM/debug-info-blocks.ll
index cc1a45f23da0772c24a61c542c51a18cec57a866..8b31e7a51d5145ad45e5b5884d24992610155bd7 100644 (file)
--- a/test/CodeGen/ARM/debug-info-blocks.ll
+++ b/test/CodeGen/ARM/debug-info-blocks.ll
@@ -155,7 +155,7 @@ define hidden void @foobar_func_block_invoke_0(i8* %.block_descriptor, %0* %load
 !47 = !DIDerivedType(tag: DW_TAG_member, name: "DestroyFuncPtr", line: 307, size: 32, align: 32, offset: 96, file: !153, scope: !40, baseType: !46)
 !48 = !DIDerivedType(tag: DW_TAG_member, name: "mydata", line: 609, size: 32, align: 32, offset: 160, file: !152, scope: !24, baseType: !49)
 !49 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 32, scope: !0, baseType: !50)
-!50 = !DICompositeType(tag: DW_TAG_structure_type, size: 224, flags: DIFlagBlockByrefStruct, file: !152, scope: !24, elements: !51)
+!50 = !DICompositeType(tag: DW_TAG_structure_type, size: 224, file: !152, scope: !24, elements: !51)
 !51 = !{!52, !53, !54, !55, !56, !57, !58}
 !52 = !DIDerivedType(tag: DW_TAG_member, name: "__isa", size: 32, align: 32, file: !152, scope: !24, baseType: !32)
 !53 = !DIDerivedType(tag: DW_TAG_member, name: "__forwarding", size: 32, align: 32, offset: 32, file: !152, scope: !24, baseType: !32)

diff --git a/test/DebugInfo/Generic/block-asan.ll b/test/DebugInfo/Generic/block-asan.ll
index ee9a52522cfe62cfcc6de14b125b3f08e93e2f00..1d706fc6b84e6d67fb428bfeb9e2818e18bd4089 100644 (file)
--- a/test/DebugInfo/Generic/block-asan.ll
+++ b/test/DebugInfo/Generic/block-asan.ll
@@ -70,7 +70,7 @@ attributes #3 = { nounwind }
 !10 = !{i32 1, !"PIC Level", i32 2}
 !11 = !{!"clang version 3.6.0 (trunk 223120) (llvm/trunk 223119)"}
 !12 = !DILocalVariable(name: "x", line: 4, scope: !4, file: !5, type: !13)
-!13 = !DICompositeType(tag: DW_TAG_structure_type, size: 224, flags: DIFlagBlockByrefStruct, file: !1, scope: !5, elements: !14)
+!13 = !DICompositeType(tag: DW_TAG_structure_type, size: 224, file: !1, scope: !5, elements: !14)
 !14 = !{!15, !17, !18, !20, !21}
 !15 = !DIDerivedType(tag: DW_TAG_member, name: "__isa", size: 64, align: 64, file: !1, scope: !5, baseType: !16)
 !16 = !DIDerivedType(tag: DW_TAG_pointer_type, size: 64, align: 64, baseType: null)

diff --git a/test/Verifier/blockbyref.ll b/test/Verifier/blockbyref.ll
index 037da7f095210738723f5fa245d06d5396bd68ad..14d705647b74af2c1b1d1d45a1972cbeb5a62104 100644 (file)
--- a/test/Verifier/blockbyref.ll
+++ b/test/Verifier/blockbyref.ll
@@ -1,6 +1,6 @@
 ; RUN: llvm-as -disable-output <%s 2>&1| FileCheck %s
 
-; CHECK: BlockByRef variable without complex expression
+; CHECK: DIBlockByRefStruct on DICompositeType is no longer supported
 ; CHECK: warning: ignoring invalid debug info
 
 define void @foo() {
@@ -16,4 +16,4 @@ declare void @llvm.dbg.declare(metadata, metadata, metadata)
 !0 = !{i32 2, !"Debug Info Version", i32 3}
 !1 = distinct !DISubprogram()
 !2 = !DILocalVariable(scope: !1, type: !3)
-!3 = !DICompositeType(tag: DW_TAG_structure_type, flags: DIFlagBlockByrefStruct)
+!3 = !DICompositeType(tag: DW_TAG_structure_type, flags: DIFlagReservedBit4)