[llvm] r341737 - Remove addBlockByrefAddress(), it is dead code as far as clang is concerned.
Adrian Prantl via llvm-commits
llvm-commits at lists.llvm.org
Fri Sep 7 17:21:55 PDT 2018
Author: adrian
Date: Fri Sep 7 17:21:55 2018
New Revision: 341737
URL: http://llvm.org/viewvc/llvm-project?rev=341737&view=rev
Log:
Remove addBlockByrefAddress(), it is dead code as far as clang is concerned.
This patch removes addBlockByrefAddress(), it is dead code as far as
clang is concerned: Every byref block capture is emitted with a
complex expression that is equivalent to what this function does.
rdar://problem/31629055
Differential Revision: https://reviews.llvm.org/D51763
Added:
llvm/trunk/test/Verifier/blockbyref.ll
Modified:
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
llvm/trunk/lib/IR/Verifier.cpp
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp?rev=341737&r1=341736&r2=341737&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp Fri Sep 7 17:21:55 2018
@@ -978,8 +978,6 @@ void DwarfCompileUnit::addVariableAddres
"block byref variable without a complex expression");
if (DV.hasComplexAddress())
addComplexAddress(DV, Die, dwarf::DW_AT_location, Location);
- else if (DV.isBlockByrefVariable())
- addBlockByrefAddress(DV, Die, dwarf::DW_AT_location, Location);
else
addAddress(Die, dwarf::DW_AT_location, Location);
}
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=341737&r1=341736&r2=341737&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Fri Sep 7 17:21:55 2018
@@ -427,138 +427,6 @@ void DwarfUnit::addSourceLine(DIE &Die,
addSourceLine(Die, Ty->getLine(), Ty->getFile());
}
-/* 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 function getBlockByrefType dives into the __Block_byref_x_VarName
- struct to find the original type of the variable, which is then assigned to
- the variable's Debug Information Entry as its real type. So far, so good.
- However now the debugger will expect the variable VarName to have the type
- SomeType. So we need the location attribute for the variable to be an
- expression that explains to the debugger how to navigate through the
- pointers and struct to find the actual variable of type SomeType.
-
- The following function does just that. We start by getting
- the "normal" location for the variable. This will be the location
- of either the struct __Block_byref_x_VarName or the pointer to the
- struct __Block_byref_x_VarName.
-
- The struct will look something like:
-
- struct __Block_byref_x_VarName {
- ... <various fields>
- struct __Block_byref_x_VarName *forwarding;
- ... <various other fields>
- SomeType VarName;
- ... <maybe more fields>
- };
-
- If we are given the struct directly (as our starting point) we
- need to tell the debugger to:
-
- 1). Add the offset of the forwarding field.
-
- 2). Follow that pointer to get the real __Block_byref_x_VarName
- struct to use (the real one may have been copied onto the heap).
-
- 3). Add the offset for the field VarName, to find the actual variable.
-
- If we started with a pointer to the struct, then we need to
- dereference that pointer first, before the other steps.
- Translating this into DWARF ops, we will need to append the following
- to the current location description for the variable:
-
- DW_OP_deref -- optional, if we start with a pointer
- DW_OP_plus_uconst <forward_fld_offset>
- DW_OP_deref
- DW_OP_plus_uconst <varName_fld_offset>
-
- That is what this function does. */
-
-void DwarfUnit::addBlockByrefAddress(const DbgVariable &DV, DIE &Die,
- dwarf::Attribute Attribute,
- const MachineLocation &Location) {
- const DIType *Ty = DV.getType();
- const DIType *TmpTy = Ty;
- uint16_t Tag = Ty->getTag();
- bool isPointer = false;
-
- StringRef varName = DV.getName();
-
- if (Tag == dwarf::DW_TAG_pointer_type) {
- auto *DTy = cast<DIDerivedType>(Ty);
- TmpTy = resolve(DTy->getBaseType());
- isPointer = true;
- }
-
- // Find the __forwarding field and the variable field in the __Block_byref
- // struct.
- DINodeArray Fields = cast<DICompositeType>(TmpTy)->getElements();
- const DIDerivedType *varField = nullptr;
- const DIDerivedType *forwardingField = nullptr;
-
- for (unsigned i = 0, N = Fields.size(); i < N; ++i) {
- auto *DT = cast<DIDerivedType>(Fields[i]);
- StringRef fieldName = DT->getName();
- if (fieldName == "__forwarding")
- forwardingField = DT;
- else if (fieldName == varName)
- varField = DT;
- }
-
- // Get the offsets for the forwarding field and the variable field.
- unsigned forwardingFieldOffset = forwardingField->getOffsetInBits() >> 3;
- unsigned varFieldOffset = varField->getOffsetInBits() >> 2;
-
- // Decode the original location, and use that as the start of the byref
- // variable's location.
- DIELoc *Loc = new (DIEValueAllocator) DIELoc;
- DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
- if (Location.isIndirect())
- DwarfExpr.setMemoryLocationKind();
-
- SmallVector<uint64_t, 6> Ops;
- // If we started with a pointer to the __Block_byref... struct, then
- // the first thing we need to do is dereference the pointer (DW_OP_deref).
- if (isPointer)
- Ops.push_back(dwarf::DW_OP_deref);
-
- // Next add the offset for the '__forwarding' field:
- // DW_OP_plus_uconst ForwardingFieldOffset. Note there's no point in
- // adding the offset if it's 0.
- if (forwardingFieldOffset > 0) {
- Ops.push_back(dwarf::DW_OP_plus_uconst);
- Ops.push_back(forwardingFieldOffset);
- }
-
- // Now dereference the __forwarding field to get to the real __Block_byref
- // struct: DW_OP_deref.
- Ops.push_back(dwarf::DW_OP_deref);
-
- // Now that we've got the real __Block_byref... struct, add the offset
- // for the variable's field to get to the location of the actual variable:
- // DW_OP_plus_uconst varFieldOffset. Again, don't add if it's 0.
- if (varFieldOffset > 0) {
- Ops.push_back(dwarf::DW_OP_plus_uconst);
- Ops.push_back(varFieldOffset);
- }
-
- DIExpressionCursor Cursor(Ops);
- const TargetRegisterInfo &TRI = *Asm->MF->getSubtarget().getRegisterInfo();
- if (!DwarfExpr.addMachineRegExpression(TRI, Cursor, Location.getReg()))
- return;
- DwarfExpr.addExpression(std::move(Cursor));
-
- // Now attach the location information to the DIE.
- addBlock(Die, Attribute, DwarfExpr.finalize());
-}
-
/// Return true if type encoding is unsigned.
static bool isUnsignedDIType(DwarfDebug *DD, const DIType *Ty) {
if (auto *CTy = dyn_cast<DICompositeType>(Ty)) {
Modified: llvm/trunk/lib/IR/Verifier.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Verifier.cpp?rev=341737&r1=341736&r2=341737&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Verifier.cpp (original)
+++ llvm/trunk/lib/IR/Verifier.cpp Fri Sep 7 17:21:55 2018
@@ -4534,6 +4534,14 @@ void Verifier::visitDbgIntrinsic(StringR
&DII, BB, F, Var, Var->getScope()->getSubprogram(), Loc,
Loc->getScope()->getSubprogram());
+ // 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);
}
Added: llvm/trunk/test/Verifier/blockbyref.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Verifier/blockbyref.ll?rev=341737&view=auto
==============================================================================
--- llvm/trunk/test/Verifier/blockbyref.ll (added)
+++ llvm/trunk/test/Verifier/blockbyref.ll Fri Sep 7 17:21:55 2018
@@ -0,0 +1,19 @@
+; RUN: llvm-as -disable-output <%s 2>&1| FileCheck %s
+
+; CHECK: BlockByRef variable without complex expression
+; CHECK: warning: ignoring invalid debug info
+
+define void @foo() {
+entry:
+ %s = alloca i32
+ call void @llvm.dbg.declare(metadata i32* %s, metadata !2, metadata !DIExpression()), !dbg !DILocation(scope: !1)
+ ret void
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+!llvm.module.flags = !{!0}
+!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)
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