[DEBUG_INFO][NVPTX] Generate DW_AT_address_class to get the values in debugger.
Summary:
According to
https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf,
the compiler should emit the DW_AT_address_class attribute for all
variable and parameter. It means, that DW_AT_address_class attribute
should be used in the non-standard way to support compatibility with the
cuda-gdb debugger.
Clang is able to generate the information about the variable address
class. This information is emitted as the expression sequence
`DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef`. The patch
tries to find all such expressions and transform them into
`DW_AT_address_class <DWARF Address Space>` if target is NVPTX and the debugger is gdb.
If the expression is not found, then default values are used. For the
local variables <DWARF Address Space> is set to ADDR_local_space(6), for
the globals <DWARF Address Space> is set to ADDR_global_space(5). The
values are taken from the table in the same section 5.2. CUDA-Specific
DWARF Definitions.
Reviewers: echristo, probinson
Subscribers: jholewinski, aprantl, llvm-commits
Differential Revision: https://reviews.llvm.org/D57157
llvm-svn: 353203
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index ec136a6..0a30ede 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -167,6 +167,7 @@
// Add location.
bool addToAccelTable = false;
DIELoc *Loc = nullptr;
+ Optional<unsigned> NVPTXAddressSpace;
std::unique_ptr<DIEDwarfExpression> DwarfExpr;
for (const auto &GE : GlobalExprs) {
const GlobalVariable *Global = GE.Var;
@@ -200,8 +201,24 @@
DwarfExpr = llvm::make_unique<DIEDwarfExpression>(*Asm, *this, *Loc);
}
- if (Expr)
+ if (Expr) {
+ // According to
+ // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
+ // cuda-gdb requires DW_AT_address_class for all variables to be able to
+ // correctly interpret address space of the variable address.
+ // Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
+ // sequence for the NVPTX + gdb target.
+ unsigned LocalNVPTXAddressSpace;
+ if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
+ const DIExpression *NewExpr =
+ DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
+ if (NewExpr != Expr) {
+ Expr = NewExpr;
+ NVPTXAddressSpace = LocalNVPTXAddressSpace;
+ }
+ }
DwarfExpr->addFragmentOffset(Expr);
+ }
if (Global) {
const MCSymbol *Sym = Asm->getSymbol(Global);
@@ -246,6 +263,15 @@
DwarfExpr->setMemoryLocationKind();
DwarfExpr->addExpression(Expr);
}
+ if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
+ // According to
+ // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
+ // cuda-gdb requires DW_AT_address_class for all variables to be able to
+ // correctly interpret address space of the variable address.
+ const unsigned NVPTX_ADDR_global_space = 5;
+ addUInt(*VariableDIE, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
+ NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_global_space);
+ }
if (Loc)
addBlock(*VariableDIE, dwarf::DW_AT_location, DwarfExpr->finalize());
@@ -591,6 +617,7 @@
if (!DV.hasFrameIndexExprs())
return VariableDie;
+ Optional<unsigned> NVPTXAddressSpace;
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
for (auto &Fragment : DV.getFrameIndexExprs()) {
@@ -602,7 +629,23 @@
SmallVector<uint64_t, 8> Ops;
Ops.push_back(dwarf::DW_OP_plus_uconst);
Ops.push_back(Offset);
- Ops.append(Expr->elements_begin(), Expr->elements_end());
+ // According to
+ // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
+ // cuda-gdb requires DW_AT_address_class for all variables to be able to
+ // correctly interpret address space of the variable address.
+ // Decode DW_OP_constu <DWARF Address Space> DW_OP_swap DW_OP_xderef
+ // sequence for the NVPTX + gdb target.
+ unsigned LocalNVPTXAddressSpace;
+ if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
+ const DIExpression *NewExpr =
+ DIExpression::extractAddressClass(Expr, LocalNVPTXAddressSpace);
+ if (NewExpr != Expr) {
+ Expr = NewExpr;
+ NVPTXAddressSpace = LocalNVPTXAddressSpace;
+ }
+ }
+ if (Expr)
+ Ops.append(Expr->elements_begin(), Expr->elements_end());
DIExpressionCursor Cursor(Ops);
DwarfExpr.setMemoryLocationKind();
if (const MCSymbol *FrameSymbol = Asm->getFunctionFrameSymbol())
@@ -612,6 +655,15 @@
*Asm->MF->getSubtarget().getRegisterInfo(), Cursor, FrameReg);
DwarfExpr.addExpression(std::move(Cursor));
}
+ if (Asm->TM.getTargetTriple().isNVPTX() && DD->tuneForGDB()) {
+ // According to
+ // https://docs.nvidia.com/cuda/archive/10.0/ptx-writers-guide-to-interoperability/index.html#cuda-specific-dwarf
+ // cuda-gdb requires DW_AT_address_class for all variables to be able to
+ // correctly interpret address space of the variable address.
+ const unsigned NVPTX_ADDR_local_space = 6;
+ addUInt(*VariableDie, dwarf::DW_AT_address_class, dwarf::DW_FORM_data1,
+ NVPTXAddressSpace ? *NVPTXAddressSpace : NVPTX_ADDR_local_space);
+ }
addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
return VariableDie;