akhuang created this revision.
Herald added subscribers: llvm-commits, cfe-commits, hiraditya.
Herald added projects: clang, LLVM.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D63361
Files:
clang/lib/CodeGen/CGDebugInfo.cpp
clang/lib/CodeGen/CGDecl.cpp
debuginfo-tests/nrvo-string.cpp
llvm/include/llvm/IR/DebugInfoMetadata.h
llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
llvm/lib/IR/DebugInfoMetadata.cpp
Index: llvm/lib/IR/DebugInfoMetadata.cpp
===================================================================
--- llvm/lib/IR/DebugInfoMetadata.cpp
+++ llvm/lib/IR/DebugInfoMetadata.cpp
@@ -936,12 +936,20 @@
}
}
-bool DIExpression::extractIfOffset(int64_t &Offset) const {
+bool DIExpression::extractIfOffset(int64_t &Offset, bool &Deref) const {
+ Deref = false;
+
if (getNumElements() == 0) {
Offset = 0;
return true;
}
+ if (getNumElements() == 1 && Elements[0] == dwarf::DW_OP_deref) {
+ Offset = 0;
+ Deref = true;
+ return true;
+ }
+
if (getNumElements() == 2 && Elements[0] == dwarf::DW_OP_plus_uconst) {
Offset = Elements[1];
return true;
Index: llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
===================================================================
--- llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -1142,9 +1142,11 @@
// If the variable has an attached offset expression, extract it.
// FIXME: Try to handle DW_OP_deref as well.
int64_t ExprOffset = 0;
- if (VI.Expr)
- if (!VI.Expr->extractIfOffset(ExprOffset))
+ bool Deref = false;
+ if (VI.Expr) {
+ if (!VI.Expr->extractIfOffset(ExprOffset, Deref))
continue;
+ }
// Get the frame register used and the offset.
unsigned FrameReg = 0;
@@ -1154,6 +1156,7 @@
// Calculate the label ranges.
LocalVarDefRange DefRange =
createDefRangeMem(CVReg, FrameOffset + ExprOffset);
+
for (const InsnRange &Range : Scope->getRanges()) {
const MCSymbol *Begin = getLabelBeforeInsn(Range.first);
const MCSymbol *End = getLabelAfterInsn(Range.second);
@@ -1164,6 +1167,9 @@
LocalVariable Var;
Var.DIVar = VI.Var;
Var.DefRanges.emplace_back(std::move(DefRange));
+ if (Deref)
+ Var.UseReferenceType = true;
+
recordLocalVariable(std::move(Var), Scope);
}
}
Index: llvm/include/llvm/IR/DebugInfoMetadata.h
===================================================================
--- llvm/include/llvm/IR/DebugInfoMetadata.h
+++ llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -2468,8 +2468,9 @@
static void appendOffset(SmallVectorImpl<uint64_t> &Ops, int64_t Offset);
/// If this is a constant offset, extract it. If there is no expression,
- /// return true with an offset of zero.
- bool extractIfOffset(int64_t &Offset) const;
+ /// or if there is one expression of DW_OP_deref, return true with an offset
+ /// of zero. Also set Deref.
+ bool extractIfOffset(int64_t &Offset, bool &Deref) const;
/// Checks if the last 4 elements of the expression are DW_OP_constu <DWARF
/// Address Space> DW_OP_swap DW_OP_xderef and extracts the <DWARF Address
Index: debuginfo-tests/nrvo-string.cpp
===================================================================
--- debuginfo-tests/nrvo-string.cpp
+++ debuginfo-tests/nrvo-string.cpp
@@ -14,10 +14,13 @@
~string() {}
int i = 0;
};
+int some_function_call(int i) { return i; }
string get_string() {
string unused;
string result = 3;
-// DEBUGGER: break 21
+ // DEBUGGER: break 21
+ result = some_function_call(47);
+ // DEBUGGER: break 23
return result;
}
int main() { get_string(); }
@@ -25,3 +28,6 @@
// DEBUGGER: r
// DEBUGGER: print result.i
// CHECK: = 3
+// DEBUGGER: c
+// DEBUGGER: print result.i
+// CHECK: = 47
Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -1403,12 +1403,11 @@
getLangOpts().OpenMP
? CGM.getOpenMPRuntime().getAddressOfLocalVariable(*this, &D)
: Address::invalid();
+ bool NRVO = getLangOpts().ElideConstructors && D.isNRVOVariable();
+
if (getLangOpts().OpenMP && OpenMPLocalAddr.isValid()) {
address = OpenMPLocalAddr;
} else if (Ty->isConstantSizeType()) {
- bool NRVO = getLangOpts().ElideConstructors &&
- D.isNRVOVariable();
-
// If this value is an array or struct with a statically determinable
// constant initializer, there are optimizations we can do.
//
@@ -1561,8 +1560,20 @@
// Emit debug info for local var declaration.
if (EmitDebugInfo && HaveInsertPoint()) {
+ Address DebugAddr = address;
DI->setLocation(D.getLocation());
- (void)DI->EmitDeclareOfAutoVariable(&D, address.getPointer(), Builder);
+
+ // NRVO variables are stored in the return register and are not always
+ // readable by the debugger. Get around this by storing a reference to
+ // the variable.
+ if (NRVO) {
+ llvm::Type *RefTy =
+ ConvertTypeForMem(getContext().getLValueReferenceType(Ty));
+ DebugAddr = CreateTempAlloca(RefTy, getPointerAlign(), "nrvo_ref");
+ Builder.CreateStore(ReturnValue.getPointer(), DebugAddr);
+ }
+
+ (void)DI->EmitDeclareOfAutoVariable(&D, DebugAddr.getPointer(), Builder);
}
if (D.hasAttr<AnnotateAttr>() && HaveInsertPoint())
Index: clang/lib/CodeGen/CGDebugInfo.cpp
===================================================================
--- clang/lib/CodeGen/CGDebugInfo.cpp
+++ clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3937,6 +3937,11 @@
}
}
+ // Add DW_OP_deref to NRVO variables because we set their debug values to be
+ // references.
+ if (VD->isNRVOVariable())
+ Expr.push_back(llvm::dwarf::DW_OP_deref);
+
// Create the descriptor for the variable.
auto *D = ArgNo ? DBuilder.createParameterVariable(
Scope, Name, *ArgNo, Unit, Line, Ty,
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