Local variables whose address is taken and passed on to a call are described
in debug info using their stack slots instead of as an indirection of param reg + 0
offset. This is done by detecting FrameIndexSDNodes in SelectionDAG and generating
FrameIndexDbgValues for them. This ultimately generates DBG_VALUEs with stack
location operands.
Differential Revision: http://reviews.llvm.org/D23283
llvm-svn: 278703
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 8374e2e..f2a8110 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1020,8 +1020,7 @@
if (Val.getNode()) {
if (!EmitFuncArgumentDbgValue(V, Variable, Expr, dl, Offset, false,
Val)) {
- SDV = DAG.getDbgValue(Variable, Expr, Val.getNode(), Val.getResNo(),
- false, Offset, dl, DbgSDNodeOrder);
+ SDV = getDbgValue(Val, Variable, Expr, Offset, dl, DbgSDNodeOrder);
DAG.AddDbgValue(SDV, Val.getNode(), false);
}
} else
@@ -4742,6 +4741,32 @@
return true;
}
+/// Return the appropriate SDDbgValue based on N.
+SDDbgValue *SelectionDAGBuilder::getDbgValue(SDValue N,
+ DILocalVariable *Variable,
+ DIExpression *Expr, int64_t Offset,
+ DebugLoc dl,
+ unsigned DbgSDNodeOrder) {
+ SDDbgValue *SDV;
+ auto *FISDN = dyn_cast<FrameIndexSDNode>(N.getNode());
+ if (FISDN && Expr->startsWithDeref()) {
+ // Construct a FrameIndexDbgValue for FrameIndexSDNodes so we can describe
+ // stack slot locations as such instead of as indirectly addressed
+ // locations.
+ ArrayRef<uint64_t> TrailingElements(Expr->elements_begin() + 1,
+ Expr->elements_end());
+ DIExpression *DerefedDIExpr =
+ DIExpression::get(*DAG.getContext(), TrailingElements);
+ int FI = FISDN->getIndex();
+ SDV = DAG.getFrameIndexDbgValue(Variable, DerefedDIExpr, FI, 0, dl,
+ DbgSDNodeOrder);
+ } else {
+ SDV = DAG.getDbgValue(Variable, Expr, N.getNode(), N.getResNo(), false,
+ Offset, dl, DbgSDNodeOrder);
+ }
+ return SDV;
+}
+
// VisualStudio defines setjmp as _setjmp
#if defined(_MSC_VER) && defined(setjmp) && \
!defined(setjmp_undefined_for_msvc)
@@ -4943,8 +4968,7 @@
if (N.getNode()) {
if (!EmitFuncArgumentDbgValue(V, Variable, Expression, dl, Offset,
false, N)) {
- SDV = DAG.getDbgValue(Variable, Expression, N.getNode(), N.getResNo(),
- false, Offset, dl, SDNodeOrder);
+ SDV = getDbgValue(N, Variable, Expression, Offset, dl, SDNodeOrder);
DAG.AddDbgValue(SDV, N.getNode(), false);
}
} else if (!V->use_empty() ) {
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
index 18c39d0..6672de0 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
@@ -942,6 +942,11 @@
/// Update the DAG and DAG builder with the relevant information after
/// a new root node has been created which could be a tail call.
void updateDAGForMaybeTailCall(SDValue MaybeTC);
+
+ /// Return the appropriate SDDbgValue based on N.
+ SDDbgValue *getDbgValue(SDValue N, DILocalVariable *Variable,
+ DIExpression *Expr, int64_t Offset, DebugLoc dl,
+ unsigned DbgSDNodeOrder);
};
/// RegsForValue - This struct represents the registers (physical or virtual)