[DebugInfo] LowerDbgDeclare: Add derefs when handling CallInst users
LowerDbgDeclare inserts a dbg.value before each use of an address
described by a dbg.declare. When inserting a dbg.value before a CallInst
use, however, it fails to append DW_OP_deref to the DIExpression.
The DW_OP_deref is needed to reflect the fact that a dbg.value describes
a source variable directly (as opposed to a dbg.declare, which relies on
pointer indirection).
This patch adds in the DW_OP_deref where needed. This results in the
correct values being shown during a debug session for a program compiled
with ASan and optimizations (see https://reviews.llvm.org/D49520). Note
that ConvertDebugDeclareToDebugValue is already correct -- no changes
there were needed.
One complication is that SelectionDAG is unable to distinguish between
direct and indirect frame-index (FRAMEIX) SDDbgValues. This patch also
fixes this long-standing issue in order to not regress integration tests
relying on the incorrect assumption that all frame-index SDDbgValues are
indirect. This is a necessary fix: the newly-added DW_OP_derefs cannot
be lowered properly otherwise. Basically the fix prevents a direct
SDDbgValue with DIExpression(DW_OP_deref) from being dereferenced twice
by a debugger. There were a handful of tests relying on this incorrect
"FRAMEIX => indirect" assumption which actually had incorrect
DW_AT_locations: these are all fixed up in this patch.
Testing:
- check-llvm, and an end-to-end test using lldb to debug an optimized
program.
- Existing unit tests for DIExpression::appendToStack fully cover the
new DIExpression::append utility.
- check-debuginfo (the debug info integration tests)
Differential Revision: https://reviews.llvm.org/D49454
llvm-svn: 338069
diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index db28d9a..910e8c2 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -841,9 +841,37 @@
return DIExpression::get(Expr->getContext(), Ops);
}
+DIExpression *DIExpression::append(const DIExpression *Expr,
+ ArrayRef<uint64_t> Ops) {
+ assert(Expr && !Ops.empty() && "Can't append ops to this expression");
+
+ // Copy Expr's current op list.
+ SmallVector<uint64_t, 16> NewOps;
+ for (auto Op : Expr->expr_ops()) {
+ // Append new opcodes before DW_OP_{stack_value, LLVM_fragment}.
+ if (Op.getOp() == dwarf::DW_OP_stack_value ||
+ Op.getOp() == dwarf::DW_OP_LLVM_fragment) {
+ NewOps.append(Ops.begin(), Ops.end());
+
+ // Ensure that the new opcodes are only appended once.
+ Ops = None;
+ }
+ Op.appendToVector(NewOps);
+ }
+
+ NewOps.append(Ops.begin(), Ops.end());
+ return DIExpression::get(Expr->getContext(), NewOps);
+}
+
DIExpression *DIExpression::appendToStack(const DIExpression *Expr,
ArrayRef<uint64_t> Ops) {
assert(Expr && !Ops.empty() && "Can't append ops to this expression");
+ assert(none_of(Ops,
+ [](uint64_t Op) {
+ return Op == dwarf::DW_OP_stack_value ||
+ Op == dwarf::DW_OP_LLVM_fragment;
+ }) &&
+ "Can't append this op");
// Append a DW_OP_deref after Expr's current op list if it's non-empty and
// has no DW_OP_stack_value.
@@ -851,30 +879,21 @@
// Match .* DW_OP_stack_value (DW_OP_LLVM_fragment A B)?.
Optional<FragmentInfo> FI = Expr->getFragmentInfo();
unsigned DropUntilStackValue = FI.hasValue() ? 3 : 0;
- bool NeedsDeref =
- (Expr->getNumElements() > DropUntilStackValue) &&
- (Expr->getElements().drop_back(DropUntilStackValue).back() !=
- dwarf::DW_OP_stack_value);
+ ArrayRef<uint64_t> ExprOpsBeforeFragment =
+ Expr->getElements().drop_back(DropUntilStackValue);
+ bool NeedsDeref = (Expr->getNumElements() > DropUntilStackValue) &&
+ (ExprOpsBeforeFragment.back() != dwarf::DW_OP_stack_value);
+ bool NeedsStackValue = NeedsDeref || ExprOpsBeforeFragment.empty();
- // Copy Expr's current op list, add a DW_OP_deref if needed, and ensure that
- // a DW_OP_stack_value is present.
+ // Append a DW_OP_deref after Expr's current op list if needed, then append
+ // the new ops, and finally ensure that a single DW_OP_stack_value is present.
SmallVector<uint64_t, 16> NewOps;
- for (auto Op : Expr->expr_ops()) {
- if (Op.getOp() == dwarf::DW_OP_stack_value ||
- Op.getOp() == dwarf::DW_OP_LLVM_fragment)
- break;
- Op.appendToVector(NewOps);
- }
if (NeedsDeref)
NewOps.push_back(dwarf::DW_OP_deref);
NewOps.append(Ops.begin(), Ops.end());
- NewOps.push_back(dwarf::DW_OP_stack_value);
-
- // If Expr is a fragment, make the new expression a fragment as well.
- if (FI)
- NewOps.append(
- {dwarf::DW_OP_LLVM_fragment, FI->OffsetInBits, FI->SizeInBits});
- return DIExpression::get(Expr->getContext(), NewOps);
+ if (NeedsStackValue)
+ NewOps.push_back(dwarf::DW_OP_stack_value);
+ return DIExpression::append(Expr, NewOps);
}
Optional<DIExpression *> DIExpression::createFragmentExpression(