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More bugs squashed.

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This commit is contained in:
Scott Duensing 2026-06-30 21:01:01 -05:00
parent d10d3b9fc6
commit 52c4416b7e
1 changed files with 25 additions and 14 deletions
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31
src/llvm/lib/Target/W65816/W65816StackSlotMerge.cpp
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@ -549,12 +549,16 @@ bool W65816StackSlotMerge::runOnMachineFunction(MachineFunction &MF) {
// a DBG_VALUE that still points at slot-X reads stale data.
//
// For DBG_VALUEs whose DIExpression has a leading constant offset that
// matches a renamed slot, we mark them as undef. This loses debug
// info at the affected PC range but never reports a wrong variable
// value. A future enhancement could rewrite the offset to point at
// the merged slot Y (the merge proves they hold equivalent values
// function-wide), but that requires DIExpression rewriting and
// re-uniquing which is non-trivial in this position.
// matches a renamed slot X, relocate them to the merged slot Y by
// rewriting that leading offset (the merge proved X and Y hold
// equivalent values function-wide, so Y's memory is a correct location
// for the variable). The trailing ops are preserved verbatim and the
// offset is re-encoded with the canonical appendOffset form, which is
// exactly what extractLeadingOffset decodes -- so this is faithful.
// This keeps the variable's location live across the rename; previously
// we dropped it (setDebugValueUndef), losing debug info at those PCs.
// Falls back to undef only if re-encoding somehow fails.
LLVMContext &Ctx = MF.getFunction().getContext();
bool Changed = false;
for (MachineBasicBlock &MBB : MF) {
for (MachineInstr &MI : MBB) {
@ -565,10 +569,17 @@ bool W65816StackSlotMerge::runOnMachineFunction(MachineFunction &MF) {
SmallVector<uint64_t, 4> Remaining;
if (!Expr->extractLeadingOffset(LeadingOff, Remaining))
continue;
if (!Renames.count(LeadingOff)) continue;
// Match: this DBG_VALUE points at slot X (now renamed). Undef
// every register debug operand to drop the location at this PC.
for (MachineOperand &Op : MI.debug_operands()) {
auto RIt = Renames.find(LeadingOff);
if (RIt == Renames.end()) continue;
// Match: this DBG_VALUE points at slot X (now renamed to Y).
SmallVector<uint64_t, 8> NewOps;
DIExpression::appendOffset(NewOps, RIt->second);
NewOps.append(Remaining.begin(), Remaining.end());
if (const DIExpression *NewExpr = DIExpression::get(Ctx, NewOps)) {
MI.getDebugExpressionOp().setMetadata(NewExpr);
} else {
// Should not happen; keep the old fail-safe behavior.
for (MachineOperand &Op : MI.debug_operands())
if (Op.isReg()) {
Op.setReg(0);
Op.setSubReg(0);