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llvm: Don't emit extra debug instructions for dbg_var_val in naked functions #21070

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llvm: Don't emit extra debug instructions for dbg_var_val in naked functions #21070

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2545019
llvm: Remove the aarch64-windows @llvm.dbg.value() workaround.
alexrp Aug 13, 2024
4a82957
llvm: Don't emit extra debug instructions for `dbg_var_val` in naked …
alexrp Aug 13, 2024
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18 changes: 4 additions & 14 deletions src/codegen/llvm.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -6709,8 +6709,6 @@ pub const FuncGen = struct {
const operand_ty = self.typeOf(pl_op.operand);
const name = self.air.nullTerminatedString(pl_op.payload);

if (needDbgVarWorkaround(o)) return .none;

const debug_local_var = try o.builder.debugLocalVar(
try o.builder.metadataString(name),
self.file,
Expand All @@ -6734,7 +6732,10 @@ pub const FuncGen = struct {
},
"",
);
} else if (owner_mod.optimize_mode == .Debug) {
} else if (owner_mod.optimize_mode == .Debug and !self.is_naked) {
// We avoid taking this path for naked functions because there's no guarantee that such
// functions even have a valid stack pointer, making the `alloca` + `store` unsafe.

const alignment = operand_ty.abiAlignment(pt).toLlvm();
const alloca = try self.buildAlloca(operand.typeOfWip(&self.wip), alignment);
_ = try self.wip.store(.normal, operand, alloca, alignment);
Expand Down Expand Up @@ -8815,7 +8816,6 @@ pub const FuncGen = struct {
if (self.is_naked) return arg_val;

const inst_ty = self.typeOfIndex(inst);
if (needDbgVarWorkaround(o)) return arg_val;

const name = self.air.instructions.items(.data)[@intFromEnum(inst)].arg.name;
if (name == .none) return arg_val;
Expand Down Expand Up @@ -11804,16 +11804,6 @@ const optional_layout_version = 3;

const lt_errors_fn_name = "__zig_lt_errors_len";

/// Without this workaround, LLVM crashes with "unknown codeview register H1"
/// https://github.com/llvm/llvm-project/issues/56484
fn needDbgVarWorkaround(o: *Object) bool {
const target = o.pt.zcu.getTarget();
if (target.os.tag == .windows and target.cpu.arch == .aarch64) {
return true;
}
return false;
}

fn compilerRtIntBits(bits: u16) u16 {
inline for (.{ 32, 64, 128 }) |b| {
if (bits <= b) {
Expand Down