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llvm: Always omit the frame pointer for naked functions.

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Alex Rønne Petersen 2024-08-13 02:03:42 +02:00
parent ab9628dd2c
commit 2bf244c0e9
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1 changed files with 16 additions and 5 deletions
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21
src/codegen/llvm.zig
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@ -2909,7 +2909,17 @@ pub const Object = struct {
function_index.setAlignment(resolved.alignment.toLlvm(), &o.builder);
// Function attributes that are independent of analysis results of the function body.
try o.addCommonFnAttributes(&attributes, owner_mod);
try o.addCommonFnAttributes(
&attributes,
owner_mod,
// Some backends don't respect the `naked` attribute in `TargetFrameLowering::hasFP()`,
// so for these backends, LLVM will happily emit code that accesses the stack through
// the frame pointer. This is nonsensical since what the `naked` attribute does is
// suppress generation of the prologue and epilogue, and the prologue is where the
// frame pointer normally gets set up. At time of writing, this is the case for at
// least x86 and RISC-V.
owner_mod.omit_frame_pointer or fn_info.cc == .Naked,
);
if (fn_info.return_type == .noreturn_type) try attributes.addFnAttr(.noreturn, &o.builder);
@ -2956,13 +2966,14 @@ pub const Object = struct {
o: *Object,
attributes: *Builder.FunctionAttributes.Wip,
owner_mod: *Package.Module,
omit_frame_pointer: bool,
) Allocator.Error!void {
const comp = o.pt.zcu.comp;
if (!owner_mod.red_zone) {
try attributes.addFnAttr(.noredzone, &o.builder);
}
if (owner_mod.omit_frame_pointer) {
if (omit_frame_pointer) {
try attributes.addFnAttr(.{ .string = .{
.kind = try o.builder.string("frame-pointer"),
.value = try o.builder.string("none"),
@ -4528,7 +4539,7 @@ pub const Object = struct {
var attributes: Builder.FunctionAttributes.Wip = .{};
defer attributes.deinit(&o.builder);
try o.addCommonFnAttributes(&attributes, zcu.root_mod);
try o.addCommonFnAttributes(&attributes, zcu.root_mod, zcu.root_mod.omit_frame_pointer);
function_index.setLinkage(.internal, &o.builder);
function_index.setCallConv(.fastcc, &o.builder);
@ -4557,7 +4568,7 @@ pub const Object = struct {
var attributes: Builder.FunctionAttributes.Wip = .{};
defer attributes.deinit(&o.builder);
try o.addCommonFnAttributes(&attributes, zcu.root_mod);
try o.addCommonFnAttributes(&attributes, zcu.root_mod, zcu.root_mod.omit_frame_pointer);
function_index.setLinkage(.internal, &o.builder);
function_index.setCallConv(.fastcc, &o.builder);
@ -9676,7 +9687,7 @@ pub const FuncGen = struct {
var attributes: Builder.FunctionAttributes.Wip = .{};
defer attributes.deinit(&o.builder);
try o.addCommonFnAttributes(&attributes, zcu.root_mod);
try o.addCommonFnAttributes(&attributes, zcu.root_mod, zcu.root_mod.omit_frame_pointer);
function_index.setLinkage(.internal, &o.builder);
function_index.setCallConv(.fastcc, &o.builder);