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rust_for_linux: -Zregparm=<N> commandline flag for X86 (#116972)
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azhogin committed Sep 17, 2024
1 parent c8dff28 commit d6a6c57
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Showing 9 changed files with 114 additions and 15 deletions.
8 changes: 7 additions & 1 deletion compiler/rustc_codegen_gcc/src/builder.rs
Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@ use rustc_span::def_id::DefId;
use rustc_span::Span;
use rustc_target::abi::call::FnAbi;
use rustc_target::abi::{self, Align, HasDataLayout, Size, TargetDataLayout, WrappingRange};
use rustc_target::spec::{HasTargetSpec, HasWasmCAbiOpt, Target, WasmCAbi};
use rustc_target::spec::{HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, Target, WasmCAbi, X86Abi};

use crate::common::{type_is_pointer, SignType, TypeReflection};
use crate::context::CodegenCx;
Expand Down Expand Up @@ -2359,6 +2359,12 @@ impl<'tcx> HasWasmCAbiOpt for Builder<'_, '_, 'tcx> {
}
}

impl<'tcx> HasX86AbiOpt for Builder<'_, '_, 'tcx> {
fn x86_abi_opt(&self) -> X86Abi {
self.cx.x86_abi_opt()
}
}

pub trait ToGccComp {
fn to_gcc_comparison(&self) -> ComparisonOp;
}
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10 changes: 9 additions & 1 deletion compiler/rustc_codegen_gcc/src/context.rs
Original file line number Diff line number Diff line change
Expand Up @@ -20,7 +20,9 @@ use rustc_span::source_map::respan;
use rustc_span::{Span, DUMMY_SP};
use rustc_target::abi::call::FnAbi;
use rustc_target::abi::{HasDataLayout, PointeeInfo, Size, TargetDataLayout, VariantIdx};
use rustc_target::spec::{HasTargetSpec, HasWasmCAbiOpt, Target, TlsModel, WasmCAbi};
use rustc_target::spec::{
HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, Target, TlsModel, WasmCAbi, X86Abi,
};

use crate::callee::get_fn;
use crate::common::SignType;
Expand Down Expand Up @@ -571,6 +573,12 @@ impl<'gcc, 'tcx> HasWasmCAbiOpt for CodegenCx<'gcc, 'tcx> {
}
}

impl<'gcc, 'tcx> HasX86AbiOpt for CodegenCx<'gcc, 'tcx> {
fn x86_abi_opt(&self) -> X86Abi {
X86Abi { regparm: self.tcx.sess.opts.unstable_opts.regparm }
}
}

impl<'gcc, 'tcx> LayoutOfHelpers<'tcx> for CodegenCx<'gcc, 'tcx> {
type LayoutOfResult = TyAndLayout<'tcx>;

Expand Down
1 change: 1 addition & 0 deletions compiler/rustc_interface/src/tests.rs
Original file line number Diff line number Diff line change
Expand Up @@ -834,6 +834,7 @@ fn test_unstable_options_tracking_hash() {
tracked!(profile_emit, Some(PathBuf::from("abc")));
tracked!(profile_sample_use, Some(PathBuf::from("abc")));
tracked!(profiler_runtime, "abc".to_string());
tracked!(regparm, Some(3));
tracked!(relax_elf_relocations, Some(true));
tracked!(remap_cwd_prefix, Some(PathBuf::from("abc")));
tracked!(sanitizer, SanitizerSet::ADDRESS);
Expand Down
16 changes: 15 additions & 1 deletion compiler/rustc_middle/src/ty/layout.rs
Original file line number Diff line number Diff line change
Expand Up @@ -17,7 +17,9 @@ use rustc_span::{ErrorGuaranteed, Span, DUMMY_SP};
use rustc_target::abi::call::FnAbi;
use rustc_target::abi::*;
use rustc_target::spec::abi::Abi as SpecAbi;
use rustc_target::spec::{HasTargetSpec, HasWasmCAbiOpt, PanicStrategy, Target, WasmCAbi};
use rustc_target::spec::{
HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, PanicStrategy, Target, WasmCAbi, X86Abi,
};
use tracing::debug;

use crate::error::UnsupportedFnAbi;
Expand Down Expand Up @@ -534,6 +536,12 @@ impl<'tcx> HasWasmCAbiOpt for TyCtxt<'tcx> {
}
}

impl<'tcx> HasX86AbiOpt for TyCtxt<'tcx> {
fn x86_abi_opt(&self) -> X86Abi {
X86Abi { regparm: self.sess.opts.unstable_opts.regparm }
}
}

impl<'tcx> HasTyCtxt<'tcx> for TyCtxt<'tcx> {
#[inline]
fn tcx(&self) -> TyCtxt<'tcx> {
Expand Down Expand Up @@ -585,6 +593,12 @@ impl<'tcx> HasWasmCAbiOpt for LayoutCx<'tcx> {
}
}

impl<'tcx> HasX86AbiOpt for LayoutCx<'tcx> {
fn x86_abi_opt(&self) -> X86Abi {
self.calc.cx.x86_abi_opt()
}
}

impl<'tcx> HasTyCtxt<'tcx> for LayoutCx<'tcx> {
fn tcx(&self) -> TyCtxt<'tcx> {
self.calc.cx
Expand Down
3 changes: 3 additions & 0 deletions compiler/rustc_session/src/options.rs
Original file line number Diff line number Diff line change
Expand Up @@ -1978,6 +1978,9 @@ options! {
"enable queries of the dependency graph for regression testing (default: no)"),
randomize_layout: bool = (false, parse_bool, [TRACKED],
"randomize the layout of types (default: no)"),
regparm: Option<u32> = (None, parse_opt_number, [TRACKED],
"On x86-32 targets, the regparm N causes the compiler to pass N arguments \
in registers EAX, EDX, and ECX instead of on the stack."),
relax_elf_relocations: Option<bool> = (None, parse_opt_bool, [TRACKED],
"whether ELF relocations can be relaxed"),
remap_cwd_prefix: Option<PathBuf> = (None, parse_opt_pathbuf, [TRACKED],
Expand Down
22 changes: 13 additions & 9 deletions compiler/rustc_target/src/abi/call/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ use rustc_macros::HashStable_Generic;
use rustc_span::Symbol;

use crate::abi::{self, Abi, Align, FieldsShape, HasDataLayout, Size, TyAbiInterface, TyAndLayout};
use crate::spec::{self, HasTargetSpec, HasWasmCAbiOpt, WasmCAbi};
use crate::spec::{self, HasTargetSpec, HasWasmCAbiOpt, HasX86AbiOpt, WasmCAbi};

mod aarch64;
mod amdgpu;
Expand Down Expand Up @@ -875,7 +875,7 @@ impl<'a, Ty> FnAbi<'a, Ty> {
) -> Result<(), AdjustForForeignAbiError>
where
Ty: TyAbiInterface<'a, C> + Copy,
C: HasDataLayout + HasTargetSpec + HasWasmCAbiOpt,
C: HasDataLayout + HasTargetSpec + HasWasmCAbiOpt + HasX86AbiOpt,
{
if abi == spec::abi::Abi::X86Interrupt {
if let Some(arg) = self.args.first_mut() {
Expand All @@ -888,14 +888,18 @@ impl<'a, Ty> FnAbi<'a, Ty> {
let spec = cx.target_spec();
match &spec.arch[..] {
"x86" => {
let flavor = if let spec::abi::Abi::Fastcall { .. }
| spec::abi::Abi::Vectorcall { .. } = abi
{
x86::Flavor::FastcallOrVectorcall
} else {
x86::Flavor::General
let (flavor, regparm) = match abi {
spec::abi::Abi::Fastcall { .. } | spec::abi::Abi::Vectorcall { .. } => {
(x86::Flavor::FastcallOrVectorcall, None)
}
spec::abi::Abi::C { .. }
| spec::abi::Abi::Cdecl { .. }
| spec::abi::Abi::Stdcall { .. } => {
(x86::Flavor::General, cx.x86_abi_opt().regparm)
}
_ => (x86::Flavor::General, None),
};
x86::compute_abi_info(cx, self, flavor);
x86::compute_abi_info(cx, self, x86::X86Options { flavor, regparm });
}
"x86_64" => match abi {
spec::abi::Abi::SysV64 { .. } => x86_64::compute_abi_info(cx, self),
Expand Down
13 changes: 10 additions & 3 deletions compiler/rustc_target/src/abi/call/x86.rs
Original file line number Diff line number Diff line change
Expand Up @@ -8,11 +8,17 @@ pub(crate) enum Flavor {
FastcallOrVectorcall,
}

pub(crate) fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>, flavor: Flavor)
pub(crate) struct X86Options {
pub flavor: Flavor,
pub regparm: Option<u32>,
}

pub(crate) fn compute_abi_info<'a, Ty, C>(cx: &C, fn_abi: &mut FnAbi<'a, Ty>, opts: X86Options)
where
Ty: TyAbiInterface<'a, C> + Copy,
C: HasDataLayout + HasTargetSpec,
{
let flavor = opts.flavor;
if !fn_abi.ret.is_ignore() {
if fn_abi.ret.layout.is_aggregate() && fn_abi.ret.layout.is_sized() {
// Returning a structure. Most often, this will use
Expand Down Expand Up @@ -128,7 +134,7 @@ where
}
}

if flavor == Flavor::FastcallOrVectorcall {
if flavor == Flavor::FastcallOrVectorcall || opts.regparm.is_some_and(|x| x > 0) {
// Mark arguments as InReg like clang does it,
// so our fastcall/vectorcall is compatible with C/C++ fastcall/vectorcall.

Expand All @@ -138,7 +144,8 @@ where
// IsSoftFloatABI is only set to true on ARM platforms,
// which in turn can't be x86?

let mut free_regs = 2;
// 2 for fastcall/vectorcall, regparm limited by 3 otherwise
let mut free_regs: u64 = opts.regparm.map_or(2, |v| std::cmp::min(v, 3)).into();

for arg in fn_abi.args.iter_mut() {
let attrs = match arg.mode {
Expand Down
12 changes: 12 additions & 0 deletions compiler/rustc_target/src/spec/mod.rs
Original file line number Diff line number Diff line change
Expand Up @@ -2050,6 +2050,18 @@ pub trait HasWasmCAbiOpt {
fn wasm_c_abi_opt(&self) -> WasmCAbi;
}

/// x86 (32-bit) abi options.
#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
pub struct X86Abi {
/// On x86-32 targets, the regparm N causes the compiler to pass arguments
/// in registers EAX, EDX, and ECX instead of on the stack.
pub regparm: Option<u32>,
}

pub trait HasX86AbiOpt {
fn x86_abi_opt(&self) -> X86Abi;
}

type StaticCow<T> = Cow<'static, T>;

/// Optional aspects of a target specification.
Expand Down
44 changes: 44 additions & 0 deletions tests/codegen/regparm-inreg.rs
Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
// Checks how `regparm` flag works with different calling conventions:
// marks function arguments as "inreg" like the C/C++ compilers for the platforms.
// x86 only.

//@ compile-flags: --target i686-unknown-linux-gnu -Zregparm=3 -O -C no-prepopulate-passes
//@ needs-llvm-components: x86

#![crate_type = "lib"]
#![no_core]
#![feature(no_core, lang_items)]

#[lang = "sized"]
trait Sized {}
#[lang = "copy"]
trait Copy {}

pub mod tests {
// regparm doesn't work for "fastcall" calling conv (only 2 inregs)
// CHECK: @f1(i32 inreg noundef %_1, i32 inreg noundef %_2, i32 noundef %_3)
#[no_mangle]
pub extern "fastcall" fn f1(_: i32, _: i32, _: i32) {}

// regparm doesn't work for "Rust" calling conv
// CHECK: @f2(i32 noundef %_1, i32 noundef %_2, i32 noundef %_3)
#[no_mangle]
pub extern "Rust" fn f2(_: i32, _: i32, _: i32) {}

// CHECK: @f3(i32 inreg noundef %_1, i32 inreg noundef %_2, i32 inreg noundef %_3)
#[no_mangle]
pub extern "C" fn f3(_: i32, _: i32, _: i32) {}

// CHECK: @f4(i32 inreg noundef %_1, i32 inreg noundef %_2, i32 inreg noundef %_3)
#[no_mangle]
pub extern "cdecl" fn f4(_: i32, _: i32, _: i32) {}

// CHECK: @f5(i32 inreg noundef %_1, i32 inreg noundef %_2, i32 inreg noundef %_3)
#[no_mangle]
pub extern "stdcall" fn f5(_: i32, _: i32, _: i32) {}

// regparm doesn't work for thiscall
// CHECK: @f6(i32 noundef %_1, i32 noundef %_2, i32 noundef %_3)
#[no_mangle]
pub extern "thiscall" fn f6(_: i32, _: i32, _: i32) {}
}

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