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Auto merge of #136146 - RalfJung:x86-abi, r=workingjubilee

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Explicitly choose x86 softfloat/hardfloat ABI

Part of https://github.com/rust-lang/rust/pull/135408:
Instead of choosing this based on the target features listed in the target spec, make that choice explicit.
All built-in targets are being updated here; custom (JSON-defined) x86 (32bit and 64bit) softfloat targets need to explicitly set `rustc-abi` to `x86-softfloat`.
This commit is contained in:
bors
2025-02-03 20:02:54 +00:00
parent 534d79adf9 8596ce141c
commit f027438f8b
22 changed files with 161 additions and 60 deletions
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52
compiler/rustc_target/src/target_features.rs
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@@ -5,7 +5,7 @@ use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
use rustc_span::{Symbol, sym};
use crate::spec::{FloatAbi, Target};
use crate::spec::{FloatAbi, RustcAbi, Target};
/// Features that control behaviour of rustc, rather than the codegen.
/// These exist globally and are not in the target-specific lists below.
@@ -422,7 +422,9 @@ const X86_FEATURES: &[(&str, Stability, ImpliedFeatures)] = &[
("sha512", Unstable(sym::sha512_sm_x86), &["avx2"]),
("sm3", Unstable(sym::sha512_sm_x86), &["avx"]),
("sm4", Unstable(sym::sha512_sm_x86), &["avx2"]),
("soft-float", Stability::Forbidden { reason: "unsound because it changes float ABI" }, &[]),
// This cannot actually be toggled, the ABI always fixes it, so it'd make little sense to
// stabilize. It must be in this list for the ABI check to be able to use it.
("soft-float", Stability::Unstable(sym::x87_target_feature), &[]),
("sse", Stable, &[]),
("sse2", Stable, &["sse"]),
("sse3", Stable, &["sse2"]),
@@ -773,23 +775,41 @@ impl Target {
// questions "which ABI is used".
match &*self.arch {
"x86" => {
// We support 2 ABIs, hardfloat (default) and softfloat.
// x86 has no sane ABI indicator so we have to use the target feature.
if self.has_feature("soft-float") {
NOTHING
} else {
// Hardfloat ABI. x87 must be enabled.
FeatureConstraints { required: &["x87"], incompatible: &[] }
// We use our own ABI indicator here; LLVM does not have anything native.
// Every case should require or forbid `soft-float`!
match self.rustc_abi {
None => {
// Default hardfloat ABI.
// x87 must be enabled, soft-float must be disabled.
FeatureConstraints { required: &["x87"], incompatible: &["soft-float"] }
}
Some(RustcAbi::X86Softfloat) => {
// Softfloat ABI, requires corresponding target feature. That feature trumps
// `x87` and all other FPU features so those do not matter.
// Note that this one requirement is the entire implementation of the ABI!
// LLVM handles the rest.
FeatureConstraints { required: &["soft-float"], incompatible: &[] }
}
}
}
"x86_64" => {
// We support 2 ABIs, hardfloat (default) and softfloat.
// x86 has no sane ABI indicator so we have to use the target feature.
if self.has_feature("soft-float") {
NOTHING
} else {
// Hardfloat ABI. x87 and SSE2 must be enabled.
FeatureConstraints { required: &["x87", "sse2"], incompatible: &[] }
// We use our own ABI indicator here; LLVM does not have anything native.
// Every case should require or forbid `soft-float`!
match self.rustc_abi {
None => {
// Default hardfloat ABI. On x86-64, this always includes SSE2.
FeatureConstraints {
required: &["x87", "sse2"],
incompatible: &["soft-float"],
}
}
Some(RustcAbi::X86Softfloat) => {
// Softfloat ABI, requires corresponding target feature. That feature trumps
// `x87` and all other FPU features so those do not matter.
// Note that this one requirement is the entire implementation of the ABI!
// LLVM handles the rest.
FeatureConstraints { required: &["soft-float"], incompatible: &[] }
}
}
}
"arm" => {