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reject unsound toggling of RISCV target features

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This commit is contained in:
Ralf Jung 2024-12-15 12:08:50 +01:00
parent d18506299b
commit 171223e01b
2 changed files with 67 additions and 4 deletions
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2
compiler/rustc_target/src/spec/mod.rs
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@ -3166,7 +3166,7 @@ impl Target {
// Note that the `lp64e` is still unstable as it's not (yet) part of the ELF psABI.
check_matches!(
&*self.llvm_abiname,
"lp64" | "lp64f" | "lp64d" | "lp64q" | "lp64e",
"lp64" | "lp64f" | "lp64d" | "lp64e",
"invalid RISC-V ABI name"
);
}

69
compiler/rustc_target/src/target_features.rs
View file

@ -590,9 +590,72 @@ const RISCV_FEATURES: &[(&str, StabilityUncomputed, ImpliedFeatures)] = &[
// tidy-alphabetical-start
("a", STABLE, &["zaamo", "zalrsc"]),
("c", STABLE, &[]),
("d", unstable(sym::riscv_target_feature), &["f"]),
("e", unstable(sym::riscv_target_feature), &[]),
("f", unstable(sym::riscv_target_feature), &[]),
(
"d",
Stability::Unstable {
nightly_feature: sym::riscv_target_feature,
allow_toggle: |target, enable| match &*target.llvm_abiname {
"ilp32d" | "lp64d" if !enable => {
// The ABI requires the `d` feature, so it cannot be disabled.
Err("feature is required by ABI")
}
"ilp32e" if enable => {
// The `d` feature apparently is incompatible with this ABI.
Err("feature is incompatible with ABI")
}
_ => Ok(()),
},
},
&["f"],
),
(
"e",
Stability::Unstable {
// Given that this is a negative feature, consider this before stabilizing:
// does it really make sense to enable this feature in an individual
// function with `#[target_feature]`?
nightly_feature: sym::riscv_target_feature,
allow_toggle: |target, enable| {
match &*target.llvm_abiname {
_ if !enable => {
// This is a negative feature, *disabling* it is always okay.
Ok(())
}
"ilp32e" | "lp64e" => {
// Embedded ABIs should already have the feature anyway, it's fine to enable
// it again from an ABI perspective.
Ok(())
}
_ => {
// *Not* an embedded ABI. Enabling `e` is invalid.
Err("feature is incompatible with ABI")
}
}
},
},
&[],
),
(
"f",
Stability::Unstable {
nightly_feature: sym::riscv_target_feature,
allow_toggle: |target, enable| {
match &*target.llvm_abiname {
"ilp32f" | "ilp32d" | "lp64f" | "lp64d" if !enable => {
// The ABI requires the `f` feature, so it cannot be disabled.
Err("feature is required by ABI")
}
_ => Ok(()),
}
},
},
&[],
),
(
"forced-atomics",
Stability::Forbidden { reason: "unsound because it changes the ABI of atomic operations" },
&[],
),
("m", STABLE, &[]),
("relax", unstable(sym::riscv_target_feature), &[]),
("unaligned-scalar-mem", unstable(sym::riscv_target_feature), &[]),