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Auto merge of #117307 - taiki-e:espidf-atomic-64, r=Amanieu

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Set max_atomic_width for riscv32*-esp-espidf to 32

Fixes #117305

> Since riscv32 does not have 64-bit atomic instructions, I do not believe there is any way to fix this problem other than setting max_atomic_width of these targets to 32.

This is a breaking change because Atomic\*64 will become unavailable, but all affected targets are tier 3, and the current Atomic*64 violates the standard library's API contract and can cause problems with code that rely on the standard library's atomic types being lock-free.

r? `@Amanieu`
cc `@ivmarkov` `@MabezDev`
This commit is contained in:
bors 2023-11-01 16:39:22 +00:00
commit f3457dbf84
2 changed files with 3 additions and 3 deletions
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2
compiler/rustc_target/src/spec/riscv32imac_esp_espidf.rs
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@ -17,7 +17,7 @@ pub fn target() -> Target {
// As RiscV32IMAC architecture does natively support atomics,
// automatically enable the support for the Rust STD library.
max_atomic_width: Some(64),
max_atomic_width: Some(32),
atomic_cas: true,
features: "+m,+a,+c".into(),

4
compiler/rustc_target/src/spec/riscv32imc_esp_espidf.rs
View File

@ -16,11 +16,11 @@ pub fn target() -> Target {
cpu: "generic-rv32".into(),
// While the RiscV32IMC architecture does not natively support atomics, ESP-IDF does support
// the __atomic* and __sync* GCC builtins, so setting `max_atomic_width` to `Some(64)`
// the __atomic* and __sync* GCC builtins, so setting `max_atomic_width` to `Some(32)`
// and `atomic_cas` to `true` will cause the compiler to emit libcalls to these builtins.
//
// Support for atomics is necessary for the Rust STD library, which is supported by the ESP-IDF framework.
max_atomic_width: Some(64),
max_atomic_width: Some(32),
atomic_cas: true,
features: "+m,+c".into(),