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74 lines
3.1 KiB
74 lines
3.1 KiB
https://github.com/rust-lang/rust/pull/120661
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From: WANG Xuerui <xen0n@gentoo.org>
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Date: Mon, 5 Feb 2024 13:18:32 +0800
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Subject: [PATCH] target: default to the medium code model on LoongArch targets
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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The Rust LoongArch targets have been using the default LLVM code model
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so far, which is "small" in LLVM-speak and "normal" in LoongArch-speak.
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As described in the "Code Model" section of LoongArch ELF psABI spec
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v20231219 [1], one can only make function calls as far as ±128MiB with
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the "normal" code model; this is insufficient for very large software
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containing Rust components that needs to be linked into the big text
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section, such as Chromium.
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Because:
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* we do not want to ask users to recompile std if they are to build
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such software,
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* objects compiled with larger code models can be linked with those
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with smaller code models without problems, and
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* the "medium" code model is comparable to the "small"/"normal" one
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performance-wise (same data access pattern; each function call
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becomes 2-insn long and indirect, but this may be relaxed back into
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the direct 1-insn form in a future LLVM version), but is able to
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perform function calls within ±128GiB,
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it is better to just switch the targets to the "medium" code model,
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which is also "medium" in LLVM-speak.
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[1]: https://github.com/loongson/la-abi-specs/blob/v2.30/laelf.adoc#code-models
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--- a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_linux_gnu.rs
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+++ b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_linux_gnu.rs
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@@ -1,4 +1,4 @@
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-use crate::spec::{base, Target, TargetOptions};
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+use crate::spec::{base, CodeModel, Target, TargetOptions};
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pub fn target() -> Target {
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Target {
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@@ -7,6 +7,7 @@ pub fn target() -> Target {
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data_layout: "e-m:e-p:64:64-i64:64-i128:128-n64-S128".into(),
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arch: "loongarch64".into(),
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options: TargetOptions {
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+ code_model: Some(CodeModel::Medium),
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cpu: "generic".into(),
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features: "+f,+d".into(),
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llvm_abiname: "lp64d".into(),
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--- a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs
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+++ b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs
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@@ -16,7 +16,7 @@ pub fn target() -> Target {
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max_atomic_width: Some(64),
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relocation_model: RelocModel::Static,
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panic_strategy: PanicStrategy::Abort,
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- code_model: Some(CodeModel::Small),
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+ code_model: Some(CodeModel::Medium),
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..Default::default()
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},
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}
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--- a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none_softfloat.rs
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+++ b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none_softfloat.rs
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@@ -17,7 +17,7 @@ pub fn target() -> Target {
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max_atomic_width: Some(64),
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relocation_model: RelocModel::Static,
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panic_strategy: PanicStrategy::Abort,
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- code_model: Some(CodeModel::Small),
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+ code_model: Some(CodeModel::Medium),
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..Default::default()
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},
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}
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--
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2.43.0
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