From 35dad14dfb63d77cf4a2077f1e8e9cff5a02a92b Mon Sep 17 00:00:00 2001 From: WANG Xuerui Date: Mon, 5 Feb 2024 13:18:32 +0800 Subject: [PATCH] target: default to the medium code model on LoongArch targets MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The Rust LoongArch targets have been using the default LLVM code model so far, which is "small" in LLVM-speak and "normal" in LoongArch-speak. As described in the "Code Model" section of LoongArch ELF psABI spec v20231219 [1], one can only make function calls as far as ±128MiB with the "normal" code model; this is insufficient for very large software containing Rust components that needs to be linked into the big text section, such as Chromium. Because: * we do not want to ask users to recompile std if they are to build such software, * objects compiled with larger code models can be linked with those with smaller code models without problems, and * the "medium" code model is comparable to the "small"/"normal" one performance-wise (same data access pattern; each function call becomes 2-insn long and indirect, but this may be relaxed back into the direct 1-insn form in a future LLVM version), but is able to perform function calls within ±128GiB, it is better to just switch the targets to the "medium" code model, which is also "medium" in LLVM-speak. [1]: https://github.com/loongson/la-abi-specs/blob/v2.30/laelf.adoc#code-models --- .../src/spec/targets/loongarch64_unknown_linux_gnu.rs | 3 ++- .../rustc_target/src/spec/targets/loongarch64_unknown_none.rs | 2 +- .../src/spec/targets/loongarch64_unknown_none_softfloat.rs | 2 +- 3 files changed, 4 insertions(+), 3 deletions(-) diff --git a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_linux_gnu.rs b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_linux_gnu.rs index 0f05e7c475a83..cb24e740c86f2 100644 --- a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_linux_gnu.rs +++ b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_linux_gnu.rs @@ -1,4 +1,4 @@ -use crate::spec::{base, Target, TargetOptions}; +use crate::spec::{base, CodeModel, Target, TargetOptions}; pub fn target() -> Target { Target { @@ -7,6 +7,7 @@ pub fn target() -> Target { data_layout: "e-m:e-p:64:64-i64:64-i128:128-n64-S128".into(), arch: "loongarch64".into(), options: TargetOptions { + code_model: Some(CodeModel::Medium), cpu: "generic".into(), features: "+f,+d".into(), llvm_abiname: "lp64d".into(), diff --git a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs index 3b1ea8e206f1c..f448017a2a58d 100644 --- a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs +++ b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none.rs @@ -16,7 +16,7 @@ pub fn target() -> Target { max_atomic_width: Some(64), relocation_model: RelocModel::Static, panic_strategy: PanicStrategy::Abort, - code_model: Some(CodeModel::Small), + code_model: Some(CodeModel::Medium), ..Default::default() }, } diff --git a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none_softfloat.rs b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none_softfloat.rs index ab9300ef9c723..d636c9599a7be 100644 --- a/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none_softfloat.rs +++ b/compiler/rustc_target/src/spec/targets/loongarch64_unknown_none_softfloat.rs @@ -17,7 +17,7 @@ pub fn target() -> Target { max_atomic_width: Some(64), relocation_model: RelocModel::Static, panic_strategy: PanicStrategy::Abort, - code_model: Some(CodeModel::Small), + code_model: Some(CodeModel::Medium), ..Default::default() }, }