From 9f0a8620bd7d325e6d42417b08daff3e55cb88f6 Mon Sep 17 00:00:00 2001
From: Ayush Singh <ayushsingh1325@gmail.com>
Date: Sat, 5 Nov 2022 14:36:38 +0530
Subject: [PATCH] Improve generating Custom entry function
This commit is aimed at making compiler generated entry functions
(Basically just C `main` right now) more generic so other targets can do
similar things for custom entry. This was initially implemented as part
of https://github.com/rust-lang/rust/pull/100316.
Currently, this moves the entry function name and Call convention to the
target spec.
Signed-off-by: Ayush Singh <ayushsingh1325@gmail.com>
---
compiler/rustc_codegen_llvm/src/abi.rs | 40 +++++++++++--------
compiler/rustc_codegen_llvm/src/context.rs | 10 ++++-
compiler/rustc_codegen_llvm/src/declare.rs | 22 ++++++++++
.../src/back/symbol_export.rs | 3 +-
compiler/rustc_target/src/abi/call/mod.rs | 28 +++++++++++++
compiler/rustc_target/src/json.rs | 25 ++++++++++++
compiler/rustc_target/src/spec/mod.rs | 27 +++++++++++++
7 files changed, 135 insertions(+), 20 deletions(-)
diff --git a/compiler/rustc_codegen_llvm/src/abi.rs b/compiler/rustc_codegen_llvm/src/abi.rs
index d478efc863a9..a6fd2a7de6bd 100644
--- a/compiler/rustc_codegen_llvm/src/abi.rs
+++ b/compiler/rustc_codegen_llvm/src/abi.rs
@@ -398,23 +398,7 @@ fn ptr_to_llvm_type(&self, cx: &CodegenCx<'ll, 'tcx>) -> &'ll Type {
}
fn llvm_cconv(&self) -> llvm::CallConv {
- match self.conv {
- Conv::C | Conv::Rust | Conv::CCmseNonSecureCall => llvm::CCallConv,
- Conv::RustCold => llvm::ColdCallConv,
- Conv::AmdGpuKernel => llvm::AmdGpuKernel,
- Conv::AvrInterrupt => llvm::AvrInterrupt,
- Conv::AvrNonBlockingInterrupt => llvm::AvrNonBlockingInterrupt,
- Conv::ArmAapcs => llvm::ArmAapcsCallConv,
- Conv::Msp430Intr => llvm::Msp430Intr,
- Conv::PtxKernel => llvm::PtxKernel,
- Conv::X86Fastcall => llvm::X86FastcallCallConv,
- Conv::X86Intr => llvm::X86_Intr,
- Conv::X86Stdcall => llvm::X86StdcallCallConv,
- Conv::X86ThisCall => llvm::X86_ThisCall,
- Conv::X86VectorCall => llvm::X86_VectorCall,
- Conv::X86_64SysV => llvm::X86_64_SysV,
- Conv::X86_64Win64 => llvm::X86_64_Win64,
- }
+ self.conv.into()
}
fn apply_attrs_llfn(&self, cx: &CodegenCx<'ll, 'tcx>, llfn: &'ll Value) {
@@ -596,3 +580,25 @@ fn get_param(&mut self, index: usize) -> Self::Value {
llvm::get_param(self.llfn(), index as c_uint)
}
}
+
+impl From<Conv> for llvm::CallConv {
+ fn from(conv: Conv) -> Self {
+ match conv {
+ Conv::C | Conv::Rust | Conv::CCmseNonSecureCall => llvm::CCallConv,
+ Conv::RustCold => llvm::ColdCallConv,
+ Conv::AmdGpuKernel => llvm::AmdGpuKernel,
+ Conv::AvrInterrupt => llvm::AvrInterrupt,
+ Conv::AvrNonBlockingInterrupt => llvm::AvrNonBlockingInterrupt,
+ Conv::ArmAapcs => llvm::ArmAapcsCallConv,
+ Conv::Msp430Intr => llvm::Msp430Intr,
+ Conv::PtxKernel => llvm::PtxKernel,
+ Conv::X86Fastcall => llvm::X86FastcallCallConv,
+ Conv::X86Intr => llvm::X86_Intr,
+ Conv::X86Stdcall => llvm::X86StdcallCallConv,
+ Conv::X86ThisCall => llvm::X86_ThisCall,
+ Conv::X86VectorCall => llvm::X86_VectorCall,
+ Conv::X86_64SysV => llvm::X86_64_SysV,
+ Conv::X86_64Win64 => llvm::X86_64_Win64,
+ }
+ }
+}
diff --git a/compiler/rustc_codegen_llvm/src/context.rs b/compiler/rustc_codegen_llvm/src/context.rs
index 79ddfd884dfa..f3ef618fff54 100644
--- a/compiler/rustc_codegen_llvm/src/context.rs
+++ b/compiler/rustc_codegen_llvm/src/context.rs
@@ -570,8 +570,14 @@ fn apply_target_cpu_attr(&self, llfn: &'ll Value) {
}
fn declare_c_main(&self, fn_type: Self::Type) -> Option<Self::Function> {
- if self.get_declared_value("main").is_none() {
- Some(self.declare_cfn("main", llvm::UnnamedAddr::Global, fn_type))
+ let entry_name = self.sess().target.entry_name.as_ref();
+ if self.get_declared_value(entry_name).is_none() {
+ Some(self.declare_entry_fn(
+ entry_name,
+ self.sess().target.entry_abi.into(),
+ llvm::UnnamedAddr::Global,
+ fn_type,
+ ))
} else {
// If the symbol already exists, it is an error: for example, the user wrote
// #[no_mangle] extern "C" fn main(..) {..}
diff --git a/compiler/rustc_codegen_llvm/src/declare.rs b/compiler/rustc_codegen_llvm/src/declare.rs
index f79ef11720df..dc21a02cec44 100644
--- a/compiler/rustc_codegen_llvm/src/declare.rs
+++ b/compiler/rustc_codegen_llvm/src/declare.rs
@@ -90,6 +90,28 @@ pub fn declare_cfn(
declare_raw_fn(self, name, llvm::CCallConv, unnamed, visibility, fn_type)
}
+ /// Declare an entry Function
+ ///
+ /// The ABI of this function can change depending on the target (although for now the same as
+ /// `declare_cfn`)
+ ///
+ /// If there’s a value with the same name already declared, the function will
+ /// update the declaration and return existing Value instead.
+ pub fn declare_entry_fn(
+ &self,
+ name: &str,
+ callconv: llvm::CallConv,
+ unnamed: llvm::UnnamedAddr,
+ fn_type: &'ll Type,
+ ) -> &'ll Value {
+ let visibility = if self.tcx.sess.target.default_hidden_visibility {
+ llvm::Visibility::Hidden
+ } else {
+ llvm::Visibility::Default
+ };
+ declare_raw_fn(self, name, callconv, unnamed, visibility, fn_type)
+ }
+
/// Declare a Rust function.
///
/// If there’s a value with the same name already declared, the function will
diff --git a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
index 752f6b1ef40c..22f534d909ab 100644
--- a/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
+++ b/compiler/rustc_codegen_ssa/src/back/symbol_export.rs
@@ -180,7 +180,8 @@ fn exported_symbols_provider_local<'tcx>(
.collect();
if tcx.entry_fn(()).is_some() {
- let exported_symbol = ExportedSymbol::NoDefId(SymbolName::new(tcx, "main"));
+ let exported_symbol =
+ ExportedSymbol::NoDefId(SymbolName::new(tcx, tcx.sess.target.entry_name.as_ref()));
symbols.push((
exported_symbol,
diff --git a/compiler/rustc_target/src/abi/call/mod.rs b/compiler/rustc_target/src/abi/call/mod.rs
index 9e5f0e4d158b..c622bd36b00c 100644
--- a/compiler/rustc_target/src/abi/call/mod.rs
+++ b/compiler/rustc_target/src/abi/call/mod.rs
@@ -3,6 +3,7 @@
use crate::spec::{self, HasTargetSpec};
use rustc_span::Symbol;
use std::fmt;
+use std::str::FromStr;
mod aarch64;
mod amdgpu;
@@ -735,6 +736,33 @@ pub fn adjust_for_foreign_abi<C>(
}
}
+impl FromStr for Conv {
+ type Err = String;
+
+ fn from_str(s: &str) -> Result<Self, Self::Err> {
+ match s {
+ "C" => Ok(Conv::C),
+ "Rust" => Ok(Conv::Rust),
+ "RustCold" => Ok(Conv::Rust),
+ "ArmAapcs" => Ok(Conv::ArmAapcs),
+ "CCmseNonSecureCall" => Ok(Conv::CCmseNonSecureCall),
+ "Msp430Intr" => Ok(Conv::Msp430Intr),
+ "PtxKernel" => Ok(Conv::PtxKernel),
+ "X86Fastcall" => Ok(Conv::X86Fastcall),
+ "X86Intr" => Ok(Conv::X86Intr),
+ "X86Stdcall" => Ok(Conv::X86Stdcall),
+ "X86ThisCall" => Ok(Conv::X86ThisCall),
+ "X86VectorCall" => Ok(Conv::X86VectorCall),
+ "X86_64SysV" => Ok(Conv::X86_64SysV),
+ "X86_64Win64" => Ok(Conv::X86_64Win64),
+ "AmdGpuKernel" => Ok(Conv::AmdGpuKernel),
+ "AvrInterrupt" => Ok(Conv::AvrInterrupt),
+ "AvrNonBlockingInterrupt" => Ok(Conv::AvrNonBlockingInterrupt),
+ _ => Err(format!("'{}' is not a valid value for entry function call convetion.", s)),
+ }
+ }
+}
+
// Some types are used a lot. Make sure they don't unintentionally get bigger.
#[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
mod size_asserts {
diff --git a/compiler/rustc_target/src/json.rs b/compiler/rustc_target/src/json.rs
index b5d926352122..75bb76a9de08 100644
--- a/compiler/rustc_target/src/json.rs
+++ b/compiler/rustc_target/src/json.rs
@@ -89,3 +89,28 @@ fn to_json(&self) -> Json {
}
}
}
+
+impl ToJson for crate::abi::call::Conv {
+ fn to_json(&self) -> Json {
+ let s = match self {
+ Self::C => "C",
+ Self::Rust => "Rust",
+ Self::RustCold => "RustCold",
+ Self::ArmAapcs => "ArmAapcs",
+ Self::CCmseNonSecureCall => "CCmseNonSecureCall",
+ Self::Msp430Intr => "Msp430Intr",
+ Self::PtxKernel => "PtxKernel",
+ Self::X86Fastcall => "X86Fastcall",
+ Self::X86Intr => "X86Intr",
+ Self::X86Stdcall => "X86Stdcall",
+ Self::X86ThisCall => "X86ThisCall",
+ Self::X86VectorCall => "X86VectorCall",
+ Self::X86_64SysV => "X86_64SysV",
+ Self::X86_64Win64 => "X86_64Win64",
+ Self::AmdGpuKernel => "AmdGpuKernel",
+ Self::AvrInterrupt => "AvrInterrupt",
+ Self::AvrNonBlockingInterrupt => "AvrNonBlockingInterrupt",
+ };
+ Json::String(s.to_owned())
+ }
+}
diff --git a/compiler/rustc_target/src/spec/mod.rs b/compiler/rustc_target/src/spec/mod.rs
index 72b088d663b1..617de46a55aa 100644
--- a/compiler/rustc_target/src/spec/mod.rs
+++ b/compiler/rustc_target/src/spec/mod.rs
@@ -34,6 +34,7 @@
//! the target's settings, though `target-feature` and `link-args` will *add*
//! to the list specified by the target, rather than replace.
+use crate::abi::call::Conv;
use crate::abi::Endian;
use crate::json::{Json, ToJson};
use crate::spec::abi::{lookup as lookup_abi, Abi};
@@ -1668,6 +1669,14 @@ pub struct TargetOptions {
/// Whether the target supports stack canary checks. `true` by default,
/// since this is most common among tier 1 and tier 2 targets.
pub supports_stack_protector: bool,
+
+ // The name of entry function.
+ // Default value is "main"
+ pub entry_name: StaticCow<str>,
+
+ // The ABI of entry function.
+ // Default value is `Conv::C`, i.e. C call convention
+ pub entry_abi: Conv,
}
/// Add arguments for the given flavor and also for its "twin" flavors
@@ -1884,6 +1893,8 @@ fn default() -> TargetOptions {
c_enum_min_bits: 32,
generate_arange_section: true,
supports_stack_protector: true,
+ entry_name: "main".into(),
+ entry_abi: Conv::C,
}
}
}
@@ -2401,6 +2412,18 @@ macro_rules! key {
}
}
} );
+ ($key_name:ident, Conv) => ( {
+ let name = (stringify!($key_name)).replace("_", "-");
+ obj.remove(&name).and_then(|o| o.as_str().and_then(|s| {
+ match Conv::from_str(s) {
+ Ok(c) => {
+ base.$key_name = c;
+ Some(Ok(()))
+ }
+ Err(e) => Some(Err(e))
+ }
+ })).unwrap_or(Ok(()))
+ } );
}
if let Some(j) = obj.remove("target-endian") {
@@ -2520,6 +2543,8 @@ macro_rules! key {
key!(c_enum_min_bits, u64);
key!(generate_arange_section, bool);
key!(supports_stack_protector, bool);
+ key!(entry_name);
+ key!(entry_abi, Conv)?;
if base.is_builtin {
// This can cause unfortunate ICEs later down the line.
@@ -2770,6 +2795,8 @@ macro_rules! target_option_val {
target_option_val!(c_enum_min_bits);
target_option_val!(generate_arange_section);
target_option_val!(supports_stack_protector);
+ target_option_val!(entry_name);
+ target_option_val!(entry_abi);
if let Some(abi) = self.default_adjusted_cabi {
d.insert("default-adjusted-cabi".into(), Abi::name(abi).to_json());
--
2.38.1