bjoernager/rust
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Improve generating Custom entry function

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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>
This commit is contained in:
Ayush Singh 2022-11-05 14:36:38 +05:30
parent 5b3e909075
commit 9f0a8620bd
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GPG key ID: 05CEF5C789E55A74
7 changed files with 135 additions and 20 deletions
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40
compiler/rustc_codegen_llvm/src/abi.rs
View file

@ -398,23 +398,7 @@ impl<'ll, 'tcx> FnAbiLlvmExt<'ll, 'tcx> for FnAbi<'tcx, Ty<'tcx>> {
}
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 @@ impl<'tcx> AbiBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
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,
}
}
}

10
compiler/rustc_codegen_llvm/src/context.rs
View file

@ -570,8 +570,14 @@ impl<'ll, 'tcx> MiscMethods<'tcx> for CodegenCx<'ll, 'tcx> {
}
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(..) {..}

22
compiler/rustc_codegen_llvm/src/declare.rs
View file

@ -90,6 +90,28 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
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