Files
wasmtime/crates/jit/src/object.rs
Ulrich Weigand 0568f4fb02 Support building big-endian objects (#2382)
The JIT build_object routine currently rejects building object files
for any big-endian platform.  However, most of the object builder
code works fine for either byte order, with the exception of a small
change in the ObjectBuilderTarget::new routine.

This patch adds that change and removes the assert in build_object.
2020-11-09 11:19:33 -06:00

63 lines
2.3 KiB
Rust

//! Object file generation.
use super::trampoline::build_trampoline;
use cranelift_frontend::FunctionBuilderContext;
use object::write::Object;
use serde::{Deserialize, Serialize};
use wasmtime_debug::DwarfSection;
use wasmtime_environ::entity::PrimaryMap;
use wasmtime_environ::isa::{unwind::UnwindInfo, TargetIsa};
use wasmtime_environ::wasm::{FuncIndex, SignatureIndex};
use wasmtime_environ::{CompiledFunctions, ModuleTranslation};
use wasmtime_obj::{ObjectBuilder, ObjectBuilderTarget};
pub use wasmtime_obj::utils;
/// Unwind information for object files functions (including trampolines).
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
pub enum ObjectUnwindInfo {
Func(FuncIndex, UnwindInfo),
Trampoline(SignatureIndex, UnwindInfo),
}
// Builds ELF image from the module `Compilation`.
pub(crate) fn build_object(
isa: &dyn TargetIsa,
translation: &ModuleTranslation,
funcs: &CompiledFunctions,
dwarf_sections: Vec<DwarfSection>,
) -> Result<(Object, Vec<ObjectUnwindInfo>), anyhow::Error> {
const CODE_SECTION_ALIGNMENT: u64 = 0x1000;
let mut unwind_info = Vec::new();
// Preserve function unwind info.
unwind_info.extend(funcs.iter().filter_map(|(index, func)| {
func.unwind_info
.as_ref()
.map(|info| ObjectUnwindInfo::Func(translation.module.func_index(index), info.clone()))
}));
let mut trampolines = PrimaryMap::with_capacity(translation.module.signatures.len());
let mut cx = FunctionBuilderContext::new();
// Build trampolines for every signature.
for (i, native_sig) in translation.native_signatures.iter() {
let func = build_trampoline(isa, &mut cx, native_sig, std::mem::size_of::<u128>())?;
// Preserve trampoline function unwind info.
if let Some(info) = &func.unwind_info {
unwind_info.push(ObjectUnwindInfo::Trampoline(i, info.clone()))
}
trampolines.push(func);
}
let target = ObjectBuilderTarget::new(isa.triple().architecture)?;
let mut builder = ObjectBuilder::new(target, &translation.module, funcs);
builder
.set_code_alignment(CODE_SECTION_ALIGNMENT)
.set_trampolines(trampolines)
.set_dwarf_sections(dwarf_sections);
let obj = builder.build()?;
Ok((obj, unwind_info))
}