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Parse relocations that apply to custom relocations.

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This rewrites the whole relocation parsing to work properly.
  * we no longer use LocalRelocation and simply assign a new SectionIndex as new sections are encountered.
  * we no longer use string matching to determine what function applies relocations to what, instead we use the field in the elf section header that tells us
  * we no longer merge sections, each section from every function is preserved as an independent custom section in the module.
  * we now discover any new sections that need to be pulled in recursively as we parse each section
  * many error cases are either handled, or report CompileErrors.
This commit is contained in:
Nick Lewycky
2020-05-15 16:10:38 -07:00
parent 2a39edc399
commit ea05e16b6d
3 changed files with 170 additions and 122 deletions
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60
lib/compiler-llvm/src/compiler.rs
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@ -82,6 +82,7 @@ impl Compiler for LLVMCompiler {
.cloned()
.unwrap_or_else(|| format!("fn{}", func_index.index()));
}
let mut module_custom_sections = PrimaryMap::new();
let mut functions = function_body_inputs
.into_iter()
.collect::<Vec<(LocalFunctionIndex, &FunctionBodyData<'_>)>>()
@ -100,44 +101,41 @@ impl Compiler for LLVMCompiler {
)
})
.collect::<Result<Vec<_>, CompileError>>()?
.into_iter()
.map(|(mut function, local_relocations, custom_sections)| {
/// We collect the sections data
for (local_idx, custom_section) in custom_sections.iter().enumerate() {
let local_idx = local_idx as u32;
// TODO: these section numbers are potentially wrong, if there's
// no Read and only a ReadExecute then ReadExecute is 0.
let (ref mut section, section_num) = match &custom_section.protection {
CustomSectionProtection::Read => {
(&mut readonly_section, SectionIndex::from_u32(0))
}
};
let offset = section.bytes.len() as i64;
section.bytes.append(&custom_section.bytes);
// TODO: we're needlessly rescanning the whole list.
for local_relocation in &local_relocations {
if local_relocation.local_section_index == local_idx {
used_readonly_section = true;
function.relocations.push(Relocation {
kind: local_relocation.kind,
reloc_target: RelocationTarget::CustomSection(section_num),
offset: local_relocation.offset,
addend: local_relocation.addend + offset,
});
.iter()
.map(|(compiled_function, function_custom_sections)| {
// TODO: remove usage of clone
let first_section = module_custom_sections.len() as u32;
for (_, custom_section) in function_custom_sections.iter() {
let mut custom_section = custom_section.clone();
for mut reloc in &mut custom_section.relocations {
match reloc.reloc_target {
RelocationTarget::CustomSection(index) => {
reloc.reloc_target = RelocationTarget::CustomSection(
SectionIndex::from_u32(first_section + index.as_u32()),
)
}
_ => {}
}
}
module_custom_sections.push(custom_section);
}
Ok(function)
let mut compiled_function = compiled_function.clone();
for mut reloc in &mut compiled_function.relocations {
match reloc.reloc_target {
RelocationTarget::CustomSection(index) => {
reloc.reloc_target = RelocationTarget::CustomSection(
SectionIndex::from_u32(first_section + index.as_u32()),
)
}
_ => {}
}
}
compiled_function
})
.collect::<Result<Vec<_>, CompileError>>()?
.into_iter()
.collect::<PrimaryMap<LocalFunctionIndex, _>>();
let mut custom_sections = PrimaryMap::new();
if used_readonly_section {
custom_sections.push(readonly_section);
}
Ok(Compilation::new(functions, custom_sections))
Ok(Compilation::new(functions, module_custom_sections))
}
fn compile_wasm_trampolines(