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lto: load bitcode sections by name

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Upstream change
llvm/llvm-project@6b539f5eb8 changed
`isSectionBitcode` works and it now only respects `.llvm.lto` sections
instead of also `.llvmbc`, which it says was never intended to be used
for LTO. We instead load sections by name, and sniff for raw bitcode by
hand.

r? @nikic
@rustbot label: +llvm-main
This commit is contained in:
Augie Fackler 2023-09-07 09:48:50 -04:00
parent cd71a37f32
commit 942bdf910c
4 changed files with 86 additions and 16 deletions
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36
compiler/rustc_codegen_llvm/src/back/write.rs
View file

@ -873,6 +873,27 @@ fn create_section_with_flags_asm(section_name: &str, section_flags: &str, data:
asm
}
fn target_is_apple(cgcx: &CodegenContext<LlvmCodegenBackend>) -> bool {
cgcx.opts.target_triple.triple().contains("-ios")
|| cgcx.opts.target_triple.triple().contains("-darwin")
|| cgcx.opts.target_triple.triple().contains("-tvos")
|| cgcx.opts.target_triple.triple().contains("-watchos")
}
fn target_is_aix(cgcx: &CodegenContext<LlvmCodegenBackend>) -> bool {
cgcx.opts.target_triple.triple().contains("-aix")
}
pub(crate) fn bitcode_section_name(cgcx: &CodegenContext<LlvmCodegenBackend>) -> &'static str {
if target_is_apple(cgcx) {
"__LLVM,__bitcode\0"
} else if target_is_aix(cgcx) {
".ipa\0"
} else {
".llvmbc\0"
}
}
/// Embed the bitcode of an LLVM module in the LLVM module itself.
///
/// This is done primarily for iOS where it appears to be standard to compile C
@ -933,11 +954,8 @@ unsafe fn embed_bitcode(
// Unfortunately, LLVM provides no way to set custom section flags. For ELF
// and COFF we emit the sections using module level inline assembly for that
// reason (see issue #90326 for historical background).
let is_aix = cgcx.opts.target_triple.triple().contains("-aix");
let is_apple = cgcx.opts.target_triple.triple().contains("-ios")
|| cgcx.opts.target_triple.triple().contains("-darwin")
|| cgcx.opts.target_triple.triple().contains("-tvos")
|| cgcx.opts.target_triple.triple().contains("-watchos");
let is_aix = target_is_aix(cgcx);
let is_apple = target_is_apple(cgcx);
if is_apple
|| is_aix
|| cgcx.opts.target_triple.triple().starts_with("wasm")
@ -952,13 +970,7 @@ unsafe fn embed_bitcode(
);
llvm::LLVMSetInitializer(llglobal, llconst);
let section = if is_apple {
"__LLVM,__bitcode\0"
} else if is_aix {
".ipa\0"
} else {
".llvmbc\0"
};
let section = bitcode_section_name(cgcx);
llvm::LLVMSetSection(llglobal, section.as_ptr().cast());
llvm::LLVMRustSetLinkage(llglobal, llvm::Linkage::PrivateLinkage);
llvm::LLVMSetGlobalConstant(llglobal, llvm::True);