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Diffstat (limited to 'compiler/rustc_codegen_llvm/src/base.rs')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/base.rs | 205 |
1 files changed, 205 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_llvm/src/base.rs b/compiler/rustc_codegen_llvm/src/base.rs new file mode 100644 index 00000000000..6a1b373ef07 --- /dev/null +++ b/compiler/rustc_codegen_llvm/src/base.rs @@ -0,0 +1,205 @@ +//! Codegen the completed AST to the LLVM IR. +//! +//! Some functions here, such as codegen_block and codegen_expr, return a value -- +//! the result of the codegen to LLVM -- while others, such as codegen_fn +//! and mono_item, are called only for the side effect of adding a +//! particular definition to the LLVM IR output we're producing. +//! +//! Hopefully useful general knowledge about codegen: +//! +//! * There's no way to find out the `Ty` type of a Value. Doing so +//! would be "trying to get the eggs out of an omelette" (credit: +//! pcwalton). You can, instead, find out its `llvm::Type` by calling `val_ty`, +//! but one `llvm::Type` corresponds to many `Ty`s; for instance, `tup(int, int, +//! int)` and `rec(x=int, y=int, z=int)` will have the same `llvm::Type`. + +use super::ModuleLlvm; + +use crate::attributes; +use crate::builder::Builder; +use crate::common; +use crate::context::CodegenCx; +use crate::llvm; +use crate::metadata; +use crate::value::Value; + +use rustc_codegen_ssa::base::maybe_create_entry_wrapper; +use rustc_codegen_ssa::mono_item::MonoItemExt; +use rustc_codegen_ssa::traits::*; +use rustc_codegen_ssa::{ModuleCodegen, ModuleKind}; +use rustc_data_structures::small_c_str::SmallCStr; +use rustc_middle::dep_graph; +use rustc_middle::middle::codegen_fn_attrs::CodegenFnAttrs; +use rustc_middle::middle::cstore::EncodedMetadata; +use rustc_middle::middle::exported_symbols; +use rustc_middle::mir::mono::{Linkage, Visibility}; +use rustc_middle::ty::TyCtxt; +use rustc_session::config::{DebugInfo, SanitizerSet}; +use rustc_span::symbol::Symbol; + +use std::ffi::CString; +use std::time::Instant; + +pub fn write_compressed_metadata<'tcx>( + tcx: TyCtxt<'tcx>, + metadata: &EncodedMetadata, + llvm_module: &mut ModuleLlvm, +) { + use snap::write::FrameEncoder; + use std::io::Write; + + let (metadata_llcx, metadata_llmod) = (&*llvm_module.llcx, llvm_module.llmod()); + let mut compressed = tcx.metadata_encoding_version(); + FrameEncoder::new(&mut compressed).write_all(&metadata.raw_data).unwrap(); + + let llmeta = common::bytes_in_context(metadata_llcx, &compressed); + let llconst = common::struct_in_context(metadata_llcx, &[llmeta], false); + let name = exported_symbols::metadata_symbol_name(tcx); + let buf = CString::new(name).unwrap(); + let llglobal = + unsafe { llvm::LLVMAddGlobal(metadata_llmod, common::val_ty(llconst), buf.as_ptr()) }; + unsafe { + llvm::LLVMSetInitializer(llglobal, llconst); + let section_name = metadata::metadata_section_name(&tcx.sess.target.target); + let name = SmallCStr::new(section_name); + llvm::LLVMSetSection(llglobal, name.as_ptr()); + + // Also generate a .section directive to force no + // flags, at least for ELF outputs, so that the + // metadata doesn't get loaded into memory. + let directive = format!(".section {}", section_name); + llvm::LLVMSetModuleInlineAsm2(metadata_llmod, directive.as_ptr().cast(), directive.len()) + } +} + +pub struct ValueIter<'ll> { + cur: Option<&'ll Value>, + step: unsafe extern "C" fn(&'ll Value) -> Option<&'ll Value>, +} + +impl Iterator for ValueIter<'ll> { + type Item = &'ll Value; + + fn next(&mut self) -> Option<&'ll Value> { + let old = self.cur; + if let Some(old) = old { + self.cur = unsafe { (self.step)(old) }; + } + old + } +} + +pub fn iter_globals(llmod: &'ll llvm::Module) -> ValueIter<'ll> { + unsafe { ValueIter { cur: llvm::LLVMGetFirstGlobal(llmod), step: llvm::LLVMGetNextGlobal } } +} + +pub fn compile_codegen_unit( + tcx: TyCtxt<'tcx>, + cgu_name: Symbol, +) -> (ModuleCodegen<ModuleLlvm>, u64) { + let prof_timer = tcx.prof.generic_activity_with_arg("codegen_module", cgu_name.to_string()); + let start_time = Instant::now(); + + let dep_node = tcx.codegen_unit(cgu_name).codegen_dep_node(tcx); + let (module, _) = + tcx.dep_graph.with_task(dep_node, tcx, cgu_name, module_codegen, dep_graph::hash_result); + let time_to_codegen = start_time.elapsed(); + drop(prof_timer); + + // We assume that the cost to run LLVM on a CGU is proportional to + // the time we needed for codegenning it. + let cost = time_to_codegen.as_secs() * 1_000_000_000 + time_to_codegen.subsec_nanos() as u64; + + fn module_codegen(tcx: TyCtxt<'_>, cgu_name: Symbol) -> ModuleCodegen<ModuleLlvm> { + let cgu = tcx.codegen_unit(cgu_name); + // Instantiate monomorphizations without filling out definitions yet... + let llvm_module = ModuleLlvm::new(tcx, &cgu_name.as_str()); + { + let cx = CodegenCx::new(tcx, cgu, &llvm_module); + let mono_items = cx.codegen_unit.items_in_deterministic_order(cx.tcx); + for &(mono_item, (linkage, visibility)) in &mono_items { + mono_item.predefine::<Builder<'_, '_, '_>>(&cx, linkage, visibility); + } + + // ... and now that we have everything pre-defined, fill out those definitions. + for &(mono_item, _) in &mono_items { + mono_item.define::<Builder<'_, '_, '_>>(&cx); + } + + // If this codegen unit contains the main function, also create the + // wrapper here + if let Some(entry) = maybe_create_entry_wrapper::<Builder<'_, '_, '_>>(&cx) { + attributes::sanitize(&cx, SanitizerSet::empty(), entry); + } + + // Run replace-all-uses-with for statics that need it + for &(old_g, new_g) in cx.statics_to_rauw().borrow().iter() { + unsafe { + let bitcast = llvm::LLVMConstPointerCast(new_g, cx.val_ty(old_g)); + llvm::LLVMReplaceAllUsesWith(old_g, bitcast); + llvm::LLVMDeleteGlobal(old_g); + } + } + + // Finalize code coverage by injecting the coverage map. Note, the coverage map will + // also be added to the `llvm.used` variable, created next. + if cx.sess().opts.debugging_opts.instrument_coverage { + cx.coverageinfo_finalize(); + } + + // Create the llvm.used variable + // This variable has type [N x i8*] and is stored in the llvm.metadata section + if !cx.used_statics().borrow().is_empty() { + cx.create_used_variable() + } + + // Finalize debuginfo + if cx.sess().opts.debuginfo != DebugInfo::None { + cx.debuginfo_finalize(); + } + } + + ModuleCodegen { + name: cgu_name.to_string(), + module_llvm: llvm_module, + kind: ModuleKind::Regular, + } + } + + (module, cost) +} + +pub fn set_link_section(llval: &Value, attrs: &CodegenFnAttrs) { + let sect = match attrs.link_section { + Some(name) => name, + None => return, + }; + unsafe { + let buf = SmallCStr::new(§.as_str()); + llvm::LLVMSetSection(llval, buf.as_ptr()); + } +} + +pub fn linkage_to_llvm(linkage: Linkage) -> llvm::Linkage { + match linkage { + Linkage::External => llvm::Linkage::ExternalLinkage, + Linkage::AvailableExternally => llvm::Linkage::AvailableExternallyLinkage, + Linkage::LinkOnceAny => llvm::Linkage::LinkOnceAnyLinkage, + Linkage::LinkOnceODR => llvm::Linkage::LinkOnceODRLinkage, + Linkage::WeakAny => llvm::Linkage::WeakAnyLinkage, + Linkage::WeakODR => llvm::Linkage::WeakODRLinkage, + Linkage::Appending => llvm::Linkage::AppendingLinkage, + Linkage::Internal => llvm::Linkage::InternalLinkage, + Linkage::Private => llvm::Linkage::PrivateLinkage, + Linkage::ExternalWeak => llvm::Linkage::ExternalWeakLinkage, + Linkage::Common => llvm::Linkage::CommonLinkage, + } +} + +pub fn visibility_to_llvm(linkage: Visibility) -> llvm::Visibility { + match linkage { + Visibility::Default => llvm::Visibility::Default, + Visibility::Hidden => llvm::Visibility::Hidden, + Visibility::Protected => llvm::Visibility::Protected, + } +} |