diff options
Diffstat (limited to 'compiler/rustc_codegen_llvm/src/base.rs')
| -rw-r--r-- | compiler/rustc_codegen_llvm/src/base.rs | 177 |
1 files changed, 177 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..b659fd02eec --- /dev/null +++ b/compiler/rustc_codegen_llvm/src/base.rs @@ -0,0 +1,177 @@ +//! Codegen the MIR to the LLVM IR. +//! +//! 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`]. +//! +//! [`Ty`]: rustc_middle::ty::Ty +//! [`val_ty`]: crate::common::val_ty + +use super::ModuleLlvm; + +use crate::attributes; +use crate::builder::Builder; +use crate::context::CodegenCx; +use crate::llvm; +use crate::value::Value; + +use cstr::cstr; + +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::mir::mono::{Linkage, Visibility}; +use rustc_middle::ty::TyCtxt; +use rustc_session::config::DebugInfo; +use rustc_span::symbol::Symbol; +use rustc_target::spec::SanitizerSet; + +use std::time::Instant; + +pub struct ValueIter<'ll> { + cur: Option<&'ll Value>, + step: unsafe extern "C" fn(&'ll Value) -> Option<&'ll Value>, +} + +impl<'ll> 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: &llvm::Module) -> ValueIter<'_> { + unsafe { ValueIter { cur: llvm::LLVMGetFirstGlobal(llmod), step: llvm::LLVMGetNextGlobal } } +} + +pub fn compile_codegen_unit(tcx: TyCtxt<'_>, cgu_name: Symbol) -> (ModuleCodegen<ModuleLlvm>, u64) { + 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, + Some(dep_graph::hash_result), + ); + let time_to_codegen = start_time.elapsed(); + + // 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_nanos() as u64; + + fn module_codegen(tcx: TyCtxt<'_>, cgu_name: Symbol) -> ModuleCodegen<ModuleLlvm> { + let cgu = tcx.codegen_unit(cgu_name); + let _prof_timer = + tcx.prof.generic_activity_with_arg_recorder("codegen_module", |recorder| { + recorder.record_arg(cgu_name.to_string()); + recorder.record_arg(cgu.size_estimate().to_string()); + }); + // 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, data) in &mono_items { + mono_item.predefine::<Builder<'_, '_, '_>>(&cx, data.linkage, data.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) { + let attrs = attributes::sanitize_attrs(&cx, SanitizerSet::empty()); + attributes::apply_to_llfn(entry, llvm::AttributePlace::Function, &attrs); + } + + // Finalize code coverage by injecting the coverage map. Note, the coverage map will + // also be added to the `llvm.compiler.used` variable, created next. + if cx.sess().instrument_coverage() { + cx.coverageinfo_finalize(); + } + + // Create the llvm.used and llvm.compiler.used variables. + if !cx.used_statics.borrow().is_empty() { + cx.create_used_variable_impl(cstr!("llvm.used"), &*cx.used_statics.borrow()); + } + if !cx.compiler_used_statics.borrow().is_empty() { + cx.create_used_variable_impl( + cstr!("llvm.compiler.used"), + &*cx.compiler_used_statics.borrow(), + ); + } + + // Run replace-all-uses-with for statics that need it. This must + // happen after the llvm.used variables are created. + for &(old_g, new_g) in cx.statics_to_rauw().borrow().iter() { + unsafe { + llvm::LLVMReplaceAllUsesWith(old_g, new_g); + llvm::LLVMDeleteGlobal(old_g); + } + } + + // 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 Some(sect) = attrs.link_section else { return }; + unsafe { + let buf = SmallCStr::new(sect.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, + } +} |