diff options
Diffstat (limited to '')
-rw-r--r-- | compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs | 385 |
1 files changed, 385 insertions, 0 deletions
diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs new file mode 100644 index 000000000..98ba38356 --- /dev/null +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs @@ -0,0 +1,385 @@ +use crate::llvm; + +use crate::abi::Abi; +use crate::builder::Builder; +use crate::common::CodegenCx; + +use libc::c_uint; +use llvm::coverageinfo::CounterMappingRegion; +use rustc_codegen_ssa::coverageinfo::map::{CounterExpression, FunctionCoverage}; +use rustc_codegen_ssa::traits::{ + BaseTypeMethods, BuilderMethods, ConstMethods, CoverageInfoBuilderMethods, CoverageInfoMethods, + MiscMethods, StaticMethods, +}; +use rustc_data_structures::fx::FxHashMap; +use rustc_hir as hir; +use rustc_hir::def_id::DefId; +use rustc_llvm::RustString; +use rustc_middle::bug; +use rustc_middle::mir::coverage::{ + CodeRegion, CounterValueReference, ExpressionOperandId, InjectedExpressionId, Op, +}; +use rustc_middle::ty; +use rustc_middle::ty::layout::FnAbiOf; +use rustc_middle::ty::subst::InternalSubsts; +use rustc_middle::ty::Instance; + +use std::cell::RefCell; +use std::ffi::CString; + +use std::iter; +use tracing::debug; + +pub mod mapgen; + +const UNUSED_FUNCTION_COUNTER_ID: CounterValueReference = CounterValueReference::START; + +const VAR_ALIGN_BYTES: usize = 8; + +/// A context object for maintaining all state needed by the coverageinfo module. +pub struct CrateCoverageContext<'ll, 'tcx> { + // Coverage data for each instrumented function identified by DefId. + pub(crate) function_coverage_map: RefCell<FxHashMap<Instance<'tcx>, FunctionCoverage<'tcx>>>, + pub(crate) pgo_func_name_var_map: RefCell<FxHashMap<Instance<'tcx>, &'ll llvm::Value>>, +} + +impl<'ll, 'tcx> CrateCoverageContext<'ll, 'tcx> { + pub fn new() -> Self { + Self { + function_coverage_map: Default::default(), + pgo_func_name_var_map: Default::default(), + } + } + + pub fn take_function_coverage_map(&self) -> FxHashMap<Instance<'tcx>, FunctionCoverage<'tcx>> { + self.function_coverage_map.replace(FxHashMap::default()) + } +} + +impl<'ll, 'tcx> CoverageInfoMethods<'tcx> for CodegenCx<'ll, 'tcx> { + fn coverageinfo_finalize(&self) { + mapgen::finalize(self) + } + + fn get_pgo_func_name_var(&self, instance: Instance<'tcx>) -> &'ll llvm::Value { + if let Some(coverage_context) = self.coverage_context() { + debug!("getting pgo_func_name_var for instance={:?}", instance); + let mut pgo_func_name_var_map = coverage_context.pgo_func_name_var_map.borrow_mut(); + pgo_func_name_var_map + .entry(instance) + .or_insert_with(|| create_pgo_func_name_var(self, instance)) + } else { + bug!("Could not get the `coverage_context`"); + } + } + + /// Functions with MIR-based coverage are normally codegenned _only_ if + /// called. LLVM coverage tools typically expect every function to be + /// defined (even if unused), with at least one call to LLVM intrinsic + /// `instrprof.increment`. + /// + /// Codegen a small function that will never be called, with one counter + /// that will never be incremented. + /// + /// For used/called functions, the coverageinfo was already added to the + /// `function_coverage_map` (keyed by function `Instance`) during codegen. + /// But in this case, since the unused function was _not_ previously + /// codegenned, collect the coverage `CodeRegion`s from the MIR and add + /// them. The first `CodeRegion` is used to add a single counter, with the + /// same counter ID used in the injected `instrprof.increment` intrinsic + /// call. Since the function is never called, all other `CodeRegion`s can be + /// added as `unreachable_region`s. + fn define_unused_fn(&self, def_id: DefId) { + let instance = declare_unused_fn(self, def_id); + codegen_unused_fn_and_counter(self, instance); + add_unused_function_coverage(self, instance, def_id); + } +} + +impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> { + fn set_function_source_hash( + &mut self, + instance: Instance<'tcx>, + function_source_hash: u64, + ) -> bool { + if let Some(coverage_context) = self.coverage_context() { + debug!( + "ensuring function source hash is set for instance={:?}; function_source_hash={}", + instance, function_source_hash, + ); + let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); + coverage_map + .entry(instance) + .or_insert_with(|| FunctionCoverage::new(self.tcx, instance)) + .set_function_source_hash(function_source_hash); + true + } else { + false + } + } + + fn add_coverage_counter( + &mut self, + instance: Instance<'tcx>, + id: CounterValueReference, + region: CodeRegion, + ) -> bool { + if let Some(coverage_context) = self.coverage_context() { + debug!( + "adding counter to coverage_map: instance={:?}, id={:?}, region={:?}", + instance, id, region, + ); + let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); + coverage_map + .entry(instance) + .or_insert_with(|| FunctionCoverage::new(self.tcx, instance)) + .add_counter(id, region); + true + } else { + false + } + } + + fn add_coverage_counter_expression( + &mut self, + instance: Instance<'tcx>, + id: InjectedExpressionId, + lhs: ExpressionOperandId, + op: Op, + rhs: ExpressionOperandId, + region: Option<CodeRegion>, + ) -> bool { + if let Some(coverage_context) = self.coverage_context() { + debug!( + "adding counter expression to coverage_map: instance={:?}, id={:?}, {:?} {:?} {:?}; \ + region: {:?}", + instance, id, lhs, op, rhs, region, + ); + let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); + coverage_map + .entry(instance) + .or_insert_with(|| FunctionCoverage::new(self.tcx, instance)) + .add_counter_expression(id, lhs, op, rhs, region); + true + } else { + false + } + } + + fn add_coverage_unreachable(&mut self, instance: Instance<'tcx>, region: CodeRegion) -> bool { + if let Some(coverage_context) = self.coverage_context() { + debug!( + "adding unreachable code to coverage_map: instance={:?}, at {:?}", + instance, region, + ); + let mut coverage_map = coverage_context.function_coverage_map.borrow_mut(); + coverage_map + .entry(instance) + .or_insert_with(|| FunctionCoverage::new(self.tcx, instance)) + .add_unreachable_region(region); + true + } else { + false + } + } +} + +fn declare_unused_fn<'tcx>(cx: &CodegenCx<'_, 'tcx>, def_id: DefId) -> Instance<'tcx> { + let tcx = cx.tcx; + + let instance = Instance::new( + def_id, + InternalSubsts::for_item(tcx, def_id, |param, _| { + if let ty::GenericParamDefKind::Lifetime = param.kind { + tcx.lifetimes.re_erased.into() + } else { + tcx.mk_param_from_def(param) + } + }), + ); + + let llfn = cx.declare_fn( + tcx.symbol_name(instance).name, + cx.fn_abi_of_fn_ptr( + ty::Binder::dummy(tcx.mk_fn_sig( + iter::once(tcx.mk_unit()), + tcx.mk_unit(), + false, + hir::Unsafety::Unsafe, + Abi::Rust, + )), + ty::List::empty(), + ), + ); + + llvm::set_linkage(llfn, llvm::Linkage::PrivateLinkage); + llvm::set_visibility(llfn, llvm::Visibility::Default); + + assert!(cx.instances.borrow_mut().insert(instance, llfn).is_none()); + + instance +} + +fn codegen_unused_fn_and_counter<'tcx>(cx: &CodegenCx<'_, 'tcx>, instance: Instance<'tcx>) { + let llfn = cx.get_fn(instance); + let llbb = Builder::append_block(cx, llfn, "unused_function"); + let mut bx = Builder::build(cx, llbb); + let fn_name = bx.get_pgo_func_name_var(instance); + let hash = bx.const_u64(0); + let num_counters = bx.const_u32(1); + let index = bx.const_u32(u32::from(UNUSED_FUNCTION_COUNTER_ID)); + debug!( + "codegen intrinsic instrprof.increment(fn_name={:?}, hash={:?}, num_counters={:?}, + index={:?}) for unused function: {:?}", + fn_name, hash, num_counters, index, instance + ); + bx.instrprof_increment(fn_name, hash, num_counters, index); + bx.ret_void(); +} + +fn add_unused_function_coverage<'tcx>( + cx: &CodegenCx<'_, 'tcx>, + instance: Instance<'tcx>, + def_id: DefId, +) { + let tcx = cx.tcx; + + let mut function_coverage = FunctionCoverage::unused(tcx, instance); + for (index, &code_region) in tcx.covered_code_regions(def_id).iter().enumerate() { + if index == 0 { + // Insert at least one real counter so the LLVM CoverageMappingReader will find expected + // definitions. + function_coverage.add_counter(UNUSED_FUNCTION_COUNTER_ID, code_region.clone()); + } else { + function_coverage.add_unreachable_region(code_region.clone()); + } + } + + if let Some(coverage_context) = cx.coverage_context() { + coverage_context.function_coverage_map.borrow_mut().insert(instance, function_coverage); + } else { + bug!("Could not get the `coverage_context`"); + } +} + +/// Calls llvm::createPGOFuncNameVar() with the given function instance's +/// mangled function name. The LLVM API returns an llvm::GlobalVariable +/// containing the function name, with the specific variable name and linkage +/// required by LLVM InstrProf source-based coverage instrumentation. Use +/// `bx.get_pgo_func_name_var()` to ensure the variable is only created once per +/// `Instance`. +fn create_pgo_func_name_var<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + instance: Instance<'tcx>, +) -> &'ll llvm::Value { + let mangled_fn_name = CString::new(cx.tcx.symbol_name(instance).name) + .expect("error converting function name to C string"); + let llfn = cx.get_fn(instance); + unsafe { llvm::LLVMRustCoverageCreatePGOFuncNameVar(llfn, mangled_fn_name.as_ptr()) } +} + +pub(crate) fn write_filenames_section_to_buffer<'a>( + filenames: impl IntoIterator<Item = &'a CString>, + buffer: &RustString, +) { + let c_str_vec = filenames.into_iter().map(|cstring| cstring.as_ptr()).collect::<Vec<_>>(); + unsafe { + llvm::LLVMRustCoverageWriteFilenamesSectionToBuffer( + c_str_vec.as_ptr(), + c_str_vec.len(), + buffer, + ); + } +} + +pub(crate) fn write_mapping_to_buffer( + virtual_file_mapping: Vec<u32>, + expressions: Vec<CounterExpression>, + mapping_regions: Vec<CounterMappingRegion>, + buffer: &RustString, +) { + unsafe { + llvm::LLVMRustCoverageWriteMappingToBuffer( + virtual_file_mapping.as_ptr(), + virtual_file_mapping.len() as c_uint, + expressions.as_ptr(), + expressions.len() as c_uint, + mapping_regions.as_ptr(), + mapping_regions.len() as c_uint, + buffer, + ); + } +} + +pub(crate) fn hash_str(strval: &str) -> u64 { + let strval = CString::new(strval).expect("null error converting hashable str to C string"); + unsafe { llvm::LLVMRustCoverageHashCString(strval.as_ptr()) } +} + +pub(crate) fn hash_bytes(bytes: Vec<u8>) -> u64 { + unsafe { llvm::LLVMRustCoverageHashByteArray(bytes.as_ptr().cast(), bytes.len()) } +} + +pub(crate) fn mapping_version() -> u32 { + unsafe { llvm::LLVMRustCoverageMappingVersion() } +} + +pub(crate) fn save_cov_data_to_mod<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + cov_data_val: &'ll llvm::Value, +) { + let covmap_var_name = llvm::build_string(|s| unsafe { + llvm::LLVMRustCoverageWriteMappingVarNameToString(s); + }) + .expect("Rust Coverage Mapping var name failed UTF-8 conversion"); + debug!("covmap var name: {:?}", covmap_var_name); + + let covmap_section_name = llvm::build_string(|s| unsafe { + llvm::LLVMRustCoverageWriteMapSectionNameToString(cx.llmod, s); + }) + .expect("Rust Coverage section name failed UTF-8 conversion"); + debug!("covmap section name: {:?}", covmap_section_name); + + let llglobal = llvm::add_global(cx.llmod, cx.val_ty(cov_data_val), &covmap_var_name); + llvm::set_initializer(llglobal, cov_data_val); + llvm::set_global_constant(llglobal, true); + llvm::set_linkage(llglobal, llvm::Linkage::PrivateLinkage); + llvm::set_section(llglobal, &covmap_section_name); + llvm::set_alignment(llglobal, VAR_ALIGN_BYTES); + cx.add_used_global(llglobal); +} + +pub(crate) fn save_func_record_to_mod<'ll, 'tcx>( + cx: &CodegenCx<'ll, 'tcx>, + func_name_hash: u64, + func_record_val: &'ll llvm::Value, + is_used: bool, +) { + // Assign a name to the function record. This is used to merge duplicates. + // + // In LLVM, a "translation unit" (effectively, a `Crate` in Rust) can describe functions that + // are included-but-not-used. If (or when) Rust generates functions that are + // included-but-not-used, note that a dummy description for a function included-but-not-used + // in a Crate can be replaced by full description provided by a different Crate. The two kinds + // of descriptions play distinct roles in LLVM IR; therefore, assign them different names (by + // appending "u" to the end of the function record var name, to prevent `linkonce_odr` merging. + let func_record_var_name = + format!("__covrec_{:X}{}", func_name_hash, if is_used { "u" } else { "" }); + debug!("function record var name: {:?}", func_record_var_name); + + let func_record_section_name = llvm::build_string(|s| unsafe { + llvm::LLVMRustCoverageWriteFuncSectionNameToString(cx.llmod, s); + }) + .expect("Rust Coverage function record section name failed UTF-8 conversion"); + debug!("function record section name: {:?}", func_record_section_name); + + let llglobal = llvm::add_global(cx.llmod, cx.val_ty(func_record_val), &func_record_var_name); + llvm::set_initializer(llglobal, func_record_val); + llvm::set_global_constant(llglobal, true); + llvm::set_linkage(llglobal, llvm::Linkage::LinkOnceODRLinkage); + llvm::set_visibility(llglobal, llvm::Visibility::Hidden); + llvm::set_section(llglobal, &func_record_section_name); + llvm::set_alignment(llglobal, VAR_ALIGN_BYTES); + llvm::set_comdat(cx.llmod, llglobal, &func_record_var_name); + cx.add_used_global(llglobal); +} |