use std::cell::{OnceCell, RefCell};
use std::ffi::{CStr, CString};
use libc::c_uint;
use rustc_codegen_ssa::traits::{
BuilderMethods, ConstCodegenMethods, CoverageInfoBuilderMethods, MiscCodegenMethods,
};
use rustc_data_structures::fx::{FxHashMap, FxIndexMap};
use rustc_llvm::RustString;
use rustc_middle::mir::coverage::CoverageKind;
use rustc_middle::ty::Instance;
use rustc_middle::ty::layout::HasTyCtxt;
use rustc_target::abi::Size;
use tracing::{debug, instrument};
use crate::builder::Builder;
use crate::common::{AsCCharPtr, CodegenCx};
use crate::coverageinfo::map_data::FunctionCoverageCollector;
use crate::llvm;
pub(crate) mod ffi;
pub(crate) mod map_data;
mod mapgen;
/// A context object for maintaining all state needed by the coverageinfo module.
pub(crate) struct CrateCoverageContext<'ll, 'tcx> {
/// Coverage data for each instrumented function identified by DefId.
pub(crate) function_coverage_map:
RefCell<FxIndexMap<Instance<'tcx>, FunctionCoverageCollector<'tcx>>>,
pub(crate) pgo_func_name_var_map: RefCell<FxHashMap<Instance<'tcx>, &'ll llvm::Value>>,
pub(crate) mcdc_condition_bitmap_map: RefCell<FxHashMap<Instance<'tcx>, Vec<&'ll llvm::Value>>>,
covfun_section_name: OnceCell<CString>,
}
impl<'ll, 'tcx> CrateCoverageContext<'ll, 'tcx> {
pub(crate) fn new() -> Self {
Self {
function_coverage_map: Default::default(),
pgo_func_name_var_map: Default::default(),
mcdc_condition_bitmap_map: Default::default(),
covfun_section_name: Default::default(),
}
}
fn take_function_coverage_map(
&self,
) -> FxIndexMap<Instance<'tcx>, FunctionCoverageCollector<'tcx>> {
self.function_coverage_map.replace(FxIndexMap::default())
}
/// LLVM use a temp value to record evaluated mcdc test vector of each decision, which is
/// called condition bitmap. In order to handle nested decisions, several condition bitmaps can
/// be allocated for a function body. These values are named `mcdc.addr.{i}` and are a 32-bit
/// integers. They respectively hold the condition bitmaps for decisions with a depth of `i`.
fn try_get_mcdc_condition_bitmap(
&self,
instance: &Instance<'tcx>,
decision_depth: u16,
) -> Option<&'ll llvm::Value> {
self.mcdc_condition_bitmap_map
.borrow()
.get(instance)
.and_then(|bitmap_map| bitmap_map.get(decision_depth as usize))
.copied() // Dereference Option<&&Value> to Option<&Value>
}
}
impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
pub(crate) fn coverageinfo_finalize(&self) {
mapgen::finalize(self)
}
/// Returns the section name to use when embedding per-function coverage information
/// in the object file, according to the target's object file format. LLVM's coverage
/// tools use information from this section when producing coverage reports.
///
/// Typical values are:
/// - `__llvm_covfun` on Linux
/// - `__LLVM_COV,__llvm_covfun` on macOS (includes `__LLVM_COV,` segment prefix)
/// - `.lcovfun$M` on Windows (includes `$M` sorting suffix)
fn covfun_section_name(&self) -> &CStr {
self.coverage_cx().covfun_section_name.get_or_init(|| {
CString::new(llvm::build_byte_buffer(|s| unsafe {
llvm::LLVMRustCoverageWriteFuncSectionNameToString(self.llmod, s);
}))
.expect("covfun section name should not contain NUL")
})
}
/// For LLVM codegen, returns a function-specific `Value` for a global
/// string, to hold the function name passed to LLVM intrinsic
/// `instrprof.increment()`. The `Value` is only created once per instance.
/// Multiple invocations with the same instance return the same `Value`.
fn get_pgo_func_name_var(&self, instance: Instance<'tcx>) -> &'ll llvm::Value {
debug!("getting pgo_func_name_var for instance={:?}", instance);
let mut pgo_func_name_var_map = self.coverage_cx().pgo_func_name_var_map.borrow_mut();
pgo_func_name_var_map
.entry(instance)
.or_insert_with(|| create_pgo_func_name_var(self, instance))
}
}
impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
fn init_coverage(&mut self, instance: Instance<'tcx>) {
let Some(function_coverage_info) =
self.tcx.instance_mir(instance.def).function_coverage_info.as_deref()
else {
return;
};
// If there are no MC/DC bitmaps to set up, return immediately.
if function_coverage_info.mcdc_bitmap_bits == 0 {
return;
}
let fn_name = self.get_pgo_func_name_var(instance);
let hash = self.const_u64(function_coverage_info.function_source_hash);
let bitmap_bits = self.const_u32(function_coverage_info.mcdc_bitmap_bits as u32);
self.mcdc_parameters(fn_name, hash, bitmap_bits);
// Create pointers named `mcdc.addr.{i}` to stack-allocated condition bitmaps.
let mut cond_bitmaps = vec![];
for i in 0..function_coverage_info.mcdc_num_condition_bitmaps {
// MC/DC intrinsics will perform loads/stores that use the ABI default
// alignment for i32, so our variable declaration should match.
let align = self.tcx.data_layout.i32_align.abi;
let cond_bitmap = self.alloca(Size::from_bytes(4), align);
llvm::set_value_name(cond_bitmap, format!("mcdc.addr.{i}").as_bytes());
self.store(self.const_i32(0), cond_bitmap, align);
cond_bitmaps.push(cond_bitmap);
}
self.coverage_cx().mcdc_condition_bitmap_map.borrow_mut().insert(instance, cond_bitmaps);
}
#[instrument(level = "debug", skip(self))]
fn add_coverage(&mut self, instance: Instance<'tcx>, kind: &CoverageKind) {
// Our caller should have already taken care of inlining subtleties,
// so we can assume that counter/expression IDs in this coverage
// statement are meaningful for the given instance.
//
// (Either the statement was not inlined and directly belongs to this
// instance, or it was inlined *from* this instance.)
let bx = self;
let Some(function_coverage_info) =
bx.tcx.instance_mir(instance.def).function_coverage_info.as_deref()
else {
debug!("function has a coverage statement but no coverage info");
return;
};
let mut coverage_map = bx.coverage_cx().function_coverage_map.borrow_mut();
let func_coverage = coverage_map
.entry(instance)
.or_insert_with(|| FunctionCoverageCollector::new(instance, function_coverage_info));
match *kind {
CoverageKind::SpanMarker | CoverageKind::BlockMarker { .. } => unreachable!(
"marker statement {kind:?} should have been removed by CleanupPostBorrowck"
),
CoverageKind::CounterIncrement { id } => {
func_coverage.mark_counter_id_seen(id);
// We need to explicitly drop the `RefMut` before calling into
// `instrprof_increment`, as that needs an exclusive borrow.
drop(coverage_map);
// The number of counters passed to `llvm.instrprof.increment` might
// be smaller than the number originally inserted by the instrumentor,
// if some high-numbered counters were removed by MIR optimizations.
// If so, LLVM's profiler runtime will use fewer physical counters.
let num_counters =
bx.tcx().coverage_ids_info(instance.def).max_counter_id.as_u32() + 1;
assert!(
num_counters as usize <= function_coverage_info.num_counters,
"num_counters disagreement: query says {num_counters} but function info only has {}",
function_coverage_info.num_counters
);
let fn_name = bx.get_pgo_func_name_var(instance);
let hash = bx.const_u64(function_coverage_info.function_source_hash);
let num_counters = bx.const_u32(num_counters);
let index = bx.const_u32(id.as_u32());
debug!(
"codegen intrinsic instrprof.increment(fn_name={:?}, hash={:?}, num_counters={:?}, index={:?})",
fn_name, hash, num_counters, index,
);
bx.instrprof_increment(fn_name, hash, num_counters, index);
}
CoverageKind::ExpressionUsed { id } => {
func_coverage.mark_expression_id_seen(id);
}
CoverageKind::CondBitmapUpdate { index, decision_depth } => {
drop(coverage_map);
let cond_bitmap = bx
.coverage_cx()
.try_get_mcdc_condition_bitmap(&instance, decision_depth)
.expect("mcdc cond bitmap should have been allocated for updating");
let cond_index = bx.const_i32(index as i32);
bx.mcdc_condbitmap_update(cond_index, cond_bitmap);
}
CoverageKind::TestVectorBitmapUpdate { bitmap_idx, decision_depth } => {
drop(coverage_map);
let cond_bitmap = bx.coverage_cx()
.try_get_mcdc_condition_bitmap(&instance, decision_depth)
.expect("mcdc cond bitmap should have been allocated for merging into the global bitmap");
assert!(
bitmap_idx as usize <= function_coverage_info.mcdc_bitmap_bits,
"bitmap index of the decision out of range"
);
let fn_name = bx.get_pgo_func_name_var(instance);
let hash = bx.const_u64(function_coverage_info.function_source_hash);
let bitmap_index = bx.const_u32(bitmap_idx);
bx.mcdc_tvbitmap_update(fn_name, hash, bitmap_index, cond_bitmap);
bx.mcdc_condbitmap_reset(cond_bitmap);
}
}
}
}
/// 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: &str = cx.tcx.symbol_name(instance).name;
let llfn = cx.get_fn(instance);
unsafe {
llvm::LLVMRustCoverageCreatePGOFuncNameVar(
llfn,
mangled_fn_name.as_c_char_ptr(),
mangled_fn_name.len(),
)
}
}
pub(crate) fn write_filenames_section_to_buffer<'a>(
filenames: impl IntoIterator<Item = &'a str>,
buffer: &RustString,
) {
let (pointers, lengths) = filenames
.into_iter()
.map(|s: &str| (s.as_c_char_ptr(), s.len()))
.unzip::<_, _, Vec<_>, Vec<_>>();
unsafe {
llvm::LLVMRustCoverageWriteFilenamesSectionToBuffer(
pointers.as_ptr(),
pointers.len(),
lengths.as_ptr(),
lengths.len(),
buffer,
);
}
}
pub(crate) fn write_mapping_to_buffer(
virtual_file_mapping: Vec<u32>,
expressions: Vec<ffi::CounterExpression>,
code_regions: &[ffi::CodeRegion],
branch_regions: &[ffi::BranchRegion],
mcdc_branch_regions: &[ffi::MCDCBranchRegion],
mcdc_decision_regions: &[ffi::MCDCDecisionRegion],
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,
code_regions.as_ptr(),
code_regions.len() as c_uint,
branch_regions.as_ptr(),
branch_regions.len() as c_uint,
mcdc_branch_regions.as_ptr(),
mcdc_branch_regions.len() as c_uint,
mcdc_decision_regions.as_ptr(),
mcdc_decision_regions.len() as c_uint,
buffer,
);
}
}
pub(crate) fn hash_bytes(bytes: &[u8]) -> u64 {
unsafe { llvm::LLVMRustCoverageHashByteArray(bytes.as_c_char_ptr(), bytes.len()) }
}
pub(crate) fn mapping_version() -> u32 {
unsafe { llvm::LLVMRustCoverageMappingVersion() }
}