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coverage: Emit mappings for unused functions without generating stubs

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This commit is contained in:
Zalathar 2023-09-24 21:06:39 +10:00
parent 249624b504
commit e964ea5bf5
2 changed files with 37 additions and 74 deletions
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76
compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs
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@ -1,6 +1,5 @@
use crate::llvm;
use crate::abi::Abi;
use crate::builder::Builder;
use crate::common::CodegenCx;
use crate::coverageinfo::ffi::{CounterExpression, CounterMappingRegion};
@ -12,17 +11,13 @@ use rustc_codegen_ssa::traits::{
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::{CounterId, CoverageKind, FunctionCoverageInfo};
use rustc_middle::mir::coverage::{CoverageKind, FunctionCoverageInfo};
use rustc_middle::mir::Coverage;
use rustc_middle::ty;
use rustc_middle::ty::layout::{FnAbiOf, HasTyCtxt};
use rustc_middle::ty::GenericArgs;
use rustc_middle::ty::Instance;
use rustc_middle::ty::Ty;
use rustc_middle::ty::layout::HasTyCtxt;
use rustc_middle::ty::{self, GenericArgs, Instance, TyCtxt};
use std::cell::RefCell;
@ -30,8 +25,6 @@ pub(crate) mod ffi;
pub(crate) mod map_data;
pub mod mapgen;
const UNUSED_FUNCTION_COUNTER_ID: CounterId = CounterId::START;
const VAR_ALIGN_BYTES: usize = 8;
/// A context object for maintaining all state needed by the coverageinfo module.
@ -77,22 +70,8 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> {
}
}
/// 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 function coverage info from MIR and add an
/// "unused" entry to the function coverage map.
fn define_unused_fn(&self, def_id: DefId, function_coverage_info: &'tcx FunctionCoverageInfo) {
let instance = declare_unused_fn(self, def_id);
codegen_unused_fn_and_counter(self, instance);
let instance = declare_unused_fn(self.tcx, def_id);
add_unused_function_coverage(self, instance, function_coverage_info);
}
}
@ -159,10 +138,8 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> {
}
}
fn declare_unused_fn<'tcx>(cx: &CodegenCx<'_, 'tcx>, def_id: DefId) -> Instance<'tcx> {
let tcx = cx.tcx;
let instance = Instance::new(
fn declare_unused_fn<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> Instance<'tcx> {
Instance::new(
def_id,
GenericArgs::for_item(tcx, def_id, |param, _| {
if let ty::GenericParamDefKind::Lifetime = param.kind {
@ -171,46 +148,7 @@ fn declare_unused_fn<'tcx>(cx: &CodegenCx<'_, 'tcx>, def_id: DefId) -> Instance<
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(
[Ty::new_unit(tcx)],
Ty::new_unit(tcx),
false,
hir::Unsafety::Unsafe,
Abi::Rust,
)),
ty::List::empty(),
),
None,
);
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>(