From e964ea5bf575d68f164d02e4d1aa45b5bf924c0d Mon Sep 17 00:00:00 2001 From: Zalathar Date: Sun, 24 Sep 2023 21:06:39 +1000 Subject: coverage: Emit mappings for unused functions without generating stubs --- .../rustc_codegen_llvm/src/coverageinfo/mod.rs | 76 ++-------------------- 1 file changed, 7 insertions(+), 69 deletions(-) (limited to 'compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs') diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs index 204a73b788a..5a5f6eb89f6 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs @@ -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>( -- cgit 1.4.1-3-g733a5 From cdeeffde64b100ceb135135aef6879241ab6682f Mon Sep 17 00:00:00 2001 From: Zalathar Date: Sun, 24 Sep 2023 22:26:12 +1000 Subject: coverage: Move unused-function helpers closer to where they are used --- .../rustc_codegen_llvm/src/coverageinfo/mapgen.rs | 43 +++++++++++++++++++--- .../rustc_codegen_llvm/src/coverageinfo/mod.rs | 39 +------------------- 2 files changed, 39 insertions(+), 43 deletions(-) (limited to 'compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs') diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs index 4f12f4af175..4653849a29d 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mapgen.rs @@ -10,6 +10,7 @@ use rustc_hir::def::DefKind; use rustc_hir::def_id::DefId; use rustc_index::IndexVec; use rustc_middle::bug; +use rustc_middle::mir; use rustc_middle::mir::coverage::CodeRegion; use rustc_middle::ty::{self, TyCtxt}; use rustc_span::Symbol; @@ -351,17 +352,47 @@ fn add_unused_functions(cx: &CodegenCx<'_, '_>) { let codegenned_def_ids = tcx.codegened_and_inlined_items(()); - for non_codegenned_def_id in - eligible_def_ids.into_iter().filter(|id| !codegenned_def_ids.contains(id)) - { + // For each `DefId` that should have coverage instrumentation but wasn't + // codegenned, add it to the function coverage map as an unused function. + for def_id in eligible_def_ids.into_iter().filter(|id| !codegenned_def_ids.contains(id)) { // Skip any function that didn't have coverage data added to it by the // coverage instrumentor. - let body = tcx.instance_mir(ty::InstanceDef::Item(non_codegenned_def_id)); + let body = tcx.instance_mir(ty::InstanceDef::Item(def_id)); let Some(function_coverage_info) = body.function_coverage_info.as_deref() else { continue; }; - debug!("generating unused fn: {:?}", non_codegenned_def_id); - cx.define_unused_fn(non_codegenned_def_id, function_coverage_info); + debug!("generating unused fn: {def_id:?}"); + let instance = declare_unused_fn(tcx, def_id); + add_unused_function_coverage(cx, instance, function_coverage_info); + } +} + +fn declare_unused_fn<'tcx>(tcx: TyCtxt<'tcx>, def_id: DefId) -> ty::Instance<'tcx> { + ty::Instance::new( + def_id, + ty::GenericArgs::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) + } + }), + ) +} + +fn add_unused_function_coverage<'tcx>( + cx: &CodegenCx<'_, 'tcx>, + instance: ty::Instance<'tcx>, + function_coverage_info: &'tcx mir::coverage::FunctionCoverageInfo, +) { + // An unused function's mappings will automatically be rewritten to map to + // zero, because none of its counters/expressions are marked as seen. + let function_coverage = FunctionCoverage::unused(instance, function_coverage_info); + + 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`"); } } diff --git a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs index 5a5f6eb89f6..cf7c7e6be60 100644 --- a/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs +++ b/compiler/rustc_codegen_llvm/src/coverageinfo/mod.rs @@ -11,13 +11,12 @@ use rustc_codegen_ssa::traits::{ StaticMethods, }; use rustc_data_structures::fx::FxHashMap; -use rustc_hir::def_id::DefId; use rustc_llvm::RustString; use rustc_middle::bug; -use rustc_middle::mir::coverage::{CoverageKind, FunctionCoverageInfo}; +use rustc_middle::mir::coverage::CoverageKind; use rustc_middle::mir::Coverage; use rustc_middle::ty::layout::HasTyCtxt; -use rustc_middle::ty::{self, GenericArgs, Instance, TyCtxt}; +use rustc_middle::ty::Instance; use std::cell::RefCell; @@ -69,11 +68,6 @@ impl<'ll, 'tcx> CodegenCx<'ll, 'tcx> { bug!("Could not get the `coverage_context`"); } } - - fn define_unused_fn(&self, def_id: DefId, function_coverage_info: &'tcx FunctionCoverageInfo) { - let instance = declare_unused_fn(self.tcx, def_id); - add_unused_function_coverage(self, instance, function_coverage_info); - } } impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> { @@ -138,35 +132,6 @@ impl<'tcx> CoverageInfoBuilderMethods<'tcx> for Builder<'_, '_, 'tcx> { } } -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 { - tcx.lifetimes.re_erased.into() - } else { - tcx.mk_param_from_def(param) - } - }), - ) -} - -fn add_unused_function_coverage<'tcx>( - cx: &CodegenCx<'_, 'tcx>, - instance: Instance<'tcx>, - function_coverage_info: &'tcx FunctionCoverageInfo, -) { - // An unused function's mappings will automatically be rewritten to map to - // zero, because none of its counters/expressions are marked as seen. - let function_coverage = FunctionCoverage::unused(instance, function_coverage_info); - - 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 -- cgit 1.4.1-3-g733a5