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Resurrect: rustc_llvm: Add a -Z print-codegen-stats option to expose LLVM statistics. #113723

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Jul 21, 2023
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4 changes: 4 additions & 0 deletions compiler/rustc_codegen_gcc/src/lib.rs
Original file line number Diff line number Diff line change
@@ -239,6 +239,10 @@ impl WriteBackendMethods for GccCodegenBackend {
unimplemented!();
}

fn print_statistics(&self) {
unimplemented!()
}

unsafe fn optimize(_cgcx: &CodegenContext<Self>, _diag_handler: &Handler, module: &ModuleCodegen<Self::Module>, config: &ModuleConfig) -> Result<(), FatalError> {
module.module_llvm.context.set_optimization_level(to_gcc_opt_level(config.opt_level));
Ok(())
24 changes: 23 additions & 1 deletion compiler/rustc_codegen_llvm/src/lib.rs
Original file line number Diff line number Diff line change
@@ -46,6 +46,7 @@ use rustc_span::symbol::Symbol;

use std::any::Any;
use std::ffi::CStr;
use std::io::Write;

mod back {
pub mod archive;
@@ -178,7 +179,28 @@ impl WriteBackendMethods for LlvmCodegenBackend {
type ThinBuffer = back::lto::ThinBuffer;
fn print_pass_timings(&self) {
unsafe {
llvm::LLVMRustPrintPassTimings();
let mut size = 0;
let cstr = llvm::LLVMRustPrintPassTimings(&mut size as *mut usize);
if cstr.is_null() {
println!("failed to get pass timings");
} else {
let timings = std::slice::from_raw_parts(cstr as *const u8, size);
std::io::stdout().write_all(timings).unwrap();
libc::free(cstr as *mut _);
}
}
}
fn print_statistics(&self) {
unsafe {
let mut size = 0;
let cstr = llvm::LLVMRustPrintStatistics(&mut size as *mut usize);
if cstr.is_null() {
println!("failed to get pass stats");
} else {
let stats = std::slice::from_raw_parts(cstr as *const u8, size);
std::io::stdout().write_all(stats).unwrap();
libc::free(cstr as *mut _);
}
}
}
fn run_link(
5 changes: 4 additions & 1 deletion compiler/rustc_codegen_llvm/src/llvm/ffi.rs
Original file line number Diff line number Diff line change
@@ -1868,7 +1868,10 @@ extern "C" {
pub fn LLVMRustGetLastError() -> *const c_char;

/// Print the pass timings since static dtors aren't picking them up.
pub fn LLVMRustPrintPassTimings();
pub fn LLVMRustPrintPassTimings(size: *const size_t) -> *const c_char;

/// Print the statistics since static dtors aren't picking them up.
pub fn LLVMRustPrintStatistics(size: *const size_t) -> *const c_char;

pub fn LLVMStructCreateNamed(C: &Context, Name: *const c_char) -> &Type;

4 changes: 4 additions & 0 deletions compiler/rustc_codegen_llvm/src/llvm_util.rs
Original file line number Diff line number Diff line change
@@ -110,6 +110,10 @@ unsafe fn configure_llvm(sess: &Session) {
// Use non-zero `import-instr-limit` multiplier for cold callsites.
add("-import-cold-multiplier=0.1", false);

if sess.print_llvm_stats() {
add("-stats", false);
}

for arg in sess_args {
add(&(*arg), true);
}
4 changes: 4 additions & 0 deletions compiler/rustc_codegen_ssa/src/back/write.rs
Original file line number Diff line number Diff line change
@@ -1945,6 +1945,10 @@ impl<B: ExtraBackendMethods> OngoingCodegen<B> {
self.backend.print_pass_timings()
}

if sess.print_llvm_stats() {
self.backend.print_statistics()
}

(
CodegenResults {
metadata: self.metadata,
1 change: 1 addition & 0 deletions compiler/rustc_codegen_ssa/src/traits/write.rs
Original file line number Diff line number Diff line change
@@ -35,6 +35,7 @@ pub trait WriteBackendMethods: 'static + Sized + Clone {
cached_modules: Vec<(SerializedModule<Self::ModuleBuffer>, WorkProduct)>,
) -> Result<(Vec<LtoModuleCodegen<Self>>, Vec<WorkProduct>), FatalError>;
fn print_pass_timings(&self);
fn print_statistics(&self);
unsafe fn optimize(
cgcx: &CodegenContext<Self>,
diag_handler: &Handler,
1 change: 1 addition & 0 deletions compiler/rustc_interface/src/tests.rs
Original file line number Diff line number Diff line change
@@ -714,6 +714,7 @@ fn test_unstable_options_tracking_hash() {
untracked!(perf_stats, true);
// `pre_link_arg` is omitted because it just forwards to `pre_link_args`.
untracked!(pre_link_args, vec![String::from("abc"), String::from("def")]);
untracked!(print_codegen_stats, true);
untracked!(print_llvm_passes, true);
untracked!(print_mono_items, Some(String::from("abc")));
untracked!(print_type_sizes, true);
24 changes: 21 additions & 3 deletions compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
#include "LLVMWrapper.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/DiagnosticHandler.h"
#include "llvm/IR/DiagnosticInfo.h"
@@ -111,9 +112,26 @@ extern "C" void LLVMRustSetNormalizedTarget(LLVMModuleRef M,
unwrap(M)->setTargetTriple(Triple::normalize(Triple));
}

extern "C" void LLVMRustPrintPassTimings() {
raw_fd_ostream OS(2, false); // stderr.
TimerGroup::printAll(OS);
extern "C" const char *LLVMRustPrintPassTimings(size_t *Len) {
std::string buf;
raw_string_ostream SS(buf);
TimerGroup::printAll(SS);
SS.flush();
*Len = buf.length();
char *CStr = (char *)malloc(*Len);
memcpy(CStr, buf.c_str(), *Len);
return CStr;
}

extern "C" const char *LLVMRustPrintStatistics(size_t *Len) {
std::string buf;
raw_string_ostream SS(buf);
llvm::PrintStatistics(SS);
SS.flush();
*Len = buf.length();
char *CStr = (char *)malloc(*Len);
memcpy(CStr, buf.c_str(), *Len);
return CStr;
}

extern "C" LLVMValueRef LLVMRustGetNamedValue(LLVMModuleRef M, const char *Name,
3 changes: 3 additions & 0 deletions compiler/rustc_session/src/options.rs
Original file line number Diff line number Diff line change
@@ -1668,6 +1668,9 @@ options! {
"use a more precise version of drop elaboration for matches on enums (default: yes). \
This results in better codegen, but has caused miscompilations on some tier 2 platforms. \
See #77382 and #74551."),
#[rustc_lint_opt_deny_field_access("use `Session::print_codegen_stats` instead of this field")]
print_codegen_stats: bool = (false, parse_bool, [UNTRACKED],
"print codegen statistics (default: no)"),
print_fuel: Option<String> = (None, parse_opt_string, [TRACKED],
"make rustc print the total optimization fuel used by a crate"),
print_llvm_passes: bool = (false, parse_bool, [UNTRACKED],
4 changes: 4 additions & 0 deletions compiler/rustc_session/src/session.rs
Original file line number Diff line number Diff line change
@@ -1057,6 +1057,10 @@ impl Session {
self.opts.unstable_opts.verbose
}

pub fn print_llvm_stats(&self) -> bool {
self.opts.unstable_opts.print_codegen_stats
}

pub fn verify_llvm_ir(&self) -> bool {
self.opts.unstable_opts.verify_llvm_ir || option_env!("RUSTC_VERIFY_LLVM_IR").is_some()
}