Use `OutputFilenames` to generate output file for `-Zllvm-time-trace`

The resulting profile will include the crate name and will be stored in
the `--out-dir` directory.

This implementation makes it convenient to use LLVM time trace together
with cargo, in the contrast to the previous implementation which would
overwrite profiles or store them in `.cargo/registry/..`.

2 files changed, 7 insertions, 3 deletions

diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index 62c17e6a10f..b52e9a6ea83 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -340,6 +340,7 @@ impl CodegenBackend for LlvmCodegenBackend {
         &self,
         ongoing_codegen: Box<dyn Any>,
         sess: &Session,
+        outputs: &OutputFilenames,
     ) -> Result<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>), ErrorReported> {
         let (codegen_results, work_products) = ongoing_codegen
             .downcast::<rustc_codegen_ssa::back::write::OngoingCodegen<LlvmCodegenBackend>>()
@@ -348,7 +349,8 @@ impl CodegenBackend for LlvmCodegenBackend {
 
         sess.time("llvm_dump_timing_file", || {
             if sess.opts.debugging_opts.llvm_time_trace {
-                llvm_util::time_trace_profiler_finish("llvm_timings.json");
+                let file_name = outputs.with_extension("llvm_timings.json");
+                llvm_util::time_trace_profiler_finish(&file_name);
             }
         });
 
diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs
index 79a261244d3..e4935ac431c 100644
--- a/compiler/rustc_codegen_llvm/src/llvm_util.rs
+++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs
@@ -4,6 +4,7 @@ use libc::c_int;
 use libloading::Library;
 use rustc_codegen_ssa::target_features::supported_target_features;
 use rustc_data_structures::fx::FxHashSet;
+use rustc_fs_util::path_to_c_string;
 use rustc_middle::bug;
 use rustc_session::config::PrintRequest;
 use rustc_session::Session;
@@ -13,6 +14,7 @@ use std::ffi::{CStr, CString};
 use tracing::debug;
 
 use std::mem;
+use std::path::Path;
 use std::ptr;
 use std::slice;
 use std::str;
@@ -134,9 +136,9 @@ unsafe fn configure_llvm(sess: &Session) {
     llvm::LLVMRustSetLLVMOptions(llvm_args.len() as c_int, llvm_args.as_ptr());
 }
 
-pub fn time_trace_profiler_finish(file_name: &str) {
+pub fn time_trace_profiler_finish(file_name: &Path) {
     unsafe {
-        let file_name = CString::new(file_name).unwrap();
+        let file_name = path_to_c_string(file_name);
         llvm::LLVMTimeTraceProfilerFinish(file_name.as_ptr());
     }
 }