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/..`.

Author: tmiasko

compiler/rustc_codegen_cranelift/src/lib.rs

@@ -205,6 +205,7 @@ impl CodegenBackend for CraneliftCodegenBackend {
         &self,
         ongoing_codegen: Box<dyn Any>,
         _sess: &Session,
+        _outputs: &OutputFilenames,
     ) -> Result<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>), ErrorReported> {
         Ok(*ongoing_codegen
             .downcast::<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>)>()

compiler/rustc_codegen_gcc/src/lib.rs

@@ -96,7 +96,7 @@ impl CodegenBackend for GccCodegenBackend {
         Box::new(res)
     }
 
-    fn join_codegen(&self, ongoing_codegen: Box<dyn Any>, sess: &Session) -> Result<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>), ErrorReported> {
+    fn join_codegen(&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<GccCodegenBackend>>()
             .expect("Expected GccCodegenBackend's OngoingCodegen, found Box<Any>")

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);
             }
         });
 

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());
     }
 }

compiler/rustc_codegen_ssa/src/traits/backend.rs

@@ -97,6 +97,7 @@ pub trait CodegenBackend {
         &self,
         ongoing_codegen: Box<dyn Any>,
         sess: &Session,
+        outputs: &OutputFilenames,
     ) -> Result<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>), ErrorReported>;
 
     /// This is called on the returned `Box<dyn Any>` from `join_codegen`

compiler/rustc_interface/src/queries.rs

@@ -335,8 +335,11 @@ pub struct Linker {
 
 impl Linker {
     pub fn link(self) -> Result<()> {
-        let (codegen_results, work_products) =
-            self.codegen_backend.join_codegen(self.ongoing_codegen, &self.sess)?;
+        let (codegen_results, work_products) = self.codegen_backend.join_codegen(
+            self.ongoing_codegen,
+            &self.sess,
+            &self.prepare_outputs,
+        )?;
 
         self.sess.compile_status()?;
 

src/test/run-make-fulldeps/hotplug_codegen_backend/the_backend.rs

@@ -46,6 +46,7 @@ impl CodegenBackend for TheBackend {
         &self,
         ongoing_codegen: Box<dyn Any>,
         _sess: &Session,
+        _outputs: &OutputFilenames,
     ) -> Result<(CodegenResults, FxHashMap<WorkProductId, WorkProduct>), ErrorReported> {
         let codegen_results = ongoing_codegen
             .downcast::<CodegenResults>()