Add support for generating unique *.profraw files by default when using the -C instrument-coverage flag.

Respond to PR comments.

compiler/rustc_codegen_llvm/src/back/write.rs

@@ -423,6 +423,14 @@ fn get_pgo_sample_use_path(config: &ModuleConfig) -> Option<CString> {
         .map(|path_buf| CString::new(path_buf.to_string_lossy().as_bytes()).unwrap())
 }
 
+fn get_instr_profile_output_path(config: &ModuleConfig) -> Option<CString> {
+    if config.instrument_coverage {
+        Some(CString::new(format!("{}", PathBuf::from("default_%m_%p.profraw").display())).unwrap())
+    } else {
+        None
+    }
+}
+
 pub(crate) unsafe fn optimize_with_new_llvm_pass_manager(
     cgcx: &CodegenContext<LlvmCodegenBackend>,
     diag_handler: &Handler,
@@ -438,6 +446,7 @@ pub(crate) unsafe fn optimize_with_new_llvm_pass_manager(
     let pgo_use_path = get_pgo_use_path(config);
     let pgo_sample_use_path = get_pgo_sample_use_path(config);
     let is_lto = opt_stage == llvm::OptStage::ThinLTO || opt_stage == llvm::OptStage::FatLTO;
+    let instr_profile_output_path = get_instr_profile_output_path(config);
     // Sanitizer instrumentation is only inserted during the pre-link optimization stage.
     let sanitizer_options = if !is_lto {
         Some(llvm::SanitizerOptions {
@@ -488,6 +497,7 @@ pub(crate) unsafe fn optimize_with_new_llvm_pass_manager(
         pgo_gen_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
         pgo_use_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
         config.instrument_coverage,
+        instr_profile_output_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
         config.instrument_gcov,
         pgo_sample_use_path.as_ref().map_or(std::ptr::null(), |s| s.as_ptr()),
         config.debug_info_for_profiling,

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -2347,6 +2347,7 @@ extern "C" {
         PGOGenPath: *const c_char,
         PGOUsePath: *const c_char,
         InstrumentCoverage: bool,
+        InstrProfileOutput: *const c_char,
         InstrumentGCOV: bool,
         PGOSampleUsePath: *const c_char,
         DebugInfoForProfiling: bool,

compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp

@@ -822,7 +822,8 @@ LLVMRustOptimizeWithNewPassManager(
     bool DisableSimplifyLibCalls, bool EmitLifetimeMarkers,
     LLVMRustSanitizerOptions *SanitizerOptions,
     const char *PGOGenPath, const char *PGOUsePath,
-    bool InstrumentCoverage, bool InstrumentGCOV,
+    bool InstrumentCoverage, const char *InstrProfileOutput,
+    bool InstrumentGCOV,
     const char *PGOSampleUsePath, bool DebugInfoForProfiling,
     void* LlvmSelfProfiler,
     LLVMRustSelfProfileBeforePassCallback BeforePassCallback,
@@ -922,8 +923,11 @@ LLVMRustOptimizeWithNewPassManager(
 
   if (InstrumentCoverage) {
     PipelineStartEPCallbacks.push_back(
-      [](ModulePassManager &MPM, OptimizationLevel Level) {
+      [InstrProfileOutput](ModulePassManager &MPM, OptimizationLevel Level) {
         InstrProfOptions Options;
+        if (InstrProfileOutput) {
+          Options.InstrProfileOutput = InstrProfileOutput;
+        }
         MPM.addPass(InstrProfiling(Options, false));
       }
     );

src/test/codegen/instrument-coverage.rs

@@ -0,0 +1,17 @@
+// Test that `-Cinstrument-coverage` creates expected __llvm_profile_filename symbol in LLVM IR.
+
+// needs-profiler-support
+// compile-flags: -Cinstrument-coverage
+
+// CHECK: @__llvm_profile_filename = {{.*}}"default_%m_%p.profraw\00"{{.*}}
+
+#![crate_type="lib"]
+
+#[inline(never)]
+fn some_function() {
+
+}
+
+pub fn some_other_function() {
+    some_function();
+}