Rollup merge of #132590 - Zalathar:z-timings-stats, r=jieyouxu

Simplify FFI calls for `-Ztime-llvm-passes` and `-Zprint-codegen-stats`
The existing code for these unstable LLVM-infodump flags was jumping through hoops to pass an allocated C string across the FFI boundary, when it's much simpler to just write to a `&RustString` instead.

Author: Zalathar

compiler/rustc_codegen_llvm/src/lib.rs

@@ -22,7 +22,6 @@
 
 use std::any::Any;
 use std::ffi::CStr;
-use std::io::Write;
 use std::mem::ManuallyDrop;
 
 use back::owned_target_machine::OwnedTargetMachine;
@@ -165,30 +164,12 @@ impl WriteBackendMethods for LlvmCodegenBackend {
 typeThinData = back::lto::ThinData;
 typeThinBuffer = back::lto::ThinBuffer;
 fnprint_pass_timings(&self){
-unsafe{
-letmut size = 0;
-let cstr = llvm::LLVMRustPrintPassTimings(&rawmut size);
-if cstr.is_null(){
-println!("failed to get pass timings");
-}else{
-let timings = std::slice::from_raw_parts(cstr as*constu8, size);
- std::io::stdout().write_all(timings).unwrap();
- libc::free(cstr as*mut_);
-}
-}
+let timings = llvm::build_string(|s| unsafe{ llvm::LLVMRustPrintPassTimings(s)}).unwrap();
+print!("{timings}");
 }
 fnprint_statistics(&self){
-unsafe{
-letmut size = 0;
-let cstr = llvm::LLVMRustPrintStatistics(&rawmut size);
-if cstr.is_null(){
-println!("failed to get pass stats");
-}else{
-let stats = std::slice::from_raw_parts(cstr as*constu8, size);
- std::io::stdout().write_all(stats).unwrap();
- libc::free(cstr as*mut_);
-}
-}
+let stats = llvm::build_string(|s| unsafe{ llvm::LLVMRustPrintStatistics(s)}).unwrap();
+print!("{stats}");
 }
 fnrun_link(
 cgcx:&CodegenContext<Self>,

compiler/rustc_codegen_llvm/src/llvm/ffi.rs

@@ -1765,11 +1765,13 @@ unsafe extern "C" {
 /// Returns a string describing the last error caused by an LLVMRust* call.
 pubfnLLVMRustGetLastError() -> *constc_char;
 
-/// Print the pass timings since static dtors aren't picking them up.
-pubfnLLVMRustPrintPassTimings(size:*constsize_t) -> *constc_char;
+/// Prints the timing information collected by `-Ztime-llvm-passes`.
+#[expect(improper_ctypes)]
+pub(crate)fnLLVMRustPrintPassTimings(OutStr:&RustString);
 
-/// Print the statistics since static dtors aren't picking them up.
-pubfnLLVMRustPrintStatistics(size:*constsize_t) -> *constc_char;
+/// Prints the statistics collected by `-Zprint-codegen-stats`.
+#[expect(improper_ctypes)]
+pub(crate)fnLLVMRustPrintStatistics(OutStr:&RustString);
 
 /// Prepares inline assembly.
 pubfnLLVMRustInlineAsm(

compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp

@@ -140,26 +140,14 @@ extern "C" void LLVMRustSetNormalizedTarget(LLVMModuleRef M,
 unwrap(M)->setTargetTriple(Triple::normalize(Triple));
 }
 
-extern"C"constchar *LLVMRustPrintPassTimings(size_t *Len) {
- std::string buf;
-autoSS = raw_string_ostream(buf);
-TimerGroup::printAll(SS);
-SS.flush();
- *Len = buf.length();
-char *CStr = (char *)malloc(*Len);
-memcpy(CStr, buf.c_str(), *Len);
-return CStr;
-}
-
-extern"C"constchar *LLVMRustPrintStatistics(size_t *Len) {
- std::string buf;
-autoSS = raw_string_ostream(buf);
-llvm::PrintStatistics(SS);
-SS.flush();
- *Len = buf.length();
-char *CStr = (char *)malloc(*Len);
-memcpy(CStr, buf.c_str(), *Len);
-return CStr;
+extern"C"voidLLVMRustPrintPassTimings(RustStringRef OutBuf) {
+autoOS = RawRustStringOstream(OutBuf);
+TimerGroup::printAll(OS);
+}
+
+extern"C"voidLLVMRustPrintStatistics(RustStringRef OutBuf) {
+autoOS = RawRustStringOstream(OutBuf);
+llvm::PrintStatistics(OS);
 }
 
 extern"C" LLVMValueRef LLVMRustGetNamedValue(LLVMModuleRef M, constchar *Name,