diff --git a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs index c95148013eb74..53d97f3520106 100644 --- a/compiler/rustc_codegen_llvm/src/llvm/ffi.rs +++ b/compiler/rustc_codegen_llvm/src/llvm/ffi.rs @@ -2249,7 +2249,7 @@ extern "C" { pub fn LLVMRustHasFeature(T: &TargetMachine, s: *const c_char) -> bool; - pub fn LLVMRustPrintTargetCPUs(T: &TargetMachine); + pub fn LLVMRustPrintTargetCPUs(T: &TargetMachine, cpu: *const c_char); pub fn LLVMRustGetTargetFeaturesCount(T: &TargetMachine) -> size_t; pub fn LLVMRustGetTargetFeature( T: &TargetMachine, diff --git a/compiler/rustc_codegen_llvm/src/llvm_util.rs b/compiler/rustc_codegen_llvm/src/llvm_util.rs index 46692fd5e8bcf..2fbdab9f8ce03 100644 --- a/compiler/rustc_codegen_llvm/src/llvm_util.rs +++ b/compiler/rustc_codegen_llvm/src/llvm_util.rs @@ -329,7 +329,14 @@ pub(crate) fn print(req: PrintRequest, sess: &Session) { require_inited(); let tm = create_informational_target_machine(sess); match req { - PrintRequest::TargetCPUs => unsafe { llvm::LLVMRustPrintTargetCPUs(tm) }, + PrintRequest::TargetCPUs => { + // SAFETY generate a C compatible string from a byte slice to pass + // the target CPU name into LLVM, the lifetime of the reference is + // at least as long as the C function + let cpu_cstring = CString::new(handle_native(sess.target.cpu.as_ref())) + .unwrap_or_else(|e| bug!("failed to convert to cstring: {}", e)); + unsafe { llvm::LLVMRustPrintTargetCPUs(tm, cpu_cstring.as_ptr()) }; + } PrintRequest::TargetFeatures => print_target_features(sess, tm), _ => bug!("rustc_codegen_llvm can't handle print request: {:?}", req), } diff --git a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp index 1acdc95ca8d2d..e88a3cdf620d1 100644 --- a/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp +++ b/compiler/rustc_llvm/llvm-wrapper/PassWrapper.cpp @@ -307,7 +307,7 @@ static size_t getLongestEntryLength(ArrayRef Table) { return MaxLen; } -extern "C" void LLVMRustPrintTargetCPUs(LLVMTargetMachineRef TM) { +extern "C" void LLVMRustPrintTargetCPUs(LLVMTargetMachineRef TM, const char* TargetCPU) { const TargetMachine *Target = unwrap(TM); const MCSubtargetInfo *MCInfo = Target->getMCSubtargetInfo(); const Triple::ArchType HostArch = Triple(sys::getDefaultTargetTriple()).getArch(); @@ -323,9 +323,18 @@ extern "C" void LLVMRustPrintTargetCPUs(LLVMTargetMachineRef TM) { printf(" %-*s - Select the CPU of the current host (currently %.*s).\n", MaxCPULen, "native", (int)HostCPU.size(), HostCPU.data()); } - for (auto &CPU : CPUTable) - printf(" %-*s\n", MaxCPULen, CPU.Key); - printf("\n"); + for (auto &CPU : CPUTable) { + // Compare cpu against current target to label the default + if (strcmp(CPU.Key, TargetCPU) == 0) { + printf(" %-*s - This is the default target CPU" + " for the current build target (currently %s).", + MaxCPULen, CPU.Key, Target->getTargetTriple().str().c_str()); + } + else { + printf(" %-*s", MaxCPULen, CPU.Key); + } + printf("\n"); + } } extern "C" size_t LLVMRustGetTargetFeaturesCount(LLVMTargetMachineRef TM) { diff --git a/src/doc/rustc/src/codegen-options/index.md b/src/doc/rustc/src/codegen-options/index.md index d7c6a884fc8fb..e2b859e705df0 100644 --- a/src/doc/rustc/src/codegen-options/index.md +++ b/src/doc/rustc/src/codegen-options/index.md @@ -574,7 +574,8 @@ change in the future. This instructs `rustc` to generate code specifically for a particular processor. You can run `rustc --print target-cpus` to see the valid options to pass -here. Each target has a default base CPU. Special values include: +and the default target CPU for the current buid target. +Each target has a default base CPU. Special values include: * `native` can be passed to use the processor of the host machine. * `generic` refers to an LLVM target with minimal features but modern tuning.