Mark condition/carry bit as clobbered in C-SKY inline assembly

compiler/rustc_codegen_llvm/src/asm.rs

@@ -286,7 +286,9 @@ impl<'ll, 'tcx> AsmBuilderMethods<'tcx> for Builder<'_, 'll, 'tcx> {
                 InlineAsmArch::M68k => {
                     constraints.push("~{ccr}".to_string());
                 }
-                InlineAsmArch::CSKY => {}
+                InlineAsmArch::CSKY => {
+                    constraints.push("~{psr}".to_string());
+                }
             }
         }
         if !options.contains(InlineAsmOptions::NOMEM) {

src/doc/unstable-book/src/language-features/asm-experimental-arch.md

@@ -199,3 +199,5 @@ These flags registers must be restored upon exiting the asm block if the `preser
 - SPARC
   - Integer condition codes (`icc` and `xcc`)
   - Floating-point condition codes (`fcc[0-3]`)
+- CSKY
+  - Condition/carry bit (C) in `PSR`.

tests/codegen/asm/csky-clobbers.rs

@@ -0,0 +1,24 @@
+//@ add-core-stubs
+//@ compile-flags: --target csky-unknown-linux-gnuabiv2
+//@ needs-llvm-components: csky
+
+#![crate_type = "rlib"]
+#![feature(no_core, asm_experimental_arch)]
+#![no_core]
+
+extern crate minicore;
+use minicore::*;
+
+// CHECK-LABEL: @flags_clobber
+// CHECK: call void asm sideeffect "", "~{psr}"()
+#[no_mangle]
+pub unsafe fn flags_clobber() {
+    asm!("", options(nostack, nomem));
+}
+
+// CHECK-LABEL: @no_clobber
+// CHECK: call void asm sideeffect "", ""()
+#[no_mangle]
+pub unsafe fn no_clobber() {
+    asm!("", options(nostack, nomem, preserves_flags));
+}