[clang] [RISCV][FMV] Support target_clones (PR #85786)

[Sam Elliott via cfe-commits]

================
@@ -0,0 +1,441 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --check-globals all --include-generated-funcs --version 4
+// RUN: %clang_cc1 -triple riscv64-linux-gnu -target-feature +i -emit-llvm -o - %s | FileCheck %s
+
+__attribute__((target_clones("default", "arch=+m"))) int foo1(void) {
+  return 1;
+}
+__attribute__((target_clones("default", "arch=+zbb", "arch=+m"))) int foo2(void) { return 2; }
+__attribute__((target_clones("default", "arch=+zbb,+c"))) int foo3(void) { return 3; }
+__attribute__((target_clones("default", "arch=+zbb,+v"))) int
+foo4(void) {
+  return 4;
+}
+__attribute__((target_clones("default"))) int foo5(void) { return 5; }
+__attribute__((target_clones("default", "arch=+zvkt"))) int foo6(void) { return 2; }
+
+__attribute__((target_clones("default", "arch=+zbb", "arch=+zba", "arch=+zbb,+zba"))) int foo7(void) { return 2; }
+__attribute__((target_clones("default", "arch=+zbb;priority=2", "arch=+zba;priority=1", "arch=+zbb,+zba;priority=3"))) int foo8(void) { return 2; }
+__attribute__((target_clones("default", "arch=+zbb;priority=1", "priority=2;arch=+zba", "priority=3;arch=+zbb,+zba"))) int foo9(void) { return 2; }
+__attribute__((target_clones("default", "arch=+zbb;priority=-1", "priority=-2;arch=+zba", "priority=3;arch=+zbb,+zba"))) int foo10(void) { return 2; }
----------------
lenary wrote:

The grammar defined in https://github.com/riscv-non-isa/riscv-c-api-doc/pull/85 does not allow for `priority=-1`, as you're only allowed the digits 0-9 after `priority=`. Was it intentional to support or not support negative priorities?

https://github.com/llvm/llvm-project/pull/85786