[clang][RISCV] Introduce preprocessor macro when Zicfiss-based shadow stack is enabled (#127592)

The `-fcf-protection=[full|return]` flag enables shadow stack
implementation based on RISC-V Zicfiss extension. This patch adds the
`__riscv_shadow_stack` predefined macro to preprocessing when such a
shadow stack implementation is enabled.

1 files changed, 6 insertions, 1 deletions

diff --git a/clang/lib/Frontend/CompilerInvocation.cpp b/clang/lib/Frontend/CompilerInvocation.cpp
index 014e629..b9a5c05 100644
--- a/clang/lib/Frontend/CompilerInvocation.cpp
+++ b/clang/lib/Frontend/CompilerInvocation.cpp
@@ -4048,8 +4048,13 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
 
   if (const Arg *A = Args.getLastArg(OPT_fcf_protection_EQ)) {
     StringRef Name = A->getValue();
-    if (Name == "full" || Name == "branch") {
+    if (Name == "full") {
+      Opts.CFProtectionBranch = 1;
+      Opts.CFProtectionReturn = 1;
+    } else if (Name == "branch") {
       Opts.CFProtectionBranch = 1;
+    } else if (Name == "return") {
+      Opts.CFProtectionReturn = 1;
     }
   }