[clang] 335e68d - [Clang][RISCV] Support -fcf-protection=return for RISC-V (#112477)

[via cfe-commits]

Author: Jesse Huang
Date: 2024-10-29T15:47:49+08:00
New Revision: 335e68d8bce5ad3f5d6471c0ec1423211c71c0f0

URL: https://github.com/llvm/llvm-project/commit/335e68d8bce5ad3f5d6471c0ec1423211c71c0f0
DIFF: https://github.com/llvm/llvm-project/commit/335e68d8bce5ad3f5d6471c0ec1423211c71c0f0.diff

LOG: [Clang][RISCV] Support -fcf-protection=return for RISC-V (#112477)

Enables the support of `-fcf-protection=return` on RISC-V, which
requires Zicfiss. It also adds a string attribute "hw-shadow-stack"
to every function if the option is set on RISC-V

Added: 
    clang/test/CodeGen/RISCV/attr-hw-shadow-stack.c

Modified: 
    clang/lib/Basic/Targets/RISCV.h
    clang/lib/CodeGen/Targets/RISCV.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/Basic/Targets/RISCV.h b/clang/lib/Basic/Targets/RISCV.h
index bf40edb8683b3e..3b418585ab4a39 100644
--- a/clang/lib/Basic/Targets/RISCV.h
+++ b/clang/lib/Basic/Targets/RISCV.h
@@ -141,6 +141,13 @@ class RISCVTargetInfo : public TargetInfo {
     return true;
   }
 
+  bool
+  checkCFProtectionReturnSupported(DiagnosticsEngine &Diags) const override {
+    if (ISAInfo->hasExtension("zicfiss"))
+      return true;
+    return TargetInfo::checkCFProtectionReturnSupported(Diags);
+  }
+
   CFBranchLabelSchemeKind getDefaultCFBranchLabelScheme() const override {
     return CFBranchLabelSchemeKind::FuncSig;
   }

diff  --git a/clang/lib/CodeGen/Targets/RISCV.cpp b/clang/lib/CodeGen/Targets/RISCV.cpp
index fd72fe673b9b14..b04e436c665f52 100644
--- a/clang/lib/CodeGen/Targets/RISCV.cpp
+++ b/clang/lib/CodeGen/Targets/RISCV.cpp
@@ -594,6 +594,11 @@ class RISCVTargetCodeGenInfo : public TargetCodeGenInfo {
     const auto *FD = dyn_cast_or_null<FunctionDecl>(D);
     if (!FD) return;
 
+    auto *Fn = cast<llvm::Function>(GV);
+
+    if (CGM.getCodeGenOpts().CFProtectionReturn)
+      Fn->addFnAttr("hw-shadow-stack");
+
     const auto *Attr = FD->getAttr<RISCVInterruptAttr>();
     if (!Attr)
       return;
@@ -604,8 +609,6 @@ class RISCVTargetCodeGenInfo : public TargetCodeGenInfo {
     case RISCVInterruptAttr::machine: Kind = "machine"; break;
     }
 
-    auto *Fn = cast<llvm::Function>(GV);
-
     Fn->addFnAttr("interrupt", Kind);
   }
 };

diff  --git a/clang/test/CodeGen/RISCV/attr-hw-shadow-stack.c b/clang/test/CodeGen/RISCV/attr-hw-shadow-stack.c
new file mode 100644
index 00000000000000..cabff7e598eb02
--- /dev/null
+++ b/clang/test/CodeGen/RISCV/attr-hw-shadow-stack.c
@@ -0,0 +1,9 @@
+// RUN: %clang_cc1 -triple riscv64 -target-feature +experimental-zicfiss -emit-llvm -o - %s -fcf-protection=return | FileCheck %s
+// RUN: %clang_cc1 -triple riscv64 -target-feature +experimental-zicfiss -emit-llvm -o - %s | FileCheck -check-prefix=NOSHADOWSTACK %s
+// RUN: %clang_cc1 -triple riscv32 -target-feature +experimental-zicfiss -emit-llvm -o - %s -fcf-protection=return | FileCheck %s
+// RUN: %clang_cc1 -triple riscv32 -target-feature +experimental-zicfiss -emit-llvm -o - %s | FileCheck -check-prefix=NOSHADOWSTACK %s
+
+int foo(int *a) { return *a; }
+
+// CHECK: attributes {{.*}}"hw-shadow-stack"{{.*}}
+// NOSHADOWSTACK-NOT: attributes {{.*}}"hw-shadow-stack"{{.*}}