Auto merge of #112000 - wesleywiser:safestack, r=Amanieu

Add support for LLVM SafeStack

Adds support for LLVM [SafeStack] which provides backward edge control
flow protection by separating the stack into two parts: data which is
only accessed in provable safe ways is allocated on the normal stack
(the "safe stack") and all other data is placed in a separate allocation
(the "unsafe stack").

SafeStack support is enabled by passing `-Zsanitizer=safestack`.

[SafeStack]: https://clang.llvm.org/docs/SafeStack.html

cc `@rcvalle` #39699

2 files changed, 3 insertions, 0 deletions

diff --git a/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h b/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
index 05890628378..af6f4d5eaf9 100644
--- a/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
+++ b/compiler/rustc_llvm/llvm-wrapper/LLVMWrapper.h
@@ -96,6 +96,7 @@ enum LLVMRustAttribute {
   AllocatedPointer = 38,
   AllocAlign = 39,
 #endif
+  SanitizeSafeStack = 40,
 };
 
 typedef struct OpaqueRustString *RustStringRef;
diff --git a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
index 49acd71b3e1..ea04899ab68 100644
--- a/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
+++ b/compiler/rustc_llvm/llvm-wrapper/RustWrapper.cpp
@@ -234,6 +234,8 @@ static Attribute::AttrKind fromRust(LLVMRustAttribute Kind) {
   case AllocAlign:
     return Attribute::AllocAlign;
 #endif
+  case SanitizeSafeStack:
+    return Attribute::SafeStack;
   }
   report_fatal_error("bad AttributeKind");
 }