[ARM] r11 is reserved when using -mframe-chain=aapcs (#86951)

When using the -mframe-chain=aapcs or -mframe-chain=aapcs-leaf options,
we cannot use r11 as an allocatable register, even if
-fomit-frame-pointer is also used. This is so that r11 will always point
to a valid frame record, even if we don't create one in every function.

1 files changed, 3 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index be7bf0b..75b1449 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -1328,6 +1328,9 @@ void CodeGenModule::Release() {
   case CodeGenOptions::FramePointerKind::None:
     // 0 ("none") is the default.
     break;
+  case CodeGenOptions::FramePointerKind::Reserved:
+    getModule().setFramePointer(llvm::FramePointerKind::Reserved);
+    break;
   case CodeGenOptions::FramePointerKind::NonLeaf:
     getModule().setFramePointer(llvm::FramePointerKind::NonLeaf);
     break;