Remove incorrectly implemented -mibt-seal

The option from D116070 does not work as intended and will not be needed when
hidden visibility is used. A function needs ENDBR if it may be reached
indirectly. If we make ThinLTO combine the address-taken property (close to
`!GV.use_empty() && !GV.hasAtLeastLocalUnnamedAddr()`), then the condition can
be expressed with:

`AddressTaken || (!F.hasLocalLinkage() && (VisibleToRegularObj || !F.hasHiddenVisibility()))`

The current `F.hasAddressTaken()` condition does not take into acount of
address-significance in another bitcode file or ELF relocatable file.

For the Linux kernel, it uses relocatable linking. lld/ELF uses a
conservative approach by setting all `VisibleToRegularObj` to true.
Using the non-relocatable semantics may under-estimate
`VisibleToRegularObj`. As @pcc mentioned on
https://github.com/ClangBuiltLinux/linux/issues/1737#issuecomment-1343414686
, we probably need a symbol list to supply additional
`VisibleToRegularObj` symbols (not part of the relocatable LTO link).

Reviewed By: samitolvanen

Differential Revision: https://reviews.llvm.org/D140363

1 files changed, 0 insertions, 3 deletions

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index fcb60e3..1d93c76 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -775,9 +775,6 @@ void CodeGenModule::Release() {
                               1);
   }
 
-  if (CodeGenOpts.IBTSeal)
-    getModule().addModuleFlag(llvm::Module::Min, "ibt-seal", 1);
-
   if (CodeGenOpts.FunctionReturnThunks)
     getModule().addModuleFlag(llvm::Module::Override, "function_return_thunk_extern", 1);