[FunctionAttrs][ArgumentPromotion][GlobalOpt] Disable some optimisations passes for naked functions
- Fix for bug 36078.
- Prevent the functionattrs, function-attrs, globalopt and argpromotion passes
from changing naked functions.
- These passes can perform some alterations to the functions that should not be
applied. An example is removing parameters that are seemingly not used because
they are only referenced in the inline assembly. Another example is marking
the function as fastcc.
llvm-svn: 325788
diff --git a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
index d3a7b0e..461c4e1 100644
--- a/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
+++ b/llvm/lib/Transforms/IPO/ArgumentPromotion.cpp
@@ -817,6 +817,12 @@
unsigned MaxElements,
Optional<function_ref<void(CallSite OldCS, CallSite NewCS)>>
ReplaceCallSite) {
+ // Don't perform argument promotion for naked functions; otherwise we can end
+ // up removing parameters that are seemingly 'not used' as they are referred
+ // to in the assembly.
+ if(F->hasFnAttribute(Attribute::Naked))
+ return nullptr;
+
// Make sure that it is local to this module.
if (!F->hasLocalLinkage())
return nullptr;