[ARM][CMSE] Implement CMSE attributes

This patch adds CMSE attributes `cmse_nonsecure_call` and
`cmse_nonsecure_entry`.  As usual, specification is available here:
https://developer.arm.com/docs/ecm0359818/latest

Patch by Javed Absar, Bradley Smith, David Green, Momchil Velikov,
possibly others.

Differential Revision: https://reviews.llvm.org/D71129

1 files changed, 7 insertions, 0 deletions

diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index c582b9a..20da9f2 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -815,6 +815,7 @@ CGFunctionInfo *CGFunctionInfo::create(unsigned llvmCC,
   FI->ASTCallingConvention = info.getCC();
   FI->InstanceMethod = instanceMethod;
   FI->ChainCall = chainCall;
+  FI->CmseNSCall = info.getCmseNSCall();
   FI->NoReturn = info.getNoReturn();
   FI->ReturnsRetained = info.getProducesResult();
   FI->NoCallerSavedRegs = info.getNoCallerSavedRegs();
@@ -1877,6 +1878,9 @@ void CodeGenModule::ConstructAttributeList(
   if (FI.isNoReturn())
     FuncAttrs.addAttribute(llvm::Attribute::NoReturn);
 
+  if (FI.isCmseNSCall())
+    FuncAttrs.addAttribute("cmse_nonsecure_call");
+
   // If we have information about the function prototype, we can learn
   // attributes from there.
   AddAttributesFromFunctionProtoType(getContext(), FuncAttrs,
@@ -2004,6 +2008,9 @@ void CodeGenModule::ConstructAttributeList(
   }
 
   if (!AttrOnCallSite) {
+    if (TargetDecl && TargetDecl->hasAttr<CmseNSEntryAttr>())
+      FuncAttrs.addAttribute("cmse_nonsecure_entry");
+
     bool DisableTailCalls = false;
 
     if (CodeGenOpts.DisableTailCalls)