[AArch64][SME] Fix inlining bug introduced in #78703 (#79994)

Calling a `__arm_locally_streaming` function from a function that
is not a streaming-SVE function would lead to incorrect inlining.

The issue didn't surface because the tests were not testing what
they were supposed to test.

(cherry picked from commit 3abf55a)

llvm/lib/Target/AArch64/AArch64TargetTransformInfo.cpp

@@ -233,15 +233,20 @@ static bool hasPossibleIncompatibleOps(const Function *F) {
 
 bool AArch64TTIImpl::areInlineCompatible(const Function *Caller,
                                          const Function *Callee) const {
-  SMEAttrs CallerAttrs(*Caller);
-  SMEAttrs CalleeAttrs(*Callee);
+  SMEAttrs CallerAttrs(*Caller), CalleeAttrs(*Callee);
+
+  // When inlining, we should consider the body of the function, not the
+  // interface.
+  if (CalleeAttrs.hasStreamingBody()) {
+    CalleeAttrs.set(SMEAttrs::SM_Compatible, false);
+    CalleeAttrs.set(SMEAttrs::SM_Enabled, true);
+  }
+
   if (CalleeAttrs.hasNewZABody())
     return false;
 
   if (CallerAttrs.requiresLazySave(CalleeAttrs) ||
-      (CallerAttrs.requiresSMChange(CalleeAttrs) &&
-       (!CallerAttrs.hasStreamingInterfaceOrBody() ||
-        !CalleeAttrs.hasStreamingBody()))) {
+      CallerAttrs.requiresSMChange(CalleeAttrs)) {
     if (hasPossibleIncompatibleOps(Callee))
       return false;
   }
@@ -4062,4 +4067,4 @@ bool AArch64TTIImpl::shouldTreatInstructionLikeSelect(const Instruction *I) {
       cast<BranchInst>(I->getNextNode())->isUnconditional())
     return true;
   return BaseT::shouldTreatInstructionLikeSelect(I);
-}
+}