[AArch64][SME] Use reportFatalUsageError rather than assert (NFC) (llvm#145491)

Fixes llvm#144351

Author: MacDue

llvm/lib/Target/AArch64/AArch64TargetMachine.cpp

@@ -481,7 +481,8 @@ AArch64TargetMachine::getSubtargetImpl(const Function &F) const {
         MaxSVEVectorSize, IsStreaming, IsStreamingCompatible, HasMinSize);
   }
 
-  assert((!IsStreaming || I->hasSME()) && "Expected SME to be available");
+  if (IsStreaming && !I->hasSME())
+    reportFatalUsageError("streaming SVE functions require SME");
 
   return I.get();
 }

llvm/test/CodeGen/AArch64/streaming-func-no-sme.ll

@@ -0,0 +1,7 @@
+; RUN: not llc -mtriple aarch64-none-linux-gnu %s 2>&1 | FileCheck %s
+
+; CHECK: LLVM ERROR: streaming SVE functions require SME
+define void @streaming(i64 noundef %n) "aarch64_pstate_sm_enabled" nounwind {
+entry:
+  ret void
+}