[llvm][ARM] Treat xscale arch as an alias of armv5te

Previously xscale was known to everything apart
from the ELF streamer so we would crash as soon
as you tried to output an object file.

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D104776

Author: DavidSpickett

llvm/lib/Target/ARM/MCTargetDesc/ARMELFStreamer.cpp

@@ -834,6 +834,7 @@ void ARMTargetELFStreamer::emitArchDefaultAttributes() {
 
   case ARM::ArchKind::ARMV4T:
   case ARM::ArchKind::ARMV5T:
+  case ARM::ArchKind::XSCALE:
   case ARM::ArchKind::ARMV5TE:
   case ARM::ArchKind::ARMV6:
     setAttributeItem(ARM_ISA_use, Allowed, false);

llvm/test/MC/ARM/directive-arch-xscale.s

@@ -0,0 +1,34 @@
+@@ Test the .arch directive for xscale
+
+@@ This test case will check the default .ARM.attributes value for the
+@@ xscale architecture.
+
+@ RUN: llvm-mc -triple arm-eabi -filetype asm %s \
+@ RUN:   | FileCheck %s -check-prefix CHECK-ASM
+@ RUN: llvm-mc -triple arm-eabi -filetype obj %s \
+@ RUN:   | llvm-readobj --arch-specific - | FileCheck %s -check-prefix CHECK-ATTR
+
+	.syntax	unified
+	.arch	xscale
+
+@ CHECK-ASM: 	.arch	xscale
+
+@ CHECK-ATTR: FileAttributes {
+@ CHECK-ATTR:   Attribute {
+@ CHECK-ATTR:     TagName: CPU_name
+@ CHECK-ATTR:     Value: xscale
+@ CHECK-ATTR:   }
+@ CHECK-ATTR:   Attribute {
+@ CHECK-ATTR:     TagName: CPU_arch
+@ CHECK-ATTR:     Description: ARM v5TE
+@ CHECK-ATTR:   }
+@ CHECK-ATTR:   Attribute {
+@ CHECK-ATTR:     TagName: ARM_ISA_use
+@ CHECK-ATTR:     Description: Permitted
+@ CHECK-ATTR:   }
+@ CHECK-ATTR:   Attribute {
+@ CHECK-ATTR:     TagName: THUMB_ISA_use
+@ CHECK-ATTR:     Description: Thumb-1
+@ CHECK-ATTR:   }
+@ CHECK-ATTR: }
+