ARM: update subtarget information for Windows on ARM

Update the subtarget information for Windows on ARM.  This enables using the MC
layer to target Windows on ARM.

llvm-svn: 205459
diff --git a/llvm/test/CodeGen/ARM/Windows/aapcs.ll b/llvm/test/CodeGen/ARM/Windows/aapcs.ll
new file mode 100644
index 0000000..3f9a09f
--- /dev/null
+++ b/llvm/test/CodeGen/ARM/Windows/aapcs.ll
@@ -0,0 +1,16 @@
+; RUN: llc -mtriple=thumbv7-windows-itanium -mcpu=cortex-a9 -o - %s | FileCheck %s
+
+; AAPCS mandates an 8-byte stack alignment.  The alloca is implicitly aligned,
+; and no bic is required.
+
+declare void @callee(i8 *%i)
+
+define void @caller() {
+  %i = alloca i8, align 8
+  call void @callee(i8* %i)
+  ret void
+}
+
+; CHECK: sub sp, #8
+; CHECK-NOT: bic
+