(sub X, imm) gets canonicalized to (add X, -imm)

There are patterns to handle immediates when they fit in the immediate field.
e.g. %sub = add i32 %x, -123
=>   sub r0, r0, #123
Add patterns to catch immediates that do not fit but should be materialized
with a single movw instruction rather than movw + movt pair.
e.g. %sub = add i32 %x, -65535
=>   movw r1, #65535
     sub r0, r0, r1

rdar://11726136


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159057 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/ARM/sub.ll

@@ -36,3 +36,15 @@ entry:
   %sel = select i1 %cmp, i32 1, i32 %sub
   ret i32 %sel
 }
+
+; rdar://11726136
+define i32 @f5(i32 %x) {
+entry:
+; CHECK: f5
+; CHECK: movw r1, #65535
+; CHECK-NOT: movt
+; CHECK-NOT: add
+; CHECK: sub r0, r0, r1
+  %sub = add i32 %x, -65535
+  ret i32 %sub
+}