Add "add immediate" instruction to the ARM integrated assembler.

tests_lit/assembler/arm32/add.ll

Index: tests_lit/assembler/arm32/add.ll
diff --git a/tests_lit/assembler/arm32/add.ll b/tests_lit/assembler/arm32/add.ll
new file mode 100644
index 0000000000000000000000000000000000000000..656137ca509094baa61975f542b81722bc91c7fd
--- /dev/null
+++ b/tests_lit/assembler/arm32/add.ll
@@ -0,0 +1,25 @@
+; Show that we know how to translate add.
+; TODO(kschimpf) Currently only know how to test add 1 to R0.
+
+; NOTE: We use -O2 to get rid of memory stores.
+
+; RUN: %p2i --filetype=asm -i %s --target=arm32 --args -O2 \
+; RUN:   | FileCheck %s --check-prefix=ASM
+; RUN: %p2i --filetype=iasm -i %s --target=arm32 --args -O2 \
+; RUN:   | FileCheck %s --check-prefix=IASM
+
+define internal i32 @add1ToR0(i32 %p) {
+  %v = add i32 %p, 1
+  ret i32 %v
+}
+
+; ASM-LABEL: add1ToR0:
+; ASM:	add	r0, r0, #1
+; ASM:	bx	lr
+
+; IASM-LABEL: add1ToR0:
+; IASM:	     .byte 0x1
+; IASM-NEXT: .byte 0x0
+; IASM-NEXT: .byte 0x80
+; IASM-NEXT: .byte 0xe2
+