Add hybrid assembler concept to ARM assembler.

tests_lit/assembler/arm32/global-load-store.ll

+; TODO(kschimpf): Show that we can handle global variable loads/stores.
+
+; REQUIRES: allow_dump
+
+; RUN: %p2i --filetype=asm -i %s --target=arm32 --args -O2 \
+; RUN:   | FileCheck %s --check-prefix=ASM
+; RUN: %p2i --filetype=hasm -i %s --target=arm32 --args -O2 \
+; RUN:   | FileCheck %s --check-prefix=IASM
+
+@global1 = internal global [4 x i8] zeroinitializer, align 4
+
+; ASM-LABEL: global1:
+; ASM-NEXT:    .zero   4
+; ASM-NEXT:    .size   global1, 4
+; ASM-NEXT:    .text
+; ASM-NEXT:    .p2alignl 4,0xe7fedef0
+
+; IASM-LABEL:global1:
+; IASM-NEXT:    .zero   4
+; IASM-NEXT:    .size   global1, 4
+; IASM-NEXT:    .text
+; IASM-NEXT:    .p2alignl 4,0xe7fedef0
+
+define internal i32 @load() {
+  %addr = bitcast [4 x i8]* @global1 to i32*
+  %v = load i32, i32* %addr, align 1
+  ret i32 %v
+}
+
+; ASM-LABEL: load:
+; ASM-NEXT: .Lload$__0:
+; ASM-NEXT:    movw    r0, #:lower16:global1
+; ASM-NEXT:    movt    r0, #:upper16:global1
+; ASM-NEXT:    ldr     r0, [r0]
+; ASM-NEXT:    bx      lr
+
+; IASM-LABEL:load:
+; IASM-NEXT:    movw    r0, #:lower16:global1
+; IASM-NEXT:    movt    r0, #:upper16:global1
+; IASM-NEXT:    ldr     r0, [r0]
+; IASM-NEXT:    .byte 0x1e
+; IASM-NEXT:    .byte 0xff
+; IASM-NEXT:    .byte 0x2f
+; IASM-NEXT:    .byte 0xe1
+
+define internal void @store(i32 %v) {
+  %addr = bitcast [4 x i8]* @global1 to i32*
+  store i32 %v, i32* %addr, align 1
+  ret void
+}
+
+; ASM-LABEL:store:
+; ASM-NEXT: .Lstore$__0:
+; ASM-NEXT:     movw    r1, #:lower16:global1
+; ASM-NEXT:     movt    r1, #:upper16:global1
+; ASM-NEXT:     str     r0, [r1]
+; ASM-NEXT:     bx      lr
+
+; IASM-LABEL:store:
+; IASM-NEXT:    movw    r1, #:lower16:global1
+; IASM-NEXT:    movt    r1, #:upper16:global1
+; IASM-NEXT:    str     r0, [r1]
+; IASM-NEXT:    .byte 0x1e
+; IASM-NEXT:    .byte 0xff
+; IASM-NEXT:    .byte 0x2f
+; IASM-NEXT:    .byte 0xe1