[Subzero][MIPS32] Adds prolog instructions for MIPS32

tests_lit/llvm2ice_tests/uncond_br.ll

 ; TODO(rkotler): Stop skipping unimplemented parts (via --skip-unimplemented)
 ; once enough infrastructure is in. Also, switch to --filetype=obj
 ; when possible.
 ; RUN: %if --need=target_MIPS32 --need=allow_dump \
 ; RUN:   --command %p2i --filetype=asm --assemble \
 ; RUN:   --disassemble --target mips32 -i %s --args -O2 --skip-unimplemented \
 ; RUN:   -allow-externally-defined-symbols \
 ; RUN:   | %if --need=target_MIPS32 --need=allow_dump \
 ; RUN:   --command FileCheck --check-prefix MIPS32 %s
 
 define internal void @uncond1(i32 %i) {
   %1 = alloca i8, i32 4, align 4
   %.bc = bitcast i8* %1 to i32*
   store i32 %i, i32* %.bc, align 1
   br label %target
 target:
   %.bc1 = bitcast i8* %1 to i32*
   %2 = load i32, i32* %.bc1, align 1
   %3 = add i32 %2, 1
   %.bc2 = bitcast i8* %1 to i32*
   store i32 %3, i32* %.bc2, align 1
   br label %target
 }
 
 ; MIPS32-LABEL: uncond1
-; MIPS32:   b  {{[0-9]+}} <.Luncond1$target>
+; MIPS32:   b  {{[0-9 | a-f]+}} <.Luncond1$target>

[Jim Stichnoth, 2016/06/09 21:19:47]

I think the regex should just be
  [0-9a-f]+
Right?
(here and below)

[sagar.thakur, 2016/06/10 09:40:35]

Yes, changed it to [0-9a-f]+.

 ; MIPS32: <.Luncond1$target>:
 ; MIPS32: li
 ; MIPS32: addu
-; MIPS32: b {{[0-9]+}} <.Luncond1$target>
+; MIPS32: b {{[0-9 | a-f]+}} <.Luncond1$target>