[Subzero][MIPS32] Implements variable alloca for MIPS32

tests_lit/llvm2ice_tests/return_immediates.ll

 ; Simple test that returns various immediates. For fixed-width instruction
 ; sets, some immediates are more complicated than others.
 ; For x86-32, it shouldn't be a problem.
 
 ; RUN: %p2i --filetype=obj --disassemble -i %s --args -O2 \
 ; RUN:      -allow-externally-defined-symbols | FileCheck %s
 
 ; TODO(jvoung): Stop skipping unimplemented parts (via --skip-unimplemented)
 ; once enough infrastructure is in. Also, switch to --filetype=obj
 ; when possible.
@@ skipping 84 matching lines @@
 define internal i32 @ret_8bits_shift_left24() {
   ret i32 4278190080
 }
 ; CHECK-LABEL: ret_8bits_shift_left24
 ; CHECK-NEXT: mov eax,0xff000000
 ; ARM32-LABEL: ret_8bits_shift_left24
 ; ARM32-NEXT: mov r0, #-16777216
 ; ARM32-NEXT: bx lr
 ; MIPS32-LABEL: ret_8bits_shift_left24
 ; MIPS32-NEXT: lui      v0,0xff00
-; MIPS32-NEXT: ori      v0,v0,0x0
 
 ; The next few cases wrap around and actually demonstrate the rotation.
 
 define internal i32 @ret_8bits_ror7() {
   ret i32 4261412865
 }
 ; CHECK-LABEL: ret_8bits_ror7
 ; CHECK-NEXT: mov eax,0xfe000001
 ; ARM32-LABEL: ret_8bits_ror7
 ; ARM32-NEXT: movw r0, #1
@@ skipping 106 matching lines @@
 define internal i32 @ret_16bits_upper() {
   ret i32 4294901760
 }
 ; CHECK-LABEL: ret_16bits_upper
 ; CHECK-NEXT: mov eax,0xffff0000
 ; ARM32-LABEL: ret_16bits_upper
 ; ARM32-NEXT: movw r0, #0
 ; ARM32-NEXT: movt r0, #65535
 ; MIPS32-LABEL: ret_16bits_upper
 ; MIPS32-NEXT: lui      v0,0xffff
-; MIPS32-NEXT: ori      v0,v0,0x0
 
 
 ; Some 32-bit immediates can be inverted, and moved in a single instruction.
 
 define internal i32 @ret_8bits_inverted_shift_left0() {
   ret i32 4294967040
 }
 ; CHECK-LABEL: ret_8bits_inverted_shift_left0
 ; CHECK-NEXT: mov eax,0xffffff00
 ; ARM32-LABEL: ret_8bits_inverted_shift_left0
@@ skipping 79 matching lines @@
 ; CHECK-LABEL: ret_addr
 ; CHECK-NEXT: mov eax,0x0 {{.*}} R_386_32 _start
 ; ARM32-LABEL: ret_addr
 ; ARM32-NEXT: movw r0, #0 {{.*}} R_ARM_MOVW_ABS_NC _start
 ; ARM32-NEXT: movt r0, #0 {{.*}} R_ARM_MOVT_ABS    _start
 ; TODO(RKotler) emitting proper li but in disassembly
 ; it shows up only in the relocation records. Should emit
 ; without the macro but we still need to add GOT implementation
 ; to finish this case
 ;