[SubZero] Implement load and store for MIPS

tests_lit/llvm2ice_tests/load.ll

 ; Simple test of the load instruction.
 
 ; REQUIRES: allow_dump
 
 ; RUN: %p2i -i %s --args --verbose inst -threads=0 | FileCheck %s
 
+; RUN: %if --need=target_MIPS32 --need=allow_dump \
+; RUN:   --command %p2i --filetype=asm --assemble \
+; RUN:   --disassemble --target mips32 -i %s --args -Om1 --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 @load_i64(i32 %addr_arg) {
 entry:
   %__1 = inttoptr i32 %addr_arg to i64*
   %iv = load i64, i64* %__1, align 1
   ret void
 
 ; CHECK:       Initial CFG
 ; CHECK:     entry:
 ; CHECK-NEXT:  %iv = load i64, i64* %addr_arg, align 1
 ; CHECK-NEXT:  ret void
 }
 
+; MIPS32-LABEL: load_i64
+; MIPS32: lw {{.*}},0({{.*}})
+; MIPS32-NEXT: lw {{.*}},4({{.*}})
+
 define internal void @load_i32(i32 %addr_arg) {
 entry:
   %__1 = inttoptr i32 %addr_arg to i32*
   %iv = load i32, i32* %__1, align 1
   ret void
 
 ; CHECK:       Initial CFG
 ; CHECK:     entry:
 ; CHECK-NEXT:  %iv = load i32, i32* %addr_arg, align 1
 ; CHECK-NEXT:  ret void
 }
 
+; MIPS32-LABEL: load_i32
+; MIPS32: lw {{.*}},0({{.*}})
+
 define internal void @load_i16(i32 %addr_arg) {
 entry:
   %__1 = inttoptr i32 %addr_arg to i16*
   %iv = load i16, i16* %__1, align 1
   ret void
 
 ; CHECK:       Initial CFG
 ; CHECK:     entry:
 ; CHECK-NEXT:  %iv = load i16, i16* %addr_arg, align 1
 ; CHECK-NEXT:  ret void
 }
 
+; MIPS32-LABEL: load_i16
+; MIPS32: lh {{.*}},0({{.*}})
+
 define internal void @load_i8(i32 %addr_arg) {
 entry:
   %__1 = inttoptr i32 %addr_arg to i8*
   %iv = load i8, i8* %__1, align 1
   ret void
 
 ; CHECK:       Initial CFG
 ; CHECK:     entry:
 ; CHECK-NEXT:  %iv = load i8, i8* %addr_arg, align 1
 ; CHECK-NEXT:  ret void
 }
+
+; MIPS32-LABEL: load_i8
+; MIPS32: lb {{.*}},0({{.*}})