implement the null function for the Mips32 subzero compiler

tests_lit/llvm2ice_tests/function_aligned.ll

Index: tests_lit/llvm2ice_tests/function_aligned.ll
diff --git a/tests_lit/llvm2ice_tests/function_aligned.ll b/tests_lit/llvm2ice_tests/function_aligned.ll
index c976dced2ec5caf658a05c9a2008e1f28193d5ec..e2f8af5ff1eea76d6a703eb7098d04ab332fa678 100644
--- a/tests_lit/llvm2ice_tests/function_aligned.ll
+++ b/tests_lit/llvm2ice_tests/function_aligned.ll
@@ -11,6 +11,9 @@
 ; RUN: %if --need=target_ARM32 --command %p2i --filetype=asm --assemble \
 ; RUN:   --disassemble --target arm32 -i %s --args -O2 --skip-unimplemented \
 ; RUN:   | %if --need=target_ARM32 --command FileCheck --check-prefix ARM32 %s
+; RUN: %if --need=target_MIPS32 --command %p2i --filetype=asm --assemble \
+; RUN:   --disassemble --target mips32 -i %s --args -O2 --skip-unimplemented \
+; RUN:   | %if --need=target_MIPS32 --command FileCheck --check-prefix MIPS32 %s
 
 define void @foo() {
   ret void
@@ -23,6 +26,11 @@ define void @foo() {
 ; ARM32-NEXT: 4: e7fedef0 udf
 ; ARM32-NEXT: 8: e7fedef0 udf
 ; ARM32-NEXT: c: e7fedef0 udf
+; TODO (Reed Kotler check this disassembly, .s file looks fine)
+; MIPS32-LABEL: foo
+; MIPS32: 4: {{.*}} jr ra
+; MIPS32-NEXT: 8: {{.*}} nop
+; MIPS32-NEXT: c: e7fedef0
 
 define void @bar() {
   ret void
@@ -31,3 +39,7 @@ define void @bar() {
 ; CHECK-NEXT: 20: {{.*}} ret
 ; ARM32-LABEL: bar
 ; ARM32-NEXT: 10: {{.*}} bx lr
+; TOOD (Reed Kotler check this disassembly, .s file looks fine)

[jvoung (off chromium), 2015/06/12 19:39:13]

TODO(reed kotler)

+; MIPS32-LABEL: bar
+; MIPS32: 14: {{.*}} jr ra
+; MIPS32-NEXT: 18: {{.*}} nop