Add option to force filetype=asm for testing

tests_lit/llvm2ice_tests/vector-bitcast.ll

 ; This file tests bitcasts of vector type. For most operations, these
 ; should be lowered to a no-op on -O2.
 
 ; RUN: %p2i -i %s --filetype=obj --disassemble --args -O2 \
 ; RUN:   | FileCheck %s
 ; RUN: %p2i -i %s --filetype=obj --disassemble --args -Om1 \
 ; RUN:   | FileCheck --check-prefix=OPTM1 %s
 
 define internal <16 x i8> @test_bitcast_v16i8_to_v16i8(<16 x i8> %arg) {
 entry:
@@ skipping 132 matching lines @@
 
 define internal <4 x float> @test_bitcast_v4f32_to_v4f32(<4 x float> %arg) {
 entry:
   %res = bitcast <4 x float> %arg to <4 x float>
   ret <4 x float> %res
 
 ; CHECK-LABEL: test_bitcast_v4f32_to_v4f32
 ; CHECK-NEXT: ret
 }
 
-define internal i8 @test_bitcast_v8i1_to_i8(<8 x i1> %arg) {
+define internal i32 @test_bitcast_v8i1_to_i8(<8 x i1> %arg) {
 entry:
   %res = bitcast <8 x i1> %arg to i8
-  ret i8 %res
+  %res.i32 = zext i8 %res to i32
+  ret i32 %res.i32
 
 ; CHECK-LABEL: test_bitcast_v8i1_to_i8
 ; CHECK: call {{.*}} R_{{.*}} __Sz_bitcast_8xi1_i8
 
 ; OPTM1-LABEL: test_bitcast_v8i1_to_i8
 ; OPMT1: call -4
 }
 
-define internal i16 @test_bitcast_v16i1_to_i16(<16 x i1> %arg) {
+define internal i32 @test_bitcast_v16i1_to_i16(<16 x i1> %arg) {
 entry:
   %res = bitcast <16 x i1> %arg to i16
-  ret i16 %res
+  %res.i32 = zext i16 %res to i32
+  ret i32 %res.i32
 
 ; CHECK-LABEL: test_bitcast_v16i1_to_i16
 ; CHECK: call {{.*}} R_{{.*}} __Sz_bitcast_16xi1_i16
 
 ; OPTM1-LABEL: test_bitcast_v16i1_to_i16
 ; OPMT1: call -4
 }
 
 define internal <8 x i1> @test_bitcast_i8_to_v8i1(i32 %arg) {
 entry:
@@ skipping 13 matching lines @@
   %arg.trunc = trunc i32 %arg to i16
   %res = bitcast i16 %arg.trunc to <16 x i1>
   ret <16 x i1> %res
 
 ; CHECK-LABEL: test_bitcast_i16_to_v16i1
 ; CHECK: call {{.*}} R_{{.*}} __Sz_bitcast_i16_16xi1
 
 ; OPTM1-LABEL: test_bitcast_i16_to_v16i1
 ; OPTM1: call {{.*}} R_{{.*}} __Sz_bitcast_i16_16xi1
 }