Add Om1 lowering with no optimizations

tests_lit/llvm2ice_tests/bitcast.ll

-; RUIN: %llvm2ice -verbose inst %s | FileCheck %s
-; RUIN: %llvm2ice --verbose none %s | FileCheck --check-prefix=ERRORS %s
+; Trivial smoke test of bitcast between integer and FP types.
+
+; RUN: %llvm2ice --verbose inst %s | FileCheck %s
+; RUN: %llvm2ice --verbose none %s | FileCheck --check-prefix=ERRORS %s
 ; RUN: %szdiff --llvm2ice=%llvm2ice %s | FileCheck --check-prefix=DUMP %s
 
 define internal i32 @cast_f2i(float %f) {
 entry:
   %v0 = bitcast float %f to i32
+; CHECK: bitcast
   ret i32 %v0
 }
 
 define internal float @cast_i2f(i32 %i) {
 entry:
   %v0 = bitcast i32 %i to float
+; CHECK: bitcast
   ret float %v0
 }
 
 define internal i64 @cast_d2ll(double %d) {
 entry:
   %v0 = bitcast double %d to i64
+; CHECK: bitcast
   ret i64 %v0
 }
 
 define internal double @cast_ll2d(i64 %ll) {
 entry:
   %v0 = bitcast i64 %ll to double
+; CHECK: bitcast
   ret double %v0
 }
 
 ; ERRORS-NOT: ICE translation error
 ; DUMP-NOT: SZ