Add Om1 lowering with no optimizations

tests_lit/llvm2ice_tests/shift.ll

-; RUIN: %llvm2ice -verbose inst %s | FileCheck %s
-; RUIN: %llvm2ice --verbose none %s | FileCheck --check-prefix=ERRORS %s
+; This is a test of C-level conversion operations that clang lowers
+; into pairs of shifts.
+
+; RUIN: %llvm2ice -O2 --verbose none %s | FileCheck %s
+; RUN: %llvm2ice -Om1 --verbose none %s | FileCheck %s
+; RUN: %llvm2ice --verbose none %s | FileCheck --check-prefix=ERRORS %s
 ; RUN: %szdiff --llvm2ice=%llvm2ice %s | FileCheck --check-prefix=DUMP %s
 
 @i1 = common global i32 0, align 4
 @i2 = common global i32 0, align 4
 @u1 = common global i32 0, align 4
 @u2 = common global i32 0, align 4
 
 define void @conv1() {
 entry:
   %v0 = load i32* @u1, align 1
   %sext = shl i32 %v0, 24
   %v1 = ashr i32 %sext, 24
   store i32 %v1, i32* @i1, align 1
   ret void
-  ; CHECK: shl eax, 24
-  ; CHECK-NEXT: sar eax, 24
 }
+; CHECK: conv1:
+; CHECK: shl {{.*}}, 24
+; CHECK: sar {{.*}}, 24
 
 define void @conv2() {
 entry:
   %v0 = load i32* @u1, align 1
   %sext1 = shl i32 %v0, 16
   %v1 = ashr i32 %sext1, 16
   store i32 %v1, i32* @i2, align 1
   ret void
-  ; CHECK: shl eax, 16
-  ; CHECK-NEXT: sar eax, 16
 }
+; CHECK: conv2:
+; CHECK: shl {{.*}}, 16
+; CHECK: sar {{.*}}, 16
 
 ; ERRORS-NOT: ICE translation error
 ; DUMP-NOT: SZ