Add Om1 lowering with no optimizations

tests_lit/llvm2ice_tests/simple-loop.ll

-; RUIN: %llvm2ice -verbose inst %s | FileCheck %s
-; RUIN: %llvm2ice --verbose none %s | FileCheck --check-prefix=ERRORS %s
+; This tests a simple loop that sums the elements of an input array.
+; The O2 check patterns represent the best code currently achieved.
+
+; RUIN: %llvm2ice -O2 --verbose none %s | FileCheck %s
+; RUN: %llvm2ice -Om1 --verbose none %s | FileCheck --check-prefix=OPTM1 %s
+; RUN: %llvm2ice --verbose none %s | FileCheck --check-prefix=ERRORS %s
 ; RUN: %szdiff --llvm2ice=%llvm2ice %s | FileCheck --check-prefix=DUMP %s
 
 define i32 @simple_loop(i32 %a, i32 %n) {
 entry:
   %cmp4 = icmp sgt i32 %n, 0
   br i1 %cmp4, label %for.body, label %for.end
 
 for.body:
   %i.06 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
   %sum.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
   %gep_array = mul i32 %i.06, 4
   %gep = add i32 %a, %gep_array
   %gep.asptr = inttoptr i32 %gep to i32*
   %v0 = load i32* %gep.asptr, align 1
   %add = add i32 %v0, %sum.05
   %inc = add i32 %i.06, 1
   %cmp = icmp slt i32 %inc, %n
   br i1 %cmp, label %for.body, label %for.end
 
 for.end:
   %sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
   ret i32 %sum.0.lcssa
 }
 
-; Checks for verbose instruction output
-
-; CHECK:  br i1 %cmp4, label %for.body, label %for.end
-; CHECK-NEXT: for.body
-; CHECK:  %i.06 = phi i32 [ %inc, %for.body ], [ 0, %entry ]
-; CHECK-NEXT:  %sum.05 = phi i32 [ %add, %for.body ], [ 0, %entry ]
-
-; Checks for emitted assembly
-
 ; CHECK:      .globl simple_loop
-
 ; CHECK:      mov ecx, dword ptr [esp+{{[0-9]+}}]
 ; CHECK:      cmp ecx, 0
 ; CHECK-NEXT: jg {{.*}}for.body
 ; CHECK-NEXT: jmp {{.*}}for.end
 
 ; TODO: the mov from ebx to esi seems redundant here - so this may need to be
 ; modified later
 
 ; CHECK:      add [[IREG:[a-z]+]], 1
 ; CHECK-NEXT: mov [[ICMPREG:[a-z]+]], [[IREG]]
 ; CHECK:      cmp [[ICMPREG]], ecx
 ; CHECK-NEXT: jl {{.*}}for.body
+;
+; There's nothing remarkable under Om1 to test for, since Om1 generates
+; such atrocious code (by design).
+; OPTM1:      .globl simple_loop
+; OPTM1:      cmp {{.*}}, 0
+; OPTM1:      jg
+; OPTM1:      ret
 
 ; ERRORS-NOT: ICE translation error
 ; DUMP-NOT: SZ