In this chapter we present examples of code generated by the Version 1.8 compiler.
Compiler writers use the Sieve of Eratosthenes benchmark to check code quality and to compare run-time performance among compilers, languages and computers.
The benchmark uses the sieve method to compute the number of odd primes between 3 and 16383.
Example A-1. Source Code for Sieve
procedure Sieve (Result : out Integer) is
Size : constant := 8190;
k, Prime : Natural;
Count : Integer;
type Ftype is array (0 .. Size) of Boolean;
Flags : Ftype;
begin
for Iter in 1 .. 10 loop
Count := 0;
for i in 0 .. Size loop
Flags (i) := True;
end loop;
for i in 0 .. Size loop
if Flags (i) then
Prime := i + i + 3;
k := i + Prime;
while k <= Size loop
Flags (k) := False;
k := k + Prime;
end loop;
Count := Count + 1;
end if;
end loop;
end loop;
Result := Count;
end Sieve;
The generated code is given in Example A-2. The code was generated at optimization level 2 with checks suppressed.
Example A-2. Generated Code for Sieve
1 .file "sieve.adb" 2 gcc2_compiled.: 3 __gnu_compiled_ada: 4 .text 5 .align 4 6 .global _ada_sieve 7 .proc 04 8 _ada_sieve: 9 0000 9DE3BF98 save %sp,-104,%sp 10 0004 80A38007 cmp %sp,%g7 11 0008 89D02009 tleu 9 12 000c 11000008 sethi %hi(8198),%o0 13 0010 90122006 or %o0,%lo(8198),%o0 14 0014 90022063 add %o0,99,%o0 15 0018 900A3FF8 and %o0,-8,%o0 16 001c 90238008 sub %sp,%o0,%o0 17 0020 80A20007 cmp %o0,%g7 18 0024 89D02009 tleu 9 19 0028 9C100008 mov %o0,%sp 20 002c 9A03A060 add %sp,96,%o5 21 0030 84102001 mov 1,%g2 22 0034 11000007 sethi %hi(8190),%o0 23 0038 981223FE or %o0,%lo(8190),%o4 24 003c 86100002 mov %g2,%g3 25 0040 B0102000 mov 0,%i0 26 .L33: 27 0044 90100018 mov %i0,%o0 28 0048 C62B4008 stb %g3,[%o5+%o0] 29 .L29: 30 004c 90022001 add %o0,1,%o0 31 0050 80A2000C cmp %o0,%o4 32 0054 24BFFFFE ble,a .L29 33 0058 C62B4008 stb %g3,[%o5+%o0] 34 005c 96102000 mov 0,%o3 35 0060 D00B400B ldub [%o5+%o3],%o0 36 .L32: 37 0064 80A22000 cmp %o0,0 38 0068 22800012 be,a .L30 39 006c 9602E001 add %o3,1,%o3 40 0070 912AE001 sll %o3,1,%o0 41 0074 90022003 add %o0,3,%o0 42 0078 9202C008 add %o3,%o0,%o1 43 007c 80A2400C cmp %o1,%o4 44 0080 3480000B bg,a .L31 45 0084 B0062001 add %i0,1,%i0 46 0088 80A2400C cmp %o1,%o4 47 .L34: 48 008c 08800003 bleu .L21 49 0090 94100009 mov %o1,%o2 50 0094 91D02005 ta 5 51 .L21: 52 0098 92024008 add %o1,%o0,%o1 53 009c 80A2400C cmp %o1,%o4 54 00a0 04BFFFFB ble .L34 55 00a4 C02B400A stb %g0,[%o5+%o2] 56 00a8 B0062001 add %i0,1,%i0 57 .L31: 58 00ac 9602E001 add %o3,1,%o3 59 .L30: 60 00b0 80A2C00C cmp %o3,%o4 61 00b4 24BFFFEC ble,a .L32 62 00b8 D00B400B ldub [%o5+%o3],%o0 63 00bc 8400A001 add %g2,1,%g2 64 00c0 80A0A00A cmp %g2,10 65 00c4 24BFFFE0 ble,a .L33 66 00c8 B0102000 mov 0,%i0 67 00cc 81C7E008 ret 68 00d0 81E80000 restore