In this chapter we present examples of code generated by the Version 1.7 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_Benchmark (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_Benchmark;
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_benchmark.adb" 2 gcc2_compiled.: 3 __gnu_compiled_ada: 4 .text 5 .global _ada_sieve_benchmark 6 _ada_sieve_benchmark: 7 0000 4AF2 1FFF sim r15,8191 8 0004 9FEE pshm r14,r14 9 0006 81EF lr r14,r15 10 0008 8260 lisp r6,1 11 000a 814F lr r4,r15 12 000c A146 ar r4,r6 13 .L5: 14 000e E555 xorr r5,r5 15 0010 8514 1FFE lim r1,8190,r4 16 0014 8104 lr r0,r4 17 .L9: 18 0016 9111 0000 stc 1,0,r1 19 001a B210 sisp r1,1 20 001c F110 cr r1,r0 21 001e 7BFC jge .L9 22 0020 E533 xorr r3,r3 23 .L15: 24 0022 8114 lr r1,r4 25 0024 A113 ar r1,r3 26 0026 8001 0000 l r0,0,r1 27 002a 4A0A 0000 cim r0,0 28 002e 750F jez .L14 29 0030 8103 lr r0,r3 30 0032 6000 sll r0,1 31 0034 A202 aisp r0,3 32 0036 8123 lr r2,r3 33 0038 7405 j .L27 34 .L19: 35 003a 8114 lr r1,r4 36 003c A112 ar r1,r2 37 003e 9101 0000 stc 0,0,r1 38 .L27: 39 0042 A120 ar r2,r0 40 0044 4A2A 1FFE cim r2,8190 41 0048 78F9 jle .L19 42 004a A250 aisp r5,1 43 .L14: 44 004c A230 aisp r3,1 45 004e 4A3A 1FFE cim r3,8190 46 0052 78E8 jle .L15 47 0054 A260 aisp r6,1 48 0056 F269 cisp r6,10 49 0058 78DB jle .L5 50 005a 8105 lr r0,r5 51 005c 81FE lr r15,r14 52 005e 8FEE popm r14,r14 53 0060 4AF1 1FFF aim r15,8191 54 0064 7FF0 urs r15