[Issue 5100] -O Degrades performance of loop statements

d-bugmail at puremagic.com d-bugmail at puremagic.com
Mon Dec 6 14:53:11 PST 2010


http://d.puremagic.com/issues/show_bug.cgi?id=5100



--- Comment #4 from Iain Buclaw <ibuclaw at ubuntu.com> 2010-12-06 14:51:32 PST ---
objdump without -O on Linux:

push   %ebp
mov    %esp,%ebp
sub    $0x4,%esp
movl   $0x0,-0x4(%ebp)
cmpl   $0x7fffffff,-0x4(%ebp)
jge    1c <_Dmain+0x1c>
addl   $0x1,-0x4(%ebp)
jmp    d <_Dmain+0xd>
xor    %eax,%eax
leave  
ret    


objdump with -O on Linux

push   %ebp
mov    %esp,%ebp
xor    %eax,%eax
add    $0x1,%eax
cmp    $0x7fffffff,%eax
jb     5 <_Dmain+0x5>
pop    %ebp
xor    %eax,%eax
ret    


Looks to be same as what Don said that was on his Windows box.


Wonder why Linux is slower... (must be a quirk, that or my Intel Atom CPU is to
blame).

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