How I can see assembler code when Optimization level > 1
lazarus / 12-Debugger

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ydd · 2020-11-18 03:28

I do not need to debug it, just to see

for example - asm code without optimization for:
  i := Length(S);

look like:

Test.lpr:134                         i := Length(S);
00000001000018C3 488b1d46170800           mov    0x81746(%rip),%rbx  
    # 0x100083010
00000001000018CA 4885db                   test   %rbx,%rbx
00000001000018CD 7404                     je     0x1000018d3 <main+51>
00000001000018CF 488b5bf8                 mov    -0x8(%rbx),%rbx
00000001000018D3 4889d8                   mov    %rbx,%rax
00000001000018D6 482d00000080             sub   
$0xffffffff80000000,%rax
00000001000018DC 48baffffffff00000000     movabs $0xffffffff,%rdx
00000001000018E6 4839d0                   cmp    %rdx,%rax
00000001000018E9 7605                     jbe    0x1000018f0 <main+80>
00000001000018EB e880b90000               callq  0x10000d270
<fpc_rangeerror>
00000001000018F0 89d8                     mov    %ebx,%eax
00000001000018F2 890528170800             mov    %eax,0x81728(%rip)  
    # 0x100083020

I believe it is possible to optimize it.
I want to see asm code when optimization is turned on.

For Delphi 2005 same code look like:

Without optimization:

Main.pas.279: i := Length(S);
004309D1 A148964300       mov eax,[$00439648]
004309D6 A354964300       mov [$00439654],eax
004309DB 833D5496430000   cmp dword ptr [$00439654],$00
004309E2 740F             jz $004309f3
004309E4 A154964300       mov eax,[$00439654]
004309E9 83E804           sub eax,$04
004309EC 8B00             mov eax,[eax]
004309EE A354964300       mov [$00439654],eax
004309F3 A154964300       mov eax,[$00439654]
004309F8 A350964300       mov [$00439650],eax

With optimization:

Main.pas.279: i := Length(S);
0042F9D3 8B1548864300     mov edx,[$00438648]
0042F9D9 8BC2             mov eax,edx
0042F9DB 85C0             test eax,eax
0042F9DD 7405             jz $0042f9e4
0042F9DF 83E804           sub eax,$04
0042F9E2 8B00             mov eax,[eax]

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bytebites · 2020-11-18 07:47

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i
O1I:=Length(S);0000000000414DF9 488d0540d91200           lea  
 rax,[rip+0x12d940]      0000000000414E00 488b18                   mov
   rbx,QWORD PTR [rax]0000000000414E03 4885db                   test 
rbx,rbx0000000000414E06 7404                     je     0x414e0c
<main+188>0000000000414E08 488b5bf8                 mov    rbx,QWORD
PTR [rbx-0x8]0000000000414E0C 4889d8                   mov  
 rax,rbx0000000000414E0F 482d00000080             sub  
 rax,0xffffffff80000000 O4I:=Length(S);000000000040BFA4 48c7c0d0335300
          mov    rax,0x5333d0000000000040BFAB 488b00                 
mov    rax,QWORD PTR [rax]000000000040BFAE 4885c0                  
test   rax,rax000000000040BFB1 7404                     je    
0x40bfb7 <main+151>000000000040BFB3 488b40f8                 mov  
 rax,QWORD PTR [rax-0x8]

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PascalDragon · 2020-11-18 08:12

Quote from: ydd on November 18, 2020, 04:28:48 amI want to see asm
code when optimization is turned on.
Simply compile your code with the option -al. The resulting assembly
file will then be called YourFile.s (in the same directory as the ppu
and o files) and will contain the assembly code as its used for the
final object file.

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ydd · 2020-11-18 13:05

Quote from: PascalDragon on November 18, 2020, 09:12:53 amSimply
compile your code with the option -al. The resulting assembly file
will then be called YourFile.s (in the same directory as the ppu and o
files) and will contain the assembly code as its used for the final
object file.

thank you, problem solved!