[fpc-pascal] Procedural generics question
Sven Barth
pascaldragon at googlemail.com
Wed Aug 26 22:51:24 CEST 2020
Am 25.08.2020 um 23:47 schrieb Benito van der Zander via fpc-pascal:
> Hi,
>
> that is generating rather odd code (r40721)
>
> project1.lpr:9 begin
> 0000000000401090 55 push %rbp
> 0000000000401091 4889e5 mov %rsp,%rbp
> 0000000000401094 488d6424f0 lea -0x10(%rsp),%rsp
> 0000000000401099 48895df8 mov %rbx,-0x8(%rbp)
> project1.lpr:10 if TypeInfo(T) =
> TypeInfo(Integer) then WriteLn('an integer');
> 000000000040109D 488d1584af0700 lea
> 0x7af84(%rip),%rdx # 0x47c028 <RTTI_$SYSTEM_$$_LONGINT>
> 00000000004010A4 488d057daf0700 lea
> 0x7af7d(%rip),%rax # 0x47c028 <RTTI_$SYSTEM_$$_LONGINT>
> 00000000004010AB 4839c2 cmp %rax,%rdx
> 00000000004010AE 752b jne 0x4010db
> <ADD$1$CRC713F463B+75>
> 00000000004010B0 e8cbcf0100 callq 0x41e080 <fpc_get_output>
> 00000000004010B5 4889c3 mov %rax,%rbx
> 00000000004010B8 488d15412f0600 lea
> 0x62f41(%rip),%rdx # 0x464000 <_$PROJECT1$_Ld1>
> 00000000004010BF 4889de mov %rbx,%rsi
> 00000000004010C2 31ff xor %edi,%edi
> 00000000004010C4 e867d30100 callq 0x41e430
> <fpc_write_text_shortstr>
> 00000000004010C9 e8d2700100 callq 0x4181a0 <fpc_iocheck>
> 00000000004010CE 4889df mov %rbx,%rdi
> 00000000004010D1 e85ad20100 callq 0x41e330
> <fpc_writeln_end>
> 00000000004010D6 e8c5700100 callq 0x4181a0 <fpc_iocheck>
> project1.lpr:11 if TypeInfo(T) =
> TypeInfo(String) then WriteLn('a string');
> 00000000004010DB 488d0546af0700 lea
> 0x7af46(%rip),%rax # 0x47c028 <RTTI_$SYSTEM_$$_LONGINT>
> 00000000004010E2 488d1537b20700 lea
> 0x7b237(%rip),%rdx # 0x47c320 <RTTI_$SYSTEM_$$_SHORTSTRING>
> 00000000004010E9 4839d0 cmp %rdx,%rax
> 00000000004010EC 752b jne 0x401119
> <ADD$1$CRC713F463B+137>
> 00000000004010EE e88dcf0100 callq 0x41e080 <fpc_get_output>
> 00000000004010F3 4889c3 mov %rax,%rbx
> 00000000004010F6 488d15132f0600 lea
> 0x62f13(%rip),%rdx # 0x464010 <_$PROJECT1$_Ld2>
> 00000000004010FD 4889de mov %rbx,%rsi
> 0000000000401100 31ff xor %edi,%edi
> 0000000000401102 e829d30100 callq 0x41e430
> <fpc_write_text_shortstr>
> 0000000000401107 e894700100 callq 0x4181a0 <fpc_iocheck>
> 000000000040110C 4889df mov %rbx,%rdi
> 000000000040110F e81cd20100 callq 0x41e330
> <fpc_writeln_end>
> 0000000000401114 e887700100 callq 0x4181a0 <fpc_iocheck>
> project1.lpr:12 end;
>
> The compiler should know everything about TypeInfo(T) and optimize it
> away where possible
For the compiler these are simply ordinary pointers, it does not (yet)
have any knowledge about "constant" pointers. Though there is a bug
report about that exact problem somewhere...
Regards,
Sven
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