View Issue Details
| ID | Project | Category | View Status | Date Submitted | Last Update |
|---|---|---|---|---|---|
| 0038353 | FPC | Compiler | public | 2021-01-13 23:19 | 2021-04-24 00:08 |
| Reporter | Pierre Muller | Assigned To | Pierre Muller | ||
| Priority | normal | Severity | minor | Reproducibility | always |
| Status | resolved | Resolution | fixed | ||
| Product Version | 3.3.1 | ||||
| Summary | 0038353: Internal x86_64 assembler generates wrong code with -Cg option | ||||
| Description | Current trunk compiler using internal and external assembler generate different relocation code with -O2 option. For x86_64-openbsd target, -Cg option is default (generate_pic_code), which leads to https://www.freepascal.org/testsuite/cgi-bin/new-testsuite2.cgi?run1id=550120&run2id=550150&previousrunid=549871&noskipped=1&failedonly=1&action=Show%2FCompare Example code below is extracted from tvectorcall1.pp test, I do not know the exact difference between R_X86_64_REX_GOTPCRELX and R_X86_64_GOTPCREL, but the main issue it the offset for this relocation is wrong in the internal assembler 17c17 < 16: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_P-0x8 --- > 16: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_P-0x4 leading to the loading of a GOT entry in-between two real entries. This error exists at least for x86_64-linux and x86_64-openbsd (the later does not require the -Cg option, as it is default) | ||||
| Steps To Reproduce | Compile test-got.pp (in between >>>> lines) >>>>>>>>>>> var p : pointer; is_aligned : boolean; begin p:=@p; if (PtrUInt(@p) and $F) <> 0 then is_aligned:=false else is_aligned:=true; end. >>>>>>>>> ppcx64 -O2 -Cg test-got objdump -dr test-got.o > test-got-trunk-O2-Cg.log ppcx64 -O2 -Cg -al test-got objdump -dr test-got.o > test-got-trunk-O2-Cg-al.log diff test-got-trunk-O2-Cg-al.log test-got-trunk-O2-Cg.log gives the following output: muller@gcc10:~/pas/check$ diff test-got-trunk-O2-Cg-al.log test-got-trunk-O2-Cg.log 12c12 < 9: R_X86_64_REX_GOTPCRELX U_$P$PROGRAM_$$_P-0x4 --- > 9: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_P-0x4 17c17 < 16: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_P-0x8 --- > 16: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_P-0x4 20c20 < 23: R_X86_64_REX_GOTPCRELX U_$P$PROGRAM_$$_IS_ALIGNED-0x4 --- > 23: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_IS_ALIGNED-0x4 25c25 < 33: R_X86_64_REX_GOTPCRELX U_$P$PROGRAM_$$_IS_ALIGNED-0x4 --- > 33: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_IS_ALIGNED-0x4 27c27 < 3a: e8 00 00 00 00 callq 3f <U_$P$PROGRAM_$$_IS_ALIGNED+0x37> --- > 3a: e8 00 00 00 00 callq 3f <main+0x3f> 28a29 > ... | ||||
| Tags | No tags attached. | ||||
| Fixed in Revision | 49252 | ||||
| FPCOldBugId | |||||
| FPCTarget | - | ||||
| Attached Files |
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Can you please also attach the logs you use? |
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I suppose you mean the full output of objdump -dr muller@gcc10:~/pas/check$ fpc -iVDWSOSPTOTP 3.3.1 2021/01/14 3.3.1-r20:48150M linux x86_64 linux x86_64 (Note that this does not contain the last commit 48156) muller@gcc10:~/pas/check$ cat test-got-331-O2-Cg.log test-got.o: file format elf64-x86-64 Disassembly of section .text.n_main: 0000000000000000 <main>: 0: 50 push %rax 1: e8 00 00 00 00 callq 6 <main+0x6> 2: R_X86_64_PLT32 fpc_initializeunits-0x4 6: 48 8b 05 00 00 00 00 mov 0x0(%rip),%rax # d <main+0xd> 9: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_P-0x4 d: 48 89 c2 mov %rax,%rdx 10: 48 89 02 mov %rax,(%rdx) 13: 48 f7 05 00 00 00 00 testq $0xf,0x0(%rip) # 1e <main+0x1e> 1a: 0f 00 00 00 16: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_P-0x4 1e: 74 10 je 30 <main+0x30> 20: 48 8b 05 00 00 00 00 mov 0x0(%rip),%rax # 27 <main+0x27> 23: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_IS_ALIGNED-0x4 27: c6 00 00 movb $0x0,(%rax) 2a: eb 0e jmp 3a <main+0x3a> 2c: 0f 1f 40 00 nopl 0x0(%rax) 30: 48 8b 05 00 00 00 00 mov 0x0(%rip),%rax # 37 <main+0x37> 33: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_IS_ALIGNED-0x4 37: c6 00 01 movb $0x1,(%rax) 3a: e8 00 00 00 00 callq 3f <main+0x3f> 3b: R_X86_64_PLT32 fpc_do_exit-0x4 ... muller@gcc10:~/pas/check$ cat test-got-331-O2-Cg-al.log test-got.o: file format elf64-x86-64 Disassembly of section .text.n_main: 0000000000000000 <main>: 0: 50 push %rax 1: e8 00 00 00 00 callq 6 <main+0x6> 2: R_X86_64_PLT32 fpc_initializeunits-0x4 6: 48 8b 05 00 00 00 00 mov 0x0(%rip),%rax # d <main+0xd> 9: R_X86_64_REX_GOTPCRELX U_$P$PROGRAM_$$_P-0x4 d: 48 89 c2 mov %rax,%rdx 10: 48 89 02 mov %rax,(%rdx) 13: 48 f7 05 00 00 00 00 testq $0xf,0x0(%rip) # 1e <main+0x1e> 1a: 0f 00 00 00 16: R_X86_64_GOTPCREL U_$P$PROGRAM_$$_P-0x8 1e: 74 10 je 30 <main+0x30> 20: 48 8b 05 00 00 00 00 mov 0x0(%rip),%rax # 27 <main+0x27> 23: R_X86_64_REX_GOTPCRELX U_$P$PROGRAM_$$_IS_ALIGNED-0x4 27: c6 00 00 movb $0x0,(%rax) 2a: eb 0e jmp 3a <main+0x3a> 2c: 0f 1f 40 00 nopl 0x0(%rax) 30: 48 8b 05 00 00 00 00 mov 0x0(%rip),%rax # 37 <main+0x37> 33: R_X86_64_REX_GOTPCRELX U_$P$PROGRAM_$$_IS_ALIGNED-0x4 37: c6 00 01 movb $0x1,(%rax) 3a: e8 00 00 00 00 callq 3f <U_$P$PROGRAM_$$_IS_ALIGNED+0x37> 3b: R_X86_64_PLT32 fpc_do_exit-0x4 |
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I forgot this: muller@gcc10:~/pas/check$ as --version GNU assembler (GNU Binutils for Debian) 2.28 Copyright (C) 2017 Free Software Foundation, Inc. This program is free software; you may redistribute it under the terms of the GNU General Public License version 3 or later. This program has absolutely no warranty. This assembler was configured for a target of `x86_64-linux-gnu'. |
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I just recompiled binutils 2.35 on gcc10, the output is the same as with binutils 2.28 for that source code. |
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I simplified the source code: with latest trunk compiler, I still get the same relocation error: bash-5.0 ~/pas/check$ cat test-addr.pp { %CPU=x86_64 } program vectorcall_hva_test1; {$IFNDEF CPUX86_64} {$FATAL This test program can only be compiled on Windows or Linux 64-bit with an Intel processor } {$ENDIF} {$ASMMODE Intel} {$PUSH} {$CODEALIGN RECORDMIN=16} {$PACKRECORDS C} type TM128 = record case Byte of 0: (M128_F32: array[0..3] of Single); 1: (M128_F64: array[0..1] of Double); end; {$POP} var HVA: TM128; begin {$ifdef verbose} writeln('@HVA=',hexstr(ptruint(@HVA),2*sizeof(ptruint))); {$endif verbose} if (PtrUInt(@HVA) and $F) <> 0 then begin {$ifdef verbose} WriteLn('FAIL: HVA is not correctly aligned.'); {$endif verbose} Halt(1); end; end. bash-5.0 ~/pas/check$ fpc -O2 test-addr -al -vx Free Pascal Compiler version 3.3.1-r20:49231 [2021/04/19] for x86_64 Copyright (c) 1993-2021 by Florian Klaempfl and others Note: Switching assembler to default source writing assembler Target OS: OpenBSD for x86-64 Compiling test-addr.pp Assembling vectorcall_hva_test1 Executing "/usr/bin/as" with command line "--64 -o test-addr.o test-addr.s" Linking test-addr Executing "/usr/bin/ld.bfd -dynamic-linker=/usr/libexec/ld.so -s -L. -o test-addr link57420.res" with fpSystem call /home/muller/pas/fpc-3.3.1/lib/fpc/3.3.1/units/x86_64-openbsd/rtl/system.o: In function `STRCOPY': ../inc/cgenstr.inc:35: warning: strcpy() is almost always misused, please use strlcpy() 34 lines compiled, 0.2 sec 1 note(s) issued bash-5.0 ~/pas/check$ ./test-addr ; echo "res=$?" res=0 bash-5.0 ~/pas/check$ objdump -dr ./test-addr.o > test-addr-al.o.dis bash-5.0 ~/pas/check$ fpc -O2 test-addr -vx Free Pascal Compiler version 3.3.1-r20:49231 [2021/04/19] for x86_64 Copyright (c) 1993-2021 by Florian Klaempfl and others Target OS: OpenBSD for x86-64 Compiling test-addr.pp Linking test-addr Executing "/usr/bin/ld.bfd -dynamic-linker=/usr/libexec/ld.so -s -L. -o test-addr link83059.res" with fpSystem call /home/muller/pas/fpc-3.3.1/lib/fpc/3.3.1/units/x86_64-openbsd/rtl/system.o: In function `STRCOPY': ../inc/cgenstr.inc:35: warning: strcpy() is almost always misused, please use strlcpy() 34 lines compiled, 0.1 sec bash-5.0 ~/pas/check$ ./test-addr ; echo "res=$?" res=1 bash-5.0 ~/pas/check$ objdump -dr ./test-addr.o > test-addr.o.dis bash-5.0 ~/pas/check$ diff test-addr-al.o.dis test-addr.o.dis 12c12 < 9: R_X86_64_GOTPCREL U_$P$VECTORCALL_HVA_TEST1_$$_HVA+0xfffffffffffffff8 --- > 9: R_X86_64_GOTPCREL U_$P$VECTORCALL_HVA_TEST1_$$_HVA+0xfffffffffffffffc 17c17 < 1d: e8 00 00 00 00 callq 22 <U_$P$VECTORCALL_HVA_TEST1_$$_HVA+0x22> --- > 1d: e8 00 00 00 00 callq 22 <PASCALMAIN+0x22> 18a19 > ... |
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This code was compiled on x86_646openbsd, for which -Cg is default. You can get the same difference in output of disassembly by adding -Cg option on x86_64-linux target. |
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I tried the following, but it crashed on ppc2 during cycle: bash-5.0 ~/pas/trunk/fpcsrc/compiler$ cat wrong-fix-for-bug-report-38353.patch Index: ogelf.pas =================================================================== --- ogelf.pas (revision 49237) +++ ogelf.pas (working copy) @@ -672,7 +672,12 @@ if assigned(objreloc) then begin objreloc.size:=len; - if reltype in [RELOC_RELATIVE{$ifdef x86},RELOC_PLT32{$endif}{$ifdef x86_64},RELOC_TLSGD,RELOC_GOTPCREL{$endif}] then + {$ifdef x86_64} + if reltype = RELOC_GOTPCREL then + dec(data,sizeof(aint)) + else + {$endif x86_64} + if reltype in [RELOC_RELATIVE{$ifdef x86},RELOC_PLT32{$endif}{$ifdef x86_64},RELOC_TLSGD{$endif}] then dec(data,len); if ElfTarget.relocs_use_addend then begin Hopefully someone can look into this issue and solve it correctly! |
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Hopefully completely solved by commit #49252. |
| Date Modified | Username | Field | Change |
|---|---|---|---|
| 2021-01-13 23:19 | Pierre Muller | New Issue | |
| 2021-01-14 21:55 | Florian | Note Added: 0128326 | |
| 2021-01-15 00:05 | Pierre Muller | Note Added: 0128333 | |
| 2021-01-15 00:06 | Pierre Muller | Note Added: 0128334 | |
| 2021-01-15 00:18 | Pierre Muller | Note Added: 0128335 | |
| 2021-04-20 00:22 | Pierre Muller | Note Added: 0130460 | |
| 2021-04-20 00:29 | Pierre Muller | Note Added: 0130461 | |
| 2021-04-20 01:22 | Pierre Muller | Note Added: 0130462 | |
| 2021-04-24 00:08 | Pierre Muller | Assigned To | => Pierre Muller |
| 2021-04-24 00:08 | Pierre Muller | Status | new => resolved |
| 2021-04-24 00:08 | Pierre Muller | Resolution | open => fixed |
| 2021-04-24 00:08 | Pierre Muller | Fixed in Revision | => 49252 |
| 2021-04-24 00:08 | Pierre Muller | FPCTarget | => - |
| 2021-04-24 00:08 | Pierre Muller | Note Added: 0130555 |
