Date: Fri, 10 Feb 2023 09:23:29 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 269455] Using LTO on powerpc64 generates broken binaries Message-ID: <bug-269455-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D269455 Bug ID: 269455 Summary: Using LTO on powerpc64 generates broken binaries Product: Base System Version: CURRENT Hardware: powerpc OS: Any Status: New Severity: Affects Many People Priority: --- Component: bin Assignee: bugs@FreeBSD.org Reporter: pkubaj@FreeBSD.org This is a repost of https://github.com/llvm/llvm-project/issues/46697. I'm creating a PR here, because it turns out that LTO itself works fine when using lld from ports, but is broken with the base lld (lld 15 is also affected). It looks like it has affected powerpc64 ever since the GCC -> LL= VM switch (so LLVM 9), but I never tried linking with ports lld until now. I have a simple test program: int main() { return 0; } and do: root@talos-powerpc64:~ # clang -fuse-ld=3D/usr/local/bin/ld.lld15 -flto tes= t.c root@talos-powerpc64:~ # ./a.out root@talos-powerpc64:~ # clang -flto test.c root@talos-powerpc64:~ # ./a.out Segmentation fault (core dumped) I also deassembled both binaries and did a diff: --- baselld.S 2023-02-09 23:53:53.171611000 +0100 +++ portslld.S 2023-02-09 23:53:58.827662000 +0100 @@ -1,5 +1,5 @@ -a.out2: file format elf64-powerpc +a.out: file format elf64-powerpc Disassembly of section .text: @@ -20,7 +20,7 @@ 10010558: fb df 00 60 std 30, 96(31) 1001055c: 7c be 2b 78 mr 30, 5 ; if (environ =3D=3D NULL) -10010560: e8 a4 80 70 ld 5, -32656(4) +10010560: e8 a4 80 58 ld 5, -32680(4) 10010564: fb 9f 00 50 std 28, 80(31) 10010568: 28 25 00 00 cmpldi 5, 0 1001056c: 7c 7c 1b 78 mr 28, 3 @@ -33,7 +33,7 @@ ; if (environ =3D=3D NULL) 10010588: 40 82 00 0c bf 2, 0x10010594 <_start+0x68> ; environ =3D env; -1001058c: 38 64 80 70 addi 3, 4, -32656 +1001058c: 38 64 80 58 addi 3, 4, -32680 10010590: fb c3 00 00 std 30, 0(3) ; if (argc > 0 && argv[0] !=3D NULL) { 10010594: 2c 1c 00 01 cmpwi 28, 1 @@ -65,7 +65,7 @@ 100105e0: 41 82 00 10 bt 2, 0x100105f0 <_start+0xc4> ; __ps_strings =3D ps_strings; 100105e4: 3c 62 00 01 addis 3, 2, 1 -100105e8: 38 63 80 68 addi 3, 3, -32664 +100105e8: 38 63 80 50 addi 3, 3, -32688 100105ec: f9 03 00 00 std 8, 0(3) ; if (&_DYNAMIC !=3D NULL) 100105f0: 3c 62 ff ff addis 3, 2, -1 @@ -95,8 +95,8 @@ 10010640: 3f 42 00 01 addis 26, 2, 1 ; for (; aux->a_type !=3D AT_NULL; aux++) { 10010644: 7c 63 f2 14 add 3, 3, 30 -10010648: 38 9b 80 78 addi 4, 27, -32648 -1001064c: 38 ba 80 7c addi 5, 26, -32644 +10010648: 38 9b 80 60 addi 4, 27, -32672 +1001064c: 38 ba 80 64 addi 5, 26, -32668 10010650: 38 63 ff f8 addi 3, 3, -8 10010654: 48 00 00 10 b 0x10010664 <_start+0x138> 10010658: 7c a7 2b 78 mr 7, 5 @@ -144,9 +144,9 @@ ; target =3D ((ifunc_resolver_t)ptr)(cpu_features, cpu_featur= es2, 100106e0: 7d 89 03 a6 mtctr 12 100106e4: 39 20 00 00 li 9, 0 -100106e8: 80 7b 80 78 lwz 3, -32648(27) +100106e8: 80 7b 80 60 lwz 3, -32672(27) 100106ec: 39 40 00 00 li 10, 0 -100106f0: 80 9a 80 7c lwz 4, -32644(26) +100106f0: 80 9a 80 64 lwz 4, -32668(26) 100106f4: 4e 80 04 21 bctrl 100106f8: e8 41 00 18 ld 2, 24(1) ; *where =3D target; @@ -169,10 +169,10 @@ 10010734: 4e 80 04 21 bctrl 10010738: e8 41 00 18 ld 2, 24(1) ; exit(main(argc, argv, env)); -1001073c: 3c 62 00 01 addis 3, 2, 1 +1001073c: 3c 62 ff fe addis 3, 2, -2 10010740: 7f a4 eb 78 mr 4, 29 10010744: 7f c5 f3 78 mr 5, 30 -10010748: 39 83 80 50 addi 12, 3, -32688 +10010748: 39 83 7e 30 addi 12, 3, 32304 1001074c: 7f 83 e3 78 mr 3, 28 10010750: 7d 89 03 a6 mtctr 12 10010754: 4e 80 04 21 bctrl @@ -452,6 +452,8 @@ 10010b04: eb e1 ff f8 ld 31, -8(1) 10010b08: 4e 80 00 20 blr ... + +0000000010010b18 <main>: 10010b18: 38 60 00 00 li 3, 0 10010b1c: 90 61 ff f4 stw 3, -12(1) 10010b20: 38 60 00 00 li 3, 0 For some reason, main function is missing when linked with the base lld. Since this issue is non-existent with lld from ports, it must be because of= how we built LLVM. It only affects powerpc64. powerpc and powerpc64le are not affected. If it's necessary to have access to some powerpc64 system for debugging, I = can arrange it. --=20 You are receiving this mail because: You are the assignee for the bug.=
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