Bug 19653 – Memory addresses in stacktraces for x86-64 ELFs are only 4 bytes long and don't fall on instruction boundary

I compile the file stacktrace.d: void main(){assert(false);} with ASLR turned off and when running I get: [email protected](2): Assertion failure ---------------- ??:? _d_assertp [0x55586ed8] ??:? _Dmain [0x55586e20] objdump -t stacktrace|grep _Dmain gives 0000000000032e0c w F .text 0000000000000019 _Dmain And if I run gdb -q -nx -ex start -ex 'disas /rs _Dmain' -ex q stacktrace: ... Dump of assembler code for function _Dmain: 0x0000555555586e0c <+0>: 55 push %rbp 0x0000555555586e0d <+1>: 48 8b ec mov %rsp,%rbp => 0x0000555555586e10 <+4>: be 02 00 00 00 mov $0x2,%esi 0x0000555555586e15 <+9>: 48 8d 3d 44 c0 02 00 lea 0x2c044(%rip),%rdi # 0x5555555b2e60 <_TMP0> 0x0000555555586e1c <+16>: e8 47 00 00 00 callq 0x555555586e68 <_d_assertp> 0x0000555555586e21 <+21>: 31 c0 xor %eax,%eax 0x0000555555586e23 <+23>: 5d pop %rbp 0x0000555555586e24 <+24>: c3 retq So even if the first two 0x55 bytes were just truncated off, 0x...86e20 given in the stack trace doesn't match the start of an instruction.

The address truncation would be fixed in https://github.com/dlang/druntime/pull/2151, which doesn't find any reviewer.

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