Add "nop" to IM_DEBUG_BREAK macro to work around GDB bug #7266
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There are two issues here - first, this macro uses AT&T specific syntax with $, which is not necessary. Also, some assemblers (nasm) emit different bytes for "int 3" and "int3", so it's better to use "int3" (cd 03 vs cc) More importantly, GDB has some failing assertion whenever stepping after hitting an "int3" instruction. This makes it practically useless, as is. For some reason, putting a nop afterwards as a workaround is okay. Related discussions: https://sourceware.org/bugzilla/show_bug.cgi?id=31194 https://lists.sr.ht/~skeeto/public-inbox/%3C2d3d7662a361ddd049f7dc65b94cecdd%40disroot.org%3E
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) There are two issues here - first, this macro uses AT&T specific syntax with $, which is not necessary. Also, some assemblers (nasm) emit different bytes for "int 3" and "int3", so it's better to use "int3" (cd 03 vs cc) More importantly, GDB has some failing assertion whenever stepping after hitting an "int3" instruction. This makes it practically useless, as is. For some reason, putting a nop afterwards as a workaround is okay. Related discussions: https://sourceware.org/bugzilla/show_bug.cgi?id=31194 https://lists.sr.ht/~skeeto/public-inbox/%3C2d3d7662a361ddd049f7dc65b94cecdd%40disroot.org%3E
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Thank you Peter! Merged as f1960b6 |
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There are two issues here - first, this macro uses AT&T specific syntax with $, which is not necessary. Also, some assemblers (nasm) emit different bytes for "int 3" and "int3" (cd 03 vs cc), so it's better to use "int3" for consistency.
More importantly, GDB (as of 14.1) has some failing assertion whenever stepping after hitting a lone "int3" instruction. This makes it practically useless, as is. For some reason, putting a nop afterwards as a workaround is okay.
Related discussions:
https://sourceware.org/bugzilla/show_bug.cgi?id=31194
https://lists.sr.ht/~skeeto/public-inbox/%3C2d3d7662a361ddd049f7dc65b94cecdd%40disroot.org%3E
Also, clang's __builtin_debugtrap() runs into this same issue with GDB. I feel uncomfortable commenting the
__builtin_debugtrap()line out, but if it's desired, I'll do so.Of course, there's also the possibility this change is entirely undesired and can be fixed on my end by defining this macro "properly" on my own.