Commit Graph

3 Commits

Author SHA1 Message Date
Zachary Turner f4b6dcf6af [PDB] Print some more details when explaining MSF fields.
When we determine that a field belongs to an MSF super block or
the free page map, we wouldn't print any additional information.

With this patch, we now print the value of the field (for super
block fields) or the allocation status of the specified byte (in
the case of offsets in the FPM).

llvm-svn: 328808
2018-03-29 17:45:34 +00:00
Zachary Turner 1b20416bfa [PDB] Fix a bug in the explain subcommand.
We were trying to dig into the super block fields and print a
description of the field at the specified offset, but we were
printing the wrong field due to an off-by-one-field-error.

llvm-svn: 328804
2018-03-29 17:11:14 +00:00
Zachary Turner ea40f40e1b [PDB] Add an explain subcommand.
When investigating various things, we often have a file offset
and what to know what's in the PDB at that address.  For example
we may be doing a binary comparison of two LLD-generated PDBs
to look for sources of non-determinism, or we may wish to compare
an LLD-generated PDB with a Microsoft generated PDB for sources
of byte-for-byte incompatibility.  In these cases, we can do a
binary diff of the two files, and once we find a mismatched byte
we can use explain to figure out what that byte is, immediately
honining in on the problem.

This patch implements this by trying to narrow the meaning of
a particular file offset down as much as possible.

Differential Revision: https://reviews.llvm.org/D44959

llvm-svn: 328799
2018-03-29 16:28:20 +00:00