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Add optional field indicating multiple symbols at an address

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Adds an optional 'm' as the first field in FUNCTION and PUBLIC records
to indicate that the address corresponds to more than one symbol.
Controls this by a command line flag for now to give symbol file users
a chance to update.

Also reduces the number of IDiaSymbols retained in memory to one per
address. This reduces memory consumption by 8% when processing
chrome.dll.pdb.

Updates the processor to parse the new optional field.

Bug: google-breakpad:751
Change-Id: I6503edaf057312d21a1d63d9c84e5a4fa019dc46
Reviewed-on: https://chromium-review.googlesource.com/773418
Reviewed-by: Mark Mentovai <mark@chromium.org>
This commit is contained in:
Mike Wittman 2017-11-29 13:29:37 -08:00 • committed by Mark Mentovai
parent 4eeb384f3e
commit b1226959a2
12 changed files with 324 additions and 148 deletions
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18
docs/symbol_files.md
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@ -100,12 +100,17 @@ the file; it may contain spaces.
A `FUNC` record describes a source-language function. It has the form:
> `FUNC` _address_ _size_ _parameter\_size_ _name_
> `FUNC` _[m]_ _address_ _size_ _parameter\_size_ _name_
For example: `FUNC c184 30 0 nsQueryInterfaceWithError::operator()(nsID const&,
For example: `FUNC m c184 30 0 nsQueryInterfaceWithError::operator()(nsID const&,
void**) const
`
The _m_ field is optional. If present it indicates that multiple symbols
reference this function's instructions. (In which case, only one symbol name is
mentioned within the breakpad file.) Multiple symbols referencing the same
instructions may occur due to identical code folding by the linker.
The _address_ and _size_ fields are hexadecimal numbers indicating the start
address and length in bytes of the machine code instructions the function
occupies. (Breakpad symbol files cannot accurately describe functions whose code
@ -158,9 +163,9 @@ A `PUBLIC` record describes a publicly visible linker symbol, such as that used
to identify an assembly language entry point or region of memory. It has the
form:
> PUBLIC _address_ _parameter\_size_ _name_
> PUBLIC _[m]_ _address_ _parameter\_size_ _name_
For example: `PUBLIC 2160 0 Public2_1
For example: `PUBLIC m 2160 0 Public2_1
`
The Breakpad processor essentially treats a `PUBLIC` record as defining a
@ -168,6 +173,11 @@ function with no line number data and an indeterminate size: the code extends to
the next address mentioned. If a given address is covered by both a `PUBLIC`
record and a `FUNC` record, the processor uses the `FUNC` data.
The _m_ field is optional. If present it indicates that multiple symbols
reference this function's instructions. (In which case, only one symbol name is
mentioned within the breakpad file.) Multiple symbols referencing the same
instructions may occur due to identical code folding by the linker.
The _address_ field is a hexadecimal number indicating the symbol's address,
relative to the module's load address.