flto-report output

[Nilesh Asher]

I am trying to build an application with flto and don't seem to be
observing any run-time benefit. I turned on the -flto-report output to
see if I could glean something from it and I was not able to. Is there
a document that might help me understand what might be going on during
the LTO process that maybe causing an issue.

Here is one snippet from the output. Any help or pointers to
documentation to help me understand the following will be appreciated.
I also got output from [WPA] statements which also would be nice to
understand.

LTRANS statistics
[LTRANS] read 52648 SCCs of average size 4.479467
[LTRANS] 235835 tree bodies read in total
[LTRANS] # of input files: 1
[LTRANS] # of input cgraph nodes: 7662
[LTRANS] # of function bodies: 3418
[LTRANS] Size of mmap'd section decls: 12350701 bytes
[LTRANS] Size of mmap'd section function_body: 9964804 bytes
[LTRANS] Size of mmap'd section statics: 0 bytes
[LTRANS] Size of mmap'd section symtab: 0 bytes
[LTRANS] Size of mmap'd section refs: 25995 bytes
[LTRANS] Size of mmap'd section asm: 0 bytes
[LTRANS] Size of mmap'd section jmpfuncs: 0 bytes
[LTRANS] Size of mmap'd section pureconst: 0 bytes
[LTRANS] Size of mmap'd section reference: 13 bytes
[LTRANS] Size of mmap'd section profile: 0 bytes
[LTRANS] Size of mmap'd section symbol_nodes: 373034 bytes
[LTRANS] Size of mmap'd section opts: 0 bytes
[LTRANS] Size of mmap'd section cgraphopt: 1158 bytes
[LTRANS] Size of mmap'd section inline: 0 bytes
[LTRANS] Size of mmap'd section ipcp_trans: 84 bytes

-flto-report: Prints a report with internal details on the workings of
the link-time optimizer. The contents of this report vary from version
to version. It is meant to be useful to GCC developers when processing
object files in LTO mode (via -flto).

Disabled by default.

-flto-report-wpa: Like -flto-report, but only print for the WPA phase
of Link Time Optimization.