[PATCH AutoFDO]Restoring indirect call value profile transformation

["bin.cheng" <bin dot cheng at linux dot alibaba dot com>]

Hi,

Due to ICE and mal-functional bugs, indirect call value profile transformation
is disabled on GCC-7/8/trunk.  This patch restores the transformation.  The
main issue is AutoFDO should store cgraph_node's profile_id of callee func in
the first histogram value's counter, rather than pointer to callee's name string
as it is now.
With the patch, some "Indirect call -> direct call" tests pass with autofdo, while
others are unstable.  I think the instability is caused by poor perf data collected
during regrets run, and can confirm these tests pass if good perf data could be
collected in manual experiments.

Bootstrap and test along with previous patches.  Is it OK?

FYI, an update about AutoFDO status: 
All AutoFDO ICEs in regtest are fixed, while several tests still failing fall in below
three categories:

Unstable indirect call value profile transformation:
FAIL: g++.dg/tree-prof/indir-call-prof.C scan-ipa-dump afdo "Indirect call -> direct call.* AA transformation on insn"
FAIL: g++.dg/tree-prof/morefunc.C scan-ipa-dump-times afdo "Indirect call -> direct call" 2
FAIL: g++.dg/tree-prof/pr35545.C scan-ipa-dump profile_estimate "Indirect call -> direct call"

loop peeling case because we don't honor autofdo profile count as reliable:
FAIL: gcc.dg/tree-prof/peel-1.c scan-tree-dump cunroll "Peeled loop ., 1 times"

cold/hot partition cases:
FAIL: gcc.dg/tree-prof/cold_partition_label.c scan-assembler foo[._]+cold
FAIL: gcc.dg/tree-prof/cold_partition_label.c scan-assembler size[ \ta-zA-Z0-0]+foo[._]+cold
FAIL: gcc.dg/tree-prof/section-attr-1.c scan-assembler .section[\t ]*.text.unlikely[\\n\\r]+[\t ]*.size[\t ]*foo.cold
FAIL: gcc.dg/tree-prof/section-attr-2.c scan-assembler .section[\t ]*.text.unlikely[\\n\\r]+[\t ]*.size[\t ]*foo.cold
FAIL: gcc.dg/tree-prof/section-attr-3.c scan-assembler .section[\t ]*.text.unlikely[\\n\\r]+[\t ]*.size[\t ]*foo.cold
These are more difficult to enable because we can't simply treat autofdo::zero
count as cold, it's just too many.

Besides regtest, I run autofdo with kernel/mysql-server, the build and performance
match expectations now, but I haven't run autofdo with any spec yet.

Thanks,
bin

2018-12-13  Bin Cheng  <bin.cheng@linux.alibaba.com>

        * auto-profile.c (afdo_indirect_call): Skip generating histogram
        value if we can't find cgraph_node for then indirected callee.  Save
        profile_id of the cgraph_node in histogram value's first counter.
        * value-prof.c (gimple_value_profile_transformations): Don't skip
        for flag_auto_profile.

Attachment: 0007-Fix-autofdo-indirect-call-value-prof-transformation.patch
Description: Binary data