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5 Commits

Author SHA1 Message Date
Arthur Eubanks
09cfe7939a [SCEV] Fix ScalarEvolution tests under NPM
Many tests use opt's -analyze feature, which does not translate well to
NPM and has better alternatives. The alternative here is to explicitly
add a pass that calls ScalarEvolution::print().

The legacy pass manager RUNs aren't changing, but they are now pinned to
the legacy pass manager.  For each legacy pass manager RUN, I added a
corresponding NPM RUN using the 'print<scalar-evolution>' pass. For
compatibility with update_analyze_test_checks.py and existing test
CHECKs, 'print<scalar-evolution>' now prints what -analyze prints per
function.

This was generated by the following Python script and failures were
manually fixed up:

import sys
for i in sys.argv:
    with open(i, 'r') as f:
        s = f.read()
    with open(i, 'w') as f:
        for l in s.splitlines():
            if "RUN:" in l and ' -analyze ' in l and '\\' not in l:
                f.write(l.replace(' -analyze ', ' -analyze -enable-new-pm=0 '))
                f.write('\n')
                f.write(l.replace(' -analyze ', ' -disable-output ').replace(' -scalar-evolution ', ' "-passes=print<scalar-evolution>" ').replace(" | ", " 2>&1 | "))
                f.write('\n')
            else:
                f.write(l)

There are a couple failures still in ScalarEvolution under NPM, but
those are due to other unrelated naming conflicts.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D83798
2020-07-16 11:24:07 -07:00
Max Kazantsev
3dbdfd12d9 Re-enable "[SCEV] Make computeExitLimit more simple and more powerful"
This patch was temporarily reverted because it has exposed bug 37229 on
PowerPC platform. The bug is unrelated to the patch and was just a general
bug in the optimization done for PowerPC platform only. The bug was fixed
by the patch rL331410.

This patch returns the disabled commit since the bug was fixed.

llvm-svn: 331427
2018-05-03 02:37:55 +00:00
Max Kazantsev
4d04ed1438 Revert "[SCEV] Make computeExitLimit more simple and more powerful"
This reverts commit 023c8be90980e0180766196cba86f81608b35d38.

This patch triggers miscompile of zlib on PowerPC platform. Most likely it is
caused by some pre-backend PPC-specific pass, but we don't clearly know the
reason yet. So we temporally revert this patch with intention to return it
once the problem is resolved. See bug 37229 for details.

llvm-svn: 330893
2018-04-26 02:07:40 +00:00
Max Kazantsev
1ba02c9778 [SCEV] Make computeExitLimit more simple and more powerful
Current implementation of `computeExitLimit` has a big piece of code
the only purpose of which is to prove that after the execution of this
block the latch will be executed. What it currently checks is actually a
subset of situations where the exiting block dominates latch.

This patch replaces all these checks for simple particular cases with
domination check over loop's latch which is the only necessary condition
of taking the exiting block into consideration. This change allows to
calculate exact loop taken count for simple loops like

  for (int i = 0; i < 100; i++) {
    if (cond) {...} else {...}
    if (i > 50) break;
    . . .
  }

Differential Revision: https://reviews.llvm.org/D44677
Reviewed By: efriedma

llvm-svn: 329047
2018-04-03 05:57:19 +00:00
Max Kazantsev
a5495e778b [SCEV] Make exact taken count calculation more optimistic
Currently, `getExact` fails if it sees two exit counts in different blocks. There is
no solid reason to do so, given that we only calculate exact non-taken count
for exiting blocks that dominate latch. Using this fact, we can simply take min
out of all exits of all blocks to get the exact taken count.

This patch makes the calculation more optimistic with enforcing our assumption
with asserts. It allows us to calculate exact backedge taken count in trivial loops
like

  for (int i = 0; i < 100; i++) {
    if (i > 50) break;
    . . .
  }

Differential Revision: https://reviews.llvm.org/D44676
Reviewed By: fhahn

llvm-svn: 328611
2018-03-27 07:30:38 +00:00