Commit Graph

29 Commits

Author SHA1 Message Date
Arnaud A. de Grandmaison a6178a179d [EarlyCSE] Fix handling of target memory intrinsics for CSE'ing loads.
Summary:
Some target intrinsics can access multiple elements, using the pointer as a
base address (e.g. AArch64 ld4). When trying to CSE such instructions,
it must be checked the available value comes from a compatible instruction
because the pointer is not enough to discriminate whether the value is
correct.

Reviewers: ssijaric

Subscribers: mcrosier, llvm-commits, aemerson

Differential Revision: http://reviews.llvm.org/D13475

llvm-svn: 249523
2015-10-07 07:41:29 +00:00
Philip Reames dfd890dd3a Allow value forwarding past release fences in EarlyCSE
A release fence acts as a publication barrier for stores within the current thread to become visible to other threads which might observe the release fence. It does not require the current thread to observe stores performed on other threads. As a result, we can allow store-load and load-store forwarding across a release fence.

We do need to make sure that stores before the fence can't be eliminated even if there's another store to the same location after the fence. In theory, we could reorder the second store above the fence and *then* eliminate the former, but we can't do this if the stores are on opposite sides of the fence.

Note: While more aggressive then what's there, this patch is still implementing a really conservative ordering.  In particular, I'm not trying to exploit undefined behavior via races, or the fact that the LangRef says only 'atomic' accesses are ordered w.r.t. fences.

Differential Revision: http://reviews.llvm.org/D11434

llvm-svn: 246134
2015-08-27 01:32:33 +00:00
Philip Reames 6bbe9743d1 Correct a mistaken comment from 238071 [NFC]
llvm-svn: 238074
2015-05-23 00:05:43 +00:00
Philip Reames 7c78ef7dd9 Extend EarlyCSE to handle basic cases from JumpThreading and CVP
This patch extends EarlyCSE to take advantage of the information that a controlling branch gives us about the value of a Value within this and dominated basic blocks. If the current block has a single predecessor with a controlling branch, we can infer what the branch condition must have been to execute this block. The actual change to support this is downright simple because EarlyCSE's existing scoped hash table logic deals with most of the complexity around merging.

The patch actually implements two optimizations.
1) The first is analogous to JumpThreading in that it enables EarlyCSE's CSE handling to fold branches which are exactly redundant due to a previous branch to branches on constants. (It doesn't actually replace the branch or change the CFG.) This is pretty clearly a win since it enables substantial CFG simplification before we start trying to inline.
2) The second is analogous to CVP in that it exploits the knowledge gained to replace dominated *uses* of the original value. EarlyCSE does not otherwise reason about specific uses, so this is the more arguable one. It does enable further simplication and constant folding within the rest of the visit by EarlyCSE.

In both cases, the added code only handles the easy dominance based case of each optimization. The general case is deferred to the existing passes.

Differential Revision: http://reviews.llvm.org/D9763

llvm-svn: 238071
2015-05-22 23:53:24 +00:00
Hal Finkel 44b81ee40b Preserve the order of READ_REGISTER and WRITE_REGISTER
At the present time, we don't have a way to represent general dependency
relationships, so everything is represented using memory dependency. In order
to preserve the data dependency of a READ_REGISTER on WRITE_REGISTER, we need
to model WRITE_REGISTER as writing (which we had been doing) and model
READ_REGISTER as reading (which we had not been doing). Fix this, and also the
way that the chain operands were generated at the SDAG level.

Patch by Nicholas Paul Johnson, thanks! Test case by me.

llvm-svn: 237584
2015-05-18 16:42:10 +00:00
David Blaikie a79ac14fa6 [opaque pointer type] Add textual IR support for explicit type parameter to load instruction
Essentially the same as the GEP change in r230786.

A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)

import fileinput
import sys
import re

pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")

for line in sys.stdin:
  sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))

Reviewers: rafael, dexonsmith, grosser

Differential Revision: http://reviews.llvm.org/D7649

llvm-svn: 230794
2015-02-27 21:17:42 +00:00
David Majnemer 44a5f22fbc EarlyCSE: Add check lines for test added in r228760
llvm-svn: 228761
2015-02-10 23:11:02 +00:00
David Majnemer 7679300d93 EarlyCSE: It isn't safe to CSE across synchronization boundaries
This fixes PR22514.

llvm-svn: 228760
2015-02-10 23:09:43 +00:00
Chandler Carruth e8c686aa86 [PM] Port EarlyCSE to the new pass manager.
I've added RUN lines both to the basic test for EarlyCSE and the
target-specific test, as this serves as a nice test that the TTI layer
in the new pass manager is in fact working well.

llvm-svn: 227725
2015-02-01 10:51:23 +00:00
Chad Rosier f9327d6fe9 Commoning of target specific load/store intrinsics in Early CSE.
Phabricator revision: http://reviews.llvm.org/D7121
Patch by Sanjin Sijaric <ssijaric@codeaurora.org>!

llvm-svn: 227149
2015-01-26 22:51:15 +00:00
Philip Reames 018dbf18c4 Tweak EarlyCSE to recognize series of dead stores
EarlyCSE is giving up on the current instruction immediately when it recognizes that the current instruction makes a previous store trivially dead. There's no reason to do this. Once the previous store has been deleted, it's perfectly legal to remember the value of the current store (for value forwarding) and the fact the store occurred (it could be dead too!).

Reviewed by: Hal
Differential Revision: http://reviews.llvm.org/D6301

llvm-svn: 222241
2014-11-18 17:46:32 +00:00
Hal Finkel 1e16fa302e EarlyCSE should ignore calls to @llvm.assume
EarlyCSE uses a simple generation scheme for handling memory-based
dependencies, and calls to @llvm.assume (which are marked as writing to memory
to ensure the preservation of control dependencies) disturb that scheme
unnecessarily. Skipping calls to @llvm.assume is legal, and the alternative
(adding AA calls in EarlyCSE) is likely undesirable (we have GVN for that).

Fixes PR21448.

llvm-svn: 221175
2014-11-03 20:21:32 +00:00
Daniel Dunbar 9efbedfd35 [tests] Cleanup initialization of test suffixes.
- Instead of setting the suffixes in a bunch of places, just set one master
   list in the top-level config. We now only modify the suffix list in a few
   suites that have one particular unique suffix (.ml, .mc, .yaml, .td, .py).

 - Aside from removing the need for a bunch of lit.local.cfg files, this enables
   4 tests that were inadvertently being skipped (one in
   Transforms/BranchFolding, a .s file each in DebugInfo/AArch64 and
   CodeGen/PowerPC, and one in CodeGen/SI which is now failing and has been
   XFAILED).

 - This commit also fixes a bunch of config files to use config.root instead of
   older copy-pasted code.

llvm-svn: 188513
2013-08-16 00:37:11 +00:00
Stephen Lin a76289aa1b Catch more CHECK that can be converted to CHECK-LABEL in Transforms for easier debugging. No functionality change.
This conversion was done with the following bash script:

  find test/Transforms -name "*.ll" | \
  while read NAME; do
    echo "$NAME"
    if ! grep -q "^; *RUN: *llc" $NAME; then
      TEMP=`mktemp -t temp`
      cp $NAME $TEMP
      sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
      while read FUNC; do
        sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)define\([^@]*\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3define\4@$FUNC(/g" $TEMP
      done
      mv $TEMP $NAME
    fi
  done

llvm-svn: 186269
2013-07-14 01:50:49 +00:00
Stephen Lin c1c7a1309c Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change.
This update was done with the following bash script:

  find test/Transforms -name "*.ll" | \
  while read NAME; do
    echo "$NAME"
    if ! grep -q "^; *RUN: *llc" $NAME; then
      TEMP=`mktemp -t temp`
      cp $NAME $TEMP
      sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
      while read FUNC; do
        sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP
      done
      mv $TEMP $NAME
    fi
  done

llvm-svn: 186268
2013-07-14 01:42:54 +00:00
David Tweed d505b24277 Initially forgotten-to-svn-add test case for r177279.
llvm-svn: 177280
2013-03-18 12:07:24 +00:00
David Tweed a11edf0ce3 There was a switch fall-through in the parser for textual LLVM that caused
bogus comparison operands to default to eq/oeq. Fix that, fix a couple of
tests that accidentally passed and test for bogus comparison opeartors
explicitly.

llvm-svn: 171733
2013-01-07 13:32:38 +00:00
Michael Ilseman c93cffb590 New EarlyCSE tests for CSE-ing across commutativity.
llvm-svn: 165510
2012-10-09 16:58:13 +00:00
Eli Friedman c8cbd06947 Fix regression from r151466: an we can't replace uses of an instruction reachable from the entry block with uses of an instruction not reachable from the entry block. PR12231.
llvm-svn: 152595
2012-03-13 01:06:07 +00:00
Eli Bendersky 924f9a671d Replace all instances of dg.exp file with lit.local.cfg, since all tests are run with LIT now and now Dejagnu. dg.exp is no longer needed.
Patch reviewed by Daniel Dunbar. It will be followed by additional cleanup patches.

llvm-svn: 150664
2012-02-16 06:28:33 +00:00
Chris Lattner 6a144a2227 Upgrade syntax of tests using volatile instructions to use 'load volatile' instead of 'volatile load', which is archaic.
llvm-svn: 145171
2011-11-27 06:54:59 +00:00
Eli Friedman 02e737b08e Move "atomic" and "volatile" designations on instructions after the opcode
of the instruction.

Note that this change affects the existing non-atomic load and store
instructions; the parser now accepts both forms, and the change is noted
in the release notes.

llvm-svn: 137527
2011-08-12 22:50:01 +00:00
Chris Lattner bde6ec1db6 Duncan deftly points out that readnone functions aren't
invalidated by stores, so they can be handled as 'simple'
operations.

llvm-svn: 122785
2011-01-03 23:38:13 +00:00
Chris Lattner 9e5e9ed79a earlycse can do trivial with-a-block dead store
elimination as well.  This deletes 60 stores in 176.gcc
that largely come from bitfield code.

llvm-svn: 122736
2011-01-03 04:17:24 +00:00
Chris Lattner e0e32a9ef0 now that loads are in their own table, we can implement
store->load forwarding.  This allows EarlyCSE to zap 600 more
loads from 176.gcc.

llvm-svn: 122732
2011-01-03 03:46:34 +00:00
Chris Lattner 0446bb23f8 add a testcase for readonly call CSE
llvm-svn: 122730
2011-01-03 03:33:47 +00:00
Chris Lattner b9a8efc960 Teach EarlyCSE to do trivial CSE of loads and read-only calls.
On 176.gcc, this catches 13090 loads and calls, and increases the
number of simple instructions CSE'd from 29658 to 36208.

llvm-svn: 122727
2011-01-03 03:18:43 +00:00
Chris Lattner 8fac5db251 add DEBUG and -stats output to earlycse.
Teach it to CSE the rest of the non-side-effecting instructions.

llvm-svn: 122716
2011-01-02 23:19:45 +00:00
Chris Lattner 18ae5436b1 Enhance earlycse to do CSE of casts, instsimplify and die.
Add a testcase.

llvm-svn: 122715
2011-01-02 23:04:14 +00:00