Commit Graph

33 Commits

Author SHA1 Message Date
Max Kazantsev 90798e09e2 Re-enable "[InstCombine] Simplify boolean Phis with const inputs using CFG"
This reverts commit b893822e32.

+ Clang test fixes
+ Insertion point fix for landing pads
2020-07-16 16:09:08 +07:00
Max Kazantsev b893822e32 Revert "[InstCombine] Simplify boolean Phis with const inputs using CFG"
This reverts commit 00472067c3.

Need to fix failing clang tests.
2020-07-16 12:58:39 +07:00
Max Kazantsev 00472067c3 [InstCombine] Simplify boolean Phis with const inputs using CFG
This patch adds simplification for pattern:
```
  if (cond)
  /       \
 ...      ...
  \       /
p = phi [true] [false]
...
br p, succ_1, succ_2
```
If we can prove that top block's branches dominate respective
inputs of a block that has a Phi with constant inputs, we can
use the branch condition (maybe inverted) instead of Phi.
This will make proofs of implication for further jump threading
more transparent.

Differential Revision: https://reviews.llvm.org/D81375
Reviewed By: xbolva00
2020-07-16 12:06:10 +07:00
Nick Desaulniers 88c965ba14 BreakCriticalEdges for callbr indirect dests
Summary:
llvm::SplitEdge was failing an assertion that the BasicBlock only had
one successor (for BasicBlocks terminated by CallBrInst, we typically
have multiple successors).  It was surprising that the earlier call to
SplitCriticalEdge did not handle the critical edge (there was an early
return).  Removing that triggered another assertion relating to creating
a BlockAddress for a BasicBlock that did not (yet) have a parent, which
is a simple order of operations issue in llvm::SplitCriticalEdge (a
freshly constructed BasicBlock must be inserted into a Function's basic
block list to have a parent).

Thanks to @nathanchance for the report.
Fixes: https://github.com/ClangBuiltLinux/linux/issues/1018

Reviewers: craig.topper, jyknight, void, fhahn, efriedma

Reviewed By: efriedma

Subscribers: eli.friedman, rnk, efriedma, fhahn, hiraditya, llvm-commits, nathanchance, srhines

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81607
2020-06-17 11:45:06 -07:00
Jonathan Roelofs 7c5d2bec76 [llvm] Fix missing FileCheck directive colons
https://reviews.llvm.org/D77352
2020-04-06 09:59:08 -06:00
Florian Hahn a63b5c9e53 [CallSiteSplitting] Simplify isPredicateOnPHI & continue checking PHIs.
As pointed out by @thakis, currently CallSiteSplitting bails out after
checking the first PHI node. We should check all PHI nodes, until we
find one where call site splitting is beneficial.

This patch also slightly simplifies the code using BasicBlock::phis().

Reviewers: davidxl, junbuml, thakis

Reviewed By: davidxl

Differential Revision: https://reviews.llvm.org/D77089
2020-04-02 10:11:27 +01:00
Matt Arsenault f80c4241b3 CallSiteSplitting: Respect convergent and noduplicate
llvm-svn: 361990
2019-05-29 16:59:48 +00:00
David Bolvansky 0290a77aa8 [SimplifyCFG] Added condition assumption for unreachable blocks
Summary: PR41688

Reviewers: spatel, efriedma, craig.topper, hfinkel, reames

Reviewed By: hfinkel

Subscribers: javed.absar, dmgreen, fhahn, hfinkel, reames, nikic, lebedev.ri, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61409

llvm-svn: 361707
2019-05-25 22:34:27 +00:00
David Bolvansky bb76cf0f96 [NFC] Update test checks
llvm-svn: 361695
2019-05-25 13:11:22 +00:00
Eric Christopher cee313d288 Revert "Temporarily Revert "Add basic loop fusion pass.""
The reversion apparently deleted the test/Transforms directory.

Will be re-reverting again.

llvm-svn: 358552
2019-04-17 04:52:47 +00:00
Eric Christopher a863435128 Temporarily Revert "Add basic loop fusion pass."
As it's causing some bot failures (and per request from kbarton).

This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.

llvm-svn: 358546
2019-04-17 02:12:23 +00:00
Joseph Tremoulet 926ee459c4 [CallSiteSplitting] Report edge deletion to DomTreeUpdater
Summary:
When splitting musttail calls, the split blocks' original terminators
get removed; inform the DTU when this happens.

Also add a testcase that fails an assertion in the DTU without this fix.


Reviewers: fhahn, junbuml

Reviewed By: fhahn

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D55027

llvm-svn: 347872
2018-11-29 15:27:04 +00:00
Florian Hahn 505091a8f2 Recommit r346483: [CallSiteSplitting] Only record conditions up to the IDom(call site).
The underlying problem causing the expensive-check failure was fixed in
rL346769.

llvm-svn: 346843
2018-11-14 10:04:30 +00:00
Florian Hahn 107d0a8756 [CSP, Cloning] Update DuplicateInstructionsInSplitBetween to use DomTreeUpdater.
This patch updates DuplicateInstructionsInSplitBetween to update a DTU
instead of applying updates to the DT directly.

Given that there only are 2 users, also updated them in this patch to
avoid churn.

I slightly moved the code in CallSiteSplitting around to reduce the
places where we have to pass in DTU. If necessary, I could split those
changes in a separate patch.

This fixes missing DT updates when dealing with musttail calls in
CallSiteSplitting, by using DTU->deleteBB.

Reviewers: junbuml, kuhar, NutshellySima, indutny, brzycki

Reviewed By: NutshellySima

llvm-svn: 346769
2018-11-13 17:54:43 +00:00
Florian Hahn 9f878e9bae Revert r346483: [CallSiteSplitting] Only record conditions up to the IDom(call site).
This cause a failure with EXPENSIVE_CHECKS

llvm-svn: 346492
2018-11-09 13:28:58 +00:00
Florian Hahn 52578f95c9 [CallSiteSplitting] Only record conditions up to the IDom(call site).
We can stop recording conditions once we reached the immediate dominator
for the block containing the call site. Conditions in predecessors of the
that node will be the same for all paths to the call site and splitting
is not beneficial.

This patch makes CallSiteSplitting dependent on the DT anlysis. because
the immediate dominators seem to be the easiest way of finding the node
to stop at.

I had to update some exiting tests, because they were checking for
conditions that were true/false on all paths to the call site. Those
should now be handled by instcombine/ipsccp.

Reviewers: davide, junbuml

Reviewed By: junbuml

Differential Revision: https://reviews.llvm.org/D44627

llvm-svn: 346483
2018-11-09 10:23:46 +00:00
Florian Hahn 5b7e21a6b7 [CallSiteSplitting] Add debug location to created PHI nodes.
There are 2 cases when we create PHI nodes:
 * For the result of the call that was duplicated in the split blocks.
   Those PHI nodes should have the debug location of the call.

 * For values produced before the call. Those instructions need to be
   duplicated in the split blocks and the PHI nodes should have the
   debug locations of those instructions.

Fixes PR37962.

Reviewers: junbuml, gbedwell, vsk

Reviewed By: junbuml

Tags: #debug-info

Differential Revision: https://reviews.llvm.org/D51919

llvm-svn: 341970
2018-09-11 17:55:58 +00:00
Xin Tong 8edff27923 [CallSiteSplit] Make sure we remove nonnull if the parameter turns out to be a constant.
Summary: We do not need nonull attribute if we know an argument is going to be constant.

Reviewers: junbuml, davide, fhahn

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D45608

llvm-svn: 330641
2018-04-23 20:09:08 +00:00
Taewook Oh e0db533feb [CallSiteSplitting] Do not perform callsite splitting inside landing pad
Summary:
If the callsite is inside landing pad, do not perform callsite splitting.

Callsite splitting uses utility function llvm::DuplicateInstructionsInSplitBetween, which eventually calls llvm::SplitEdge. llvm::SplitEdge calls llvm::SplitCriticalEdge with an assumption that the function returns nullptr only when the target edge is not a critical edge (and further assumes that if the return value was not nullptr, the predecessor of the original target edge always has a single successor because critical edge splitting was successful). However, this assumtion is not true because SplitCriticalEdge returns nullptr if the destination block is a landing pad. This invalid assumption results assertion failure.

Fundamental solution might be fixing llvm::SplitEdge to not to rely on the invalid assumption. However, it'll involve a lot of work because current API assumes that llvm::SplitEdge never fails. Instead, this patch makes callsite splitting to not to attempt splitting if the callsite is in a landing pad.

Attached test case will crash with assertion failure without the fix.

Reviewers: fhahn, junbuml, dberlin

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D45130

llvm-svn: 329250
2018-04-05 04:16:23 +00:00
Florian Hahn 517dc51c48 [CallSiteSplitting] Do not crash when BB's terminator changes.
Change doCallSiteSplitting to iterate until we reach the terminator instruction.
tryToSplitCallSite can replace BB's terminator in case BB is a successor of
itself. Then IE will be invalidated and we also have to check the current
terminator.

Reviewers: junbuml, davidxl, davide, fhahn

Reviewed By: fhahn, junbuml

Differential Revision: https://reviews.llvm.org/D43824

llvm-svn: 326793
2018-03-06 14:00:58 +00:00
Fedor Indutny f9e09c1dd0 [CallSiteSplitting] properly split musttail calls
Summary:
`musttail` calls can't be naively splitted. The split blocks must
include not only the call instruction itself, but also (optional)
`bitcast` and `return` instructions that follow it.

Clone `bitcast` and `ret`, place them into the split blocks, and
remove the tail block when done.

Reviewers: junbuml, mcrosier, davidxl, davide, fhahn

Reviewed By: fhahn

Subscribers: JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D43729

llvm-svn: 326666
2018-03-03 21:40:14 +00:00
Florian Hahn b4e3bad89b Recommit r325001: [CallSiteSplitting] Support splitting of blocks with instrs before call.
For basic blocks with instructions between the beginning of the block
and a call we have to duplicate the instructions before the call in all
split blocks and add PHI nodes for uses of the duplicated instructions
after the call.

Currently, the threshold for the number of instructions before a call
is quite low, to keep the impact on binary size low.

Reviewers: junbuml, mcrosier, davidxl, davide

Reviewed By: junbuml

Differential Revision: https://reviews.llvm.org/D41860

llvm-svn: 325126
2018-02-14 13:59:12 +00:00
Florian Hahn 35d744d388 Revert r325001: [CallSiteSplitting] Support splitting of blocks with instrs before call.
Due to memsan not being happy with the array of ValueToValue maps.

llvm-svn: 325009
2018-02-13 14:48:39 +00:00
Florian Hahn b0884b6443 [CallSiteSplitting] Support splitting of blocks with instrs before call.
For basic blocks with instructions between the beginning of the block
and a call we have to duplicate the instructions before the call in all
split blocks and add PHI nodes for uses of the duplicated instructions
after the call.

Currently, the threshold for the number of instructions before a call
is quite low, to keep the impact on binary size low.

Reviewers: junbuml, mcrosier, davidxl, davide

Reviewed By: junbuml

Differential Revision: https://reviews.llvm.org/D41860

llvm-svn: 325001
2018-02-13 12:00:48 +00:00
Florian Hahn 212afb9fd9 [CallSiteSplitting] Fix infinite loop when recording conditions.
Fix infinite loop when recording conditions by correctly marking basic
blocks as visited.

Fixes https://bugs.llvm.org/show_bug.cgi?id=36105

llvm-svn: 323515
2018-01-26 10:36:50 +00:00
Florian Hahn c6c89bffdc [CallSiteSplitting] Pass list of (BB, Conditions) pairs to splitCallSite.
This removes some duplication from splitCallSite and makes it easier to
add additional code dealing with each predecessor. It also allows us to
split for more than 2 predecessors, although that is not enabled for
now.

Reviewers: junbuml, mcrosier, davidxl, davide

Reviewed By: junbuml

Differential Revision: https://reviews.llvm.org/D41858

llvm-svn: 322599
2018-01-16 22:13:15 +00:00
Florian Hahn 7e9328906b [CallSiteSplitting] Remove isOrHeader restriction.
By following the single predecessors of the predecessors of the call
site, we do not need to restrict the control flow.

Reviewed By: junbuml, davide

Differential Revision: https://reviews.llvm.org/D40729

llvm-svn: 321413
2017-12-23 20:02:26 +00:00
Florian Hahn beda7d517d [CallSiteSplitting] Refactor creating callsites.
Summary:
This change makes the call site creation more general if any of the
arguments is predicated on a condition in the call site's predecessors.

If we find a callsite, that potentially can be split, we collect the set
of conditions for the call site's predecessors (currently only 2
predecessors are allowed). To do that, we traverse each predecessor's
predecessors as long as it only has single predecessors and record the
condition, if it is relevant to the call site. For each condition, we
also check if the condition is taken or not. In case it is not taken,
we record the inverse predicate.

We use the recorded conditions to create the new call sites and split
the basic block.

This has 2 benefits: (1) it is slightly easier to see what is going on
(IMO) and (2) we can easily extend it to handle more complex control
flow.

Reviewers: davidxl, junbuml

Reviewed By: junbuml

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D40728

llvm-svn: 320547
2017-12-13 03:05:20 +00:00
Mikael Holmen 66cf383761 [CallSiteSplitting] Don't let debug intrinsics affect optimizations
Summary:
This solves PR35616.

We don't want the compiler to generate different code when we compile
with/without -g, so we now ignore debug intrinsics when determining if
the optimization can trigger or not.

Reviewers: junbuml

Subscribers: davide, JDevlieghere, llvm-commits

Differential Revision: https://reviews.llvm.org/D41068

llvm-svn: 320460
2017-12-12 07:29:57 +00:00
Florian Hahn 2a266a343f [CallSiteSplitting] Remove some indirection (NFC).
Summary:
With this patch I tried to reduce the complexity of the code sightly, by
removing some indirection. Please let me know what you think.

Reviewers: junbuml, mcrosier, davidxl

Reviewed By: junbuml

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D40037

llvm-svn: 318593
2017-11-18 18:14:13 +00:00
Jun Bum Lim 0c99007db1 Recommit r317351 : Add CallSiteSplitting pass
This recommit r317351 after fixing a buildbot failure.

Original commit message:

    Summary:
    This change add a pass which tries to split a call-site to pass
    more constrained arguments if its argument is predicated in the control flow
    so that we can expose better context to the later passes (e.g, inliner, jump
    threading, or IPA-CP based function cloning, etc.).
    As of now we support two cases :

    1) If a call site is dominated by an OR condition and if any of its arguments
    are predicated on this OR condition, try to split the condition with more
    constrained arguments. For example, in the code below, we try to split the
    call site since we can predicate the argument (ptr) based on the OR condition.

    Split from :
          if (!ptr || c)
            callee(ptr);
    to :
          if (!ptr)
            callee(null ptr)  // set the known constant value
          else if (c)
            callee(nonnull ptr)  // set non-null attribute in the argument

    2) We can also split a call-site based on constant incoming values of a PHI
    For example,
    from :
          BB0:
           %c = icmp eq i32 %i1, %i2
           br i1 %c, label %BB2, label %BB1
          BB1:
           br label %BB2
          BB2:
           %p = phi i32 [ 0, %BB0 ], [ 1, %BB1 ]
           call void @bar(i32 %p)
    to
          BB0:
           %c = icmp eq i32 %i1, %i2
           br i1 %c, label %BB2-split0, label %BB1
          BB1:
           br label %BB2-split1
          BB2-split0:
           call void @bar(i32 0)
           br label %BB2
          BB2-split1:
           call void @bar(i32 1)
           br label %BB2
          BB2:
           %p = phi i32 [ 0, %BB2-split0 ], [ 1, %BB2-split1 ]

llvm-svn: 317362
2017-11-03 20:41:16 +00:00
Jun Bum Lim 0eb1c2d63a Revert "Add CallSiteSplitting pass"
Revert due to Buildbot failure.

This reverts commit r317351.

llvm-svn: 317353
2017-11-03 19:17:11 +00:00
Jun Bum Lim 2a58933519 Add CallSiteSplitting pass
Summary:
This change add a pass which tries to split a call-site to pass
more constrained arguments if its argument is predicated in the control flow
so that we can expose better context to the later passes (e.g, inliner, jump
threading, or IPA-CP based function cloning, etc.).
As of now we support two cases :

1) If a call site is dominated by an OR condition and if any of its arguments
are predicated on this OR condition, try to split the condition with more
constrained arguments. For example, in the code below, we try to split the
call site since we can predicate the argument (ptr) based on the OR condition.

Split from :
      if (!ptr || c)
        callee(ptr);
to :
      if (!ptr)
        callee(null ptr)  // set the known constant value
      else if (c)
        callee(nonnull ptr)  // set non-null attribute in the argument

2) We can also split a call-site based on constant incoming values of a PHI
For example,
from :
      BB0:
       %c = icmp eq i32 %i1, %i2
       br i1 %c, label %BB2, label %BB1
      BB1:
       br label %BB2
      BB2:
       %p = phi i32 [ 0, %BB0 ], [ 1, %BB1 ]
       call void @bar(i32 %p)
to
      BB0:
       %c = icmp eq i32 %i1, %i2
       br i1 %c, label %BB2-split0, label %BB1
      BB1:
       br label %BB2-split1
      BB2-split0:
       call void @bar(i32 0)
       br label %BB2
      BB2-split1:
       call void @bar(i32 1)
       br label %BB2
      BB2:
       %p = phi i32 [ 0, %BB2-split0 ], [ 1, %BB2-split1 ]

Reviewers: davidxl, huntergr, chandlerc, mcrosier, eraman, davide

Reviewed By: davidxl

Subscribers: sdesmalen, ashutosh.nema, fhahn, mssimpso, aemerson, mgorny, mehdi_amini, kristof.beyls, llvm-commits

Differential Revision: https://reviews.llvm.org/D39137

llvm-svn: 317351
2017-11-03 19:01:57 +00:00