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192539 Commits

Author SHA1 Message Date
Pavel Labath
87036fd412 Recommit "[DWARFDebugLine] Avoid dumping prologue members we did not parse"
The patch was reverted in 69da40033 because of test failures on windows.
The problem was the unpredictable order of some of the error messages,
which I've tried to strenghten in that patch.

It turns out this is not possible to do in verbose mode because there
the data is being writted as it is being parsed. No amount of flushing
(as I've done in the non-verbose mode) will help that. Indeed, even
without any buffering the warning messages can end in the middle of a
line in non-verbose mode.

In this patch, I have reverted the changes which tested the relative
position of the warning message, except for the messages about
unsupported initial length, which are the ones I really wanted to test,
and which do come out reasonably.

The original commit message was:

This patch if motivated by D74560, specifically the subthread about what
to print upon encountering reserved initial length values.

If the debug_line prologue has an unsupported version, we skip parsing
the rest of the data. If we encounter an reserved initial length field,
we don't even parse the version. However, we still print out all members
(with value 0) in the dump function.

This patch introduces early exits in the Prologue::dump function so that
we print only the fields that were parsed successfully. In case of an
unsupported version, we skip printing all subsequent prologue fields --
because we don't even know if this version has those fields. In case of a
reserved unit length, we don't print anything -- if the very first field
of the prologue is invalid, it's hard to say if we even have a prologue
to begin with.

Note that the user will still be able to see the invalid/reserved
initial length value in the error message. I've modified (reordered)
debug_line_invalid.test to show that the error message comes straight
after the debug_line offset. I've also added some flush() calls to the
dumping code to ensure this is the case in all situations (without that,
the warnings could get out of sync if the output was not a terminal -- I
guess this is why std::iostreams have the tie() function).

Reviewers: jhenderson, ikudrin, dblaikie

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75043
2020-02-26 16:42:25 +01:00
Nicolai Hähnle
5308258af1 Full fix for "AMDGPU/SIInsertSkips: Fix the determination of whether early-exit-after-kill is possible" (hopefully)
Properly preserve the MachineDominatorTree in all cases.

Change-Id: I54cf0c0a20934168a356920ba8ed5097a93c4131
2020-02-26 16:21:44 +01:00
Simon Tatham
fa3bb1ebe7 [ARM,MVE] Add predicated intrinsics for many unary functions.
Summary:
This commit adds the predicated MVE intrinsics for the same set of
unary operations that I added in their unpredicated forms in

* D74333 (vrint)
* D74334 (vrev)
* D74335 (vclz, vcls)
* D74336 (vmovl)
* D74337 (vmovn)

but since the predicated versions are a lot more similar to each
other, I've kept them all together in a single big patch. Everything
here is done in the standard way we've been doing other predicated
operations: an IR intrinsic called `@llvm.arm.mve.foo.predicated` and
some isel rules that match that alongside whatever they accept for the
unpredicated version of the same instruction.

In order to write the isel rules conveniently, I've refactored the
existing isel rules for the affected instructions into multiclasses
parametrised by a vector-type class, in the usual way. All those
refactorings are intended to leave the existing isel rules unchanged:
the only difference should be that new ones for the predicated
intrinsics are introduced.

The only tiny infrastructure change I needed in this commit was to
change the implementation of `IntrinsicMX` in `arm_mve_defs.td` so
that the records it defines are anonymous rather than named (and use
`NameOverride` to set the output intrinsic name), which allows me to
call it twice in two multiclasses with the same `NAME` without a
tablegen-time error.

Reviewers: dmgreen, MarkMurrayARM, miyuki, ostannard

Reviewed By: MarkMurrayARM

Subscribers: kristof.beyls, hiraditya, cfe-commits, llvm-commits

Tags: #clang, #llvm

Differential Revision: https://reviews.llvm.org/D75165
2020-02-26 15:12:07 +00:00
Xiangling Liao
05574570dd [AIX] Remove whitelist checking for ExternalSymbolSDNodes
Allow all ExternalSymbolSDNode on AIX, and rely on the linker error to find
symbols which we don't have definitions from any library/compiler-rt.

Differential Revision: https://reviews.llvm.org/D75075
2020-02-26 10:09:25 -05:00
Nicolai Hähnle
cf6f168a7d Quick fix for bot failure on "AMDGPU/SIInsertSkips: Fix the determination of whether early-exit-after-kill is possible"
Apparently the dominator tree update is incorrect, will investigate.

Change-Id: Ie76f8d11b22a552af1f098c893773f3d85e02d4f
2020-02-26 16:02:22 +01:00
Jay Foad
b7d809934c AMDGPU: Fix some more incorrect check lines 2020-02-26 14:37:22 +00:00
Nicolai Hähnle
f5f9572e91 AMDGPU/SIInsertSkips: Fix the determination of whether early-exit-after-kill is possible
Summary:
The old code made some incorrect assumptions about the order in which
basic blocks are laid out in a function. This could lead to incorrect
early-exits, especially when kills occurred inside of loops.

The new approach is to check whether the point where the conditional
kill occurs dominates all reachable code. If that is the case, there
cannot be any other threads in the wave that are waiting to rejoin
at a later point in the CFG, i.e. if exec=0 at that point, then all
threads really are dead and we can exit the wave.

Make some other minor cleanups to the pass while we're at it.

v2: preserve the dominator tree

Reviewers: arsenm, cdevadas, foad, critson

Subscribers: kzhuravl, jvesely, wdng, yaxunl, dstuttard, tpr, t-tye, hiraditya, kerbowa, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74908

Change-Id: Ia0d2b113ac944ad642d1c622b6da1b20aa1aabcc
2020-02-26 15:30:42 +01:00
Nico Weber
62d32d531a [gn build] re-"gn format" all gn files 2020-02-26 08:38:34 -05:00
evgeny
bd658f9fa5 [Assembler] Allow assembling empty index with non-zero flags
Differential revision: https://reviews.llvm.org/D74778
2020-02-26 16:34:11 +03:00
Nico Weber
897342c406 [gn build] (manually) port 2f6cc21f44e 2020-02-26 08:36:05 -05:00
Nico Weber
2719a69c96 [gn build] (manually) merge e058667a2e01 2020-02-26 07:33:32 -05:00
Hans Wennborg
eebd0b92ac Revert "[compiler-rt] Add a critical section when flushing gcov counters"
See discussion on PR44792.

This reverts commit 02ce9d8ef5a84bc884de4105eae5f8736ef67634.

It also reverts the follow-up commits
8f46269f0 "[profile] Don't dump counters when forking and don't reset when calling exec** functions"
62c7d8402 "[profile] gcov_mutex must be static"
2020-02-26 13:27:44 +01:00
Kerry McLaughlin
b66f8caef4 [AArch64][SVE] Add SVE2 intrinsics for bit permutation & table lookup
Summary:
Implements the following intrinsics:
 - @llvm.aarch64.sve.bdep.x
 - @llvm.aarch64.sve.bext.x
 - @llvm.aarch64.sve.bgrp.x
 - @llvm.aarch64.sve.tbl2
 - @llvm.aarch64.sve.tbx

The SelectTableSVE2 function in this patch is used to select the TBL2
intrinsic & ensures that the vector registers allocated are consecutive.

Reviewers: sdesmalen, andwar, dancgr, cameron.mcinally, efriedma, rengolin

Reviewed By: efriedma

Subscribers: tschuett, kristof.beyls, hiraditya, rkruppe, psnobl, cfe-commits, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74912
2020-02-26 11:22:23 +00:00
Sam Parker
128c7bf2c9 [ARM][RDA] add getUniqueReachingMIDef
Add getUniqueReachingMIDef to RDA which performs a global search for
a machine instruction that produces a unique definition of a given
register at a given point. Also add two helper functions
(getMIOperand) that wrap around this functionality to get the
incoming definition uses of a given instruction. These now replace
the uses of getReachingMIDef in ARMLowOverheadLoops. getReachingMIDef
has been renamed to getReachingLocalMIDef and has been made private
along with getInstFromId.

Differential Revision: https://reviews.llvm.org/D74605
2020-02-26 11:15:26 +00:00
Florian Hahn
50b109e86a [AArch64] Flip default for register renaming in the ld/st optimizier.
Turn on register renaming again after disabling it for the 10.0 release,
to help flushing out any issues.
2020-02-26 11:08:17 +00:00
James Henderson
0b366c7be2 [docs][llvm-objcopy][llvm-strip] Move --wildcard description earlier
This moves it above the response file description, which should be at
the end.
2020-02-26 10:51:17 +00:00
James Henderson
a4bfc73d55 [docs][llvm-symbolizer] Fix indentation of inline option examples
The examples for different options were inconsistently indented in
the HTML display. As they are tied to the options, this change
normalises to indent them the same as the option description body.
2020-02-26 10:51:16 +00:00
James Henderson
6332f8afde [docs][llvm-symbolizer] Fix --functions description
"--functions none" and "--functions=none" are not the same. One is the
option "--functions" with its default value of "linkage", followed by an
input address of "none", and the other is "--functions" with the value
"none". This patch fixes the doc to match the actual behaviour by adding
an extra '=' sign in the allowed values description.
2020-02-26 10:50:24 +00:00
Jay Foad
366b1cc00b AMDGPU: Fix some incorrect FUNC-LABEL checks 2020-02-26 09:43:13 +00:00
serge-sans-paille
9479b0618c Remove no un-necessary require for load_extension.ll
Local testing on OSX no longer exhibit the linking error mentioned in
https://reviews.llvm.org/D71959#1860286
2020-02-26 08:29:09 +01:00
Michael Liao
467a5f54d7 Add missing dependency to fix shared library build. 2020-02-26 01:59:53 -05:00
Juneyoung Lee
9381a34667 [SimpleLoopUnswitch] Canonicalize variable names 2020-02-26 15:33:02 +09:00
Jim Lin
a11e0eb481 [ARC][NFC] Remove trailing space 2020-02-26 13:38:51 +08:00
Greg Clayton
75aaaf95b6 Add a llvm-gsymutil tool that can convert object files to GSYM and perform lookups.
Summary:
This patch creates the llvm-gsymutil binary that can convert object files to GSYM using the --convert <path> option. It can also dump and lookup addresses within GSYM files that have been saved to disk.

To dump a file:

llvm-gsymutil /path/to/a.gsym

To perform address lookups, like with atos, on GSYM files:

llvm-gsymutil --address 0x1000 --address 0x1100 /path/to/a.gsym

To convert a mach-o or ELF file, including any DWARF debug info contained within the object files:

llvm-gsymutil --convert /path/to/a.out --out-file /path/to/a.out.gsym

Conversion highlights:
- convert DWARF debug info in mach-o or ELF files to GSYM
- convert symbols in symbol table to GSYM and don't convert symbols that overlap with DWARF debug info
- extract UUID from object files
- extract .text (read + execute) section address ranges and filter out any DWARF or symbols that don't fall in those ranges.
- if .text sections are extracted, and if the last gsym::FunctionInfo object has no size, cap the size to the end of the section the function was contained in

Dumping GSYM files will dump all sections of the GSYM file in textual format.

Reviewers: labath, aadsm, serhiy.redko, jankratochvil, xiaobai, wallace, aprantl, JDevlieghere, jdoerfert

Subscribers: mgorny, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D74883
2020-02-25 21:11:05 -08:00
Juneyoung Lee
33f45df52d [SimpleLoopUnswitch] Fix introduction of UB when hoisted condition may be undef or poison
Summary:
Loop unswitch hoists branches on loop-invariant conditions. However, if this
condition is poison/undef and the branch wasn't originally reachable, loop
unswitch introduces UB (since the optimized code will branch on poison/undef and
the original one didn't)).
We fix this problem by freezing the condition to ensure we don't introduce UB.

We will now transform the following:
  while (...) {
    if (C) { A }
    else   { B }
  }

Into:
  C' = freeze(C)
  if (C') {
    while (...) { A }
  } else {
    while (...) { B }
  }

This patch fixes the root cause of the following bug reports (which use the old loop unswitch, but can be reproduced with minor changes in the code and -enable-nontrivial-unswitch):
- https://llvm.org/bugs/show_bug.cgi?id=27506
- https://llvm.org/bugs/show_bug.cgi?id=31652

Reviewers: reames, majnemer, chenli, sanjoy, hfinkel

Reviewed By: reames

Subscribers: hiraditya, jvesely, nhaehnle, filcab, regehr, trentxintong, nlopes, llvm-commits, mzolotukhin

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D29015
2020-02-26 13:47:33 +09:00
Kang Zhang
012c99178d [PowerPC] Fix the unexpected modification caused by D62993 in LowerSELECT_CC for power9
Summary:
The patch D62993 : `[PowerPC] Emit scalar min/max instructions with unsafe fp math`
has modified the functionality when `Subtarget.hasP9Vector() && (!HasNoInfs || !HasNoNaNs)`,
 this modification is not expected.

Reviewed By: nemanjai

Differential Revision: https://reviews.llvm.org/D74701
2020-02-26 02:59:03 +00:00
Fangrui Song
a962b08ed4 [MC] Default MCContext::UseNamesOnTempLabels to false and only set it to true for MCAsmStreamer
Only MCAsmStreamer (assembly output) needs to keep names of temporary labels created by
MCContext::createTempSymbol().

This change made the rL236642 optimization available for cc2as and
probably some other users.

This eliminates a behavior difference between llvm-mc -filetype=obj and cc1as, which caused
https://reviews.llvm.org/D74006#1890487

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D75097
2020-02-25 18:23:10 -08:00
Fangrui Song
4214138dd0 [MC][ARM] Don't create multiple .ARM.exidx associated to one .text
Fixed an issue exposed by D74006.

In clang cc1as, MCContext::UseNamesOnTempLabels is true.
When parsing a .fnstart directive, FnStart gets redefined to a temporary symbol of a different name (.Ltmp0, .Ltmp1, ...).
MCContext::getELFSection() called by SwitchToEHSection() will create a different .ARM.exidx each time.

llvm-mc uses `Ctx.setUseNamesOnTempLabels(false);` and FnStart is unnamed.
MCContext::getELFSection() called by SwitchToEHSection() will reuse the same .ARM.exidx .

Reviewed By: efriedma

Differential Revision: https://reviews.llvm.org/D75095
2020-02-25 18:18:13 -08:00
Craig Topper
a2db04da96 [SelectionDAG][PowerPC][AArch64][X86][ARM] Add chain input and output the ISD::FLT_ROUNDS_
This node reads the rounding control which means it needs to be ordered properly with operations that change the rounding control. So it needs to be chained to maintain order.

This patch adds a chain input and output to the node and connects it to the chain in SelectionDAGBuilder. I've update all in-tree targets to connect their chain through their lowering code.

Differential Revision: https://reviews.llvm.org/D75132
2020-02-25 16:58:23 -08:00
Lang Hames
e1f68ca3b5 [ORC] Remove the JITDylib::SymbolTableEntry::isInMaterializingState() method.
It was being used inconsistently. Uses have been replaced with direct checks
on the symbol state.
2020-02-25 16:44:12 -08:00
Adrian Prantl
1760eceffa Fix a null dereference in the LLDB data formatters. 2020-02-25 16:43:55 -08:00
Quentin Colombet
02cfbd1931 [GISel][KnownBits] Update a comment regarding the effect of cache on PHIs
Unlike what I claimed in my previous commit. The caching is
actually not NFC on PHIs.

When we put a big enough max depth, we end up simulating loops.
The cache is effectively cutting the simulation short and we
get less information as a result.
E.g.,
```
v0 = G_CONSTANT i8 0xC0
jump
v1 = G_PHI i8 v0, v2
v2 = G_LSHR i8 v1, 1
```

Let say we want the known bits of v1.
- With cache:
Set v1 cache to we know nothing
v1 is v0 & v2
v0 gives us 0xC0
v2 gives us known bits of v1 >> 1
v1 is in the cache
=> v1 is 0, thus v2 is 0x80
Finally v1 is v0 & v2 => 0x80

- Without cache and enough depth to do two iteration of the loop:
v1 is v0 & v2
v0 gives us 0xC0
v2 gives us known bits of v1 >> 1
v1 is v0 & v2
v0 is 0xC0
v2 is v1 >> 1
Reach the max depth for v1...
unwinding
v1 is know nothing
v2 is 0x80
v0 is 0xC0
v1 is 0x80
v2 is 0xC0
v0 is 0xC0
v1 is 0xC0

Thus now v1 is 0xC0 instead of 0x80.

I've added a unittest demonstrating that.

NFC
2020-02-25 15:56:15 -08:00
Vedant Kumar
224bca4498 Revert "[X86MCTargetDesc.h] Speculative fix for macro collision with sys/param.h"
This reverts commit eee22ec3c3712a1089cbdbe66ccf36dd89be507a.

This is not the correct fix, the root cause seems to be a bug in the
stage1 host clang compiler. See https://reviews.llvm.org/D75091 for more
discussion.
2020-02-25 14:38:46 -08:00
Cyndy Ishida
f6b2bf396a [llvm][TextAPI] rename test vars, NFC
* Conforms to clang tidy
2020-02-25 14:28:36 -08:00
Johannes Doerfert
8b8bfe27e8 [OpenMP][Opt] Combine struct ident_t* during deduplication
If we deduplicate OpenMP runtime calls we have multiple `ident_t*` that
represent information like source location. So far, we simply kept the
one used by the replacement call. However, as exposed by PR44893, that
can cause problems if we have stack allocated `ident_t` objects. While
we need to revisit the use of these as well, it is clear that we
eventually want to merge source location information in some way. With
this patch we add the infrastructure to do so but without doing the
actual merge. Instead we pick a global `ident_t` from the replaced
calls, if possible, or create a new one with an unknown location
instead.

Reviewed By: JonChesterfield

Differential Revision: https://reviews.llvm.org/D74925
2020-02-25 14:07:14 -08:00
Thomas Lively
eeefaba5f2 [WebAssembly] Simplify extract_vector lowering
Summary:
Removes patterns that were not doing useful work, changes the
default extract instructions to be the unsigned versions now that
they are enabled by default, fixes PR44988, and adds tests for
sext_inreg lowering.

Reviewers: aheejin

Reviewed By: aheejin

Subscribers: dschuff, sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D75005
2020-02-25 13:54:48 -08:00
Akira Hatanaka
7959a50eda [ObjC][ARC] Don't move a retain call living outside a loop into the loop
body

We started seeing cases where ARC optimizer would move retain calls into
loop bodies, causing imbalance in the number of retain and release
calls, after changes were made to delete inert ARC calls since the inert
calls that used to block code motion are gone.

Fix the bug by setting the CFG hazard flag when visiting a loop header.

rdar://problem/56908836
2020-02-25 13:00:10 -08:00
Craig Topper
6f1baa331b [X86] Add test to show incorrect ordering of flt.rounds intrinsic relative to calls to fesetround.
We don't order flt.rounds intrinsics relative to side effecting
operations in SelectionDAG. And we CSE multiple calls because of
this.
2020-02-25 12:50:28 -08:00
Roman Lebedev
576141ca11 [SCEV][IndVars] Always provide insertion point to the SCEVExpander::isHighCostExpansion()
Summary: This addresses the `llvm/test/Transforms/IndVarSimplify/elim-extend.ll` `@nestedIV` regression from D73728

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73777
2020-02-25 23:05:59 +03:00
Roman Lebedev
845a27780f [SCEV] rewriteLoopExitValues(): even if have hard uses, still rewrite if cheap (PR44668)
Summary:
Replacing uses of IV outside of the loop is likely generally useful,
but `rewriteLoopExitValues()` is cautious, and if it isn't told to always
perform the replacement, and there are hard uses of IV in loop,
it doesn't replace.

In [[ https://bugs.llvm.org/show_bug.cgi?id=44668 | PR44668 ]],
that prevents `-indvars` from replacing uses of induction variable
after the loop, which might be one of the optimization failures
preventing that code from being vectorized.

Instead, now that the cost model is fixed, i believe we should be
a little bit more optimistic, and also perform replacement
if we believe it is within our budget.

Fixes [[ https://bugs.llvm.org/show_bug.cgi?id=44668 | PR44668 ]].

Reviewers: reames, mkazantsev, asbirlea, fhahn, skatkov

Reviewed By: mkazantsev

Subscribers: nikic, hiraditya, zzheng, javed.absar, dmgreen, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73501
2020-02-25 23:05:59 +03:00
Roman Lebedev
f3dbbac126 [SCEV] SCEVExpander::isHighCostExpansionHelper(): cost-model min/max (PR44668)
Summary:
Previosly we simply always said that `SCEVMinMaxExpr` is too costly to expand.
But this isn't really true, it expands into just a comparison+swap pair.
And again much like with add/mul, there will be one less such pair
than the number of operands. And we need to count the cost of operands themselves.

This does change a number of testcases, and as far as i can tell,
all of these changes are improvements, in the sense that
we fixed up more latches to do the [in]equality comparison.

This concludes cost-modelling changes, no other SCEV expressions exist as of now.

This is a part of addressing [[ https://bugs.llvm.org/show_bug.cgi?id=44668 | PR44668 ]].

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: hiraditya, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73744
2020-02-25 23:05:59 +03:00
Roman Lebedev
5776ddc9b2 [SCEV] SCEVExpander::isHighCostExpansionHelper(): cost-model polynomial recurrence
Summary:
So, i wouldn't call this *obviously* correct,
but i think i got it right this time :)

Roughly, we have
```
Op0*x^0 + Op1*x^1 + Op2*x^2 ...
```
where `Op_{n} * x^{n}` is called term, and `n` the degree of term.

Due to the way they are stored internally in `SCEVAddRecExpr`,
i believe we can have `Op_{n}` to be `0`, so we should not charge for those.

I think it is most straight-forward to count the cost in 4 steps:
1. First, count it the same way we counted `scAddExpr`, but be sure to skip terms with zero constants.
   Much like with `add` expr we will have one less addition than number of terms.
2. Each non-constant term (term degree >= 1) requires a multiplication between the `Op_{n}` and `x^{n}`.
   But again, only charge for it if it is required - `Op_{n}` must not be 0 (no term) or 1 (no multiplication needed),
   and obviously don't charge constant terms (`x^0 == 1`).
3. We must charge for all the `x^0`..`x^{poly_degree}` themselves.
   Since `x^{poly_degree}` is `x * x * ...  * x`, i.e. `poly_degree` `x`'es multiplied,
   for final `poly_degree` term we again require `poly_degree-1` multiplications.
   Note that all the `x^{0}`..`x^{poly_degree-1}` will be computed for the free along the way there.
4. And finally, the operands themselves.

Here, much like with add/mul exprs, we really don't look for preexisting instructions..

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: hiraditya, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73741
2020-02-25 23:05:58 +03:00
Roman Lebedev
ab734775f8 [SCEV] SCEVExpander::isHighCostExpansionHelper(): cost-model add/mul
Summary:
While this resolves the regression from D73722 in `llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll`,
this now regresses `llvm/test/Transforms/IndVarSimplify/elim-extend.ll` `@nestedIV` test,
we no longer can perform that expansion within default budget of `4`, but require budget of `6`.
That regression is being addressed by D73777.

The basic idea here is simple.
```
Op0,  Op1, Op2 ...
 |     |    |
 \--+--/    |
    |       |
    \---+---/
```
I.e. given N operands, we will have N-1 operations,
so we have to add cost of an add (mul) for **every** Op processed,
**except** the first one, plus we need to recurse into *every* Op.

I'm guessing there's already canonicalization that ensures we won't
have `1` operand in `scMulExpr`, and no `0` in `scAddExpr`/`scMulExpr`.

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73728
2020-02-25 23:05:58 +03:00
Roman Lebedev
9cb2cc0245 [SCEV] SCEVExpander::isHighCostExpansionHelper(): cost-model plain UDiv
Summary:
If we don't believe this UDiv is actually a LShr in disguise, things are much worse.
First, we try to see if this UDiv actually originates from user code,
by looking for `S + 1`, and if found considering this UDiv to be free.
But otherwise, we always considered this UDiv to be high-cost.

However that is no longer the case with TTI-driven cost model:
our default budget is 4, which matches the default cost of UDiv,
so now we allow a single UDiv to not be counted as high-cost.

While that is the case, it is evident this is actually a regression
due to the fact that cost-modelling is incomplete - we did not account
for the `add`, `mul` costs yet. That is being addressed in D73728.

Cost-modelling for UDiv also seems pretty straight-forward:
subtract cost of the UDiv itself, and recurse into both the LHS and RHS.

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73722
2020-02-25 23:05:58 +03:00
Roman Lebedev
5c8b9ed0bc [NFC][IndVarSimplify] Adjust value names in IndVarSimplify/exit_value_test2.ll
%tmp prefix confuses auto-update scripts
2020-02-25 23:05:58 +03:00
Roman Lebedev
b612c015f2 [SCEV] SCEVExpander::isHighCostExpansionHelper(): cost-model UDiv by power-of-two as LShr
Summary:
Like with casts, we need to subtract the cost of `lshr` instruction
from budget, and recurse into LHS operand.
Seems "pretty obviously correct" to me?

To be noted, there is a number of other shortcuts we //could// cost-model:
* `... + (-1 * ...)` -> `... - ...` <-  likely very frequent case
* `x - (rem x, power-of-2)`, which is currently `(x udiv power-of-2) * power-of-2` -> `x & -log2(power-of-2)`
* `rem x, power-of-2`, which is currently `x - ((x udiv power-of-2) * power-of-2)` -> `x & log2(power-of-2)-1`
* `... * power-of-2` -> `... << log2(power-of-2)` <- likely not very beneficial

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73718
2020-02-25 23:05:58 +03:00
Roman Lebedev
16fb7a66c8 [SCEV] SCEVExpander::isHighCostExpansionHelper(): begin cost modelling - model cast cost
Summary:
This is not a NFC, although it does not change any of the existing tests.
I'm not really sure if we should have specific tests for the cost modelling itself.

This is the first patch that actually makes `SCEVExpander::isHighCostExpansionHelper()`
account for the cost of the SCEV expression, and consider the budget available,
by modelling cast expressions.

I believe the logic itself is "pretty obviously correct" - from budget,
we need to subtract the cost of the cast expression from inner type `Op->getType()`
to the `S->getType()` type, and recurse into the expression we are casting.

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: xbolva00, hiraditya, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73716
2020-02-25 23:05:57 +03:00
Roman Lebedev
3c83b93b49 [SCEV] SCEVExpander::isHighCostExpansion(): assert if TTI is not provided
Summary:
Currently, as per `check-llvm`, we never call `SCEVExpander::isHighCostExpansion()` with null TTI,
so this appears to be a safe restriction.

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: javed.absar, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73712
2020-02-25 23:05:57 +03:00
Roman Lebedev
0d6012de7b [NFC][SCEV] SCEVExpander::isHighCostExpansionHelper(): check that we processed expression first
Summary:
As far as i can tell this is still NFC.
Initially in rL146438 it was added at the top of the function,
later rL238507 dethroned it, and rL244474 did it again.

I'm not sure if we have already checked the cost of this expansion, we should be doing that again.

Reviewers: reames, mkazantsev, wmi, sanjoy, atrick, igor-laevsky

Reviewed By: mkazantsev

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73706
2020-02-25 23:05:57 +03:00
Roman Lebedev
56183251f2 [NFC][SCEV] Piping to pass new SCEVCheapExpansionBudget option into SCEVExpander::isHighCostExpansionHelper()
Summary:
In future patches`SCEVExpander::isHighCostExpansionHelper()` will respect the budget allocated by performing TTI cost modelling.
This is a fully NFC patch to make things reviewable.

Reviewers: reames, mkazantsev, wmi, sanjoy

Reviewed By: mkazantsev

Subscribers: hiraditya, zzheng, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73705
2020-02-25 23:05:57 +03:00