Commit Graph

35 Commits

Author SHA1 Message Date
Sanjay Patel 6f2cf73b37 [PhaseOrdering] remove stale comments; NFC
Forgot to update this with rL331937.

llvm-svn: 331939
2018-05-09 23:10:46 +00:00
Sanjay Patel ac3951a735 [AggressiveInstCombine] convert a chain of 'and-shift' bits into masked compare
This is a follow-up to D45986. As suggested there, we should match the "all-bits-set" 
pattern in addition to "any-bits-set".

This was a little more complicated than I thought it would be initially because the 
"and 1" instruction can be anywhere in the chain. Hopefully, the code comments make 
that logic understandable, but if you see a way to simplify or improve that, it's 
most appreciated.

This transforms patterns that emerge from bitfield tests as seen in PR37098:
https://bugs.llvm.org/show_bug.cgi?id=37098

I think it would also help reduce the large test from:
D46336
D46595 
but we need something to reassociate that case to the forms we're expecting here first.

Differential Revision: https://reviews.llvm.org/D46649

llvm-svn: 331937
2018-05-09 23:08:15 +00:00
Sanjay Patel d2025a2e31 [AggressiveInstCombine] convert a chain of 'or-shift' bits into masked compare
and (or (lshr X, C), ...), 1 --> (X & C') != 0

I initially thought about implementing the minimal pattern in instcombine as mentioned here:
https://bugs.llvm.org/show_bug.cgi?id=37098#c6

...but we need to do better to catch the more general sequence from the motivating test 
(more than 2 bits in the compare). And a test-suite run with statistics showed that this 
pattern only happened 2 times currently. It would potentially happen more often if 
reassociation worked better (D45842), but it's probably still not too frequent?

This is small enough that I didn't see a need to create a whole new class/file within 
AggressiveInstCombine. There are likely other relatively small matchers like what was 
discussed in D44266 that would slide under foldUnusualPatterns() (name suggestions welcome). 
We could potentially also consolidate matchers for ctpop, bswap, etc under here.

Differential Revision: https://reviews.llvm.org/D45986

llvm-svn: 331311
2018-05-01 21:02:09 +00:00
Sanjay Patel 2b36e95d45 [PhaseOrdering] add tests for bittest patterns from bitfields; NFC
As mentioned in D45986, there's a potential ordering dependency 
between instcombine and aggressive-instcombine for detecting these,
so I'm adding a few tests to confirm that the expected folds occur
using -O3 (because aggressive-instcombine only runs at -O3 currently).

llvm-svn: 331308
2018-05-01 20:53:44 +00:00
Elena Demikhovsky 945b7e5aa6 Adding a width of the GEP index to the Data Layout.
Making a width of GEP Index, which is used for address calculation, to be one of the pointer properties in the Data Layout.
p[address space]:size:memory_size:alignment:pref_alignment:index_size_in_bits.
The index size parameter is optional, if not specified, it is equal to the pointer size.

Till now, the InstCombiner normalized GEPs and extended the Index operand to the pointer width.
It works fine if you can convert pointer to integer for address calculation and all registered targets do this.
But some ISAs have very restricted instruction set for the pointer calculation. During discussions were desided to retrieve information for GEP index from the Data Layout.
http://lists.llvm.org/pipermail/llvm-dev/2018-January/120416.html

I added an interface to the Data Layout and I changed the InstCombiner and some other passes to take the Index width into account.
This change does not affect any in-tree target. I added tests to cover data layouts with explicitly specified index size.

Differential Revision: https://reviews.llvm.org/D42123

llvm-svn: 325102
2018-02-14 06:58:08 +00:00
Sanjay Patel 0ab0c1a201 [SimplifyCFG] don't sink common insts too soon (PR34603)
This should solve:
https://bugs.llvm.org/show_bug.cgi?id=34603
...by preventing SimplifyCFG from altering redundant instructions before early-cse has a chance to run.
It changes the default (canonical-forming) behavior of SimplifyCFG, so we're only doing the
sinking transform later in the optimization pipeline.

Differential Revision: https://reviews.llvm.org/D38566

llvm-svn: 320749
2017-12-14 22:05:20 +00:00
Sanjay Patel 956dec63fb [PassManager, SimplifyCFG] add test for PR34603 / D38566; NFC
This is a recommit of r316908 which was reverted by r317444.

llvm-svn: 318300
2017-11-15 16:37:30 +00:00
Sanjay Patel 3e29890a7f [(new) Pass Manager] instantiate SimplifyCFG with the same options as the old PM
This is a recommit of r316869 which was speculatively reverted with r317444 and 
subsequently shown to not be the cause of PR35210. That crash should be fixed
after r318237.

Original commit message:

The old PM sets the options of what used to be known as "latesimplifycfg" on the
instantiation after the vectorizers have run, so that's what we'redoing here.

FWIW, there's a later SimplifyCFGPass instantiation in both PMs where we do not
set the "late" options. I'm not sure if that's intentional or not.

Differential Revision: https://reviews.llvm.org/D39407

llvm-svn: 318299
2017-11-15 16:33:11 +00:00
David L. Jones 82b22e0327 [PassManager, SimplifyCFG] Revert r316908 and r316869.
These cause Clang to crash with a segfault. See PR35210 for details.

llvm-svn: 317444
2017-11-06 00:32:01 +00:00
Sanjay Patel 85b60ff68c [PassManager, SimplifyCFG] add test for PR34603 / D38566; NFC
Sinking common insts and converting to select early can inhibit better folds in other passes.

llvm-svn: 316908
2017-10-30 14:34:30 +00:00
Sanjay Patel adf38911d8 [(new) Pass Manager] instantiate SimplifyCFG with the same options as the old PM
The old PM sets the options of what used to be known as "latesimplifycfg" on the 
instantiation after the vectorizers have run, so that's what we'redoing here.

FWIW, there's a later SimplifyCFGPass instantiation in both PMs where we do not 
set the "late" options. I'm not sure if that's intentional or not.

Differential Revision: https://reviews.llvm.org/D39407

llvm-svn: 316869
2017-10-29 20:49:31 +00:00
Sanjay Patel bdc0bf7ba9 [PassManager] add test to show the new PM uses -latesimplifycfg early; NFC
llvm-svn: 316351
2017-10-23 17:30:17 +00:00
Nikolai Bozhenov 95fc644148 Make globalaa-retained.ll test catching more cases.
Summary:
* Add checks for store. That is needed because GlobalsAA is called
  twice in the current pipeline with different sets of Function passes
  following it. However, the loads are eliminated using instcombine
  which happens everywhere. On the other hand, DeadStoreElimination is
  performed only once so by checking for store we'll be able to catch
  more cases when GlobalsAA is invalidated unintentionally.
* Add empty function above/below the test so that we don't depend on
  the relative order of instcombine/dead-store-elimination and the
  pass that invalidates the analysis (inside the same
  FunctionPassManager).

Reviewers: kristof.beyls

Reviewed By: kristof.beyls

Subscribers: llvm-commits, n.bozhenov

Differential Revision: https://reviews.llvm.org/D32015
Patch by Andrei Elovikov <andrei.elovikov@intel.com>

llvm-svn: 300553
2017-04-18 13:29:26 +00:00
Kristof Beyls c08f70588d Mark that SpeculativeExecution preserves Globals Alias Analysis.
A few benchmarks with lots of accesses to global variables in the hot
loops regressed a lot since r266399, which added the
SpeculativeExecution pass to the default pipeline. The problem is that
this pass doesn't mark Globals Alias Analysis as preserved. Globals
Alias Analysis is computed in a module pass, whereas
SpeculativeExecution is a function pass, and a lot of passes dependent
on the Globals Alias Analysis to optimize these benchmarks are also
function passes. As such, the Globals Alias Analysis information cannot
be recomputed between SpeculativeExecution and the following function
passes needing that information.

SpeculativeExecution doesn't invalidate Globals Alias Analysis, so mark
it as such to fix those performance regressions.

Differential Revision: http://reviews.llvm.org/D19806

llvm-svn: 268370
2016-05-03 08:33:26 +00:00
David Majnemer 7fddeccb8b Move the personality function from LandingPadInst to Function
The personality routine currently lives in the LandingPadInst.

This isn't desirable because:
- All LandingPadInsts in the same function must have the same
  personality routine.  This means that each LandingPadInst beyond the
  first has an operand which produces no additional information.

- There is ongoing work to introduce EH IR constructs other than
  LandingPadInst.  Moving the personality routine off of any one
  particular Instruction and onto the parent function seems a lot better
  than have N different places a personality function can sneak onto an
  exceptional function.

Differential Revision: http://reviews.llvm.org/D10429

llvm-svn: 239940
2015-06-17 20:52:32 +00:00
David Blaikie 23af64846f [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction
See r230786 and r230794 for similar changes to gep and load
respectively.

Call is a bit different because it often doesn't have a single explicit
type - usually the type is deduced from the arguments, and just the
return type is explicit. In those cases there's no need to change the
IR.

When that's not the case, the IR usually contains the pointer type of
the first operand - but since typed pointers are going away, that
representation is insufficient so I'm just stripping the "pointerness"
of the explicit type away.

This does make the IR a bit weird - it /sort of/ reads like the type of
the first operand: "call void () %x(" but %x is actually of type "void
()*" and will eventually be just of type "ptr". But this seems not too
bad and I don't think it would benefit from repeating the type
("void (), void () * %x(" and then eventually "void (), ptr %x(") as has
been done with gep and load.

This also has a side benefit: since the explicit type is no longer a
pointer, there's no ambiguity between an explicit type and a function
that returns a function pointer. Previously this case needed an explicit
type (eg: a function returning a void() function was written as
"call void () () * @x(" rather than "call void () * @x(" because of the
ambiguity between a function returning a pointer to a void() function
and a function returning void).

No ambiguity means even function pointer return types can just be
written alone, without writing the whole function's type.

This leaves /only/ the varargs case where the explicit type is required.

Given the special type syntax in call instructions, the regex-fu used
for migration was a bit more involved in its own unique way (as every
one of these is) so here it is. Use it in conjunction with the apply.sh
script and associated find/xargs commands I've provided in rr230786 to
migrate your out of tree tests. Do let me know if any of this doesn't
cover your cases & we can iterate on a more general script/regexes to
help others with out of tree tests.

About 9 test cases couldn't be automatically migrated - half of those
were functions returning function pointers, where I just had to manually
delete the function argument types now that we didn't need an explicit
function type there. The other half were typedefs of function types used
in calls - just had to manually drop the * from those.

import fileinput
import sys
import re

pat = re.compile(r'((?:=|:|^|\s)call\s(?:[^@]*?))(\s*$|\s*(?:(?:\[\[[a-zA-Z0-9_]+\]\]|[@%](?:(")?[\\\?@a-zA-Z0-9_.]*?(?(3)"|)|{{.*}}))(?:\(|$)|undef|inttoptr|bitcast|null|asm).*$)')
addrspace_end = re.compile(r"addrspace\(\d+\)\s*\*$")
func_end = re.compile("(?:void.*|\)\s*)\*$")

def conv(match, line):
  if not match or re.search(addrspace_end, match.group(1)) or not re.search(func_end, match.group(1)):
    return line
  return line[:match.start()] + match.group(1)[:match.group(1).rfind('*')].rstrip() + match.group(2) + line[match.end():]

for line in sys.stdin:
  sys.stdout.write(conv(re.search(pat, line), line))

llvm-svn: 235145
2015-04-16 23:24:18 +00:00
David Blaikie f72d05bc7b [opaque pointer type] Add textual IR support for explicit type parameter to gep operator
Similar to gep (r230786) and load (r230794) changes.

Similar migration script can be used to update test cases, which
successfully migrated all of LLVM and Polly, but about 4 test cases
needed manually changes in Clang.

(this script will read the contents of stdin and massage it into stdout
- wrap it in the 'apply.sh' script shown in previous commits + xargs to
apply it over a large set of test cases)

import fileinput
import sys
import re

rep = re.compile(r"(getelementptr(?:\s+inbounds)?\s*\()((<\d*\s+x\s+)?([^@]*?)(|\s*addrspace\(\d+\))\s*\*(?(3)>)\s*)(?=$|%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|zeroinitializer|<|\[\[[a-zA-Z]|\{\{)", re.MULTILINE | re.DOTALL)

def conv(match):
  line = match.group(1)
  line += match.group(4)
  line += ", "
  line += match.group(2)
  return line

line = sys.stdin.read()
off = 0
for match in re.finditer(rep, line):
  sys.stdout.write(line[off:match.start()])
  sys.stdout.write(conv(match))
  off = match.end()
sys.stdout.write(line[off:])

llvm-svn: 232184
2015-03-13 18:20:45 +00:00
Mehdi Amini 46a43556db Make DataLayout Non-Optional in the Module
Summary:
DataLayout keeps the string used for its creation.

As a side effect it is no longer needed in the Module.
This is "almost" NFC, the string is no longer
canonicalized, you can't rely on two "equals" DataLayout
having the same string returned by getStringRepresentation().

Get rid of DataLayoutPass: the DataLayout is in the Module

The DataLayout is "per-module", let's enforce this by not
duplicating it more than necessary.
One more step toward non-optionality of the DataLayout in the
module.

Make DataLayout Non-Optional in the Module

Module->getDataLayout() will never returns nullptr anymore.

Reviewers: echristo

Subscribers: resistor, llvm-commits, jholewinski

Differential Revision: http://reviews.llvm.org/D7992

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 231270
2015-03-04 18:43:29 +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 Blaikie 79e6c74981 [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction
One of several parallel first steps to remove the target type of pointers,
replacing them with a single opaque pointer type.

This adds an explicit type parameter to the gep instruction so that when the
first parameter becomes an opaque pointer type, the type to gep through is
still available to the instructions.

* This doesn't modify gep operators, only instructions (operators will be
  handled separately)

* Textual IR changes only. Bitcode (including upgrade) and changing the
  in-memory representation will be in separate changes.

* geps of vectors are transformed as:
    getelementptr <4 x float*> %x, ...
  ->getelementptr float, <4 x float*> %x, ...
  Then, once the opaque pointer type is introduced, this will ultimately look
  like:
    getelementptr float, <4 x ptr> %x
  with the unambiguous interpretation that it is a vector of pointers to float.

* address spaces remain on the pointer, not the type:
    getelementptr float addrspace(1)* %x
  ->getelementptr float, float addrspace(1)* %x
  Then, eventually:
    getelementptr float, ptr addrspace(1) %x

Importantly, the massive amount of test case churn has been automated by
same crappy python code. I had to manually update a few test cases that
wouldn't fit the script's model (r228970,r229196,r229197,r229198). The
python script just massages stdin and writes the result to stdout, I
then wrapped that in a shell script to handle replacing files, then
using the usual find+xargs to migrate all the files.

update.py:
import fileinput
import sys
import re

ibrep = re.compile(r"(^.*?[^%\w]getelementptr inbounds )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))")
normrep = re.compile(       r"(^.*?[^%\w]getelementptr )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))")

def conv(match, line):
  if not match:
    return line
  line = match.groups()[0]
  if len(match.groups()[5]) == 0:
    line += match.groups()[2]
  line += match.groups()[3]
  line += ", "
  line += match.groups()[1]
  line += "\n"
  return line

for line in sys.stdin:
  if line.find("getelementptr ") == line.find("getelementptr inbounds"):
    if line.find("getelementptr inbounds") != line.find("getelementptr inbounds ("):
      line = conv(re.match(ibrep, line), line)
  elif line.find("getelementptr ") != line.find("getelementptr ("):
    line = conv(re.match(normrep, line), line)
  sys.stdout.write(line)

apply.sh:
for name in "$@"
do
  python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name"
  rm -f "$name.tmp"
done

The actual commands:
From llvm/src:
find test/ -name *.ll | xargs ./apply.sh
From llvm/src/tools/clang:
find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}"
From llvm/src/tools/polly:
find test/ -name *.ll | xargs ./apply.sh

After that, check-all (with llvm, clang, clang-tools-extra, lld,
compiler-rt, and polly all checked out).

The extra 'rm' in the apply.sh script is due to a few files in clang's test
suite using interesting unicode stuff that my python script was throwing
exceptions on. None of those files needed to be migrated, so it seemed
sufficient to ignore those cases.

Reviewers: rafael, dexonsmith, grosser

Differential Revision: http://reviews.llvm.org/D7636

llvm-svn: 230786
2015-02-27 19:29:02 +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 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
Jakub Staszak 9b59d14fc4 Revert 179826. Tests were worthless.
llvm-svn: 179845
2013-04-19 09:32:30 +00:00
Jakub Staszak 2c1daf75b9 Don't run expensive -O2 and -O3 in tests.
llvm-svn: 179825
2013-04-19 01:10:45 +00:00
Dmitri Gribenko b137c9e551 Tests: rewrite 'opt ... %s' to 'opt ... < %s' so that opt does not emit a ModuleID
This is done to avoid odd test failures, like the one fixed in r171243.

llvm-svn: 171246
2012-12-30 01:28:40 +00:00
Evan Cheng 9e99f0c40d Add test case for r164850.
llvm-svn: 164867
2012-09-29 00:12:08 +00:00
Jakob Stoklund Olesen 43bcb970e5 Reapply r155136 after fixing PR12599.
Original commit message:

Defer some shl transforms to DAGCombine.

The shl instruction is used to represent multiplication by a constant
power of two as well as bitwise left shifts. Some InstCombine
transformations would turn an shl instruction into a bit mask operation,
making it difficult for later analysis passes to recognize the
constsnt multiplication.

Disable those shl transformations, deferring them to DAGCombine time.
An 'shl X, C' instruction is now treated mostly the same was as 'mul X, C'.

These transformations are deferred:

  (X >>? C) << C   --> X & (-1 << C)  (When X >> C has multiple uses)
  (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)   (When C2 > C1)
  (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)  (When C1 > C2)

The corresponding exact transformations are preserved, just like
div-exact + mul:

  (X >>?,exact C) << C   --> X
  (X >>?,exact C1) << C2 --> X << (C2-C1)
  (X >>?,exact C1) << C2 --> X >>?,exact (C1-C2)

The disabled transformations could also prevent the instruction selector
from recognizing rotate patterns in hash functions and cryptographic
primitives. I have a test case for that, but it is too fragile.

llvm-svn: 155362
2012-04-23 17:39:52 +00:00
Jakob Stoklund Olesen 205ee3b389 Revert r155136 "Defer some shl transforms to DAGCombine."
While the patch was perfect and defect free, it exposed a really nasty
bug in X86 SelectionDAG that caused an llc crash when compiling lencod.

I'll put the patch back in after fixing the SelectionDAG problem.

llvm-svn: 155181
2012-04-20 00:38:45 +00:00
Jakob Stoklund Olesen 6b6c81e6b2 Defer some shl transforms to DAGCombine.
The shl instruction is used to represent multiplication by a constant
power of two as well as bitwise left shifts. Some InstCombine
transformations would turn an shl instruction into a bit mask operation,
making it difficult for later analysis passes to recognize the
constsnt multiplication.

Disable those shl transformations, deferring them to DAGCombine time.
An 'shl X, C' instruction is now treated mostly the same was as 'mul X, C'.

These transformations are deferred:

  (X >>? C) << C   --> X & (-1 << C)  (When X >> C has multiple uses)
  (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)   (When C2 > C1)
  (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)  (When C1 > C2)

The corresponding exact transformations are preserved, just like
div-exact + mul:

  (X >>?,exact C) << C   --> X
  (X >>?,exact C1) << C2 --> X << (C2-C1)
  (X >>?,exact C1) << C2 --> X >>?,exact (C1-C2)

The disabled transformations could also prevent the instruction selector
from recognizing rotate patterns in hash functions and cryptographic
primitives. I have a test case for that, but it is too fragile.

llvm-svn: 155136
2012-04-19 16:46:26 +00:00
Jakob Stoklund Olesen 201ba5fa00 Extract the broken part of XFAILed test into its own file.
llvm-svn: 155081
2012-04-19 00:20:38 +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
Eric Christopher 8af4e41734 Add file.
llvm-svn: 138083
2011-08-19 21:21:20 +00:00
Nick Lewycky 40b4e80ce8 This directory was missing the dg.exp to cause the tests to run. Some time since
it was added, the test has regressed, so XFAIL it.

llvm-svn: 132686
2011-06-06 20:23:00 +00:00
Chris Lattner 1777601a74 final step needed to resolve PR6627, which allows us to flatten the code down to
a nice and tidy:
  %x1 = load i32* %0, align 4
  %1 = icmp eq i32 %x1, 1179403647
  br i1 %1, label %if.then, label %if.end

instead of doing lots of loads and branches.  May the FreeBSD bootloader
long fit in its allocated space.

llvm-svn: 130416
2011-04-28 18:15:47 +00:00
Chris Lattner 029afe4787 make a couple of changes to the standard pass pipeline:
1. Only run the early (in the module pass pipe) instcombine/simplifycfg
   if the "unit at a time" passes they are cleaning up after runs.

2. Move the "clean up after the unroller" pass to the very end of the
   function-level pass pipeline.  Loop unroll uses instsimplify now,
   so it doesn't create a ton of trash.  Moving instcombine later allows
   it to clean up after opportunities are exposed by GVN, DSE, etc.

3. Introduce some phase ordering tests for things that are specifically
   intended to be simplified by the full optimizer as a whole.

This resolves PR2338, and is progress towards PR6627, which will be 
generating code that looks similar to test2.

llvm-svn: 130241
2011-04-26 20:45:33 +00:00