Commit Graph

37 Commits

Author SHA1 Message Date
Shuxin Yang
253449db20 PR14904: Segmentation fault running pass 'Recognize loop idioms'
The root cause is mistakenly taking for granted that 
    "dyn_cast<Instruction>(a-Value)"
return a non-NULL instruction.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172145 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-10 23:32:01 +00:00
David Tweed
35d711aee0 Fix a mistaken commit that included some debugging code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171734 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-07 13:41:55 +00:00
David Tweed
d80d608f76 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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171733 91177308-0d34-0410-b5e6-96231b3b80d8
2013-01-07 13:32:38 +00:00
Shuxin Yang
5518a1355b - Re-enable population count loop idiom recognization
- fix a bug which cause sigfault.
- add two testing cases which was causing crash


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169687 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-09 03:12:46 +00:00
Chandler Carruth
7065a2bcec Revert the patches adding a popcount loop idiom recognition pass.
There are still bugs in this pass, as well as other issues that are
being worked on, but the bugs are crashers that occur pretty easily in
the wild. Test cases have been sent to the original commit's review
thread.

This reverts the commits:
  r169671: Fix a logic error.
  r169604: Move the popcnt tests to an X86 subdirectory.
  r168931: Initial commit adding the pass.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169683 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-08 22:18:29 +00:00
David Tweed
9f90c73415 The test unconditionally assumes a particular cpu has a backend build in the target.
Buildbots for some hosts may choose to build only their own backend in order to
maximise testing-turnaround time. Move the test into a prefixed directory so
lit's standard "backend specific" suppression can be done.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169604 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-07 15:57:45 +00:00
Shuxin Yang
84fca61ca5 rdar://12100355 (part 1)
This revision attempts to recognize following population-count pattern:

 while(a) { c++; ... ; a &= a - 1; ... },
  where <c> and <a>could be used multiple times in the loop body.

 TODO: On X8664 and ARM, __buildin_ctpop() are not expanded to a efficent 
instruction sequence, which need to be improved in the following commits.

Reviewed by Nadav, really appreciate!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168931 91177308-0d34-0410-b5e6-96231b3b80d8
2012-11-29 19:38:54 +00:00
Chandler Carruth
52df6c2eec Add a testcase to loop-idiom to cover PR14241 when we start handling
strided loops again.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167287 91177308-0d34-0410-b5e6-96231b3b80d8
2012-11-02 08:40:24 +00:00
Chandler Carruth
a864748284 Revert the switch of loop-idiom to use the new dependence analysis.
The new analysis is not yet ready for prime time. It has a *critical*
flawed assumption, and some troubling shortages of testing. Until it's
been hammered into better shape, let's stick with the working code. This
should be easy to revert itself when the analysis is ready.

Fixes PR14241, a miscompile of any memcpy-able loop which uses a pointer
as the induction mechanism. If you have been seeing miscompiles in this
revision range, you really want to test with this backed out. The
results of this miscompile are a bit subtle as they can lead to
downstream passes concluding things are impossible which are in fact
possible.

Thanks to David Blaikie for the majority of the reduction of this
miscompile. I'll be checking in the test case in a non-revert commit.

Revesions reverted here:

r167045: LoopIdiom: Fix a serious missed optimization: we only turned
         top-level loops into memmove.
r166877: LoopIdiom: Add checks to avoid turning memmove into an infinite
         loop.
r166875: LoopIdiom: Recognize memmove loops.
r166874: LoopIdiom: Replace custom dependence analysis with
         DependenceAnalysis.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167286 91177308-0d34-0410-b5e6-96231b3b80d8
2012-11-02 08:33:25 +00:00
Benjamin Kramer
4ad3d981b9 LCSSA: Add a workaround for another nasty SCEV cache invalidation issue.
I'm not entirely happy with this solution, but I don't see a smarter way currently.
Fixes PR14214.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167112 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-31 10:01:29 +00:00
Benjamin Kramer
061938b90b DependenceAnalysis: Don't crash if there is no constant operand.
This makes the code match the comments. Resolves a crash in loop idiom (PR14219).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167110 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-31 09:20:38 +00:00
Benjamin Kramer
415f869cf3 LoopIdiom: Fix a serious missed optimization: we only turned top-level loops into memmove.
Thanks to Preston Briggs for catching this!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167045 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-30 19:49:39 +00:00
Benjamin Kramer
badffcf8fd LoopIdiom: Add checks to avoid turning memmove into an infinite loop.
I don't think this is possible with the current implementation but that may change eventually.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166877 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-27 15:18:28 +00:00
Benjamin Kramer
d11c5d08a5 LoopIdiom: Recognize memmove loops.
This turns loops like
  for (unsigned i = 0; i != n; ++i)
    p[i] = p[i+1];
into memmove, which has a highly optimized implementation in most libcs.

This was really easy with the new DependenceAnalysis :)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166875 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-27 14:25:51 +00:00
Benjamin Kramer
96c8735e28 LoopIdiom: Replace custom dependence analysis with DependenceAnalysis.
Requires a lot less code and complexity on loop-idiom's side and the more
precise analysis can catch more cases, like the one I included as a test case.
This also fixes the edge-case miscompilation from PR9481.

Compile time performance seems to be slightly worse, but this is mostly due
to an extra LCSSA run scheduled by the PassManager and should be fixed there.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166874 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-27 14:25:44 +00:00
Benjamin Kramer
3740e798bc Revert r166390 "LoopIdiom: Replace custom dependence analysis with LoopDependenceAnalysis."
It passes all tests, produces better results than the old code but uses the
wrong pass, LoopDependenceAnalysis, which is old and unmaintained. "Why is it
still in tree?", you might ask. The answer is obviously: "To confuse developers."

Just swapping in the new dependency pass sends the pass manager into an infinte
loop, I'll try to figure out why tomorrow.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166399 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-21 19:31:16 +00:00
Benjamin Kramer
5c6e9ae14e LoopIdiom: Replace custom dependence analysis with LoopDependenceAnalysis.
Requires a lot less code and complexity on loop-idiom's side and the more
precise analysis can catch more cases, like the one I included as a test case.
This also fixes the edge-case miscompilation from PR9481. I'm not entirely
sure that all cases are handled that the old checks handled but LDA will
certainly become smarter in the future.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@166390 91177308-0d34-0410-b5e6-96231b3b80d8
2012-10-21 15:03:07 +00:00
Benjamin Kramer
28aff84ceb LoopIdiom: Give up when the loop is not in canonical form.
We rely on it when doing the transforms. This can happen when there is an
indirectbr in  the loop.

Fixes PR13892.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@164383 91177308-0d34-0410-b5e6-96231b3b80d8
2012-09-21 17:27:23 +00:00
Eli Bendersky
0f0c411079 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.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150664 91177308-0d34-0410-b5e6-96231b3b80d8
2012-02-16 06:28:33 +00:00
Benjamin Kramer
a9390a4d5f Stop emitting instructions with the name "tmp" they eat up memory and have to be uniqued, without any benefit.
If someone prefers %tmp42 to %42, run instnamer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140634 91177308-0d34-0410-b5e6-96231b3b80d8
2011-09-27 20:39:19 +00:00
Chad Rosier
72d6f34af1 A real testcase for r135286.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135299 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-15 20:58:38 +00:00
Chad Rosier
96a7db084f Add testcase for r135286.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135291 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-15 19:06:58 +00:00
Chris Lattner
4f81b54192 Fix PR9815: I was trying to get out of "generating code and then
failing to form a memset, then having to delete it" but my approximation
isn't safe for self recurrent loops.  Instead of doign a hack, just
do it the right way.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131858 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-22 17:39:56 +00:00
Devang Patel
cd77a50e63 Preserve line no. info.
Radar 9097659


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127182 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-07 22:43:45 +00:00
Chris Lattner
80e8b506b8 rewrite the memset_pattern pattern generation stuff to accept any 2/4/8/16-byte
constant, including globals.  This makes us generate much more "pretty" pattern
globals as well because it doesn't break it down to an array of bytes all the
time.

This enables us to handle stores of relocatable globals.  This kicks in about
48 times in 254.gap, giving us stuff like this:

@.memset_pattern40 = internal constant [2 x %struct.TypHeader* (%struct.TypHeader*, %struct.TypHeader*)*] [%struct.TypHeader* (%struct.TypHeader*, %struct
.TypHeader*)* @IsFalse, %struct.TypHeader* (%struct.TypHeader*, %struct.TypHeader*)* @IsFalse], align 16

...
  call void @memset_pattern16(i8* %scevgep5859, i8* bitcast ([2 x %struct.TypHeader* (%struct.TypHeader*, %struct.TypHeader*)*]* @.memset_pattern40 to i8*
), i64 %tmp75) nounwind



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126044 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-19 19:56:44 +00:00
Chris Lattner
41bfbb0a87 Stores of null pointers should turn into memset, we weren't recognizing
them as splat values.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126041 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-19 19:35:49 +00:00
Chris Lattner
3a393728a6 Implement rdar://9009151, transforming strided loop stores of
unsplatable values into memset_pattern16 when it is available
(recent darwins).  This transforms lots of strided loop stores
of ints for example, like 5 in vpr:

  Formed memset:   call void @memset_pattern16(i8* %4, i8* getelementptr inbounds ([16 x i8]* @.memset_pattern9, i32 0, i32 0), i64 %tmp25)
    from store to: {%3,+,4}<%11> at:   store i32 3, i32* %scevgep, align 4, !tbaa !4




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126040 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-19 19:31:39 +00:00
Chris Lattner
e41d3c015c Teach loop-idiom to turn a loop containing a memset into a larger memset
when safe.

The testcase is basically this nested loop:
void foo(char *X) {
  for (int i = 0; i != 100; ++i) 
    for (int j = 0; j != 100; ++j)
      X[j+i*100] = 0;
}

which gets turned into a single memset now.  clang -O3 doesn't optimize
this yet though due to a phase ordering issue I haven't analyzed yet.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122806 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-04 07:46:33 +00:00
Chris Lattner
63f9c3c49a fix a miscompilation of tramp3d-v4: when forming a memcpy, we have to make
sure that the loop we're promoting into a memcpy doesn't mutate the input
of the memcpy.  Before we were just checking that the dest of the memcpy
wasn't mod/ref'd by the loop.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122712 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-02 21:14:18 +00:00
Chris Lattner
8e08e73f0e If a loop iterates exactly once (has backedge count = 0) then don't
mess with it.  We'd rather peel/unroll it than convert all of its 
stores into memsets.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122711 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-02 20:24:21 +00:00
Chris Lattner
62c50fdf69 enhance loop idiom recognition to scan *all* unconditionally executed
blocks in a loop, instead of just the header block.  This makes it more
aggressive, able to handle Duncan's Ada examples.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122704 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-02 19:01:03 +00:00
Chris Lattner
cf078f2b20 Allow loop-idiom to run on multiple BB loops, but still only scan the loop
header for now for memset/memcpy opportunities.  It turns out that loop-rotate
is successfully rotating loops, but *DOESN'T MERGE THE BLOCKS*, turning "for 
loops" into 2 basic block loops that loop-idiom was ignoring.

With this fix, we form many *many* more memcpy and memsets than before, including
on the "history" loops in the viterbi benchmark, which look like this:

        for (j=0; j<MAX_history; ++j) {
          history_new[i][j+1] = history[2*i][j];
        }

Transforming these loops into memcpy's speeds up the viterbi benchmark from
11.98s to 3.55s on my machine.  Woo.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122685 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-02 07:58:36 +00:00
Chris Lattner
e2c4392091 teach loop idiom recognition to form memcpy's from simple loops.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122678 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-02 03:37:56 +00:00
Chris Lattner
bafa117e8f add a validity check that was missed, fixing a crash on the
new testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122662 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-01 20:12:04 +00:00
Chris Lattner
a64cbf067d improve validity check to handle constant-trip-count loops more
aggressively.  In practice, this doesn't help anything though,
see the todo.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122660 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-01 19:54:22 +00:00
Chris Lattner
30980b6815 implement the "no aliasing accesses in loop" safety check. This pass
should be correct now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122659 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-01 19:39:01 +00:00
Chris Lattner
a92ff91a96 implement enough of the memset inference algorithm to recognize and insert
memsets.  This is still missing one important validity check, but this is enough
to compile stuff like this:

void test0(std::vector<char> &X) {
  for (std::vector<char>::iterator I = X.begin(), E = X.end(); I != E; ++I)
    *I = 0;
}

void test1(std::vector<int> &X) {
  for (long i = 0, e = X.size(); i != e; ++i)
    X[i] = 0x01010101;
}

With:
 $ clang t.cpp -S -o - -O2 -emit-llvm | opt -loop-idiom | opt -O3 | llc 

to:

__Z5test0RSt6vectorIcSaIcEE:            ## @_Z5test0RSt6vectorIcSaIcEE
## BB#0:                                ## %entry
	subq	$8, %rsp
	movq	(%rdi), %rax
	movq	8(%rdi), %rsi
	cmpq	%rsi, %rax
	je	LBB0_2
## BB#1:                                ## %bb.nph
	subq	%rax, %rsi
	movq	%rax, %rdi
	callq	___bzero
LBB0_2:                                 ## %for.end
	addq	$8, %rsp
	ret
...
__Z5test1RSt6vectorIiSaIiEE:            ## @_Z5test1RSt6vectorIiSaIiEE
## BB#0:                                ## %entry
	subq	$8, %rsp
	movq	(%rdi), %rax
	movq	8(%rdi), %rdx
	subq	%rax, %rdx
	cmpq	$4, %rdx
	jb	LBB1_2
## BB#1:                                ## %for.body.preheader
	andq	$-4, %rdx
	movl	$1, %esi
	movq	%rax, %rdi
	callq	_memset
LBB1_2:                                 ## %for.end
	addq	$8, %rsp
	ret



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122573 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-26 23:42:51 +00:00