293 Commits

Author SHA1 Message Date
Chris Lattner
1499119975 make qsort predicate more conformant by returning 0 for equal values.
llvm-svn: 121838
2010-12-15 04:52:41 +00:00
Chris Lattner
c1aaf52608 - Insert new instructions before DomBlock's terminator,
which is simpler than finding a place to insert in BB.
 - Don't perform the 'if condition hoisting' xform on certain
   i1 PHIs, as it interferes with switch formation.

This re-fixes "example 7", without breaking the world hopefully.

llvm-svn: 121764
2010-12-14 08:46:09 +00:00
Chris Lattner
22d4dc5a4d fix two significant issues with FoldTwoEntryPHINode:
first, it can kick in on blocks whose conditions have been
folded to a constant, even though one of the edges will be
trivially folded.

second, it doesn't clean up the "if diamond" that it just 
eliminated away.  This is a problem because other simplifycfg
xforms kick in depending on the order of block visitation,
causing pointless work.

llvm-svn: 121762
2010-12-14 08:01:53 +00:00
Chris Lattner
362f9a82c0 remove the instsimplify logic I added in r121754. It is apparently
breaking the selfhost builds, though I can't fathom how.

llvm-svn: 121761
2010-12-14 07:53:03 +00:00
Chris Lattner
c2e42269ae clean up logic, convert std::set to SmallPtrSet, handle the case
when all 2-entry phis are simplified away.

llvm-svn: 121760
2010-12-14 07:41:39 +00:00
Chris Lattner
8e4194276b tidy up a bit, move DEBUG down to when we commit to doing the transform so we
don't print it unless the xform happens.

llvm-svn: 121758
2010-12-14 07:23:10 +00:00
Chris Lattner
811462b2f4 use SimplifyInstruction instead of reimplementing part of it.
llvm-svn: 121757
2010-12-14 07:20:29 +00:00
Chris Lattner
e2400eb801 simplify GetIfCondition by using getSinglePredecessor.
llvm-svn: 121756
2010-12-14 07:15:21 +00:00
Chris Lattner
8ea88e66dd use AddPredecessorToBlock in 3 places instead of a manual loop.
llvm-svn: 121755
2010-12-14 07:09:42 +00:00
Chris Lattner
a87ac36a54 make FoldTwoEntryPHINode use instsimplify a bit, make
GetIfCondition faster by avoiding pred_iterator.  No
really interesting change.

llvm-svn: 121754
2010-12-14 07:00:00 +00:00
Chris Lattner
d9436ab7d7 improve DEBUG's a bit, switch to eraseFromParent() to simplify
code a bit, switch from constant folding to instsimplify.

llvm-svn: 121751
2010-12-14 06:17:25 +00:00
Chris Lattner
093b5b256d reapply my recent change that disables a piece of the switch formation
work, but fixes 400.perlbmk.

llvm-svn: 121749
2010-12-14 05:57:30 +00:00
Owen Anderson
5536134dc4 Fix recent buildbot breakage by pulling SimplifyCFG back to its state as of r121694, the most recent state
where I'm confident there were no crashes or miscompilations.  XFAIL the test added since then for now.

llvm-svn: 121733
2010-12-13 23:49:28 +00:00
Chris Lattner
dcba81d96f temporarily disable part of my previous patch, which causes an iterator invalidation issue, causing a crash on some versions of perlbmk.
llvm-svn: 121728
2010-12-13 23:02:19 +00:00
Chris Lattner
759d8aa712 add some DEBUG's.
llvm-svn: 121711
2010-12-13 19:55:30 +00:00
Benjamin Kramer
7f1cdac1e4 Fix sort predicate. qsort(3)'s predicate semantics differ from std::sort's. Fixes PR 8780.
llvm-svn: 121705
2010-12-13 18:20:38 +00:00
Chris Lattner
0368bf7457 reinstate my patch: the miscompile was caused by an inverted branch in the
'and' case.

llvm-svn: 121695
2010-12-13 08:12:19 +00:00
Chris Lattner
caad324345 Completely disable the optimization I added in r121680 until
I can track down a miscompile.  This should bring the buildbots
back to life

llvm-svn: 121693
2010-12-13 07:41:29 +00:00
Chris Lattner
5ce3e42d80 Make simplifycfg reprocess newly formed "br (cond1 | cond2)" conditions
when simplifying, allowing them to be eagerly turned into switches.  This
is the last step required to get "Example 7" from this blog post:
http://blog.regehr.org/archives/320

On X86, we now generate this machine code, which (to my eye) seems better
than the ICC generated code:

_crud:                                  ## @crud
## BB#0:                                ## %entry
	cmpb	$33, %dil
	jb	LBB0_4
## BB#1:                                ## %switch.early.test
	addb	$-34, %dil
	cmpb	$58, %dil
	ja	LBB0_3
## BB#2:                                ## %switch.early.test
	movzbl	%dil, %eax
	movabsq	$288230376537592865, %rcx ## imm = 0x400000017001421
	btq	%rax, %rcx
	jb	LBB0_4
LBB0_3:                                 ## %lor.rhs
	xorl	%eax, %eax
	ret
LBB0_4:                                 ## %lor.end
	movl	$1, %eax
	ret

llvm-svn: 121690
2010-12-13 07:00:06 +00:00
Chris Lattner
20b9e84c7e make this logic a bit simpler.
llvm-svn: 121689
2010-12-13 06:36:51 +00:00
Chris Lattner
74d917e19d split all the guts of SimplifyCFGOpt::run out into one function
per terminator kind.

llvm-svn: 121688
2010-12-13 06:25:44 +00:00
Chris Lattner
ea15ce73be fix a bug in r121680 that upset the various buildbots.
llvm-svn: 121687
2010-12-13 05:34:18 +00:00
Chris Lattner
1eb2e235c8 refactor the speculative execution logic to be factored into the cond branch code instead of
doing a cfg search for every block simplified.

llvm-svn: 121686
2010-12-13 05:26:52 +00:00
Chris Lattner
4b9e3a31b0 simplify a bunch of code.
llvm-svn: 121685
2010-12-13 05:20:28 +00:00
Chris Lattner
d79dd057bf move HoistThenElseCodeToIf up to a more logical and efficient-to-handle place.
llvm-svn: 121684
2010-12-13 05:15:29 +00:00
Chris Lattner
80f8577d74 move 'MergeBlocksIntoPredecessor' call earlier. Use
getSinglePredecessor to simplify code.

llvm-svn: 121683
2010-12-13 05:10:48 +00:00
Chris Lattner
7ad8e06c3b factor new code out to a SimplifyBranchOnICmpChain helper function.
llvm-svn: 121681
2010-12-13 05:03:41 +00:00
Chris Lattner
5cbbcc56ad enhance the "change or icmp's into switch" xform to handle one value in an
'or sequence' that it doesn't understand.  This allows us to optimize
something insane like this:

int crud (unsigned char c, unsigned x)
 {
   if(((((((((( (int) c <= 32 ||
                    (int) c == 46) || (int) c == 44)
                  || (int) c == 58) || (int) c == 59) || (int) c == 60)
               || (int) c == 62) || (int) c == 34) || (int) c == 92)
            || (int) c == 39) != 0)
     foo();
 }

into:

define i32 @crud(i8 zeroext %c, i32 %x) nounwind ssp noredzone {
entry:
  %cmp = icmp ult i8 %c, 33
  br i1 %cmp, label %if.then, label %switch.early.test

switch.early.test:                                ; preds = %entry
  switch i8 %c, label %if.end [
    i8 39, label %if.then
    i8 44, label %if.then
    i8 58, label %if.then
    i8 59, label %if.then
    i8 60, label %if.then
    i8 62, label %if.then
    i8 46, label %if.then
    i8 92, label %if.then
    i8 34, label %if.then
  ]

by pulling the < comparison out ahead of the newly formed switch.

llvm-svn: 121680
2010-12-13 04:50:38 +00:00
Chris Lattner
f6be61e969 merge two very similar functions into one that has a bool argument.
llvm-svn: 121678
2010-12-13 04:26:26 +00:00
Chris Lattner
003b79e2d3 don't bother handling non-canonical icmp's
llvm-svn: 121676
2010-12-13 04:18:32 +00:00
Chris Lattner
9bd0b12342 inline a function, making the result much simpler.
llvm-svn: 121675
2010-12-13 04:15:19 +00:00
Chris Lattner
25b642edfd Fix my previous patch to handle a degenerate case that the llvm-gcc
bootstrap buildbot tripped over.

llvm-svn: 121674
2010-12-13 03:43:57 +00:00
Chris Lattner
9b089512e9 convert some methods to be static functions
llvm-svn: 121673
2010-12-13 03:30:12 +00:00
Chris Lattner
46cc5158bb zap two more std::sorts.
llvm-svn: 121672
2010-12-13 03:24:30 +00:00
Chris Lattner
a21c02e807 fix a fairly serious oversight with switch formation from
or'd conditions.  Previously we'd compile something like this:

int crud (unsigned char c) {
   return c == 62 || c == 34 || c == 92;
}

into:

  switch i8 %c, label %lor.rhs [
    i8 62, label %lor.end
    i8 34, label %lor.end
  ]

lor.rhs:                                          ; preds = %entry
  %cmp8 = icmp eq i8 %c, 92
  br label %lor.end

lor.end:                                          ; preds = %entry, %entry, %lor.rhs
  %0 = phi i1 [ true, %entry ], [ %cmp8, %lor.rhs ], [ true, %entry ]
  %lor.ext = zext i1 %0 to i32
  ret i32 %lor.ext

which failed to merge the compare-with-92 into the switch.  With this patch
we simplify this all the way to:

  switch i8 %c, label %lor.rhs [
    i8 62, label %lor.end
    i8 34, label %lor.end
    i8 92, label %lor.end
  ]

lor.rhs:                                          ; preds = %entry
  br label %lor.end

lor.end:                                          ; preds = %entry, %entry, %entry, %lor.rhs
  %0 = phi i1 [ true, %entry ], [ false, %lor.rhs ], [ true, %entry ], [ true, %entry ]
  %lor.ext = zext i1 %0 to i32
  ret i32 %lor.ext

which is much better for codegen's switch lowering stuff.  This kicks in 33 times
on 176.gcc (for example) cutting 103 instructions off the generated code.

llvm-svn: 121671
2010-12-13 03:18:54 +00:00
Chris Lattner
134d892049 convert an std::sort to array_pod_sort.
llvm-svn: 121669
2010-12-13 02:00:58 +00:00
Chris Lattner
153b680cdd move the "br (X == 0 | X == 1), T, F" -> switch optimization to a new
location in simplifycfg.  In the old days, SimplifyCFG was never run on
the entry block, so we had to scan over all preds of the BB passed into
simplifycfg to do this xform, now we can just check blocks ending with
a condbranch.  This avoids a scan over all preds of every simplified 
block, which should be a significant compile-time perf win on functions
with lots of edges.  No functionality change.

llvm-svn: 121668
2010-12-13 01:57:34 +00:00
Chris Lattner
644a93e06b reduce indentation and generally simplify code, no functionality change.
llvm-svn: 121667
2010-12-13 01:47:07 +00:00
Chris Lattner
859fad7373 use getFirstNonPHIOrDbg to simplify this code.
llvm-svn: 121664
2010-12-13 01:28:06 +00:00
Frits van Bommel
31cf7b99f9 Teach SimplifyCFG to turn
(indirectbr (select cond, blockaddress(@fn, BlockA),
                            blockaddress(@fn, BlockB)))
into
  (br cond, BlockA, BlockB).

llvm-svn: 120943
2010-12-05 18:29:03 +00:00
Duncan Sands
5b25503aab Fix PR8445: a block with no predecessors may be the entry block, in which case
it isn't unreachable and should not be zapped.  The check for the entry block
was missing in one case: a block containing a unwind instruction.  While there,
do some small cleanups: "M" is not a great name for a Function* (it would be
more appropriate for a Module*), change it to "Fn"; use Fn in more places.

llvm-svn: 117224
2010-10-24 12:23:30 +00:00
Dan Gohman
9178d0792f Instead, teach SimplifyCFG to trim non-address-taken blocks from
indirectbr destination lists.

llvm-svn: 111122
2010-08-16 14:41:14 +00:00
Dan Gohman
d04a608a73 Teach SimplifyCFG how to simplify indirectbr instructions.
- Eliminate redundant successors.
 - Convert an indirectbr with one successor into a direct branch.

Also, generalize SimplifyCFG to be able to be run on a function entry block.
It knows quite a few simplifications which are applicable to the entry
block, and it only needs a few checks to avoid trouble with the entry block.

llvm-svn: 111060
2010-08-14 00:29:42 +00:00
Gabor Greif
87ef691878 pass dereferenced iterator to dyn_cast
llvm-svn: 109098
2010-07-22 11:43:44 +00:00
Owen Anderson
b9f325bab4 Remove unneeded check, and correct style.
llvm-svn: 108427
2010-07-15 16:38:22 +00:00
Owen Anderson
5de6c42ebd Extend SimplifyCFG's common-destination folding heuristic to allow a single
"bonus" instruction to be speculatively executed.  Add a heuristic to
ensure we're not tripping up out-of-order execution by checking that this bonus
instruction only uses values that were already guaranteed to be available.

This allows us to eliminate the short circuit in (x&1)&&(x&2).

llvm-svn: 108351
2010-07-14 19:52:16 +00:00
Gabor Greif
95805d51b8 cache dereferenced iterators
llvm-svn: 108133
2010-07-12 10:59:23 +00:00
Gabor Greif
dcaa85787c cache result of operator*
llvm-svn: 107974
2010-07-09 15:25:09 +00:00
Dan Gohman
4bdd10c6df Fix a grammaro.
llvm-svn: 99917
2010-03-30 20:04:57 +00:00
Gabor Greif
598b097171 fix two cases where the arguments were extracted from the wrong range out of the InvokeInst
spotted by baldrick -- thanks\!

llvm-svn: 99914
2010-03-30 19:20:53 +00:00