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Commit Graph

141 Commits

Author SHA1 Message Date
Nick Lewycky
a5f89b09c6 Teach jump threading to look at comparisons between phi nodes and non-constants.
llvm-svn: 73755
2009-06-19 04:56:29 +00:00
Chris Lattner
84cf4d62a8 fix some problems spotted by Duncan and Nicolas Geoffray
llvm-svn: 70872
2009-05-04 16:29:24 +00:00
Chris Lattner
6807ddd3d9 * Sink 4 duplicates of edge threading validity checks and DOUT prints into
ThreadEdge directly.  This shares the code, but is just a refactoring.
* Make JumpThreading compute the set of loop headers and avoid threading
  across them.  This prevents jump threading from forming irreducible 
  loops (goodness) but also prevents it from threading in other cases that
  are beneficial (see the comment above FindFunctionBackedges).

llvm-svn: 70820
2009-05-04 02:28:08 +00:00
Dale Johannesen
0e13f2b022 Fix a debug info dependency in jump threading.
llvm-svn: 67064
2009-03-17 00:38:24 +00:00
Chris Lattner
a66675581a this wasn't intended to go in.
llvm-svn: 66252
2009-03-06 05:42:30 +00:00
Chris Lattner
1b05680d5f Change various llvm utilities to use PrettyStackTraceProgram in
their main routines.  This makes the tools print their argc/argv
commands if they crash.

llvm-svn: 66248
2009-03-06 05:34:10 +00:00
Chris Lattner
b88febb5cd Fix PR3353, infinitely jump threading an infinite loop make from switches.
llvm-svn: 62529
2009-01-19 21:20:34 +00:00
Chris Lattner
6140ea4f18 Fix PR3298, a crash in Jump Threading. Apparently even
jump threading can have bugs, who knew? ;-)

llvm-svn: 61983
2009-01-09 06:08:12 +00:00
Chris Lattner
23e2ac8894 remove DebugIterations option. Despite the accusations,
jump threading has been shown to only expose problems not
have bugs itself.  I'm sure it's completely bug free! ;-)

llvm-svn: 60725
2008-12-08 22:44:07 +00:00
Chris Lattner
7b3576824a Start simplifying a switch that has a successor that is a switch.
llvm-svn: 60534
2008-12-04 06:31:07 +00:00
Chris Lattner
2677286c25 add a debugging option to help track down j-t problems.
llvm-svn: 60514
2008-12-04 00:07:59 +00:00
Chris Lattner
f00b2f3fb4 Teach jump threading some more simple tricks:
1) have it fold "br undef", which does occur with
   surprising frequency as jump threading iterates.
2) teach j-t to delete dead blocks.  This removes the successor
   edges, reducing the in-edges of other blocks, allowing 
   recursive simplification.
3) Fold things like:
     br COND, BBX, BBY
  BBX:
     br COND, BBZ, BBW

   which also happens because jump threading iterates.

llvm-svn: 60470
2008-12-03 07:48:08 +00:00
Chris Lattner
f72f8e3b74 switch a couple more calls to use array_pod_sort.
llvm-svn: 60337
2008-12-01 06:52:57 +00:00
Chris Lattner
c92e1e104b Teach jump threading to clean up after itself, DCE and constfolding the
new instructions it simplifies.  Because we're threading jumps on edges
with constants coming in from PHI's, we inherently are exposing a lot more
constants to the new block.  Folding them and deleting dead conditions
allows the cost model in jump threading to be more accurate as it iterates.

llvm-svn: 60327
2008-12-01 04:48:07 +00:00
Chris Lattner
a854ab3760 don't call MergeBasicBlockIntoOnlyPred on a block whose only
predecessor is itself.  This doesn't make sense, and this is
a dead infinite loop anyway.

llvm-svn: 60210
2008-11-28 19:54:49 +00:00
Chris Lattner
73b251b3bf Fix PR3138: if we merge the entry block into another block, make sure to
move the other block back up into the entry position!

llvm-svn: 60179
2008-11-27 19:25:19 +00:00
Chris Lattner
577096bcaa move FindAvailableLoadedValue from JumpThreading to Transforms/Utils.
llvm-svn: 60166
2008-11-27 08:10:05 +00:00
Chris Lattner
bb86dff3fe move MergeBasicBlockIntoOnlyPred to Transforms/Utils.
llvm-svn: 60162
2008-11-27 07:43:12 +00:00
Chris Lattner
98f62336b7 rename ThreadBlock to ProcessBlock, since it does other things than
just simple threading.

llvm-svn: 60157
2008-11-27 07:20:04 +00:00
Chris Lattner
532458b89f Make jump threading substantially more powerful, in the following ways:
1. Make it fold blocks separated by an unconditional branch.  This enables
   jump threading to see a broader scope.
2. Make jump threading able to eliminate locally redundant loads when they
   feed the branch condition of a block.  This frequently occurs due to
   reg2mem running.
3. Make jump threading able to eliminate *partially redundant* loads when
   they feed the branch condition of a block.  This is common in code with
   lots of loads and stores like C++ code and 255.vortex.

This implements thread-loads.ll and rdar://6402033.

Per the fixme's, several pieces of this should be moved into Transforms/Utils.

llvm-svn: 60148
2008-11-27 05:07:53 +00:00
Dan Gohman
e1f9be27bc Tidy up several unbeseeming casts from pointer to intptr_t.
llvm-svn: 55779
2008-09-04 17:05:41 +00:00
Dan Gohman
6564581be0 Enable first-class aggregates support.
Remove the GetResultInst instruction. It is still accepted in LLVM assembly
and bitcode, where it is now auto-upgraded to ExtractValueInst. Also, remove
support for return instructions with multiple values. These are auto-upgraded
to use InsertValueInst instructions.

The IRBuilder still accepts multiple-value returns, and auto-upgrades them
to InsertValueInst instructions.

llvm-svn: 53941
2008-07-23 00:34:11 +00:00
Duncan Sands
4757a8dd76 Fix some constructs that gcc-4.4 warns about.
llvm-svn: 51591
2008-05-27 11:50:51 +00:00
Dan Gohman
8b6f4366ae Tidy up BasicBlock::getFirstNonPHI, and change a bunch of places to
use it instead of duplicating its functionality.

llvm-svn: 51499
2008-05-23 21:05:58 +00:00
Matthijs Kooijman
9247675761 Fix typo.
llvm-svn: 51303
2008-05-20 07:26:45 +00:00
Dan Gohman
bab18cae46 Clean up the use of static and anonymous namespaces. This turned up
several things that were neither in an anonymous namespace nor static
but not intended to be global.

llvm-svn: 51017
2008-05-13 00:00:25 +00:00
Chris Lattner
8ec87dd865 restore doxygen comment.
llvm-svn: 50881
2008-05-09 04:43:13 +00:00
Gordon Henriksen
846171a09e Improve pass documentation and comments.
Patch by Matthijs Kooijman!

llvm-svn: 50861
2008-05-08 17:46:35 +00:00
Chris Lattner
a75e149023 fix typo Duncan noticed
llvm-svn: 50699
2008-05-06 02:31:18 +00:00
Chris Lattner
50d16c2939 Fix a crash when threading a block that includes a MRV call result.
DemoteRegToStack doesn't work with MRVs yet, because it relies on the
ability to load/store things.

This fixes PR2285.

llvm-svn: 50667
2008-05-05 20:21:22 +00:00
Chris Lattner
1a6268f776 Don't infininitely thread branches when a threaded edge
goes back to the block, e.g.:

  Threading edge through bool from 'bb37.us.thread3829' to 'bb37.us' with cost: 1, across block:

bb37.us:		; preds = %bb37.us.thread3829, %bb37.us, %bb33
	%D1361.1.us = phi i32 [ %tmp36, %bb33 ], [ %D1361.1.us, %bb37.us ], [ 0, %bb37.us.thread3829 ]		; <i32> [#uses=2]
	%tmp39.us = icmp eq i32 %D1361.1.us, 0		; <i1> [#uses=1]
	br i1 %tmp39.us, label %bb37.us, label %bb42.us

llvm-svn: 50251
2008-04-25 04:12:29 +00:00
Chris Lattner
e304ae5621 Start doing the significantly useful part of jump threading: handle cases
where a comparison has a phi input and that phi is a constant.  For example,
stuff like:

  Threading edge through bool from 'bb2149' to 'bb2231' with cost: 1, across block:
bb2237:		; preds = %bb2231, %bb2149
	%tmp2328.rle = phi i32 [ %tmp2232, %bb2231 ], [ %tmp2232439, %bb2149 ]		; <i32> [#uses=2]
	%done.0 = phi i32 [ %done.2, %bb2231 ], [ 0, %bb2149 ]		; <i32> [#uses=1]
	%tmp2239 = icmp eq i32 %done.0, 0		; <i1> [#uses=1]
	br i1 %tmp2239, label %bb2231, label %bb2327

or

bb38.i298:		; preds = %bb33.i295, %bb1693
	%tmp39.i296.rle = phi %struct.ibox* [ null, %bb1693 ], [ %tmp39.i296.rle1109, %bb33.i295 ]		; <%struct.ibox*> [#uses=2]
	%minspan.1.i291.reg2mem.1 = phi i32 [ 32000, %bb1693 ], [ %minspan.0.i288, %bb33.i295 ]		; <i32> [#uses=1]
	%tmp40.i297 = icmp eq %struct.ibox* %tmp39.i296.rle, null		; <i1> [#uses=1]
	br i1 %tmp40.i297, label %implfeeds.exit311, label %bb43.i301

This triggers thousands of times in spec.

llvm-svn: 50110
2008-04-22 21:40:39 +00:00
Chris Lattner
c59cf9c8da Dig through multiple levels of AND to thread jumps if needed.
llvm-svn: 50106
2008-04-22 20:46:09 +00:00
Chris Lattner
dcbc6443ae Teach jump threading to thread through blocks like:
br (and X, phi(Y, Z, false)), label L1, label L2

This triggers once on 252.eon and 6 times on 176.gcc.  Blocks 
in question often look like this:

bb262:		; preds = %bb261, %bb248
	%iftmp.251.0 = phi i1 [ true, %bb261 ], [ false, %bb248 ]		; <i1> [#uses=4]
	%tmp270 = icmp eq %struct.rtx_def* %tmp.0.i, null		; <i1> [#uses=1]
	%bothcond = or i1 %iftmp.251.0, %tmp270		; <i1> [#uses=1]
	br i1 %bothcond, label %bb288, label %bb273

In this case, it is clear that it doesn't matter if tmp.0.i is null when coming from bb261.  When coming from bb248, it is all that matters.


Another random example:

check_asm_operands.exit:		; preds = %check_asm_operands.exit.thr_comm, %bb30.i, %bb12.i, %bb6.i413
	%tmp.0.i420 = phi i1 [ true, %bb6.i413 ], [ true, %bb12.i ], [ true, %bb30.i ], [ false, %check_asm_operands.exit.thr_comm ; <i1> [#uses=1]
	call void @llvm.stackrestore( i8* %savedstack ) nounwind 
	%tmp4389 = icmp eq i32 %added_sets_1.0, 0		; <i1> [#uses=1]
	%tmp4394 = icmp eq i32 %added_sets_2.0, 0		; <i1> [#uses=1]
	%bothcond80 = and i1 %tmp4389, %tmp4394		; <i1> [#uses=1]
	%bothcond81 = and i1 %bothcond80, %tmp.0.i420		; <i1> [#uses=1]
	br i1 %bothcond81, label %bb4398, label %bb4397

Here is the case from 252.eon:

bb290.i.i:		; preds = %bb23.i57.i.i, %bb8.i39.i.i, %bb100.i.i, %bb100.i.i, %bb85.i.i110
	%myEOF.1.i.i = phi i1 [ true, %bb100.i.i ], [ true, %bb100.i.i ], [ true, %bb85.i.i110 ], [ true, %bb8.i39.i.i ], [ false, %bb23.i57.i.i ]		; <i1> [#uses=2]
	%i.4.i.i = phi i32 [ %i.1.i.i, %bb85.i.i110 ], [ %i.0.i.i, %bb100.i.i ], [ %i.0.i.i, %bb100.i.i ], [ %i.3.i.i, %bb8.i39.i.i ], [ %i.3.i.i, %bb23.i57.i.i ]		; <i32> [#uses=3]
	%tmp292.i.i = load i8* %tmp16.i.i100, align 1		; <i8> [#uses=1]
	%tmp293.not.i.i = icmp ne i8 %tmp292.i.i, 0		; <i1> [#uses=1]
	%bothcond.i.i = and i1 %tmp293.not.i.i, %myEOF.1.i.i		; <i1> [#uses=1]
	br i1 %bothcond.i.i, label %bb202.i.i, label %bb301.i.i
  Factoring out 3 common predecessors.

On the path from any blocks other than bb23.i57.i.i, the load and compare 
are dead.

llvm-svn: 50096
2008-04-22 07:05:46 +00:00
Chris Lattner
003d69adef refactor some code, no functionality change.
llvm-svn: 50094
2008-04-22 06:36:15 +00:00
Chris Lattner
6e88cf849b fix grammar-o, thanks to Duncan for noticing.
llvm-svn: 50047
2008-04-21 18:25:01 +00:00
Chris Lattner
9a21fbcf81 Use the new SplitBlockPredecessors to implement a todo.
llvm-svn: 50022
2008-04-21 02:57:57 +00:00
Chris Lattner
56fbe56c25 finish the first cut of a jump threading pass implementation.
llvm-svn: 50006
2008-04-20 22:39:42 +00:00
Chris Lattner
c714a8cee8 we can only thread blocks when there is a pred we can determine the succ of.
llvm-svn: 50003
2008-04-20 21:18:09 +00:00
Chris Lattner
4fcfb808fb improve comments, infrastructure, and add some validity checks for threading.
Add a cost function.

llvm-svn: 50002
2008-04-20 21:13:06 +00:00
Chris Lattner
c8c74f39db Add a new Jump Threading pass, which will handle cases
such as those in PR2235.  Right now the pass is not very
effective. :)

llvm-svn: 50000
2008-04-20 20:35:01 +00:00