Commit Graph

180 Commits

Author SHA1 Message Date
Dan Gohman a484d17ec5 Make these tests more interesting by using
-verify-dom-info and -verify-loop-info, which enable additional
(expensive) consistency checks.

llvm-svn: 85017
2009-10-24 23:23:04 +00:00
Chris Lattner 7f903681ac alternate fix for PR5258 which avoids worklist problems, with reduced testcase.
llvm-svn: 84667
2009-10-20 20:27:49 +00:00
Torok Edwin cf10ec951d Fix PR5258, jump-threading creating invalid PHIs.
When an incoming value for a PHI is updated, we must also updated all other
incoming values for the same BB to match, otherwise we create invalid PHIs.

llvm-svn: 84638
2009-10-20 15:42:00 +00:00
Chris Lattner 85c85c5e04 when folding duplicate conditions, delete the
now-probably-dead instruction tree feeding it.

llvm-svn: 83778
2009-10-11 18:39:58 +00:00
Chris Lattner 97b1405207 implement a transformation in jump threading that is currently
done by condprop, but do it in a much more general form.  The
basic idea is that we can do a limited form of tail duplication
in the case when we have a branch on a phi.  Moving the branch
up in to the predecessor block makes instruction selection
much easier and encourages chained jump threadings.

llvm-svn: 83759
2009-10-11 07:24:57 +00:00
Chris Lattner 4140d8bd5c another testcase jump threading shouldn't crash on.
llvm-svn: 83758
2009-10-11 07:11:11 +00:00
Chris Lattner ece16f2335 rename a file, remove a poorly reduced testcase.
llvm-svn: 83757
2009-10-11 07:10:28 +00:00
Chris Lattner f99a74e24b make jump threading on a phi with undef inputs happen.
llvm-svn: 83754
2009-10-11 04:18:15 +00:00
Chris Lattner 8d186bfafb merge two tests.
llvm-svn: 83751
2009-10-11 03:55:30 +00:00
Chris Lattner 041c1dca8b simplify some run lines, convert a test to filecheck.
llvm-svn: 83750
2009-10-11 03:54:21 +00:00
Dan Gohman 1880092722 Change tests from "opt %s" to "opt < %s" so that opt doesn't see the
input filename so that opt doesn't print the input filename in the
output so that grep lines in the tests don't unintentionally match
strings in the input filename.

llvm-svn: 81537
2009-09-11 18:01:28 +00:00
Dan Gohman c8054d90fb Eliminate more uses of llvm-as and llvm-dis.
llvm-svn: 81293
2009-09-09 00:09:15 +00:00
Dan Gohman 72a13d2476 Use opt -S instead of piping bitcode output through llvm-dis.
llvm-svn: 81257
2009-09-08 22:34:10 +00:00
Dan Gohman 9737a63ed8 Change these tests to feed the assembly files to opt directly, instead
of using llvm-as, now that opt supports this.

llvm-svn: 81226
2009-09-08 16:50:01 +00:00
Chris Lattner d0a363e03b make jump threading handle lexically identical compare instructions
as if they were multiple uses of the same instruction.  This interacts
well with the existing loadpre that j-t does to open up many new jump
threads earlier.

llvm-svn: 73768
2009-06-19 16:27:56 +00:00
Nick Lewycky 77585a24ac 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 d579cb1167 * 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
Chris Lattner 6f34e317e9 Fix PR3353, infinitely jump threading an infinite loop make from switches.
llvm-svn: 62529
2009-01-19 21:20:34 +00:00
Chris Lattner 482eb70a10 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 350fc5721d testcase for br undef folding.
llvm-svn: 60471
2008-12-03 07:48:27 +00:00
Chris Lattner 595c7279bd 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 8a172daa55 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 5dfbfcd80d 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 98d89d1b1b 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
Chris Lattner 8ed8e3d0e6 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 f7de528463 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 37e9c187b0 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 d5425e8f8d Dig through multiple levels of AND to thread jumps if needed.
llvm-svn: 50106
2008-04-22 20:46:09 +00:00
Chris Lattner 3df4c15dc7 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 3cc28ce1ed add a basic testcase.
llvm-svn: 50093
2008-04-22 06:35:14 +00:00