Commit Graph

71 Commits

Author SHA1 Message Date
Owen Anderson
36c4debc94 Fix PR8247: JumpThreading can cause a block to become unreachable while still having predecessor, if it is part of a self-loop.
Because of this, we cannot use the Simplify* APIs, as they can assert-fail on unreachable code.  Since it's not easy to determine
if a given threading will cause a block to become unreachable, simply defer simplifying simplification to later InstCombine and/or
DCE passes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@115082 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-29 20:34:41 +00:00
Owen Anderson
2a0fd011c2 Remove dead option from tests.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@113855 91177308-0d34-0410-b5e6-96231b3b80d8
2010-09-14 21:03:40 +00:00
Owen Anderson
e1aa33f2a2 Merge 2010-08-31-InfiniteRecursion.ll into crash.ll.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112635 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-31 20:27:17 +00:00
Owen Anderson
b95df124b2 Add a test for the duplicated-conditional situation illutrated by PR5652.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112621 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-31 18:49:12 +00:00
Owen Anderson
047f4f5c91 Manually reduce this testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112615 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-31 18:16:29 +00:00
Owen Anderson
421cc4c999 Add a micro-test for the transforms I added to JumpThreading.
I have not been able to find a way to test each in isolation, for a few reasons:
1) The ability to look-through non-i1 BinaryOperator's requires the ability to look through non-constant
   ICmps in order for it to ever trigger.
2) The ability to do LVI-powered PHI value determination only matters in cases that ProcessBranchOnPHI
   can't handle.  Since it already handles all the cases without other instructions in the def-use chain
   between the PHI and the branch, it requires the ability to look through ICmps and/or BinaryOperators
   as well.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112611 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-31 17:59:07 +00:00
Owen Anderson
cb21190cbd More Chris-inspired JumpThreading fixes: use ConstantExpr to correctly constant-fold undef, and be more careful with its return value.
This actually exposed an infinite recursion bug in ComputeValueKnownInPredecessors which theoretically already existed (in JumpThreading's
handling of and/or of i1's), but never manifested before.  This patch adds a tracking set to prevent this case.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112589 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-31 07:36:34 +00:00
Owen Anderson
660cab32fe Use LVI to eliminate conditional branches where we've tested a related condition previously. Update tests for this change.
This fixes PR5652.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112270 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27 17:12:29 +00:00
Owen Anderson
62efd3b385 Make JumpThreading smart enough to properly thread StrSwitch when it's compiled with clang++.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112198 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-26 17:40:24 +00:00
Owen Anderson
6cd2075549 In the default address space, any GEP off of null results in a trap value if you try to load it. Thus,
any load in the default address space that completes implies that the base value that it GEP'd from
was not null.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112015 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-25 01:16:47 +00:00
Chris Lattner
2fa7b48eb5 Fix PR7755: knowing something about an inval for a pred
from the LHS should disable reconsidering that pred on the
RHS.  However, knowing something about the pred on the RHS
shouldn't disable subsequent additions on the RHS from
happening.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111349 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-18 03:14:36 +00:00
Owen Anderson
88dafec7f9 Fix a test with malformed IR. Not sure why this didn't fail before.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109422 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-26 18:44:56 +00:00
Chris Lattner
d2bfe54b0a Fix PR7647, handling the case when 'To' ends up being
mutated by recursive simplification.  This also enhances
ReplaceAndSimplifyAllUses to actually do a real RAUW
at the end of it, which updates any value handles
pointing to "From" to start pointing to "To".  This
seems useful for debug info and random other VH users.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108415 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-15 06:36:08 +00:00
Chris Lattner
0a96144aac if jump threading is able to infer interesting values on both
the LHS and RHS of an and/or instruction, don't multiply add
known predecessor values.  This fixes the crash on testcase
from PR7498


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@108114 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-12 00:47:34 +00:00
Chris Lattner
e58867e55e jump threading can't split a critical edge from an indirectbr. This
fixes PR7356.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105950 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-14 19:45:43 +00:00
Chris Lattner
6f285d2105 fix PR6743, a case where we'd delete an instruction before using it
in some cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100937 91177308-0d34-0410-b5e6-96231b3b80d8
2010-04-10 18:26:57 +00:00
Chris Lattner
37914c8e83 fix PR6305 by handling BlockAddress in a helper function
called by jump threading.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96263 91177308-0d34-0410-b5e6-96231b3b80d8
2010-02-15 20:47:49 +00:00
Chris Lattner
1e452650c6 Make jump threading honor x|undef -> true and x&undef -> false,
instead of considering x|undef -> x, which may not be true.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95850 91177308-0d34-0410-b5e6-96231b3b80d8
2010-02-11 04:40:44 +00:00
Chris Lattner
d668839cb9 third bug from PR6119: the xor dupe extension allows
for arbitrary terminators in predecessors, don't assume
it is a conditional or uncond branch.  The testcase shows
an example where they can happen with switches.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94323 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-23 19:21:31 +00:00
Chris Lattner
2dd7657a5b add an early out to ProcessBranchOnXOR to speed it up,
handle the case when we can infer an input to the xor
from all inputs that agree, instead of going into an
infinite loop.  Another part of PR6199


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94321 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-23 19:16:25 +00:00
Chris Lattner
8231fd1e6c fix a crash in jump threading, PR6119
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94319 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-23 18:56:07 +00:00
Chris Lattner
972a46c96a 1) Use the new SimplifyInstructionsInBlock routine instead of the copy
in JT.

2) When cloning blocks for PHI or xor conditions, use
instsimplify to simplify the code as we go.  This allows us to 
squish common cases early in JT which opens up opportunities for
subsequent iterations, and allows it to completely simplify the
testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93253 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-12 20:41:47 +00:00
Chris Lattner
2249a0b1bd Teach jump threading to duplicate small blocks when the branch
condition is a xor with a phi node.  This eliminates nonsense
like this from 176.gcc in several places:

 LBB166_84:
        testl   %eax, %eax
-       setne   %al
-       xorb    %cl, %al
-       notb    %al
-       testb   $1, %al
-       je      LBB166_85
+       je      LBB166_69
+       jmp     LBB166_85

This is rdar://7391699



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93221 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-12 02:07:17 +00:00
Chris Lattner
08bc2701a2 fix PR5698
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90708 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-06 17:17:23 +00:00
Chris Lattner
46875c0bfb fix PR5640 by tracking whether a block is the header of a loop more
precisely, which prevents us from infinitely peeling the loop.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90211 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-01 06:04:43 +00:00
Gabor Greif
8bedf029f0 typo
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86980 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 09:44:17 +00:00
Chris Lattner
66c04c48de use getPredicateOnEdge to fold comparisons through PHI nodes,
which implements GCC PR18046.  This also gets us 360 more
jump threads on 176.gcc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86953 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 05:24:05 +00:00
Chris Lattner
3e04a05672 should not commit when distracted.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86929 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 02:04:17 +00:00
Chris Lattner
a5810add9c We now thread some impossible condition information with LVI.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86927 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 01:55:20 +00:00
Chris Lattner
87e9f59c7a with the new code we can thread non-instruction values. This
allows us to handle the test10 testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86924 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 01:41:34 +00:00
Chris Lattner
b8c124c343 move some stuff into DEBUG's and turn on lazy-value-info for
the basic.ll testcase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86918 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 01:22:16 +00:00
Chris Lattner
2b9024c877 oops, didn't mean to commit this, no harm, but add a todoops, didn't mean to commit this, no harm, but add a todoo
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86768 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 00:27:54 +00:00
Chris Lattner
10f2d13d58 Stub out a new lazy value info pass, which will eventually
vend value constraint information to the optimizer.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86767 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 00:22:30 +00:00
Chris Lattner
055d046f48 implement a TODO by teaching jump threading about "xor x, 1".
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86739 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-10 22:39:16 +00:00
Chris Lattner
f3183f6da6 Make jump threading eliminate blocks that just contain phi nodes,
debug intrinsics, and an unconditional branch when possible.  This
reuses the TryToSimplifyUncondBranchFromEmptyBlock function split
out of simplifycfg.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86722 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-10 21:40:01 +00:00
Chris Lattner
fddcf47a24 make jump threading recursively simplify expressions instead of doing it
just one level deep.  On the testcase we go from getting this:

F1:                                               ; preds = %T2
  %F = and i1 true, %cond                         ; <i1> [#uses=1]
  br i1 %F, label %X, label %Y

to a fully threaded:

F1:                                               ; preds = %T2
  br label %Y


This changes gets us to the point where we're forming (too many) switch 
instructions on doug's strswitch testcase.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86646 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-10 01:57:31 +00:00
Chris Lattner
5729d38c81 reapply 86289, 86278, 86270, 86267, 86266 & 86264 plus a fix
(making pred factoring only happen if threading is guaranteed
to be successful).

This now survives an X86-64 bootstrap of llvm-gcc.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86355 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-07 08:05:03 +00:00
Devang Patel
12d53dba36 Revert following patches to fix llvmgcc bootstrap.
86289, 86278, 86270, 86267, 86266 & 86264
Chris, please take a look.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86321 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-07 01:32:59 +00:00
Chris Lattner
82114b98c9 Fix a problem discovered on self host.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86278 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-06 19:21:48 +00:00
Chris Lattner
785672534d Extend jump threading to support much more general threading
predicates.  This allows us to jump thread things like:

_ZN12StringSwitchI5ColorE4CaseILj7EEERS1_RAT__KcRKS0_.exit119:
  %tmp1.i24166 = phi i8 [ 1, %bb5.i117 ], [ %tmp1.i24165, %_Z....exit ], [ %tmp1.i24165, %bb4.i114 ] 
  %toBoolnot.i87 = icmp eq i8 %tmp1.i24166, 0     ; <i1> [#uses=1]
  %tmp4.i90 = icmp eq i32 %tmp2.i, 6              ; <i1> [#uses=1]
  %or.cond173 = and i1 %toBoolnot.i87, %tmp4.i90  ; <i1> [#uses=1]
  br i1 %or.cond173, label %bb4.i96, label %_ZN12...

Where it is "obvious" that when coming from %bb5.i117 that the 'and' is always 
false.  This triggers a surprisingly high number of times in the testsuite, 
and gets us closer to generating good code for doug's strswitch testcase.

This also make a bunch of other code in jump threading redundant, I'll rip
out in the next patch.  This survived an enable-checking llvm-gcc bootstrap.




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86264 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-06 18:15:14 +00:00
Chris Lattner
e4bddf1837 merge a few crash tests into crash.ll
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86119 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-05 05:57:34 +00:00
Dan Gohman
2b110caabf Make these tests more interesting by using
-verify-dom-info and -verify-loop-info, which enable additional
(expensive) consistency checks.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85017 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-24 23:23:04 +00:00
Chris Lattner
88a8624f8e alternate fix for PR5258 which avoids worklist problems, with reduced testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84667 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-20 20:27:49 +00:00
Torok Edwin
f993327e71 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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84638 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-20 15:42:00 +00:00
Chris Lattner
5a06cf644f when folding duplicate conditions, delete the
now-probably-dead instruction tree feeding it.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83778 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11 18:39:58 +00:00
Chris Lattner
78c552ef30 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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83759 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11 07:24:57 +00:00
Chris Lattner
113e4c6070 another testcase jump threading shouldn't crash on.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83758 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11 07:11:11 +00:00
Chris Lattner
c6c167f3bf rename a file, remove a poorly reduced testcase.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83757 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11 07:10:28 +00:00
Chris Lattner
e33583b7c2 make jump threading on a phi with undef inputs happen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83754 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11 04:18:15 +00:00
Chris Lattner
41fb43bb1e merge two tests.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83751 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11 03:55:30 +00:00