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.

llvm-svn: 94323

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

llvm-svn: 94321

llvm-svn: 94319

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.

llvm-svn: 93253

llvm-svn: 93222

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

llvm-svn: 93221

on branches by renaming it and checking for a branch at the call site.

llvm-svn: 93208

llvm-svn: 92912

llvm-svn: 92614

llvm-svn: 92211

llvm-svn: 90708

precisely, which prevents us from infinitely peeling the loop.

llvm-svn: 90211

llvm-svn: 88865

llvm-svn: 88864

which implements GCC PR18046.  This also gets us 360 more
jump threads on 176.gcc.

llvm-svn: 86953

llvm-svn: 86952

making the new LVI stuff smart enough to subsume some special
cases in the old code.  Disable them when LVI is around, the
testcase still passes.

llvm-svn: 86951

allows us to handle the test10 testcase.

llvm-svn: 86924

llvm-svn: 86923

llvm-svn: 86920

uses LVI info when -enable-jump-threading-lvi is passed.

llvm-svn: 86886

start using them in a trivial way when -enable-jump-threading-lvi
is passed.  enable-jump-threading-lvi will be my playground for 
awhile.

llvm-svn: 86789

llvm-svn: 86766

llvm-svn: 86739

into libanalysis and transformutils.

llvm-svn: 86735

llvm-svn: 86723

debug intrinsics, and an unconditional branch when possible.  This
reuses the TryToSimplifyUncondBranchFromEmptyBlock function split
out of simplifycfg.

llvm-svn: 86722

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.

llvm-svn: 86646

llvm-svn: 86639

except that the result may not be a constant.  Switch jump threading to 
use it so that it gets things like (X & 0) -> 0, which occur when phi preds
are deleted and the remaining phi pred was a zero.

llvm-svn: 86637

Simplify[IF]Cmp pieces.  Add some predicates to CmpInst to 
determine whether a predicate is fp or int.

llvm-svn: 86624

llvm-svn: 86616

simplifies instruction users of PHIs when the phi is eliminated.  This
will be moved to transforms/utils after some other refactoring.

llvm-svn: 86603

llvm-svn: 86497

(making pred factoring only happen if threading is guaranteed
to be successful).

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

llvm-svn: 86355

86289, 86278, 86270, 86267, 86266 & 86264
Chris, please take a look.

llvm-svn: 86321

llvm-svn: 86314

set only once even if it has multiple edges to BB.

llvm-svn: 86299

llvm-svn: 86289

llvm-svn: 86278