Commit Graph

7492 Commits

Author SHA1 Message Date
Chris Lattner bf0aa927cc split dom frontier handling stuff out to its own DominanceFrontier header,
so that Dominators.h is *just* domtree.  Also prune #includes a bit.

llvm-svn: 122714
2011-01-02 22:09:33 +00:00
Chris Lattner 704541bb23 sketch out a new early cse pass. No functionality yet.
llvm-svn: 122713
2011-01-02 21:47:05 +00:00
Chris Lattner 9c69406f2b fix a miscompilation of tramp3d-v4: when forming a memcpy, we have to make
sure that the loop we're promoting into a memcpy doesn't mutate the input
of the memcpy.  Before we were just checking that the dest of the memcpy
wasn't mod/ref'd by the loop.

llvm-svn: 122712
2011-01-02 21:14:18 +00:00
Chris Lattner 5702a43c09 If a loop iterates exactly once (has backedge count = 0) then don't
mess with it.  We'd rather peel/unroll it than convert all of its 
stores into memsets.

llvm-svn: 122711
2011-01-02 20:24:21 +00:00
Nick Lewycky 5361b84184 Also remove functions that use complex constant expressions in terms of
another function.

llvm-svn: 122705
2011-01-02 19:16:44 +00:00
Chris Lattner 8455b6e45e enhance loop idiom recognition to scan *all* unconditionally executed
blocks in a loop, instead of just the header block.  This makes it more
aggressive, able to handle Duncan's Ada examples.

llvm-svn: 122704
2011-01-02 19:01:03 +00:00
Chris Lattner 0cdc6f62a5 make inSubLoop much more efficient.
llvm-svn: 122703
2011-01-02 18:53:08 +00:00
Chris Lattner 27497ece96 rip out isExitBlockDominatedByBlockInLoop, calling DomTree::dominates instead.
isExitBlockDominatedByBlockInLoop is a relic of the days when domtree was 
*just* a tree and didn't have DFS numbers.  Checking DFS numbers is faster
and easier than "limiting the search of the tree".

llvm-svn: 122702
2011-01-02 18:45:39 +00:00
Chris Lattner 0469e01c02 add a list of opportunities for future improvement.
llvm-svn: 122701
2011-01-02 18:32:09 +00:00
Duncan Sands 64f1c0dcda Fix PR8702 by not having LoopSimplify claim to preserve LCSSA form. As described
in the PR, the pass could break LCSSA form when inserting preheaders.  It probably
would be easy enough to fix this, but since currently we always go into LCSSA form
after running this pass, doing so is not urgent.

llvm-svn: 122695
2011-01-02 13:38:21 +00:00
Chris Lattner ddf58010bd Allow loop-idiom to run on multiple BB loops, but still only scan the loop
header for now for memset/memcpy opportunities.  It turns out that loop-rotate
is successfully rotating loops, but *DOESN'T MERGE THE BLOCKS*, turning "for 
loops" into 2 basic block loops that loop-idiom was ignoring.

With this fix, we form many *many* more memcpy and memsets than before, including
on the "history" loops in the viterbi benchmark, which look like this:

        for (j=0; j<MAX_history; ++j) {
          history_new[i][j+1] = history[2*i][j];
        }

Transforming these loops into memcpy's speeds up the viterbi benchmark from
11.98s to 3.55s on my machine.  Woo.

llvm-svn: 122685
2011-01-02 07:58:36 +00:00
Chris Lattner 5b5a043d82 remove debugging code.
llvm-svn: 122683
2011-01-02 07:37:13 +00:00
Chris Lattner 12f91befce add some -stats output.
llvm-svn: 122682
2011-01-02 07:36:44 +00:00
Chris Lattner 679572e584 improve loop rotation to use CodeMetrics to analyze the
size of a loop header instead of its own code size estimator.
This allows it to handle bitcasts etc more precisely.

llvm-svn: 122681
2011-01-02 07:35:53 +00:00
Chris Lattner 85b6d81d41 teach loop idiom recognition to form memcpy's from simple loops.
llvm-svn: 122678
2011-01-02 03:37:56 +00:00
Nick Lewycky 4e250c8245 Remove functions from the FnSet when one of their callee's is being merged. This
maintains the guarantee that the DenseSet expects two elements it contains to
not go from inequal to equal under its nose.

As a side-effect, this also lets us switch from iterating to a fixed-point to
actually maintaining a work queue of functions to look at again, and we don't
add thunks to our work queue so we don't need to detect and ignore them.

llvm-svn: 122677
2011-01-02 02:46:33 +00:00
Chris Lattner 1903c42b97 fix a globalopt crash on two Adobe-C++ testcases that the recent
loop idiom pass exposed.

llvm-svn: 122674
2011-01-01 22:31:46 +00:00
Chris Lattner a3514441e0 add a validity check that was missed, fixing a crash on the
new testcase.

llvm-svn: 122662
2011-01-01 20:12:04 +00:00
Chris Lattner 91a4435875 improve validity check to handle constant-trip-count loops more
aggressively.  In practice, this doesn't help anything though,
see the todo.

llvm-svn: 122660
2011-01-01 19:54:22 +00:00
Chris Lattner 8b3baf6d75 implement the "no aliasing accesses in loop" safety check. This pass
should be correct now.

llvm-svn: 122659
2011-01-01 19:39:01 +00:00
Duncan Sands 2c440fa403 Simplify this pass by using a depth-first iterator to ensure that all
operands are visited before the instructions themselves.

llvm-svn: 122647
2010-12-31 17:49:05 +00:00
Duncan Sands 6cc7126ed9 Zap dead instructions harder.
llvm-svn: 122645
2010-12-31 16:17:54 +00:00
Benjamin Kramer 570dd787a6 Make a bunch of symbols internal.
llvm-svn: 122642
2010-12-30 22:34:44 +00:00
Chris Lattner 65a699d4d0 simplify this, isBytewiseValue handles the extra check. We still
check for "multiple of a byte" in size to make it clear that the
>> 3 below is safe.

llvm-svn: 122604
2010-12-28 18:53:48 +00:00
Duncan Sands 5cf10e691b Silence gcc warning about an unused variable when doing a release build.
llvm-svn: 122593
2010-12-28 09:41:15 +00:00
Chris Lattner cb18bfa3d2 fix some issues Frits noticed, add AliasAnalysis as a dependency
llvm-svn: 122585
2010-12-27 18:39:08 +00:00
Benjamin Kramer 84bd73c527 BuildLibCalls: Nuke EmitMemCpy, EmitMemMove and EmitMemSet. They are dead and superseded by IRBuilder.
llvm-svn: 122576
2010-12-27 00:25:32 +00:00
Benjamin Kramer 7cba269dfb SimplifyLibCalls: Use IRBuilder to simplify code.
llvm-svn: 122575
2010-12-27 00:16:46 +00:00
Chris Lattner b9fe685b9a have loop-idiom nuke instructions that feed stores that get removed.
llvm-svn: 122574
2010-12-27 00:03:23 +00:00
Chris Lattner 29e14edc8d implement enough of the memset inference algorithm to recognize and insert
memsets.  This is still missing one important validity check, but this is enough
to compile stuff like this:

void test0(std::vector<char> &X) {
  for (std::vector<char>::iterator I = X.begin(), E = X.end(); I != E; ++I)
    *I = 0;
}

void test1(std::vector<int> &X) {
  for (long i = 0, e = X.size(); i != e; ++i)
    X[i] = 0x01010101;
}

With:
 $ clang t.cpp -S -o - -O2 -emit-llvm | opt -loop-idiom | opt -O3 | llc 

to:

__Z5test0RSt6vectorIcSaIcEE:            ## @_Z5test0RSt6vectorIcSaIcEE
## BB#0:                                ## %entry
	subq	$8, %rsp
	movq	(%rdi), %rax
	movq	8(%rdi), %rsi
	cmpq	%rsi, %rax
	je	LBB0_2
## BB#1:                                ## %bb.nph
	subq	%rax, %rsi
	movq	%rax, %rdi
	callq	___bzero
LBB0_2:                                 ## %for.end
	addq	$8, %rsp
	ret
...
__Z5test1RSt6vectorIiSaIiEE:            ## @_Z5test1RSt6vectorIiSaIiEE
## BB#0:                                ## %entry
	subq	$8, %rsp
	movq	(%rdi), %rax
	movq	8(%rdi), %rdx
	subq	%rax, %rdx
	cmpq	$4, %rdx
	jb	LBB1_2
## BB#1:                                ## %for.body.preheader
	andq	$-4, %rdx
	movl	$1, %esi
	movq	%rax, %rdi
	callq	_memset
LBB1_2:                                 ## %for.end
	addq	$8, %rsp
	ret

llvm-svn: 122573
2010-12-26 23:42:51 +00:00
Chris Lattner 6cf8d6cc6e start using irbuilder to make mem intrinsics in a few passes.
llvm-svn: 122572
2010-12-26 22:57:41 +00:00
Chris Lattner 7c5f9c35d1 sketch more of this out.
llvm-svn: 122567
2010-12-26 20:45:45 +00:00
Chris Lattner 9cb1035f94 move isBytewiseValue out to ValueTracking.h/cpp
llvm-svn: 122565
2010-12-26 20:15:01 +00:00
Chris Lattner 81ae3f299a actually add the file...
llvm-svn: 122563
2010-12-26 19:39:38 +00:00
Chris Lattner 2ef535a4e4 Start of a pass for recognizing memset and memcpy idioms.
No functionality yet.

llvm-svn: 122562
2010-12-26 19:32:44 +00:00
Benjamin Kramer 30342fb1fd Simplify code.
llvm-svn: 122561
2010-12-26 15:23:45 +00:00
Chris Lattner d729d0dcdb don't lose TD info
llvm-svn: 122556
2010-12-25 20:52:04 +00:00
Chris Lattner 20fca48341 switch the inliner alignment enforcement stuff to use the
getOrEnforceKnownAlignment function, which simplifies the code
and makes it stronger.

llvm-svn: 122555
2010-12-25 20:42:38 +00:00
Chris Lattner 6fcd32e7d7 Move getOrEnforceKnownAlignment out of instcombine into Transforms/Utils.
llvm-svn: 122554
2010-12-25 20:37:57 +00:00
Benjamin Kramer b90b2f0635 Fix a thinko pointed out by Frits van Bommel: looking through global variables in isBytewiseValue is not safe.
llvm-svn: 122550
2010-12-24 22:23:59 +00:00
Benjamin Kramer ea9152e551 MemCpyOpt: Turn memcpys from a constant into a memset if possible.
This allows us to compile "int cst[] = {-1, -1, -1};" into
  movl  $-1, 16(%rsp)
  movq  $-1, 8(%rsp)
instead of
  movl  _cst+8(%rip), %eax
  movl  %eax, 16(%rsp)
  movq  _cst(%rip), %rax
  movq  %rax, 8(%rsp)

llvm-svn: 122548
2010-12-24 21:17:12 +00:00
Owen Anderson 226ac14afb When determining if we can fold (x >> C1) << C2, the bits that we need to verify are zero
are not the low bits of x, but the bits that WILL be the low bits after the operation completes.

llvm-svn: 122529
2010-12-23 23:56:24 +00:00
Owen Anderson 5d690d4168 It is possible for SimplifyCFG to cause PHI nodes to become redundant too late in the optimization
pipeline to be caught by instcombine, and it's not feasible to catch them in SimplifyCFG because the
use-lists are in an inconsistent state at the point where it could know that it need to simplify them.
Instead, have CodeGenPrepare look for trivially redundant PHIs as part of its general cleanup effort.

llvm-svn: 122516
2010-12-23 20:57:35 +00:00
Mon P Wang 18b762a946 Preserve the address space when generating bitcasts for MemTransferInst in ConvertToScalarInfo
llvm-svn: 122462
2010-12-23 01:41:32 +00:00
Jeffrey Yasskin 9b43f33620 Change all self assignments X=X to (void)X, so that we can turn on a
new gcc warning that complains on self-assignments and
self-initializations.

llvm-svn: 122458
2010-12-23 00:58:24 +00:00
Benjamin Kramer 8ef5001b27 InstCombine: creating selects from -1 and 0 is fine, they combine into a sext from i1.
llvm-svn: 122453
2010-12-22 23:12:15 +00:00
Duncan Sands fbb9ac3cca Add a generic expansion transform: A op (B op' C) -> (A op B) op' (A op C)
if both A op B and A op C simplify.  This fires fairly often but doesn't
make that much difference.  On gcc-as-one-file it removes two "and"s and
turns one branch into a select.

llvm-svn: 122399
2010-12-22 13:36:08 +00:00
Duncan Sands 3547d2ebd8 Add some statistics, good for understanding how much more powerful
instcombine is compared to instsimplify.

llvm-svn: 122397
2010-12-22 09:40:51 +00:00
Owen Anderson 5ab8d4b5e5 Give GVN back the ability to perform simple conditional propagation on conditional branch values.
I still think that LVI should be handling this, but that capability is some ways off in the future,
and this matters for some significant benchmarks.

llvm-svn: 122378
2010-12-21 23:54:34 +00:00
Owen Anderson 12470778d7 Remove dead code.
llvm-svn: 122371
2010-12-21 22:31:24 +00:00
Benjamin Kramer 43493c089f GVN's Expression is not POD-like (it contains a SmallVector). Simplify code while at it.
llvm-svn: 122362
2010-12-21 21:30:19 +00:00
Duncan Sands 3b8af41a3e Visit instructions deterministically. Use a FIFO so as to approximately
visit instructions before their uses, since InstructionSimplify does a
better job in that case.  All this prompted by Frits van Bommel.

llvm-svn: 122343
2010-12-21 17:08:55 +00:00
Duncan Sands e7cbb64ec0 If an instruction simplifies, try again to simplify any uses of it. This is
not very important since the pass is only used for testing, but it does make
it more realistic.  Suggested by Frits van Bommel.

llvm-svn: 122336
2010-12-21 16:12:03 +00:00
Duncan Sands d0eb6d39f8 Pull a few more simplifications out of instcombine (there are still
plenty left though!), in particular for multiplication.

llvm-svn: 122330
2010-12-21 14:00:22 +00:00
Duncan Sands eaff500c7b Oops, forgot to add the pass itself!
llvm-svn: 122265
2010-12-20 21:07:42 +00:00
Duncan Sands a436cbe4bf Add a new convenience pass for testing InstructionSimplify. Previously
it could only be tested indirectly, via instcombine, gvn or some other
pass that makes use of InstructionSimplify, which means that testcases
had to be carefully contrived to dance around any other transformations
that that pass did.

llvm-svn: 122264
2010-12-20 20:54:37 +00:00
Benjamin Kramer f7957d0463 Add a check missing from my last commit and avoid a potential overflow situation.
llvm-svn: 122258
2010-12-20 20:00:31 +00:00
Benjamin Kramer 2bca3a67b3 Reduce indentation.
llvm-svn: 122249
2010-12-20 16:21:59 +00:00
Benjamin Kramer 68531baea9 Teach InstCombine to merge (icmp ult (X + CA), C1) | (icmp eq X, C2) into (icmp ult (X + CA), C1 + 1) if C2 + CA == C1.
InstCombine creates these so now we compile x == 23 || x == 24 || x == 25 to
  %x.off = add i32 %x, -23
  %1 = icmp ult i32 %x.off, 3
instead of
  %x.off = add i32 %x, -23
  %1 = icmp ult i32 %x.off, 2
  %cmp3 = icmp eq i32 %x, 25
  %ret2 = or i1 %1, %cmp3

llvm-svn: 122248
2010-12-20 16:18:51 +00:00
Chris Lattner 27ca8ebd4b fix PR8807 by making transformConstExprCastCall aware of byval arguments.
llvm-svn: 122238
2010-12-20 08:36:38 +00:00
Chris Lattner 7398965b67 various cleanups for transformConstExprCastCall
llvm-svn: 122237
2010-12-20 08:25:06 +00:00
Chris Lattner 0f11495289 when eliding a byval copy due to inlining a readonly function, we have
to make sure that the reused alloca has sufficient alignment.

llvm-svn: 122236
2010-12-20 08:10:40 +00:00
Chris Lattner 0099744506 pull byval processing out to its own helper function.
llvm-svn: 122235
2010-12-20 07:57:41 +00:00
Chris Lattner 7394680a00 fix PR8769, a miscompilation by inliner when inlining a function with a byval
argument.  The generated alloca has to have at least the alignment of the
byval, if not, the client may be making assumptions that the new alloca won't
satisfy.

llvm-svn: 122234
2010-12-20 07:45:28 +00:00
Mon P Wang 1991c47ec1 Avoid dropping the address space when InstCombine optimizes memset
llvm-svn: 122215
2010-12-20 01:05:30 +00:00
Chris Lattner 4fb9dd4c74 fix an oversight caught by Frits!
llvm-svn: 122204
2010-12-19 23:24:04 +00:00
Chris Lattner b6252a376a tidy up
llvm-svn: 122190
2010-12-19 20:24:28 +00:00
Chris Lattner 3e635d2e99 move a transformation to a more logical place, simplifying it.
llvm-svn: 122183
2010-12-19 19:43:52 +00:00
Chris Lattner 5e0c0c72e9 recognize an unsigned add with overflow idiom into uadd.
This resolves a README entry and technically resolves PR4916,
but we still get poor code for the testcase in that PR because
GVN isn't CSE'ing uadd with add, filed as PR8817.

Previously we got:

_test7:                                 ## @test7
	addq	%rsi, %rdi
	cmpq	%rdi, %rsi
	movl	$42, %eax
	cmovaq	%rsi, %rax
	ret

Now we get:

_test7:                                 ## @test7
	addq	%rsi, %rdi
	movl	$42, %eax
	cmovbq	%rsi, %rax
	ret

llvm-svn: 122182
2010-12-19 19:37:52 +00:00
Chris Lattner 33dc3f0cfa optimize uadd(x, cst) into a comparison when the normal
result is dead.  This is required for my next patch to not
regress the testsuite.

llvm-svn: 122181
2010-12-19 19:35:32 +00:00
Chris Lattner ce2995ae58 use IC.ReplaceInstUsesWith instead of a raw RAUW so that uses of
the old thing end up on the instcombine worklist.  Not doing this
can cause an extra top-level iteration of instcombine, burning
compile time.

llvm-svn: 122179
2010-12-19 18:38:44 +00:00
Chris Lattner 79874566ce generalize the sadd creation code to not require that the
sadd formed is half the size of the original type. We can
now compile this into a sadd.i8:

unsigned char X(char a, char b) {
  int res = a+b;
  if ((unsigned )(res+128) > 255U)
    abort();
  return res;
}

llvm-svn: 122178
2010-12-19 18:35:09 +00:00
Chris Lattner c56c845377 fix another miscompile in the llvm.sadd formation logic: it wasn't
checking to see if the high bits of the original add result were dead.
Inserting a smaller add and zexting back to that size is not good enough.

This is likely to be the fix for 8816.

llvm-svn: 122177
2010-12-19 18:22:06 +00:00
Chris Lattner f29562db25 fix a bug (possibly 8816) in the sadd forming xform: it isn't
profitable (or safe) to promote code when the add-with-constant
has other uses.

llvm-svn: 122175
2010-12-19 17:59:02 +00:00
Chris Lattner ee61c1d820 rework the code added in r122072 to pull it out to its own
helper function, clean up comments, and reduce indentation.
No functionality change.

llvm-svn: 122174
2010-12-19 17:52:50 +00:00
Chris Lattner 408a684d29 Enhance LICM to promote alias sets whose pointers themselves are stored,
which doesn't affect the memory address being promoted.

llvm-svn: 122172
2010-12-19 05:57:25 +00:00
Chris Lattner 3337a81450 fix PR8602, a bug in an assertion: a volatile store *of* a pointer
does not make the alias set for that pointer volatile, just stores
*to* the pointer.

llvm-svn: 122171
2010-12-19 05:51:54 +00:00
Chris Lattner fb888622c3 revert r122164, I'm going to go with a different approach.
llvm-svn: 122168
2010-12-19 04:23:03 +00:00
Chris Lattner 583ec6fa44 first step to fixing PR8642: don't fold away empty basic blocks
which have trapping constant exprs in them due to PHI nodes.
Eliminating them can cause the constant expr to be evalutated
on new paths if the input edges are critical.

llvm-svn: 122164
2010-12-19 03:02:34 +00:00
Chris Lattner 6b8b4855ff simplify this a bit.
llvm-svn: 122156
2010-12-18 20:22:49 +00:00
Bill Wendling 5e3605552e Whitespace fixes. No functionality change.
llvm-svn: 122110
2010-12-17 23:27:41 +00:00
Nate Begeman 7aa18bf46a Add vector versions of some existing scalar transforms to aid codegen in matching psign & pblend operations to the IR produced by clang/gcc for their C idioms.
llvm-svn: 122105
2010-12-17 23:12:19 +00:00
Owen Anderson 1294ea7d53 Reapply r121905 (automatic synthesis of @llvm.sadd.with.overflow) with a fix for a bug that manifested itself
on the DragonEgg self-host bot.  Unfortunately, the testcase is pretty messy and doesn't reduce well due to
interactions with other parts of InstCombine.

llvm-svn: 122072
2010-12-17 18:08:00 +00:00
Benjamin Kramer e5f49c4ff2 SimplifyCFG: Ranges can be larger than 64 bits. Fixes Release-selfhost build.
llvm-svn: 122054
2010-12-17 10:48:14 +00:00
Chris Lattner d14b0f1db7 improve switch formation to handle small range
comparisons formed by comparisons.  For example,
this:

void foo(unsigned x) {
  if (x == 0 || x == 1 || x == 3 || x == 4 || x == 6) 
    bar();
}

compiles into:

_foo:                                   ## @foo
## BB#0:                                ## %entry
	cmpl	$6, %edi
	ja	LBB0_2
## BB#1:                                ## %entry
	movl	%edi, %eax
	movl	$91, %ecx
	btq	%rax, %rcx
	jb	LBB0_3

instead of:

_foo:                                   ## @foo
## BB#0:                                ## %entry
	cmpl	$2, %edi
	jb	LBB0_4
## BB#1:                                ## %switch.early.test
	cmpl	$6, %edi
	ja	LBB0_3
## BB#2:                                ## %switch.early.test
	movl	%edi, %eax
	movl	$88, %ecx
	btq	%rax, %rcx
	jb	LBB0_4

This catches a bunch of cases in GCC, which look like this:

 %804 = load i32* @which_alternative, align 4, !tbaa !0
 %805 = icmp ult i32 %804, 2
 %806 = icmp eq i32 %804, 3
 %or.cond121 = or i1 %805, %806
 %807 = icmp eq i32 %804, 4
 %or.cond124 = or i1 %or.cond121, %807
 br i1 %or.cond124, label %.thread, label %808

turning this into a range comparison.

llvm-svn: 122045
2010-12-17 06:20:15 +00:00
Dan Gohman 93dc2b808f Revert r64460. strtol and friends cannot be marked readonly, even with
a null endptr argument, because they may write to errno.

This fixes a seflhost miscompile observed on Linux targets when TBAA
was enabled.

llvm-svn: 122014
2010-12-17 01:09:43 +00:00
Frits van Bommel 9bbe849fc3 Fix a bug in the loop in JumpThreading::ProcessThreadableEdges() where it could falsely produce a MultipleDestSentinel value if the first predecessor ended with an 'indirectbr'. If that happened, it caused an unnecessary FindMostPopularDest() call.
This wasn't a correctness problem, but it broke the fast path for single-predecessor blocks.

llvm-svn: 121966
2010-12-16 12:16:00 +00:00
Duncan Sands 8d1ab6f6e1 Speculatively revert commit 121905 since it looks like it might have broken the
dragonegg self-host buildbot.  Original commit message:

Add an InstCombine transform to recognize instances of manual overflow-safe addition
(performing the addition in a wider type and explicitly checking for overflow), and
fold them down to intrinsics.  This currently only supports signed-addition, but could
be generalized if someone works out the magic constant formulas for other operations.

llvm-svn: 121965
2010-12-16 09:40:54 +00:00
Dan Gohman e1a17a3473 Make memcpyopt TBAA-aware.
llvm-svn: 121944
2010-12-16 02:51:19 +00:00
Dan Gohman 4467aa5294 Preserve TBAA tags when doing load PRE.
llvm-svn: 121921
2010-12-15 23:53:55 +00:00
Owen Anderson 1cf8881299 Add an InstCombine transform to recognize instances of manual overflow-safe addition
(performing the addition in a wider type and explicitly checking for overflow), and
fold them down to intrinsics.  This currently only supports signed-addition, but could
be generalized if someone works out the magic constant formulas for other operations.

Fixes <rdar://problem/8558713>.

llvm-svn: 121905
2010-12-15 22:32:38 +00:00
Dan Gohman a4fcd2418d Move Value::getUnderlyingObject to be a standalone
function so that it can live in Analysis instead of
VMCore.

llvm-svn: 121885
2010-12-15 20:02:24 +00:00
Duncan Sands 0a2c416894 Move Sub simplifications and additional Add simplifications out of
instcombine and into InstructionSimplify.

llvm-svn: 121861
2010-12-15 14:07:39 +00:00
Frits van Bommel 3d1803495e Teach jump threading to "look through" a select when the branch direction of a terminator depends on it.
When it sees a promising select it now tries to figure out whether the condition of the select is known in any of the predecessors and if so it maps the operands appropriately.

llvm-svn: 121859
2010-12-15 09:51:20 +00:00
Chris Lattner e893e2601e make qsort predicate more conformant by returning 0 for equal values.
llvm-svn: 121838
2010-12-15 04:52:41 +00:00
Owen Anderson 35609d97ae Fix PR8790, another instance where unreachable code can cause instruction simplification to fail,
this case involve a select that simplifies to itself.

llvm-svn: 121817
2010-12-15 00:55:35 +00:00
Owen Anderson 15c85c916f Cleanup trailing whitespace.
llvm-svn: 121816
2010-12-15 00:52:44 +00:00
Chris Lattner 7499b452c1 - 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 335f0e4ad4 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 dc20a7d38c 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