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273 Commits

Author SHA1 Message Date
Chris Lattner
25c3af35d8 split all the guts of SimplifyCFGOpt::run out into one function 
per terminator kind.

llvm-svn: 121688
 2010-12-13 06:25:44 +00:00
Chris Lattner
cb570f87e5 fix a bug in r121680 that upset the various buildbots. 
llvm-svn: 121687
 2010-12-13 05:34:18 +00:00
Chris Lattner
a6db741f3d refactor the speculative execution logic to be factored into the cond branch code instead of 
doing a cfg search for every block simplified.

llvm-svn: 121686
 2010-12-13 05:26:52 +00:00
Chris Lattner
466f54ffcf simplify a bunch of code. 
llvm-svn: 121685
 2010-12-13 05:20:28 +00:00
Chris Lattner
6df7bdd810 move HoistThenElseCodeToIf up to a more logical and efficient-to-handle place. 
llvm-svn: 121684
 2010-12-13 05:15:29 +00:00
Chris Lattner
2e3832d9a0 move 'MergeBlocksIntoPredecessor' call earlier. Use 
getSinglePredecessor to simplify code.

llvm-svn: 121683
 2010-12-13 05:10:48 +00:00
Chris Lattner
a69c443459 factor new code out to a SimplifyBranchOnICmpChain helper function. 
llvm-svn: 121681
 2010-12-13 05:03:41 +00:00
Chris Lattner
a442f24a36 enhance the "change or icmp's into switch" xform to handle one value in an 
'or sequence' that it doesn't understand.  This allows us to optimize
something insane like this:

int crud (unsigned char c, unsigned x)
 {
   if(((((((((( (int) c <= 32 ||
                    (int) c == 46) || (int) c == 44)
                  || (int) c == 58) || (int) c == 59) || (int) c == 60)
               || (int) c == 62) || (int) c == 34) || (int) c == 92)
            || (int) c == 39) != 0)
     foo();
 }

into:

define i32 @crud(i8 zeroext %c, i32 %x) nounwind ssp noredzone {
entry:
  %cmp = icmp ult i8 %c, 33
  br i1 %cmp, label %if.then, label %switch.early.test

switch.early.test:                                ; preds = %entry
  switch i8 %c, label %if.end [
    i8 39, label %if.then
    i8 44, label %if.then
    i8 58, label %if.then
    i8 59, label %if.then
    i8 60, label %if.then
    i8 62, label %if.then
    i8 46, label %if.then
    i8 92, label %if.then
    i8 34, label %if.then
  ]

by pulling the < comparison out ahead of the newly formed switch.

llvm-svn: 121680
 2010-12-13 04:50:38 +00:00
Chris Lattner
5a177e681e merge two very similar functions into one that has a bool argument. 
llvm-svn: 121678
 2010-12-13 04:26:26 +00:00
Chris Lattner
9b1af510cb don't bother handling non-canonical icmp's 
llvm-svn: 121676
 2010-12-13 04:18:32 +00:00
Chris Lattner
395252d93e inline a function, making the result much simpler. 
llvm-svn: 121675
 2010-12-13 04:15:19 +00:00
Chris Lattner
62cc76e9cc Fix my previous patch to handle a degenerate case that the llvm-gcc 
bootstrap buildbot tripped over.

llvm-svn: 121674
 2010-12-13 03:43:57 +00:00
Chris Lattner
11dafaa3ec convert some methods to be static functions 
llvm-svn: 121673
 2010-12-13 03:30:12 +00:00
Chris Lattner
4642d79fb0 zap two more std::sorts. 
llvm-svn: 121672
 2010-12-13 03:24:30 +00:00
Chris Lattner
d9bacc088a fix a fairly serious oversight with switch formation from 
or'd conditions.  Previously we'd compile something like this:

int crud (unsigned char c) {
   return c == 62 || c == 34 || c == 92;
}

into:

  switch i8 %c, label %lor.rhs [
    i8 62, label %lor.end
    i8 34, label %lor.end
  ]

lor.rhs:                                          ; preds = %entry
  %cmp8 = icmp eq i8 %c, 92
  br label %lor.end

lor.end:                                          ; preds = %entry, %entry, %lor.rhs
  %0 = phi i1 [ true, %entry ], [ %cmp8, %lor.rhs ], [ true, %entry ]
  %lor.ext = zext i1 %0 to i32
  ret i32 %lor.ext

which failed to merge the compare-with-92 into the switch.  With this patch
we simplify this all the way to:

  switch i8 %c, label %lor.rhs [
    i8 62, label %lor.end
    i8 34, label %lor.end
    i8 92, label %lor.end
  ]

lor.rhs:                                          ; preds = %entry
  br label %lor.end

lor.end:                                          ; preds = %entry, %entry, %entry, %lor.rhs
  %0 = phi i1 [ true, %entry ], [ false, %lor.rhs ], [ true, %entry ], [ true, %entry ]
  %lor.ext = zext i1 %0 to i32
  ret i32 %lor.ext

which is much better for codegen's switch lowering stuff.  This kicks in 33 times
on 176.gcc (for example) cutting 103 instructions off the generated code.

llvm-svn: 121671
 2010-12-13 03:18:54 +00:00
Chris Lattner
7c8e6047d6 convert an std::sort to array_pod_sort. 
llvm-svn: 121669
 2010-12-13 02:00:58 +00:00
Chris Lattner
1475987634 move the "br (X == 0 | X == 1), T, F" -> switch optimization to a new 
location in simplifycfg.  In the old days, SimplifyCFG was never run on
the entry block, so we had to scan over all preds of the BB passed into
simplifycfg to do this xform, now we can just check blocks ending with
a condbranch.  This avoids a scan over all preds of every simplified 
block, which should be a significant compile-time perf win on functions
with lots of edges.  No functionality change.

llvm-svn: 121668
 2010-12-13 01:57:34 +00:00
Chris Lattner
4088e2b8e4 reduce indentation and generally simplify code, no functionality change. 
llvm-svn: 121667
 2010-12-13 01:47:07 +00:00
Chris Lattner
7cb7867d7a use getFirstNonPHIOrDbg to simplify this code. 
llvm-svn: 121664
 2010-12-13 01:28:06 +00:00
Frits van Bommel
8fb69ee805 Teach SimplifyCFG to turn 
(indirectbr (select cond, blockaddress(@fn, BlockA),
                            blockaddress(@fn, BlockB)))
into
  (br cond, BlockA, BlockB).

llvm-svn: 120943
 2010-12-05 18:29:03 +00:00
Duncan Sands
31c803b2ba Fix PR8445: a block with no predecessors may be the entry block, in which case 
it isn't unreachable and should not be zapped.  The check for the entry block
was missing in one case: a block containing a unwind instruction.  While there,
do some small cleanups: "M" is not a great name for a Function* (it would be
more appropriate for a Module*), change it to "Fn"; use Fn in more places.

llvm-svn: 117224
 2010-10-24 12:23:30 +00:00
Dan Gohman
250b754428 Instead, teach SimplifyCFG to trim non-address-taken blocks from 
indirectbr destination lists.

llvm-svn: 111122
 2010-08-16 14:41:14 +00:00
Dan Gohman
4a63fad976 Teach SimplifyCFG how to simplify indirectbr instructions. 
- Eliminate redundant successors.
 - Convert an indirectbr with one successor into a direct branch.

Also, generalize SimplifyCFG to be able to be run on a function entry block.
It knows quite a few simplifications which are applicable to the entry
block, and it only needs a few checks to avoid trouble with the entry block.

llvm-svn: 111060
 2010-08-14 00:29:42 +00:00
Gabor Greif
36f25dfd33 pass dereferenced iterator to dyn_cast 
llvm-svn: 109098
 2010-07-22 11:43:44 +00:00
Owen Anderson
13700ebb02 Remove unneeded check, and correct style. 
llvm-svn: 108427
 2010-07-15 16:38:22 +00:00
Owen Anderson
2cfe91379b Extend SimplifyCFG's common-destination folding heuristic to allow a single 
"bonus" instruction to be speculatively executed.  Add a heuristic to
ensure we're not tripping up out-of-order execution by checking that this bonus
instruction only uses values that were already guaranteed to be available.

This allows us to eliminate the short circuit in (x&1)&&(x&2).

llvm-svn: 108351
 2010-07-14 19:52:16 +00:00
Gabor Greif
8629f12bb8 cache dereferenced iterators 
llvm-svn: 108133
 2010-07-12 10:59:23 +00:00
Gabor Greif
329c4d8ed9 cache result of operator* 
llvm-svn: 107974
 2010-07-09 15:25:09 +00:00
Dan Gohman
39027c403c Fix a grammaro. 
llvm-svn: 99917
 2010-03-30 20:04:57 +00:00
Gabor Greif
b469818279 fix two cases where the arguments were extracted from the wrong range out of the InvokeInst 
spotted by baldrick -- thanks\!

llvm-svn: 99914
 2010-03-30 19:20:53 +00:00
Bill Wendling
ee84f27536 Make returns more consistent with others. 
llvm-svn: 98490
 2010-03-14 10:40:28 +00:00
Duncan Sands
19d0b47b1f There are two ways of checking for a given type, for example isa<PointerType>(T) 
and T->isPointerTy().  Convert most instances of the first form to the second form.
Requested by Chris.

llvm-svn: 96344
 2010-02-16 11:11:14 +00:00
Duncan Sands
9dff9bec31 Uniformize the names of type predicates: rather than having isFloatTy and 
isInteger, we now have isFloatTy and isIntegerTy.  Requested by Chris!

llvm-svn: 96223
 2010-02-15 16:12:20 +00:00
Jakob Stoklund Olesen
916f48a054 Teach SimplifyCFG about magic pointer constants. 
Weird code sometimes uses pointer constants other than null. This patch
teaches SimplifyCFG to build switch instructions in those cases.

Code like this:

void f(const char *x) {
  if (!x)
    puts("null");
  else if ((uintptr_t)x == 1)
    puts("one");
  else if (x == (char*)2 || x == (char*)3)
    puts("two");
  else if ((intptr_t)x == 4)
    puts("four");
  else
    puts(x);
}

Now becomes a switch:

define void @f(i8* %x) nounwind ssp {
entry:
  %magicptr23 = ptrtoint i8* %x to i64            ; <i64> [#uses=1]
  switch i64 %magicptr23, label %if.else16 [
    i64 0, label %if.then
    i64 1, label %if.then2
    i64 2, label %if.then9
    i64 3, label %if.then9
    i64 4, label %if.then14
  ]

Note that LLVM's own DenseMap uses magic pointers.

llvm-svn: 95439
 2010-02-05 22:03:18 +00:00
Benjamin Kramer
a81a6dff0d Convert a ton of simple integer type equality tests to the new predicate. 
llvm-svn: 92760
 2010-01-05 20:07:06 +00:00
Benjamin Kramer
ccce8bae14 Avoid going through the LLVMContext for type equality where it's safe to dereference the type pointer. 
llvm-svn: 92726
 2010-01-05 13:12:22 +00:00
David Greene
725c7c3f2e Change errs() to dbgs(). 
llvm-svn: 92604
 2010-01-05 01:26:52 +00:00
Devang Patel
be94f23992 Remove dead debug info intrinsics. 
Intrinsic::dbg_stoppoint
 Intrinsic::dbg_region_start 
 Intrinsic::dbg_region_end 
 Intrinsic::dbg_func_start
AutoUpgrade simply ignores these intrinsics now.

llvm-svn: 92557
 2010-01-05 01:10:40 +00:00
Jim Grosbach
d831ef4945 Move EliminateDuplicatePHINodes() from SimplifyCFG.cpp to Local.cpp 
llvm-svn: 90324
 2009-12-02 17:06:45 +00:00
Jim Grosbach
cc69a1ba9a Make EliminateDuplicatePHINodes() available as a utility function 
llvm-svn: 89297
 2009-11-19 02:02:10 +00:00
Chris Lattner
cbd18fc93d refactor TryToSimplifyUncondBranchFromEmptyBlock out of SimplifyCFG. 
llvm-svn: 86666
 2009-11-10 05:59:26 +00:00
Chris Lattner
46b5c642b9 remove a bunch of extraneous LLVMContext arguments 
from various APIs, addressing PR5325.

llvm-svn: 86231
 2009-11-06 04:27:31 +00:00
Dan Gohman
7f7d97eb73 Add a comment about a missed opportunity. 
llvm-svn: 85635
 2009-10-30 23:15:43 +00:00
Dan Gohman
1a95106602 Teach SimplifyCFG how to eliminate duplicate PHI nodes within a block. 
This reduces codesize on a variety of codes by 1-2% on x86-64. It also
helps clean up after SSAUpdater.

llvm-svn: 85626
 2009-10-30 22:39:04 +00:00
Chris Lattner
19788ca686 change simplifycfg to not duplicate 'unwind' instructions. Hopefully 
this will increase the likelihood of common code getting sunk towards
the unwind.

llvm-svn: 83996
 2009-10-13 18:13:05 +00:00
Nick Lewycky
42fb7452df Instruction::clone does not need to take an LLVMContext&. Remove that and 
update all the callers.

llvm-svn: 82889
 2009-09-27 07:38:41 +00:00
Dan Gohman
c8a27f2a5c Rename Instruction::isIdenticalTo to Instruction::isIdenticalToWhenDefined, 
and introduce a new Instruction::isIdenticalTo which tests for full
identity, including the SubclassOptionalData flags. Also, fix the
Instruction::clone implementations to preserve the SubclassOptionalData
flags. Finally, teach several optimizations how to handle
SubclassOptionalData correctly, given these changes.

This fixes the counterintuitive behavior of isIdenticalTo not comparing
the full value, and clone not returning an identical clone, as well as
some subtle bugs that could be caused by these.

Thanks to Nick Lewycky for reporting this, and for an initial patch!

llvm-svn: 80038
 2009-08-25 22:11:20 +00:00
Daniel Dunbar
5e0a58bef4 Fix -Asserts warnings. 
llvm-svn: 79849
 2009-08-23 10:29:55 +00:00
Chris Lattner
b25de3ff60 eliminate the "Value" printing methods that print to a std::ostream. 
This required converting a bunch of stuff off DOUT and other cleanups.

llvm-svn: 79819
 2009-08-23 04:37:46 +00:00
Eli Friedman
d56fca4708 Fix for PR3016: detect the tricky case, where there are 
unfoldable references to a PHI node in the block being folded, and disable
the transformation in that case.  The correct transformation of such PHI
nodes depends on whether BB dominates Succ, and dominance is expensive 
to compute here.  (Alternatively, it's possible to check whether any 
uses are live, but that's also essentially a dominance calculation. 
Another alternative is to use reg2mem, but it probably isn't a good idea to
use that in simplifycfg.)

Also, remove some incorrect code from CanPropagatePredecessorsForPHIs 
which is made unnecessary with this patch: it didn't consider the case 
where a PHI node in BB has multiple uses.

llvm-svn: 79174
 2009-08-16 04:23:49 +00:00