Commit Graph

120 Commits

Author SHA1 Message Date
Bob Wilson
8eab75f390 Reapply my if-conversion cleanup from svn r106939 with fixes.
There are 2 changes relative to the previous version of the patch:

1) For the "simple" if-conversion case, there's no need to worry about
RemoveExtraEdges not handling an unanalyzable branch.  Predicated terminators
are ignored in this context, so RemoveExtraEdges does the right thing.
This might break someday if we ever treat indirect branches (BRIND) as
predicable, but for now, I just removed this part of the patch, because
in the case where we do not add an unconditional branch, we rely on keeping
the fall-through edge to CvtBBI (which is empty after this transformation).

The change relative to the previous patch is:

@@ -1036,10 +1036,6 @@
     IterIfcvt = false;
   }
 
-  // RemoveExtraEdges won't work if the block has an unanalyzable branch,
-  // which is typically the case for IfConvertSimple, so explicitly remove
-  // CvtBBI as a successor.
-  BBI.BB->removeSuccessor(CvtBBI->BB);
   RemoveExtraEdges(BBI);
 
   // Update block info. BB can be iteratively if-converted.


2) My patch exposed a bug in the code for merging the tail of a "diamond",
which had previously never been exercised.  The code was simply checking that
the tail had a single predecessor, but there was a case in
MultiSource/Benchmarks/VersaBench/dbms where that single predecessor was
neither edge of the diamond.  I added the following change to check for
that:

@@ -1276,7 +1276,18 @@
   // tail, add a unconditional branch to it.
   if (TailBB) {
     BBInfo TailBBI = BBAnalysis[TailBB->getNumber()];
-    if (TailBB->pred_size() == 1 && !TailBBI.HasFallThrough) {
+    bool CanMergeTail = !TailBBI.HasFallThrough;
+    // There may still be a fall-through edge from BBI1 or BBI2 to TailBB;
+    // check if there are any other predecessors besides those.
+    unsigned NumPreds = TailBB->pred_size();
+    if (NumPreds > 1)
+      CanMergeTail = false;
+    else if (NumPreds == 1 && CanMergeTail) {
+      MachineBasicBlock::pred_iterator PI = TailBB->pred_begin();
+      if (*PI != BBI1->BB && *PI != BBI2->BB)
+        CanMergeTail = false;
+    }
+    if (CanMergeTail) {
       MergeBlocks(BBI, TailBBI);
       TailBBI.IsDone = true;
     } else {

With these fixes, I was able to run all the SingleSource and MultiSource
tests successfully.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107110 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-29 00:55:23 +00:00
Jim Grosbach
d459f457b8 new, no longer brain-dead, r106907
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107060 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-28 20:26:00 +00:00
Daniel Dunbar
c4abe3aaaf Revert r106907, "make sure to handle dbg_value instructions in the middle of the
block, not...", it caused a bunch of nightly test regressions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107009 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-28 15:47:17 +00:00
Bob Wilson
de4fe23139 Revert my if-conversion cleanup since it caused a bunch of nightly test
regressions.

--- Reverse-merging r106939 into '.':
U    test/CodeGen/Thumb2/thumb2-ifcvt3.ll
U    lib/CodeGen/IfConversion.cpp


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106951 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-26 17:47:06 +00:00
Bob Wilson
ccd9bcca14 Clean up some problems with extra CFG edges being introduced during
if-conversion.  The RemoveExtraEdges function doesn't work for blocks that
end with unanalyzable branches, so in those cases, the "extra" edges must
be explicitly removed.  The CopyAndPredicateBlock and MergeBlocks methods
can also avoid copying successor edges due to branches that have already
been removed.  The latter case is especially helpful when MergeBlocks is
called for handling "diamond" if-conversions, where otherwise you can end
up with some weird intermediate states in the CFG.  Unfortunately I've
been unable to find cases where this cleanup actually makes a significant
difference in the code.  There is one test where we manage to remove an
empty block at the end of a function.  Radar 6911268.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106939 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-26 04:27:33 +00:00
Jim Grosbach
9f054f017c make sure to handle dbg_value instructions in the middle of the block, not
just at the head, when doing diamond if-conversion. rdar://7797940

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106907 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-25 23:05:46 +00:00
Evan Cheng
13151432ed Change if-conversion block size limit checks to add some flexibility.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106901 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-25 22:42:03 +00:00
Jim Grosbach
135ec50ce2 80 column and typo fix
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106894 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-25 22:02:28 +00:00
Dan Gohman
fe60104ac9 Use pre-increment instead of post-increment when the result is not used.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106542 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-22 15:08:57 +00:00
Bob Wilson
54eee524f1 Tidy.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106383 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-19 05:33:57 +00:00
Evan Cheng
86050dc8cc Allow ARM if-converter to be run after post allocation scheduling.
- This fixed a number of bugs in if-converter, tail merging, and post-allocation
  scheduler. If-converter now runs branch folding / tail merging first to
  maximize if-conversion opportunities.
- Also changed the t2IT instruction slightly. It now defines the ITSTATE
  register which is read by instructions in the IT block.
- Added Thumb2 specific hazard recognizer to ensure the scheduler doesn't
  change the instruction ordering in the IT block (since IT mask has been
  finalized). It also ensures no other instructions can be scheduled between
  instructions in the IT block.

This is not yet enabled.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106344 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-18 23:09:54 +00:00
Evan Cheng
6a5e2832d0 Fix an inverted condition.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106330 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-18 22:17:13 +00:00
Evan Cheng
a9934dc20a Teach iff-converter to properly count # of dups. It was not skipping over dbg_value's which resulted in non-duplicated instructions being deleted. rdar://8104384.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106323 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-18 21:52:57 +00:00
Bob Wilson
f50e952b0d Fix PR7372: Conditional branches (at least on ARM) are treated as predicated,
so when IfConverter::CopyAndPredicateBlock checks to see if it should ignore
an instruction because it is a branch, it should not check if the branch is
predicated.

This case (when IgnoreBr is true) is only relevant from IfConvertTriangle,
where new branches are inserted after the block has been copied and predicated.
If the original branch is not removed, we end up with multiple conditional
branches (possibly conflicting) at the end of the block.  Aside from any
immediate errors resulting from that, this confuses the AnalyzeBranch functions
so that the branches are not analyzable.  That in turn causes the IfConverter to
think that the "Simple" pattern can be applied, and things go downhill fast
because the "Simple" pattern does _not_ apply if the block can fall through.

This is pretty fragile.  If there are other degenerate cases where AnalyzeBranch
fails, but where the block may still fall through, the IfConverter should not
perform its "Simple" if-conversion.  But, I don't know how to do that with the
current AnalyzeBranch interface, so for now, the best thing seems to be to
avoid creating branches that AnalyzeBranch cannot handle.

Evan, please review!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106291 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-18 17:07:23 +00:00
Stuart Hastings
3bf9125933 Add a DebugLoc parameter to TargetInstrInfo::InsertBranch(). This
addresses a longstanding deficiency noted in many FIXMEs scattered
across all the targets.

This effectively moves the problem up one level, replacing eleven
FIXMEs in the targets with eight FIXMEs in CodeGen, plus one path
through FastISel where we actually supply a DebugLoc, fixing Radar
7421831.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106243 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-17 22:43:56 +00:00
Evan Cheng
46df4eb46e Make post-ra scheduling, anti-dep breaking, and register scavenger (conservatively) aware of predicated instructions. This enables ARM to move if-conversion before post-ra scheduler.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106091 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-16 07:35:02 +00:00
Bob Wilson
92fffe0405 Fix 80col violations, remove trailing whitespace, and clarify a comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106057 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-15 22:18:54 +00:00
Bob Wilson
6fb124bee9 IfConversion's AnalyzeBlocks method always returns false; clean it up.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106027 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-15 18:57:15 +00:00
Bob Wilson
669db04130 Fix a comment typo.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106015 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-15 18:19:27 +00:00
Jim Grosbach
c834f413ae More dbg_value cleanup so the presence of debug info doesn't affect code-gen.
Make sure to skip the dbg_value instructions when moving dups out of the
diamond. rdar://7797940

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105965 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-14 21:30:32 +00:00
Jim Grosbach
66f360e990 Cleanup. Process the dbg_values separately
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105554 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-07 21:28:55 +00:00
Jim Grosbach
41a628237c Move exit check where it really belongs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105541 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-07 19:12:21 +00:00
Jim Grosbach
870c80540d Make if-conversion ignore dbg_value instructions in its analysis. rdar://7797940
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105498 91177308-0d34-0410-b5e6-96231b3b80d8
2010-06-04 23:01:26 +00:00
David Greene
083b7ffb4d Change errs() to dbgs().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92520 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-04 22:02:01 +00:00
Evan Cheng
e54cb16308 Allow target to disable if-converting predicable instructions. e.g. NEON instructions under ARM mode.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89541 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-21 06:20:26 +00:00
Bob Wilson
a597103c32 Revert r85346 change to control tail merging by CodeGenOpt::Level.
I'm going to redo this using the OptimizeForSize function attribute.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85426 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-28 20:46:46 +00:00
Bob Wilson
cd4f04d6bc Record CodeGen optimization level in the BranchFolding pass so that we can
use it to control tail merging when there is a tradeoff between performance
and code size.  When there is only 1 instruction in the common tail, we have
been merging.  That can be good for code size but is a definite loss for
performance.  Now we will avoid tail merging in that case when the
optimization level is "Aggressive", i.e., "-O3".  Radar 7338114.

Since the IfConversion pass invokes BranchFolding, it too needs to know
the optimization level.  Note that I removed the RegisterPass instantiation
for IfConversion because it required a default constructor.  If someone
wants to keep that for some reason, we can add a default constructor with
a hard-wired optimization level.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85346 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-27 23:49:38 +00:00
Nick Lewycky
6726b6d75a Remove VISIBILITY_HIDDEN from class/struct found inside anonymous namespaces.
Chris claims we should never have visibility_hidden inside any .cpp file but
that's still not true even after this commit.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85042 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-25 06:33:48 +00:00
Evan Cheng
030a0a0cdb Run branch folding if if-converter make some transformations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80994 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-04 07:47:40 +00:00
Chris Lattner
705e07f578 remove various std::ostream version of printing methods from
MachineInstr and MachineOperand.  This required eliminating a
bunch of stuff that was using DOUT, I hope that bill doesn't
mind me stealing his fun. ;-)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79813 91177308-0d34-0410-b5e6-96231b3b80d8
2009-08-23 03:41:05 +00:00
Bill Wendling
44ff7949c7 Convert DOUT to DEBUG(errs()...).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79751 91177308-0d34-0410-b5e6-96231b3b80d8
2009-08-22 20:11:17 +00:00
Daniel Dunbar
ce63ffb52f More migration to raw_ostream, the water has dried up around the iostream hole.
- Some clients which used DOUT have moved to DEBUG. We are deprecating the
   "magic" DOUT behavior which avoided calling printing functions when the
   statement was disabled. In addition to being unnecessary magic, it had the
   downside of leaving code in -Asserts builds, and of hiding potentially
   unnecessary computations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@77019 91177308-0d34-0410-b5e6-96231b3b80d8
2009-07-25 00:23:56 +00:00
Torok Edwin
c23197a26f llvm_unreachable->llvm_unreachable(0), LLVM_UNREACHABLE->llvm_unreachable.
This adds location info for all llvm_unreachable calls (which is a macro now) in
!NDEBUG builds.
In NDEBUG builds location info and the message is off (it only prints
"UREACHABLE executed").


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75640 91177308-0d34-0410-b5e6-96231b3b80d8
2009-07-14 16:55:14 +00:00
Torok Edwin
f36892335b Fix assert(0) conversion, as suggested by Chris.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75423 91177308-0d34-0410-b5e6-96231b3b80d8
2009-07-12 20:07:01 +00:00
Torok Edwin
7d696d8040 Convert more assert(0)+abort() -> LLVM_UNREACHABLE,
and abort()/exit() -> llvm_report_error().


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@75363 91177308-0d34-0410-b5e6-96231b3b80d8
2009-07-11 13:10:19 +00:00
Owen Anderson
13bbe4bb9a Fewer static variables, part 3 of many.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@74140 91177308-0d34-0410-b5e6-96231b3b80d8
2009-06-24 23:41:44 +00:00
Evan Cheng
2077e18caf ifcvt should ignore cfg where true and false successors are the same.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73423 91177308-0d34-0410-b5e6-96231b3b80d8
2009-06-15 21:24:34 +00:00
Bob Wilson
4bb3374b6d Revert r71744. I must not have understood this correctly, because the
assertion is failing for some tests.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71779 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-14 18:08:41 +00:00
Bob Wilson
df1ed67890 The IfConverter::MergeBlocks method appears to be used only to merge a basic
block with its unique predecessor.  Change the code to assert if that is not
the case, instead of trying to handle situations where the block has
multiple predecessors.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71744 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-13 23:54:13 +00:00
Bob Wilson
8308e8fae0 Revert a portion of Dan's change r71018 that I'm convinced is wrong.
Dan was trying to catch the case where a basic block ends with a conditional
branch to the fall-through block.  In this case, all the instructions have
been moved out of FromBBI, leaving it empty.  It cannot end with a
conditional branch.  As the existing comment indicates, it will always fall
through to the next block.  If the block already had the next block (NBB)
listed as a successor, the preceding loop has a check for that and does not
remove it.  Thus, we need to check and add the successor only when it is
not already listed.

With Dan's change, the empty block often ends up with the fall-through
successor listed twice.  This exposed the problem in pr4195, where
CodePlacementOpt did not handle the same predecessor listed more than once.
It is also at least partially responsible for pr4202 and probably a similar
issue with Thumb branches being out of range.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71742 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-13 23:48:58 +00:00
Bob Wilson
596e22e2b3 Merge adjacent conditional.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71741 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-13 23:35:38 +00:00
Bob Wilson
e19fb7de63 Remove an unused variable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71740 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-13 23:31:30 +00:00
Bob Wilson
9c4856a4cf Fix some typos and spelling and grammar, mostly in comments, but also one
field name.  No functional changes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71739 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-13 23:25:24 +00:00
Dan Gohman
5412d06e9c If a MachineBasicBlock has multiple ways of reaching another block,
allow it to have multiple CFG edges to that block. This is needed
to allow MachineBasicBlock::isOnlyReachableByFallthrough to work
correctly. This fixes PR4126.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71018 91177308-0d34-0410-b5e6-96231b3b80d8
2009-05-05 21:10:19 +00:00
Duncan Sands
20d629cb90 Fix typo. Patch by nlewycky.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58709 91177308-0d34-0410-b5e6-96231b3b80d8
2008-11-04 18:05:30 +00:00
Nuno Lopes
7ecbfd1157 fix leakage of IfcvtTokens
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@58690 91177308-0d34-0410-b5e6-96231b3b80d8
2008-11-04 13:02:59 +00:00
Dan Gohman
279c22e6da Optimized FCMP_OEQ and FCMP_UNE for x86.
Where previously LLVM might emit code like this:

        ucomisd %xmm1, %xmm0
        setne   %al
        setp    %cl
        orb     %al, %cl
        jne     .LBB4_2

it now emits this:

        ucomisd %xmm1, %xmm0
        jne     .LBB4_2
        jp      .LBB4_2

It has fewer instructions and uses fewer registers, but it does
have more branches. And in the case that this code is followed by
a non-fallthrough edge, it may be followed by a jmp instruction,
resulting in three branch instructions in sequence. Some effort
is made to avoid this situation.

To achieve this, X86ISelLowering.cpp now recognizes FCMP_OEQ and
FCMP_UNE in lowered form, and replace them with code that emits
two branches, except in the case where it would require converting
a fall-through edge to an explicit branch.

Also, X86InstrInfo.cpp's branch analysis and transform code now
knows now to handle blocks with multiple conditional branches. It
uses loops instead of having fixed checks for up to two
instructions. It can now analyze and transform code generated
from FCMP_OEQ and FCMP_UNE.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@57873 91177308-0d34-0410-b5e6-96231b3b80d8
2008-10-21 03:29:32 +00:00
Dan Gohman
ae73dc1448 Tidy up several unbeseeming casts from pointer to intptr_t.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55779 91177308-0d34-0410-b5e6-96231b3b80d8
2008-09-04 17:05:41 +00:00
Dan Gohman
1501cdbf63 Fix SmallVector's size calculation so that a size of 0 is
handled correctly, and change a few SmallVector uses to use
size 0 to more clearly reflect their intent.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@55181 91177308-0d34-0410-b5e6-96231b3b80d8
2008-08-22 16:07:55 +00:00
Owen Anderson
44eb65cf58 Convert uses of std::vector in TargetInstrInfo to SmallVector. This change had to be propoagated down into all the targets and up into all clients of this API.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54802 91177308-0d34-0410-b5e6-96231b3b80d8
2008-08-14 22:49:33 +00:00