Commit Graph

175 Commits

Author SHA1 Message Date
Dan Gohman
30fc5bbfd1 Fix a bug which prevented tail merging of return instructions in
beneficial cases. See the changes in test/CodeGen/X86/tail-opts.ll and
test/CodeGen/ARM/ifcvt2.ll for details.

The fix is to change HashEndOfMBB to hash at most one instruction,
instead of trying to apply heuristics about when it will be profitable to
consider more than one instruction. The regular tail-merging heuristics
are already prepared to handle the same cases, and they're more precise.

Also, make test/CodeGen/ARM/ifcvt5.ll and
test/CodeGen/Thumb2/thumb2-branch.ll slightly more complex so that they
continue to test what they're intended to test.

And, this eliminates the problem in
test/CodeGen/Thumb2/2009-10-15-ITBlockBranch.ll, the testcase from
PR5204. Update it accordingly.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102907 91177308-0d34-0410-b5e6-96231b3b80d8
2010-05-03 14:35:47 +00:00
Dale Johannesen
93d6a7e9c2 Teach AnalyzeBranch, RemoveBranch and the branch
folder to be tolerant of debug info following the
branch(es) at the end of a block.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100168 91177308-0d34-0410-b5e6-96231b3b80d8
2010-04-02 01:38:09 +00:00
Bob Wilson
80d23705e6 Stop trying to merge identical jump tables. This had been inadvertently
disabled for several months (since svn r88806) and no one noticed.  My fix
for pr6543 yesterday reenabled it, but broke the ARM port's code for using
TBB/TBH.  Rather than adding a target hook to disable merging for Thumb2 only,
I'm just taking this out.  It is not common to have identical jump tables,
the code we used to merge them was O(N^2), and it only helps code size, not
performance.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98977 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-19 19:05:41 +00:00
Bob Wilson
a1bdfc3c7f Remove a check that can no longer be true, after r84803.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98694 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-16 23:40:32 +00:00
Chris Lattner
18589de9b1 eliminate InvalidateLabel and LabelIDList from MMI and replace
them with a counter.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98462 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-14 02:24:55 +00:00
Dale Johannesen
2cd9ffef6e Fix another place where DEBUG_VALUE affected codegen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98181 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-10 19:57:56 +00:00
Dale Johannesen
c5cf227f3d This survived a bootstrap, so let's try 98104 again.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98137 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-10 05:45:47 +00:00
Dale Johannesen
7dda453410 Speculatively revert 98104; could be what's causing crashes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98108 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-10 00:11:34 +00:00
Dale Johannesen
7f876967c0 Ever more complicated DEBUG_VALUE fixes for branch folding.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98104 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-09 23:52:37 +00:00
Dale Johannesen
84839daa59 Fix dbg value handling in tail merging.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97938 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-08 05:38:13 +00:00
Dale Johannesen
b0812f114b Fix some more places where dbg_value affected codegen.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@97765 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-05 00:02:59 +00:00
Chris Lattner
518bb53485 move target-independent opcodes out of TargetInstrInfo
into TargetOpcodes.h.  #include the new TargetOpcodes.h
into MachineInstr.  Add new inline accessors (like isPHI())
to MachineInstr, and start using them throughout the 
codebase.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@95687 91177308-0d34-0410-b5e6-96231b3b80d8
2010-02-09 19:54:29 +00:00
Chris Lattner
071c62fad0 Rearrange handling of jump tables. Highlights:
1. MachineJumpTableInfo is now created lazily for a function the first time
   it actually makes a jump table instead of for every function.
2. The encoding of jump table entries is now described by the
   MachineJumpTableInfo::JTEntryKind enum.  This enum is determined by the
   TLI::getJumpTableEncoding() hook, instead of by lots of code scattered
   throughout the compiler that "knows" that jump table entries are always
   32-bits in pic mode (for example).
3. The size and alignment of jump table entries is now calculated based on
   their kind, instead of at machinefunction creation time.

Future work includes using the EntryKind in more places in the compiler,
eliminating other logic that "knows" the layout of jump tables in various
situations.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94470 91177308-0d34-0410-b5e6-96231b3b80d8
2010-01-25 23:26:13 +00:00
David Greene
465e2b950d Change errs() to dbgs().
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92097 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-24 00:34:21 +00:00
Bill Wendling
fe586b3e38 Initialize uninitialized variables.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91477 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-16 00:01:27 +00:00
Bill Wendling
408e9d166a Initialize uninitialized variables.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91475 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-16 00:00:18 +00:00
Bill Wendling
43cf6c3939 Revert these. They may have been causing 483_xalancbmk to fail:
$ svn merge -c -91161 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r91161 into '.':
U    lib/CodeGen/BranchFolding.cpp
U    lib/CodeGen/MachineBasicBlock.cpp
$ svn merge -c -91113 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r91113 into '.':
G    lib/CodeGen/MachineBasicBlock.cpp
$ svn merge -c -91101 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r91101 into '.':
U    include/llvm/CodeGen/MachineBasicBlock.h
G    lib/CodeGen/MachineBasicBlock.cpp
$ svn merge -c -91092 https://llvm.org/svn/llvm-project/llvm/trunk
--- Reverse-merging r91092 into '.':
G    include/llvm/CodeGen/MachineBasicBlock.h
G    lib/CodeGen/MachineBasicBlock.cpp



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91376 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-15 00:39:24 +00:00
Bill Wendling
c42a0b75a4 Don't try to move a MBB into the fall-through position if it's a landing pad or
branches only to a landing pad. Without this check, the compiler would go into
an infinite loop because the branch to a landing pad is an "abnormal" edge which
wasn't being taken into account.

This is the meat of that fix:

  if (!PrevBB.canFallThrough() && !MBB->BranchesToLandingPad(MBB)) {

The other stuff is simplification of the "branches to a landing pad" code.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@91161 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-11 21:47:36 +00:00
Dan Gohman
864e2efce2 Remove the target hook TargetInstrInfo::BlockHasNoFallThrough in favor of
MachineBasicBlock::canFallThrough(), which is target-independent and more
thorough.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90634 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-05 00:44:40 +00:00
Chris Lattner
7896c9f436 improve portability to avoid conflicting with std::next in c++'0x.
Patch by Howard Hinnant!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90365 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-03 00:50:42 +00:00
Bob Wilson
15acadde5f Split tail duplication into a separate pass. This is needed to avoid
running tail duplication when doing branch folding for if-conversion, and
we also want to be able to run tail duplication earlier to fix some
reg alloc problems.  Move the CanFallThrough function from BranchFolding
to MachineBasicBlock so that it can be shared by TailDuplication.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89904 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-26 00:32:21 +00:00
Bob Wilson
f8c4cfb7cc Refactor target hook for tail duplication as requested by Chris.
Make tail duplication of indirect branches much more aggressive (for targets
that indicate that it is profitable), based on further experience with
this transformation.  I compiled 3 large applications with and without
this more aggressive tail duplication and measured minimal changes in code
size.  ("size" on Darwin seems to round the text size up to the nearest
page boundary, so I can only say that any code size increase was less than
one 4k page.) Radar 7421267.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89814 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-24 23:35:49 +00:00
Bob Wilson
fbb6b67df0 There should be no need to keep renumbering blocks during tail duplication.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89275 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-18 23:48:57 +00:00
Bob Wilson
60f34b9fb0 Tail duplication still needs to iterate. Duplicating new instructions onto
the tail of a block may make that block a new candidate for duplication.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89264 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-18 22:52:37 +00:00
Bob Wilson
79d621035e Add another statistic to measure code size due to tail duplication.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89254 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-18 22:12:31 +00:00
Bob Wilson
7cd5d3e05c Add statistics for tail duplication.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89225 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-18 19:29:37 +00:00
Bob Wilson
834b08af8d Add a target hook to allow changing the tail duplication limit based on the
contents of the block to be duplicated.  Use this for ARM Cortex A8/9 to
be more aggressive tail duplicating indirect branches, since it makes it
much more likely that they will be predicted in the branch target buffer.
Testcase coming soon.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89187 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-18 03:34:27 +00:00
Bob Wilson
aa60ddac39 Remove a special case for tail merging that seems to be both broken and
unnecessary.  It is broken because the "isIdenticalTo" check should be
negated.  If that is fixed, this code causes the CodeGen/X86/tail-opts.ll
test to fail, in the dont_merge_oddly function.  And, I confirmed that the
regression is real -- the generated code is worse.  As far as I can tell,
that tail-opts.ll test is checking for what this code is supposed to handle
and we're doing the right thing anyway.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89121 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-17 18:30:09 +00:00
Dan Gohman
37d60fd142 Set MadeChange instead of MadeChangeThisIteration.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89114 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-17 18:04:15 +00:00
Bob Wilson
465c8252f2 Update a comment, now that tail duplication happens after other branch
folding optimizations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89109 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-17 17:40:31 +00:00
Bob Wilson
56ea69c3a2 Perform tail duplication only once, after tail merging is complete.
It was too difficult to keep the heuristics for merging and duplication
consistent.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89105 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-17 17:06:18 +00:00
Bob Wilson
4a504c6ff8 Fix a comment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88940 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-16 19:33:27 +00:00
Bob Wilson
c4a0c843e4 Fix some comments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88932 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-16 18:54:08 +00:00
Bob Wilson
d34f5d91bc Whitespace: be consistent with pointer syntax.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88929 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-16 18:08:46 +00:00
Bob Wilson
3cbc312087 Clean up whitespace.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88927 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-16 17:56:13 +00:00
Dan Gohman
c4c550c758 When optimizing for size, don't tail-merge unless it's likely to be a
code-size win, and not when it's only likely to be code-size neutral,
such as when only a single instruction would be eliminated and a new
branch would be required.

This fixes rdar://7392894.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@88692 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-13 21:02:15 +00:00
Dan Gohman
72b2990a74 Make the BranchFolderPass class local to BranchFolding.cpp.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86928 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 01:59:26 +00:00
Dan Gohman
8520149db1 Minor code cleanups.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86926 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 01:51:28 +00:00
Dan Gohman
ad6af45dc1 Tail merge at any size when there are two potentials blocks and one
can be made to fall through into the other.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86909 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-12 00:39:10 +00:00
Dan Gohman
ffe644ebf4 Promote MergePotentialsElt and SameTailElt to be regular classes
instead of typedefs for std::pair. This simplifies the type of
SameTails, which previously was std::vector<std::pair<std::vector<std::pair<unsigned, MachineBasicBlock *> >::iterator, MachineBasicBlock::iterator>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86885 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 21:57:02 +00:00
Dan Gohman
7cc253e3b8 Revert this line of 86871.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86875 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 19:56:05 +00:00
Dan Gohman
2210c0bea8 Add support for tail duplication to BranchFolding, and extend
tail merging support to handle more cases.
 - Recognize several cases where tail merging is beneficial even when
   the tail size is smaller than the generic threshold.
 - Make use of MachineInstrDesc::isBarrier to help detect
   non-fallthrough blocks.
 - Check for and avoid disrupting fall-through edges in more cases.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86871 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 19:48:59 +00:00
Dan Gohman
cdc06ba5df Fix indentation level.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86856 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 18:42:28 +00:00
Dan Gohman
4e3f125e18 Whitespace cleanups.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86855 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 18:38:14 +00:00
Dan Gohman
a127edceae Prefix MBB numbers with "BB#" in debug output to make it clear what
the numbers mean.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86854 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 18:23:17 +00:00
Dan Gohman
d194498d26 Minor code simplification.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86853 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-11 18:18:34 +00:00
Dan Gohman
7071528e4e Remove an unused variable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86642 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-10 01:37:57 +00:00
Dan Gohman
b2e40990c4 Minor code simplification.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86641 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-10 01:36:20 +00:00
Bob Wilson
888acc35a3 Fix branch folding bug for indirect branches: for a block containing only
an unconditional branch (possibly from tail merging), this code is
trying to redirect all of its predecessors to go directly to the branch
target, but that isn't feasible for indirect branches.  The other
predecessors (that don't end with indirect branches) could theoretically
still be handled, but that is not easily done right now.

The AnalyzeBranch interface doesn't currently let us distinguish jump table
branches from indirect branches, and this code is currently handling
jump tables.  To avoid punting on address-taken blocks, we would have to give
up handling jump tables.  That seems like a bad tradeoff.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85975 91177308-0d34-0410-b5e6-96231b3b80d8
2009-11-03 23:44:31 +00:00
Dan Gohman
ab918103d2 Don't delete blocks which have their address taken.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85572 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-30 02:13:27 +00:00