Commit Graph

323 Commits

Author SHA1 Message Date
Benjamin Kramer
10fcfb53fd SimplifyCFG: Use ComputeMaskedBits to prune dead cases from switch instructions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131345 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-14 15:57:25 +00:00
Peter Collingbourne
57808b3da0 SimplifyCFG: Expose phi node folding cost threshold as command line parameter
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130528 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-29 18:47:38 +00:00
Peter Collingbourne
f15907fead SimplifyCFG: Add CostRemaining parameter to DominatesMergePoint
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130527 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-29 18:47:31 +00:00
Peter Collingbourne
8a70192b51 SimplifyCFG: Add Trunc, ZExt and SExt to the list of cheap instructions for phi node folding
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130526 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-29 18:47:25 +00:00
Chris Lattner
3c6e746b5f rework FoldBranchToCommonDest to exit earlier when there is a bonus
instruction around, reducing work.

Greatly simplify handling of debug instructions.  There is no need to
build up a vector of them and then move them into the one predecessor
if we're processing a block.  Instead just rescan the block and *copy*
them into the pred.  If a block gets merged into multiple preds, this
will retain more debug info.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129502 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-14 02:44:53 +00:00
Chris Lattner
c8fbc34869 comment cleanup, use moveBefore instead of removeFromParent+insertBefore.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129319 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-11 23:24:57 +00:00
Devang Patel
60d490cdc7 Do not let debug info interfer with branch folding.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129114 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-07 23:11:25 +00:00
Devang Patel
949666ea16 While hoisting common code from if/else, hoist debug info intrinsics if they match.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129078 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-07 17:27:36 +00:00
Devang Patel
ae6c95b58e Simplify. isIdenticalToWhenDefined() checks opcode.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129041 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-07 00:30:15 +00:00
Devang Patel
d418194036 While folding branch to a common destination into a predecessor, copy dbg values also.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129035 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-06 22:37:20 +00:00
Jay Foad
3ecfc861b4 Remove PHINode::reserveOperandSpace(). Instead, add a parameter to
PHINode::Create() giving the (known or expected) number of operands.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128537 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-30 11:28:46 +00:00
Jay Foad
d8b4fb4aab (Almost) always call reserveOperandSpace() on newly created PHINodes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128535 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-30 11:19:20 +00:00
Eli Friedman
b1a6eab655 PR9450: Make switch optimization in SimplifyCFG not dependent on the ordering
of pointers in an std::map.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127650 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-15 02:23:35 +00:00
Eli Friedman
2adc5b6a17 PR9420; an instruction before an unreachable is guaranteed not to have any
reachable uses, but there still might be uses in dead blocks.  Use the
standard solution of replacing all the uses with undef.  This is
a rare case because it's very sensitive to phase ordering in SimplifyCFG.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127299 91177308-0d34-0410-b5e6-96231b3b80d8
2011-03-09 00:48:33 +00:00
Frits van Bommel
f7b2a9d7df Teach SimplifyCFG that (switch (select cond, X, Y)) is better expressed as a branch.
Based on a patch by Alistair Lynn.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126647 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-28 09:44:07 +00:00
Benjamin Kramer
278be783b5 Revert "SimplifyCFG: GEPs with just one non-constant index are also cheap."
Yes, there are other types than i8* and GEPs on them can produce an add+multiply.
We don't consider that cheap enough to be speculatively executed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126481 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-25 10:33:33 +00:00
Benjamin Kramer
9ae59e3444 SimplifyCFG: GEPs with just one non-constant index are also cheap.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126452 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-24 23:26:09 +00:00
Benjamin Kramer
9b61c550c2 SimplifyCFG: GEPs with constant indices are cheap enough to be executed unconditionally.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@126445 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-24 22:46:11 +00:00
Benjamin Kramer
33828bcb24 SimplifyCFG: Track the number of used icmps when turning a icmp chain into a switch. If we used only one icmp, don't turn it into a switch.
Also prevent the switch-to-icmp transform from creating identity adds, noticed by Marius Wachtler.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125056 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-07 22:37:28 +00:00
Benjamin Kramer
042b27f40e SimplifyCFG: Also transform switches that represent a range comparison but are not sorted into sub+icmp.
This transforms another 1000 switches in gcc.c.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124826 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-03 22:51:41 +00:00
Benjamin Kramer
56442dfdcf SimplifyCFG: Turn switches into sub+icmp+branch if possible.
This makes the job of the later optzn passes easier, allowing the vast amount of
icmp transforms to chew on it.

We transform 840 switches in gcc.c, leading to a 16k byte shrink of the resulting
binary on i386-linux.

The testcase from README.txt now compiles into
  decl  %edi
  cmpl  $3, %edi
  sbbl  %eax, %eax
  andl  $1, %eax
  ret

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124724 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-02 15:56:22 +00:00
Evan Cheng
c3f507f98a Re-apply r124518 with fix. Watch out for invalidated iterator.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124526 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-29 04:46:23 +00:00
Evan Cheng
b0a42fdb36 Revert r124518. It broke Linux self-host.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124522 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-29 02:43:04 +00:00
Evan Cheng
5e6940788f Re-commit r124462 with fixes. Tail recursion elim will now dup ret into unconditional predecessor to enable TCE on demand.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124518 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-29 01:29:26 +00:00
Evan Cheng
1b5c0cb71d Revert r124462. There are a few big regressions that I need to fix first.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124478 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-28 07:12:38 +00:00
Evan Cheng
40f64cb0de - Stop simplifycfg from duplicating "ret" instructions into unconditional
branches. PR8575, rdar://5134905, rdar://8911460.
- Allow codegen tail duplication to dup small return blocks after register
  allocation is done.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124462 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-28 02:19:21 +00:00
Frits van Bommel
65fdded319 Factor the actual simplification out of SimplifyIndirectBrOnSelect and into a new helper function so it can be reused in e.g. an upcoming SimplifySwitchOnSelect.
No functional change.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123234 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-11 12:52:11 +00:00
Chris Lattner
a37029cd24 simplify this a bit.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122156 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-18 20:22:49 +00:00
Benjamin Kramer
14c0987bd9 SimplifyCFG: Ranges can be larger than 64 bits. Fixes Release-selfhost build.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122054 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-17 10:48:14 +00:00
Chris Lattner
e27db74a60 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.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122045 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-17 06:20:15 +00:00
Chris Lattner
ba3c815570 make qsort predicate more conformant by returning 0 for equal values.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121838 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-15 04:52:41 +00:00
Chris Lattner
3aff13b82a - 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.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121764 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 08:46:09 +00:00
Chris Lattner
60d410d7bb 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.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121762 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 08:01:53 +00:00
Chris Lattner
071edc81f2 remove the instsimplify logic I added in r121754. It is apparently
breaking the selfhost builds, though I can't fathom how.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121761 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 07:53:03 +00:00
Chris Lattner
44da7ca421 clean up logic, convert std::set to SmallPtrSet, handle the case
when all 2-entry phis are simplified away.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121760 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 07:41:39 +00:00
Chris Lattner
e0b18e5912 tidy up a bit, move DEBUG down to when we commit to doing the transform so we
don't print it unless the xform happens.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121758 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 07:23:10 +00:00
Chris Lattner
07ff3539f5 use SimplifyInstruction instead of reimplementing part of it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121757 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 07:20:29 +00:00
Chris Lattner
995ba1bd49 simplify GetIfCondition by using getSinglePredecessor.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121756 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 07:15:21 +00:00
Chris Lattner
6de0a28dfb use AddPredecessorToBlock in 3 places instead of a manual loop.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121755 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 07:09:42 +00:00
Chris Lattner
73c50a68a7 make FoldTwoEntryPHINode use instsimplify a bit, make
GetIfCondition faster by avoiding pred_iterator.  No
really interesting change.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121754 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 07:00:00 +00:00
Chris Lattner
302ba6fc1c improve DEBUG's a bit, switch to eraseFromParent() to simplify
code a bit, switch from constant folding to instsimplify.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121751 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 06:17:25 +00:00
Chris Lattner
117f8cffc5 reapply my recent change that disables a piece of the switch formation
work, but fixes 400.perlbmk.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121749 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-14 05:57:30 +00:00
Owen Anderson
2d9220e8f5 Fix recent buildbot breakage by pulling SimplifyCFG back to its state as of r121694, the most recent state
where I'm confident there were no crashes or miscompilations.  XFAIL the test added since then for now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121733 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-13 23:49:28 +00:00
Chris Lattner
f9a1b2a4cf temporarily disable part of my previous patch, which causes an iterator invalidation issue, causing a crash on some versions of perlbmk.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121728 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-13 23:02:19 +00:00
Chris Lattner
94c58a0906 add some DEBUG's.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121711 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-13 19:55:30 +00:00
Benjamin Kramer
cf8b3257c0 Fix sort predicate. qsort(3)'s predicate semantics differ from std::sort's. Fixes PR 8780.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121705 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-13 18:20:38 +00:00
Chris Lattner
a9f6bbea62 reinstate my patch: the miscompile was caused by an inverted branch in the
'and' case.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121695 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-13 08:12:19 +00:00
Chris Lattner
92407e5895 Completely disable the optimization I added in r121680 until
I can track down a miscompile.  This should bring the buildbots
back to life


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121693 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-13 07:41:29 +00:00
Chris Lattner
daa02ab70c Make simplifycfg reprocess newly formed "br (cond1 | cond2)" conditions
when simplifying, allowing them to be eagerly turned into switches.  This
is the last step required to get "Example 7" from this blog post:
http://blog.regehr.org/archives/320

On X86, we now generate this machine code, which (to my eye) seems better
than the ICC generated code:

_crud:                                  ## @crud
## BB#0:                                ## %entry
	cmpb	$33, %dil
	jb	LBB0_4
## BB#1:                                ## %switch.early.test
	addb	$-34, %dil
	cmpb	$58, %dil
	ja	LBB0_3
## BB#2:                                ## %switch.early.test
	movzbl	%dil, %eax
	movabsq	$288230376537592865, %rcx ## imm = 0x400000017001421
	btq	%rax, %rcx
	jb	LBB0_4
LBB0_3:                                 ## %lor.rhs
	xorl	%eax, %eax
	ret
LBB0_4:                                 ## %lor.end
	movl	$1, %eax
	ret



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121690 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-13 07:00:06 +00:00
Chris Lattner
021c9d3bd4 make this logic a bit simpler.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121689 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-13 06:36:51 +00:00