caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
104,478 Commits 1 Branch 0 Tags
1c229c0472edfd59ce61ba063a93517df609ceb4
Commit Graph

132 Commits

Author SHA1 Message Date
Devang Patel
bc3d8b212f Do not let debug info interfer with branch folding. 
llvm-svn: 129114
 2011-04-07 23:11:25 +00:00
Devang Patel
197c35298a While hoisting common code from if/else, hoist debug info intrinsics if they match. 
llvm-svn: 129078
 2011-04-07 17:27:36 +00:00
Eli Friedman
c4414c6e92 PR9450: Make switch optimization in SimplifyCFG not dependent on the ordering 
of pointers in an std::map.

llvm-svn: 127650
 2011-03-15 02:23:35 +00:00
Benjamin Kramer
1885d21700 Fix mistyped CHECK lines. 
llvm-svn: 127366
 2011-03-09 22:07:31 +00:00
Eli Friedman
aac35b3fbb 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.

llvm-svn: 127299
 2011-03-09 00:48:33 +00:00
Frits van Bommel
8ae07996c9 Teach SimplifyCFG that (switch (select cond, X, Y)) is better expressed as a branch. 
Based on a patch by Alistair Lynn.

llvm-svn: 126647
 2011-02-28 09:44:07 +00:00
Benjamin Kramer
ceb5daa567 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.

llvm-svn: 126481
 2011-02-25 10:33:33 +00:00
Benjamin Kramer
dfdca1a14d SimplifyCFG: GEPs with just one non-constant index are also cheap. 
llvm-svn: 126452
 2011-02-24 23:26:09 +00:00
Benjamin Kramer
27361a7124 SimplifyCFG: GEPs with constant indices are cheap enough to be executed unconditionally. 
llvm-svn: 126445
 2011-02-24 22:46:11 +00:00
Benjamin Kramer
8d6a8c130b 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.

llvm-svn: 125056
 2011-02-07 22:37:28 +00:00
Benjamin Kramer
62aa46b852 SimplifyCFG: Also transform switches that represent a range comparison but are not sorted into sub+icmp. 
This transforms another 1000 switches in gcc.c.

llvm-svn: 124826
 2011-02-03 22:51:41 +00:00
Benjamin Kramer
f4ea1d5f79 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

llvm-svn: 124724
 2011-02-02 15:56:22 +00:00
Evan Cheng
d983eba7dc Re-apply r124518 with fix. Watch out for invalidated iterator. 
llvm-svn: 124526
 2011-01-29 04:46:23 +00:00
Evan Cheng
65b8ccf6ac Revert r124518. It broke Linux self-host. 
llvm-svn: 124522
 2011-01-29 02:43:04 +00:00
Evan Cheng
d4eff31476 Re-commit r124462 with fixes. Tail recursion elim will now dup ret into unconditional predecessor to enable TCE on demand. 
llvm-svn: 124518
 2011-01-29 01:29:26 +00:00
Evan Cheng
aaa9606b2f Revert r124462. There are a few big regressions that I need to fix first. 
llvm-svn: 124478
 2011-01-28 07:12:38 +00:00
Evan Cheng
417fca86c4 - 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.

llvm-svn: 124462
 2011-01-28 02:19:21 +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
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
f130661688 fix yet anohter broken line 
llvm-svn: 121750
 2010-12-14 06:09:07 +00:00
Chris Lattner
5a9d59d918 reapply my recent change that disables a piece of the switch formation 
work, but fixes 400.perlbmk.

llvm-svn: 121749
 2010-12-14 05:57:30 +00:00
Owen Anderson
3e5648896e 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.

llvm-svn: 121733
 2010-12-13 23:49:28 +00:00
Chris Lattner
a6e5d5694a temporarily disable part of my previous patch, which causes an iterator invalidation issue, causing a crash on some versions of perlbmk. 
llvm-svn: 121728
 2010-12-13 23:02:19 +00:00
Benjamin Kramer
1e155ab7e1 Fix sort predicate. qsort(3)'s predicate semantics differ from std::sort's. Fixes PR 8780. 
llvm-svn: 121705
 2010-12-13 18:20:38 +00:00
Chris Lattner
fb836f8c1a reinstate my patch: the miscompile was caused by an inverted branch in the 
'and' case.

llvm-svn: 121695
 2010-12-13 08:12:19 +00:00
Chris Lattner
79db357d80 Completely disable the optimization I added in r121680 until 
I can track down a miscompile.  This should bring the buildbots
back to life

llvm-svn: 121693
 2010-12-13 07:41:29 +00:00
Chris Lattner
fbeb55844b 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

llvm-svn: 121690
 2010-12-13 07:00:06 +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
bc9e6d9dbe make these tests a bit less fragile 
llvm-svn: 121682
 2010-12-13 05:10:30 +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
a737721d14 merge two tests 
llvm-svn: 121679
 2010-12-13 04:45:56 +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
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
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
Dan Gohman
a826a88755 Factor out Instruction::isSafeToSpeculativelyExecute's code for 
testing for dereferenceable pointers into a helper function,
isDereferenceablePointer.  Teach it how to reason about GEPs
with simple non-zero indices.

Also eliminate ArgumentPromtion's IsAlwaysValidPointer,
which didn't check for weak externals or out of range gep
indices.

llvm-svn: 118840
 2010-11-11 21:23:25 +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
Duncan Sands
68c30907cc Correct bogus module triple specifications. 
llvm-svn: 112469
 2010-08-30 10:48:29 +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
Benjamin Kramer
6e42d53cb3 Test case for r105914. 
llvm-svn: 105915
 2010-06-13 16:16:54 +00:00
Chris Lattner
84d4618659 make simplifycfg insert an llvm.trap before the 'unreachable' it introduces 
when it detects undefined behavior.  llvm.trap generally codegens into some
thing really small (e.g. a 2 byte ud2 instruction on x86) and debugging this
sort of thing is "nontrivial".  For example, we now compile:

void foo() { *(int*)0 = 42; }

into:

_foo:
	pushl	%ebp
	movl	%esp, %ebp
	ud2

Some may even claim that this is a security hole, though that seems dubious
to me.  This addresses rdar://7958343 - Optimizing away null dereference 
potentially allows arbitrary code execution

llvm-svn: 103356
 2010-05-08 22:15:59 +00:00
Gabor Greif
6882a5eea1 testcase for r99914, provided by baldrick! 
llvm-svn: 100043
 2010-03-31 20:37:13 +00:00
Dan Gohman
6f34abd092 Floating-point add, sub, and mul are now spelled fadd, fsub, and fmul, 
respectively.

llvm-svn: 97531
 2010-03-02 01:11:08 +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
Dan Gohman
fb4193625a Delete useless trailing semicolons. 
llvm-svn: 92740
 2010-01-05 17:55:26 +00:00
Chris Lattner
c5c08899e4 fix two bogus tests that the asmparser now rejects. 
llvm-svn: 92303
 2009-12-30 05:54:51 +00:00
Chris Lattner
f21a220bcd Implement PR5795 by merging duplicated return blocks. This could go further 
by merging all returns in a function into a single one, but simplifycfg 
currently likes to duplicate the return (an unfortunate choice!)

llvm-svn: 91890
 2009-12-22 06:07:30 +00:00
Chris Lattner
2b297ed9ee convert to filecheck 
llvm-svn: 91889
 2009-12-22 06:04:26 +00:00