Commit Graph

41 Commits

Author SHA1 Message Date
Shuxin Yang
6c7a7c6474 Fix PR17952.
The symptom is that an assertion is triggered. The assertion was added by
me to detect the situation when value is propagated from dead blocks.
(We can certainly get rid of assertion; it is safe to do so, because propagating
 value from dead block to alive join node is certainly ok.)

  The root cause of this bug is : edge-splitting is conducted on the fly,
the edge being split could be a dead edge, therefore the block that 
split the critial edge needs to be flagged "dead" as well.

  There are 3 ways to fix this bug:
  1) Get rid of the assertion as I mentioned eariler 
  2) When an dead edge is split, flag the inserted block "dead".
  3) proactively split the critical edges connecting dead and live blocks when
     new dead blocks are revealed.

  This fix go for 3) with additional 2 LOC.

  Testing case was added by Rafael the other day.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194424 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-11 22:00:23 +00:00
Bill Wendling
855c29d82c Revert "Resurrect r191017 " GVN proceeds in the presence of dead code" plus a fix to PR17307 & 17308."
This causes PR17852.

This reverts commit d93e8a06b2.

Conflicts:
	test/Transforms/GVN/cond_br2.ll

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194348 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-10 07:34:34 +00:00
Matt Arsenault
b7ff48e374 Fix GVN creating bitcast between address spaces
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193710 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-30 19:05:41 +00:00
Shuxin Yang
d93e8a06b2 Resurrect r191017 " GVN proceeds in the presence of dead code" plus a fix to PR17307 & 17308.
The problem of r191017 is that when GVN fabricate a val-number for a dead instruction (in order
to make following expr-PRE happy), it forget to fabricate a leader-table entry for it as well.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191118 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-20 23:12:57 +00:00
Joerg Sonnenberger
fc572d87d2 Revert r191017, it results in segmentation faults in Qt.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191104 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-20 20:33:57 +00:00
Shuxin Yang
1bc7315c02 GVN proceeds in the presence of dead code.
This is how it ignores the dead code:
1) When a dead branch target, say block B, is identified, all the
    blocks dominated by B is dead as well.

2) The PHIs of those blocks in dominance-frontier(B) is updated such
   that the operands corresponding to dead predecessors are replaced
   by "UndefVal".

   Using lattice's jargon, the "UndefVal" is the "Top" in essence.
   Phi node like this "phi(v1 bb1, undef xx)" will be optimized into
   "v1" if v1 is constant, or v1 is an instruction which dominate this
   PHI node.

3) When analyzing the availability of a load L, all dead mem-ops which
   L depends on disguise as a load which evaluate exactly same value as L.

4) The dead mem-ops will be materialized as "UndefVal" during code motion.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191017 91177308-0d34-0410-b5e6-96231b3b80d8
2013-09-19 17:22:51 +00:00
Stephen Lin
39f4e8d9cc Update Transforms tests to use CHECK-LABEL for easier debugging. No functionality change.
This update was done with the following bash script:

  find test/Transforms -name "*.ll" | \
  while read NAME; do
    echo "$NAME"
    if ! grep -q "^; *RUN: *llc" $NAME; then
      TEMP=`mktemp -t temp`
      cp $NAME $TEMP
      sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
      while read FUNC; do
        sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP
      done
      mv $TEMP $NAME
    fi
  done


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186268 91177308-0d34-0410-b5e6-96231b3b80d8
2013-07-14 01:42:54 +00:00
Jakub Staszak
94aa3bd0c1 unHECKify test. It was fixed by Chris in 2009.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170017 91177308-0d34-0410-b5e6-96231b3b80d8
2012-12-12 20:43:00 +00:00
NAKAMURA Takumi
562b1d883f llvm/ConstantFolding.cpp: Make ReadDataFromGlobal() and FoldReinterpretLoadFromConstPtr() Big-endian-aware.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167595 91177308-0d34-0410-b5e6-96231b3b80d8
2012-11-08 20:34:25 +00:00
Benjamin Kramer
4e81d40545 Fix broken check lines.
I really need to find a way to automate this, but I can't come up with a regex
that has no false positives while handling tricky cases like custom check
prefixes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162097 91177308-0d34-0410-b5e6-96231b3b80d8
2012-08-17 12:28:26 +00:00
Nick Lewycky
9f47fb6637 Fix crasher in GVN due to my recent capture tracking changes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@145047 91177308-0d34-0410-b5e6-96231b3b80d8
2011-11-21 19:42:56 +00:00
Nick Lewycky
88990248d3 Refactor capture tracking (which already had a couple flags for whether returns
and stores capture) to permit the caller to see each capture point and decide
whether to continue looking.

Use this inside memdep to do an analysis that basicaa won't do. This lets us
solve another devirtualization case, fixing PR8908!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@144580 91177308-0d34-0410-b5e6-96231b3b80d8
2011-11-14 22:49:42 +00:00
Chris Lattner
b85e4eba85 rip out a ton of intrinsic modernization logic from AutoUpgrade.cpp, which is
for pre-2.9 bitcode files.  We keep x86 unaligned loads, movnt, crc32, and the
target indep prefetch change.

As usual, updating the testsuite is a PITA.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133337 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-18 06:05:24 +00:00
Dan Gohman
a3351a0e5d Disable the main feature of 130180, the elimination of loads that are
redundant with partially-aliasing loads.

When computing what portion of a clobbering load value is needed,
it doesn't consider phi-translation which may have occurred
between the clobbing load and the redundant load.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132631 91177308-0d34-0410-b5e6-96231b3b80d8
2011-06-04 06:48:50 +00:00
Chris Lattner
0e959394ad remove a trivial test, make some other tests less trivial.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131846 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-22 07:02:43 +00:00
Chris Lattner
0a9e3d613b final step needed to resolve PR6627, which allows us to flatten the code down to
a nice and tidy:
  %x1 = load i32* %0, align 4
  %1 = icmp eq i32 %x1, 1179403647
  br i1 %1, label %if.then, label %if.end

instead of doing lots of loads and branches.  May the FreeBSD bootloader
long fit in its allocated space.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130416 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-28 18:15:47 +00:00
Chris Lattner
4034e14985 teach GVN to widen integer loads when they are overaligned, when doing an
wider load would allow elimination of subsequent loads, and when the wider
load is still a native integer type.  This eliminates a ton of loads on 
various benchmarks involving struct fields, though it is somewhat hobbled
by clang not being very aggressive about field alignment.

This is yet another step along the way towards resolving PR6627.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130390 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-28 07:29:08 +00:00
Chris Lattner
9750acc079 Improve the bail-out predicate to really only kick in when phi
translation fails.  We were bailing out in some cases that would
cause us to miss GVN'ing some non-local cases away.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130206 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-26 17:41:02 +00:00
Chris Lattner
1f821512fc Enhance MemDep: When alias analysis returns a partial alias result,
return it as a clobber.  This allows GVN to do smart things.

Enhance GVN to be smart about the case when a small load is clobbered
by a larger overlapping load.  In this case, forward the value.  This
allows us to compile stuff like this:

int test(void *P) {
  int tmp = *(unsigned int*)P;
  return tmp+*((unsigned char*)P+1);
}

into:

_test:                                  ## @test
	movl	(%rdi), %ecx
	movzbl	%ch, %eax
	addl	%ecx, %eax
	ret

which has one load.  We already handled the case where the smaller
load was from a must-aliased base pointer.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130180 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-26 01:21:15 +00:00
Dan Gohman
c1be92f3bb Make BasicAliasAnalysis a normal AliasAnalysis implementation which
does normal initialization and normal chaining. Change the default
AliasAnalysis implementation to NoAlias.

Update StandardCompileOpts.h and friends to explicitly request
BasicAliasAnalysis.

Update tests to explicitly request -basicaa.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116720 91177308-0d34-0410-b5e6-96231b3b80d8
2010-10-18 18:04:47 +00:00
Chris Lattner
219d77430b fix PR6642, GVN forwarding from memset to load of the base of the memset.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99488 91177308-0d34-0410-b5e6-96231b3b80d8
2010-03-25 05:58:19 +00:00
Chris Lattner
af064aeee6 fix hte last remaining known (by me) phi translation bug. When we reanalyze
clobbers to forward pieces of large stores to small loads, we need to consider
the properly phi translated pointer in the store block.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90978 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-09 18:21:46 +00:00
Chris Lattner
55fe79f044 the code in GVN that tries to forward large loads to small
stores is not phi translating, thus it miscompiles really
crazy testcases.  This is from inspection, I haven't seen
this in the wild.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90930 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-09 02:43:05 +00:00
Chris Lattner
05e15f8897 Switch GVN and memdep to use PHITransAddr, which correctly handles
phi translation of complex expressions like &A[i+1].  This has the
following benefits:

1. The phi translation logic is all contained in its own class with
   a strong interface and verification that it is self consistent.

2. The logic is more correct than before.  Previously, if intermediate
   expressions got PHI translated, we'd miss the update and scan for
   the wrong pointers in predecessor blocks.  @phi_trans2 is a testcase
   for this.

3. We have a lot less code in memdep.

We can handle phi translation across blocks of things like @phi_trans3,
which is pretty insane :).

This patch should fix the miscompiles of 255.vortex, and I tested it 
with a bootstrap of llvm-gcc, llvm-test and dejagnu of course.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90926 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-09 01:59:31 +00:00
Chris Lattner
bc9a28dd54 constant fold loads from memcpy's from global constants. This is important
because clang lowers nontrivial automatic struct/array inits to memcpy from
a global array.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90698 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-06 05:29:56 +00:00
Chris Lattner
cb9cbc4949 add support for forwarding mem intrinsic values to non-local loads.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90697 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-06 04:54:31 +00:00
Chris Lattner
faf815b938 Handle forwarding local memsets to loads. For example, we optimize this:
short x(short *A) {
  memset(A, 1, sizeof(*A)*100);
  return A[42];
}

to 'return 257' instead of doing the load.  



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90695 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-06 01:57:02 +00:00
Chris Lattner
f616ee2895 merge two tests.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90691 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-06 01:47:24 +00:00
Chris Lattner
e4968a4b9d Small and carefully crafted testcase showing a miscompilation by GVN
that I'm working on.  This is manifesting as a miscompile of 255.vortex
on some targets.  No check lines yet because it fails.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90520 91177308-0d34-0410-b5e6-96231b3b80d8
2009-12-04 02:12:12 +00:00
Chris Lattner
8b2bc3d574 fix PR5016, a crash I introduced in GVN handing first class
arrays and structs, which cannot be bitcast to integers.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82460 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-21 17:24:04 +00:00
Chris Lattner
4fbd14e80e enable non-local analysis and PRE of large store -> little load.
This doesn't kick in too much because of phi translation issues,
but this can be resolved in the future.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82447 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-21 06:48:08 +00:00
Chris Lattner
f716330c90 add pr#
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82440 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-21 05:57:47 +00:00
Chris Lattner
eed919b1ba Improve GVN to be able to forward substitute a small load
from a piece of a large store when both are in the same block.

This allows clang to compile the testcase in PR4216 to this code:

_test_bitfield:
	movl	4(%esp), %eax
	movl	%eax, %ecx
	andl	$-65536, %ecx
	orl	$32962, %eax
	andl	$40186, %eax
	orl	%ecx, %eax
	ret

This is not ideal, but is a whole lot better than the code produced
by llvm-gcc:

_test_bitfield:
	movw	$-32574, %ax
	orw	4(%esp), %ax
	andw	$-25350, %ax
	movw	%ax, 4(%esp)
	movw	7(%esp), %cx
	shlw	$8, %cx
	movzbl	6(%esp), %edx
	orw	%cx, %dx
	movzwl	%dx, %ecx
	shll	$16, %ecx
	movzwl	%ax, %eax
	orl	%ecx, %eax
	ret

and dramatically better than that produced by gcc 4.2:

_test_bitfield:
	pushl	%ebx
	call	L3
"L00000000001$pb":
L3:
	popl	%ebx
	movl	8(%esp), %eax
	leal	0(,%eax,4), %edx
	sarb	$7, %dl
	movl	%eax, %ecx
	andl	$7168, %ecx
	andl	$-7201, %ebx
	movzbl	%dl, %edx
	andl	$1, %edx
	sall	$5, %edx
	orl	%ecx, %ebx
	orl	%edx, %ebx
	andl	$24, %eax
	andl	$-58336, %ebx
	orl	%eax, %ebx
	orl	$32962, %ebx
	movl	%ebx, %eax
	popl	%ebx
	ret



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82439 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-21 05:57:11 +00:00
Chris Lattner
8111576521 fix a FileCheck bug where:
; CHECK: foo
; CHECK-NOT: foo
; CHECK: bar

would always fail.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82424 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-21 02:30:42 +00:00
Daniel Dunbar
3d4138bd58 Work around a FileCheck bug, for now.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82416 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-20 23:30:31 +00:00
Chris Lattner
66364346e0 Revert r82404, it is causing a bootstrap miscompile. This is very very
scary, as it indicates a lurking bug. yay.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82411 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-20 22:44:26 +00:00
Chris Lattner
6a089c3257 this was not supposed to be committed
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82409 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-20 22:36:11 +00:00
Chris Lattner
f15380ba8a implement and document support for CHECK-NOT
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82408 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-20 22:35:26 +00:00
Chris Lattner
386251341f improve memdep to eliminate bitcasts (and aliases, and noop geps)
early for the stated reasons: this allows it to find more 
equivalences and depend less on code layout.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82404 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-20 21:00:18 +00:00
Chris Lattner
771a5422e1 Move CoerceAvailableValueToLoadType earlier in GVN.cpp. Hook it up
so that nonlocal and partially redundant loads can use it as well.
The testcase shows examples of craziness this can handle.  This triggers
*many* times in 176.gcc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82403 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-20 20:09:34 +00:00
Chris Lattner
bb6495cc67 enhance GVN to forward substitute a stored value to a load
(and load -> load) when the base pointers must alias but when
they are different types.  This occurs very very frequently in
176.gcc and other code that uses bitfields a lot.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82399 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-20 19:03:47 +00:00