50 Commits

Author SHA1 Message Date
Jakob Stoklund Olesen
72847f3057 Reapply r155136 after fixing PR12599.
Original commit message:

Defer some shl transforms to DAGCombine.

The shl instruction is used to represent multiplication by a constant
power of two as well as bitwise left shifts. Some InstCombine
transformations would turn an shl instruction into a bit mask operation,
making it difficult for later analysis passes to recognize the
constsnt multiplication.

Disable those shl transformations, deferring them to DAGCombine time.
An 'shl X, C' instruction is now treated mostly the same was as 'mul X, C'.

These transformations are deferred:

  (X >>? C) << C   --> X & (-1 << C)  (When X >> C has multiple uses)
  (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)   (When C2 > C1)
  (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)  (When C1 > C2)

The corresponding exact transformations are preserved, just like
div-exact + mul:

  (X >>?,exact C) << C   --> X
  (X >>?,exact C1) << C2 --> X << (C2-C1)
  (X >>?,exact C1) << C2 --> X >>?,exact (C1-C2)

The disabled transformations could also prevent the instruction selector
from recognizing rotate patterns in hash functions and cryptographic
primitives. I have a test case for that, but it is too fragile.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155362 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-23 17:39:52 +00:00
Jakob Stoklund Olesen
eece9dc81c Revert r155136 "Defer some shl transforms to DAGCombine."
While the patch was perfect and defect free, it exposed a really nasty
bug in X86 SelectionDAG that caused an llc crash when compiling lencod.

I'll put the patch back in after fixing the SelectionDAG problem.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155181 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-20 00:38:45 +00:00
Jakob Stoklund Olesen
0d5fcae6cd Defer some shl transforms to DAGCombine.
The shl instruction is used to represent multiplication by a constant
power of two as well as bitwise left shifts. Some InstCombine
transformations would turn an shl instruction into a bit mask operation,
making it difficult for later analysis passes to recognize the
constsnt multiplication.

Disable those shl transformations, deferring them to DAGCombine time.
An 'shl X, C' instruction is now treated mostly the same was as 'mul X, C'.

These transformations are deferred:

  (X >>? C) << C   --> X & (-1 << C)  (When X >> C has multiple uses)
  (X >>? C1) << C2 --> X << (C2-C1) & (-1 << C2)   (When C2 > C1)
  (X >>? C1) << C2 --> X >>? (C1-C2) & (-1 << C2)  (When C1 > C2)

The corresponding exact transformations are preserved, just like
div-exact + mul:

  (X >>?,exact C) << C   --> X
  (X >>?,exact C1) << C2 --> X << (C2-C1)
  (X >>?,exact C1) << C2 --> X >>?,exact (C1-C2)

The disabled transformations could also prevent the instruction selector
from recognizing rotate patterns in hash functions and cryptographic
primitives. I have a test case for that, but it is too fragile.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@155136 91177308-0d34-0410-b5e6-96231b3b80d8
2012-04-19 16:46:26 +00:00
Nick Lewycky
148fd55ef3 Teach instcombine all sorts of great stuff about shifts that have exact, nuw or
nsw bits on them.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147528 91177308-0d34-0410-b5e6-96231b3b80d8
2012-01-04 09:28:29 +00:00
Nick Lewycky
57ed0948b8 Make use of the exact bit when optimizing '(X >>exact 3) << 1' to eliminate the
'and' that would zero out the trailing bits, and to produce an exact shift
ourselves.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147391 91177308-0d34-0410-b5e6-96231b3b80d8
2011-12-31 21:30:22 +00:00
Eli Friedman
ef71597242 Make sure to correctly clear the exact/nuw/nsw flags off of shifts when they are combined together. <rdar://problem/9859829>
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136435 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-29 00:18:19 +00:00
Chris Lattner
05cd886561 Transform any logical shift of a power of two into an exact/NUW shift when
in a known-non-zero context.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131887 91177308-0d34-0410-b5e6-96231b3b80d8
2011-05-23 00:21:50 +00:00
Benjamin Kramer
c2e31c1461 InstCombine: turn (C1 << A) << C2) into (C1 << C2) << A)
Fixes PR9809.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130485 91177308-0d34-0410-b5e6-96231b3b80d8
2011-04-29 08:15:41 +00:00
Chris Lattner
7a6aa1a391 Enhance a bunch of transformations in instcombine to start generating
exact/nsw/nuw shifts and have instcombine infer them when it can prove
that the relevant properties are true for a given shift without them.

Also, a variety of refactoring to use the new patternmatch logic thrown
in for good luck.  I believe that this takes care of a bunch of related
code quality issues attached to PR8862.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125267 91177308-0d34-0410-b5e6-96231b3b80d8
2011-02-10 05:36:31 +00:00
Duncan Sands
c43cee3fbb Move some shift transforms out of instcombine and into InstructionSimplify.
While there, I noticed that the transform "undef >>a X -> undef" was wrong.
For example if X is 2 then the top two bits must be equal, so the result can
not be anything.  I fixed this in the constant folder as well.  Also, I made
the transform for "X << undef" stronger: it now folds to undef always, even
though X might be zero.  This is in accordance with the LangRef, but I must
admit that it is fairly aggressive.  Also, I added "i32 X << 32 -> undef"
following the LangRef and the constant folder, likewise fairly aggressive.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123417 91177308-0d34-0410-b5e6-96231b3b80d8
2011-01-14 00:37:45 +00:00
Owen Anderson
ec3953ff95 When determining if we can fold (x >> C1) << C2, the bits that we need to verify are zero
are not the low bits of x, but the bits that WILL be the low bits after the operation completes.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@122529 91177308-0d34-0410-b5e6-96231b3b80d8
2010-12-23 23:56:24 +00:00
Benjamin Kramer
c21a821e9f The srem -> urem transform is not safe for any divisor that's not a power of two.
E.g. -5 % 5 is 0 with srem and 1 with urem.

Also addresses Frits van Bommel's comments.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120049 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-23 20:33:57 +00:00
Benjamin Kramer
b70ebd2aa3 InstCombine: Reduce "X shift (A srem B)" to "X shift (A urem B)" iff B is positive.
This allows to transform the rem in "1 << ((int)x % 8);" to an and.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@120028 91177308-0d34-0410-b5e6-96231b3b80d8
2010-11-23 18:52:42 +00:00
Chris Lattner
11493aa471 tidy up test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112321 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27 23:15:21 +00:00
Chris Lattner
4ece577019 Enhance the shift propagator to handle the case when you have:
A = shl x, 42
...
B = lshr ..., 38

which can be transformed into:
A = shl x, 4
...

iff we can prove that the would-be-shifted-in bits
are already zero.  This eliminates two shifts in the testcase
and allows eliminate of the whole i128 chain in the real example.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112314 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27 22:53:44 +00:00
Chris Lattner
29cc0b3660 Implement a pretty general logical shift propagation
framework, which is good at ripping through bitfield
operations.  This generalize a bunch of the existing
xforms that instcombine does, such as 
  (x << c) >> c -> and
to handle intermediate logical nodes.  This is useful for
ripping up the "promote to large integer" code produced by
SRoA.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112304 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27 22:24:38 +00:00
Chris Lattner
d07ad66791 merge and filecheckize test
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112289 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27 20:44:45 +00:00
Chris Lattner
7673290a96 merge two tests
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112288 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-27 20:42:10 +00:00
Chris Lattner
90d4f3a077 merge test into shift.ll, this also eliminates awful grepping on -stats output
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83802 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11 22:39:58 +00:00
Chris Lattner
490ff6310a convert to filecheck.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@83801 91177308-0d34-0410-b5e6-96231b3b80d8
2009-10-11 22:36:59 +00:00
Dan Gohman
3e054fe9ef Use opt -S instead of piping bitcode output through llvm-dis.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81257 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-08 22:34:10 +00:00
Dan Gohman
b1e1e82c54 Change these tests to feed the assembly files to opt directly, instead
of using llvm-as, now that opt supports this.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81226 91177308-0d34-0410-b5e6-96231b3b80d8
2009-09-08 16:50:01 +00:00
Chris Lattner
4f9797d683 two changes:
1. Make instcombine always canonicalize trunc x to i1 into an icmp(x&1).  This 
   exposes the AND to other instcombine xforms and is more of what the code
   generator expects.
2. Rewrite the remaining trunc pattern match to use 'match', which 
   simplifies it a lot.
   


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@67635 91177308-0d34-0410-b5e6-96231b3b80d8
2009-03-24 18:15:30 +00:00
Tanya Lattner
76806b6a43 Remove llvm-upgrade and update tests.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48103 91177308-0d34-0410-b5e6-96231b3b80d8
2008-03-09 08:16:40 +00:00
Tanya Lattner
ec9a35a6f9 Remove llvm-upgrade and update test cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47793 91177308-0d34-0410-b5e6-96231b3b80d8
2008-03-01 09:15:35 +00:00
Reid Spencer
2b544beda3 For PR1319:
Upgrade tests to work with new llvm.exp version of llvm_runtest.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36013 91177308-0d34-0410-b5e6-96231b3b80d8
2007-04-14 20:13:02 +00:00
Reid Spencer
69ccadd753 Use the llvm-upgrade program to upgrade llvm assembly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32115 91177308-0d34-0410-b5e6-96231b3b80d8
2006-12-02 04:23:10 +00:00
Chris Lattner
82b98a0646 Make these tests fail if opt crashes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@26127 91177308-0d34-0410-b5e6-96231b3b80d8
2006-02-12 01:32:58 +00:00
Chris Lattner
6c7fbb8503 A case that instcombine is not catching.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25127 91177308-0d34-0410-b5e6-96231b3b80d8
2006-01-06 07:48:28 +00:00
Chris Lattner
ab4ea6e980 new testcase
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23380 91177308-0d34-0410-b5e6-96231b3b80d8
2005-09-18 05:10:39 +00:00
Chris Lattner
a9c83c73da new testcase
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21774 91177308-0d34-0410-b5e6-96231b3b80d8
2005-05-08 17:31:24 +00:00
Chris Lattner
1b50d062c8 new testcase
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21714 91177308-0d34-0410-b5e6-96231b3b80d8
2005-05-06 04:11:32 +00:00
Chris Lattner
59359f1e84 New testcases
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16547 91177308-0d34-0410-b5e6-96231b3b80d8
2004-09-28 18:18:35 +00:00
Chris Lattner
907c7c7dd1 Testcases for rev 250 of InstructionCombining.cpp
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@16522 91177308-0d34-0410-b5e6-96231b3b80d8
2004-09-27 16:21:26 +00:00
Chris Lattner
256b7a452b New testcase
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13739 91177308-0d34-0410-b5e6-96231b3b80d8
2004-05-25 06:30:49 +00:00
Chris Lattner
1c48527330 Testcase to make sure we can apply the shift to the operands of the select,
eliminating the shifts


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@12801 91177308-0d34-0410-b5e6-96231b3b80d8
2004-04-09 23:47:24 +00:00
Misha Brukman
e78760e179 Renamed as' => llvm-as', dis' => llvm-dis', link' => llvm-link'.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8558 91177308-0d34-0410-b5e6-96231b3b80d8
2003-09-16 15:29:54 +00:00
Chris Lattner
ab04c365b8 Update test to represent new cannonicalization rules for multiplies
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7804 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-13 04:20:06 +00:00
Chris Lattner
dc20a3e7d3 Right, instcombine cannot remove ((X >> C) << C) if it's signed.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7790 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-12 21:22:51 +00:00
Chris Lattner
b310196abc New testcases
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7789 91177308-0d34-0410-b5e6-96231b3b80d8
2003-08-12 21:20:49 +00:00
Chris Lattner
709ad40dc8 New testcases for signed shifts
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@7294 91177308-0d34-0410-b5e6-96231b3b80d8
2003-07-24 18:38:09 +00:00
Chris Lattner
060c1f816c Remove usage of grep-not script
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6966 91177308-0d34-0410-b5e6-96231b3b80d8
2003-06-28 23:32:04 +00:00
Chris Lattner
c6cab24151 Convert scripts from using explicit control flow to use the new grep-not script
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@6955 91177308-0d34-0410-b5e6-96231b3b80d8
2003-06-28 22:44:42 +00:00
Chris Lattner
c232870b6f Add a bunch of new tests
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5730 91177308-0d34-0410-b5e6-96231b3b80d8
2003-03-10 19:16:20 +00:00
Chris Lattner
a66e2fa195 Modernize testcase
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@5726 91177308-0d34-0410-b5e6-96231b3b80d8
2003-03-10 18:20:53 +00:00
Chris Lattner
af1b4ad24c Add new testcase for arithmetic shr of -1
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@4069 91177308-0d34-0410-b5e6-96231b3b80d8
2002-10-08 16:10:35 +00:00
Chris Lattner
dabb94adc1 Check for cannonicalization of shl X, 1 -> add X, X
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3670 91177308-0d34-0410-b5e6-96231b3b80d8
2002-09-10 23:03:10 +00:00
Chris Lattner
4a6e4b30b4 These tests should not run -dce pass to cleanup instcombine.
If instcombine is making dead instructions, ALL that should be used is -die


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@3221 91177308-0d34-0410-b5e6-96231b3b80d8
2002-08-02 19:27:58 +00:00
Chris Lattner
79a31b1782 Fix testcase, the 'shift out all bits' doesn't apply to signed types.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2482 91177308-0d34-0410-b5e6-96231b3b80d8
2002-05-06 16:11:31 +00:00
Chris Lattner
33a90b18e0 New testcases so I don't forget about these algebraic simplifications
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@2479 91177308-0d34-0410-b5e6-96231b3b80d8
2002-05-06 05:43:36 +00:00