Commit Graph

85 Commits

Author SHA1 Message Date
Sanjay Patel 0753c06d9c [InstCombine] LogicOpc (zext X), C --> zext (LogicOpc X, C) (PR28476)
The benefits of this change include:
1. Remove DeMorgan-matching code that was added specifically to work-around 
   the missing transform in http://reviews.llvm.org/rL248634.
2. Makes the DeMorgan transform work for vectors too.
3. Fix PR28476: https://llvm.org/bugs/show_bug.cgi?id=28476

Extending this transform to other casts and other associative operators may
be useful too. See https://reviews.llvm.org/D22421 for a prerequisite for
doing that though.

Differential Revision: https://reviews.llvm.org/D22271

llvm-svn: 276221
2016-07-21 00:24:18 +00:00
Matt Arsenault 8fd5978811 Revert "Revert "Revert "InstCombine: Reduce trunc (shl x, K) width."""
This seems to be causing an infinite loop / crash in instcombine
on some bots.

llvm-svn: 273069
2016-06-17 23:36:38 +00:00
Matt Arsenault d76efc14b9 Revert "Revert "InstCombine: Reduce trunc (shl x, K) width.""
Reapply r272987. Condition should be in terms of the destination type,
and the flags should not be copied.

llvm-svn: 273045
2016-06-17 20:33:53 +00:00
Matt Arsenault ce56f7bbaa Revert "InstCombine: Reduce trunc (shl x, K) width."
This reverts commit r272987.

This might be causing crashes on some bots.

llvm-svn: 272990
2016-06-17 06:28:53 +00:00
Matt Arsenault 028fd50642 InstCombine: Reduce trunc (shl x, K) width.
llvm-svn: 272987
2016-06-17 04:43:22 +00:00
Sanjay Patel a6fbc82392 [InstCombine] allow vector icmp bool transforms
llvm-svn: 271843
2016-06-05 17:49:45 +00:00
Sanjay Patel ea8a211169 [InstCombine] allow vector constants for cast+icmp fold
This is step 1 of unknown towards fixing PR28001:
https://llvm.org/bugs/show_bug.cgi?id=28001

llvm-svn: 271810
2016-06-04 22:04:05 +00:00
Sanjay Patel 8e63999bee [InstCombine] add test for missing vector optimization
llvm-svn: 271808
2016-06-04 21:41:25 +00:00
Sanjay Patel ec41cd2461 remove blank lines
llvm-svn: 268246
2016-05-02 15:49:09 +00:00
Sanjay Patel 1540b19407 [InstCombine] regenerate checks
llvm-svn: 268232
2016-05-02 14:21:55 +00:00
Mehdi Amini 1c131b37ed Instcombine: destructor loads of structs that do not contains padding
For non padded structs, we can just proceed and deaggregate them.
We don't want ot do this when there is padding in the struct as to not
lose information about this padding (the subsequents passes would then
try hard to preserve the padding, which is undesirable).

Also update extractvalue.ll and cast.ll so that they use structs with padding.

Remove the FIXME in the extractvalue of laod case as the non padded case is
handled when processing the load, and we don't want to do it on the padded
case.

Patch by: Amaury SECHET <deadalnix@gmail.com>

Differential Revision: http://reviews.llvm.org/D14483

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 255600
2015-12-15 01:44:07 +00:00
Rafael Espindola d1beb07d39 Have a single way for creating unique value names.
We had two code paths. One would create names like "foo.1" and the other
names like "foo1".

For globals it is important to use "foo.1" to help C++ name demangling.
For locals there is no strong reason to go one way or the other so I
kept the most common mangling (foo1).

llvm-svn: 253804
2015-11-22 00:16:24 +00:00
Jakub Kuderski 58ea4eeb9e There is a trunc(lshr (zext A), Cst) optimization in InstCombineCasts that
removes cast by performing the lshr on smaller types. However, currently there
is no trunc(lshr (sext A), Cst) variant.
This patch add such optimization by transforming trunc(lshr (sext A), Cst)
to ashr A, Cst.

Differential Revision: http://reviews.llvm.org/D12520

llvm-svn: 247271
2015-09-10 11:31:20 +00:00
David Majnemer d34dbf07bd Revert trunc(lshr (sext A), Cst) to ashr A, Cst
This reverts commit r246997, it introduced a regression (PR24763).

llvm-svn: 247180
2015-09-09 20:20:08 +00:00
Jakub Kuderski 7cd4810021 There is a trunc(lshr (zext A), Cst) optimization in InstCombineCasts that
removes cast by performing the lshr on smaller types. However, currently there
is no trunc(lshr (sext A), Cst) variant.
This patch add such optimization by transforming trunc(lshr (sext A), Cst)
to ashr A, Cst.

Differential Revision: http://reviews.llvm.org/D12520

llvm-svn: 246997
2015-09-08 10:03:17 +00:00
David Majnemer 7fddeccb8b Move the personality function from LandingPadInst to Function
The personality routine currently lives in the LandingPadInst.

This isn't desirable because:
- All LandingPadInsts in the same function must have the same
  personality routine.  This means that each LandingPadInst beyond the
  first has an operand which produces no additional information.

- There is ongoing work to introduce EH IR constructs other than
  LandingPadInst.  Moving the personality routine off of any one
  particular Instruction and onto the parent function seems a lot better
  than have N different places a personality function can sneak onto an
  exceptional function.

Differential Revision: http://reviews.llvm.org/D10429

llvm-svn: 239940
2015-06-17 20:52:32 +00:00
Sunil Srivastava d79dfcbc37 Changed renaming of local symbols by inserting a dot vefore the numeric suffix.
One code change and several test changes to match that
details in http://reviews.llvm.org/D9481

llvm-svn: 237150
2015-05-12 16:47:30 +00:00
David Blaikie 445e3fbc54 [opaque pointer type] Add textual IR support for explicit type parameter to the invoke instruction
Same as r235145 for the call instruction - the justification, tradeoffs,
etc are all the same. The conversion script worked the same without any
false negatives (after replacing 'call' with 'invoke').

llvm-svn: 235755
2015-04-24 19:32:54 +00:00
David Majnemer 7d0e99c601 [InstCombine] Use a more targeted fix instead of r235544
Only clear out the NSW/NUW flags if we are optimizing 'add'/'sub' while
taking advantage that the sign bit is not set.  We do this optimization
to further shrink the mask but shrinking the mask isn't NSW/NUW
preserving in this case.

llvm-svn: 235558
2015-04-22 22:42:05 +00:00
David Majnemer fe58d13a17 [InstCombine] Clear out nsw/nuw if we modify computation in the chain
An nsw/nuw operation relies on the values feeding into it to not
overflow if 'poison' is not to be produced.  This means that
optimizations which make modifications to the bottom of a chain (like
SimplifyDemandedBits) must strip out nsw/nuw if they cannot ensure that
they will be preserved.

This fixes PR23309.

llvm-svn: 235544
2015-04-22 20:59:28 +00:00
Fiona Glaser 0d41db11a2 InstCombine: fold (sitofp (zext x)) to (uitofp x)
This is okay because the zext guarantees the high bit is zero,
and so the value is unsigned.

llvm-svn: 235364
2015-04-21 00:05:41 +00:00
David Blaikie 23af64846f [opaque pointer type] Add textual IR support for explicit type parameter to the call instruction
See r230786 and r230794 for similar changes to gep and load
respectively.

Call is a bit different because it often doesn't have a single explicit
type - usually the type is deduced from the arguments, and just the
return type is explicit. In those cases there's no need to change the
IR.

When that's not the case, the IR usually contains the pointer type of
the first operand - but since typed pointers are going away, that
representation is insufficient so I'm just stripping the "pointerness"
of the explicit type away.

This does make the IR a bit weird - it /sort of/ reads like the type of
the first operand: "call void () %x(" but %x is actually of type "void
()*" and will eventually be just of type "ptr". But this seems not too
bad and I don't think it would benefit from repeating the type
("void (), void () * %x(" and then eventually "void (), ptr %x(") as has
been done with gep and load.

This also has a side benefit: since the explicit type is no longer a
pointer, there's no ambiguity between an explicit type and a function
that returns a function pointer. Previously this case needed an explicit
type (eg: a function returning a void() function was written as
"call void () () * @x(" rather than "call void () * @x(" because of the
ambiguity between a function returning a pointer to a void() function
and a function returning void).

No ambiguity means even function pointer return types can just be
written alone, without writing the whole function's type.

This leaves /only/ the varargs case where the explicit type is required.

Given the special type syntax in call instructions, the regex-fu used
for migration was a bit more involved in its own unique way (as every
one of these is) so here it is. Use it in conjunction with the apply.sh
script and associated find/xargs commands I've provided in rr230786 to
migrate your out of tree tests. Do let me know if any of this doesn't
cover your cases & we can iterate on a more general script/regexes to
help others with out of tree tests.

About 9 test cases couldn't be automatically migrated - half of those
were functions returning function pointers, where I just had to manually
delete the function argument types now that we didn't need an explicit
function type there. The other half were typedefs of function types used
in calls - just had to manually drop the * from those.

import fileinput
import sys
import re

pat = re.compile(r'((?:=|:|^|\s)call\s(?:[^@]*?))(\s*$|\s*(?:(?:\[\[[a-zA-Z0-9_]+\]\]|[@%](?:(")?[\\\?@a-zA-Z0-9_.]*?(?(3)"|)|{{.*}}))(?:\(|$)|undef|inttoptr|bitcast|null|asm).*$)')
addrspace_end = re.compile(r"addrspace\(\d+\)\s*\*$")
func_end = re.compile("(?:void.*|\)\s*)\*$")

def conv(match, line):
  if not match or re.search(addrspace_end, match.group(1)) or not re.search(func_end, match.group(1)):
    return line
  return line[:match.start()] + match.group(1)[:match.group(1).rfind('*')].rstrip() + match.group(2) + line[match.end():]

for line in sys.stdin:
  sys.stdout.write(conv(re.search(pat, line), line))

llvm-svn: 235145
2015-04-16 23:24:18 +00:00
David Blaikie a79ac14fa6 [opaque pointer type] Add textual IR support for explicit type parameter to load instruction
Essentially the same as the GEP change in r230786.

A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)

import fileinput
import sys
import re

pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")

for line in sys.stdin:
  sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))

Reviewers: rafael, dexonsmith, grosser

Differential Revision: http://reviews.llvm.org/D7649

llvm-svn: 230794
2015-02-27 21:17:42 +00:00
David Blaikie 79e6c74981 [opaque pointer type] Add textual IR support for explicit type parameter to getelementptr instruction
One of several parallel first steps to remove the target type of pointers,
replacing them with a single opaque pointer type.

This adds an explicit type parameter to the gep instruction so that when the
first parameter becomes an opaque pointer type, the type to gep through is
still available to the instructions.

* This doesn't modify gep operators, only instructions (operators will be
  handled separately)

* Textual IR changes only. Bitcode (including upgrade) and changing the
  in-memory representation will be in separate changes.

* geps of vectors are transformed as:
    getelementptr <4 x float*> %x, ...
  ->getelementptr float, <4 x float*> %x, ...
  Then, once the opaque pointer type is introduced, this will ultimately look
  like:
    getelementptr float, <4 x ptr> %x
  with the unambiguous interpretation that it is a vector of pointers to float.

* address spaces remain on the pointer, not the type:
    getelementptr float addrspace(1)* %x
  ->getelementptr float, float addrspace(1)* %x
  Then, eventually:
    getelementptr float, ptr addrspace(1) %x

Importantly, the massive amount of test case churn has been automated by
same crappy python code. I had to manually update a few test cases that
wouldn't fit the script's model (r228970,r229196,r229197,r229198). The
python script just massages stdin and writes the result to stdout, I
then wrapped that in a shell script to handle replacing files, then
using the usual find+xargs to migrate all the files.

update.py:
import fileinput
import sys
import re

ibrep = re.compile(r"(^.*?[^%\w]getelementptr inbounds )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))")
normrep = re.compile(       r"(^.*?[^%\w]getelementptr )(((?:<\d* x )?)(.*?)(| addrspace\(\d\)) *\*(|>)(?:$| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$))")

def conv(match, line):
  if not match:
    return line
  line = match.groups()[0]
  if len(match.groups()[5]) == 0:
    line += match.groups()[2]
  line += match.groups()[3]
  line += ", "
  line += match.groups()[1]
  line += "\n"
  return line

for line in sys.stdin:
  if line.find("getelementptr ") == line.find("getelementptr inbounds"):
    if line.find("getelementptr inbounds") != line.find("getelementptr inbounds ("):
      line = conv(re.match(ibrep, line), line)
  elif line.find("getelementptr ") != line.find("getelementptr ("):
    line = conv(re.match(normrep, line), line)
  sys.stdout.write(line)

apply.sh:
for name in "$@"
do
  python3 `dirname "$0"`/update.py < "$name" > "$name.tmp" && mv "$name.tmp" "$name"
  rm -f "$name.tmp"
done

The actual commands:
From llvm/src:
find test/ -name *.ll | xargs ./apply.sh
From llvm/src/tools/clang:
find test/ -name *.mm -o -name *.m -o -name *.cpp -o -name *.c | xargs -I '{}' ../../apply.sh "{}"
From llvm/src/tools/polly:
find test/ -name *.ll | xargs ./apply.sh

After that, check-all (with llvm, clang, clang-tools-extra, lld,
compiler-rt, and polly all checked out).

The extra 'rm' in the apply.sh script is due to a few files in clang's test
suite using interesting unicode stuff that my python script was throwing
exceptions on. None of those files needed to be migrated, so it seemed
sufficient to ignore those cases.

Reviewers: rafael, dexonsmith, grosser

Differential Revision: http://reviews.llvm.org/D7636

llvm-svn: 230786
2015-02-27 19:29:02 +00:00
Philip Reames 5b3ce71b62 Add a test case for argument type coercion in an invoke of a vararg function
This would have caught the bug I fixed in 223370.  

llvm-svn: 223378
2014-12-04 19:13:45 +00:00
Chandler Carruth 816d26fe5e [InstCombine] Change LLVM To canonicalize toward the value type being
stored rather than the pointer type.

This change is analogous to r220138 which changed the canonicalization
for loads. The rationale is the same: memory does not have a type,
operations (and thus the values they produce) have a type. We should
match that type as closely as possible rather than reading some form of
semantics into the pointer type.

With this change, loads and stores should no longer be made with
nonsensical types for the values that tehy load and store. This is
particularly important when trying to match specific loaded and stored
types in the process of doing other instcombines, which is what led me
down this twisty maze of miscanonicalization.

I've put quite some effort into looking through IR to find places where
LLVM's optimizer was being unreasonably conservative in the face of
mismatched load and store types, however it is possible (let's say,
likely!) I have missed some. If you see regressions here, or from
r220138, the likely cause is some part of LLVM failing to cope with load
and store types differing. Test cases appreciated, it is important that
we root all of these out of LLVM.

llvm-svn: 222748
2014-11-25 10:09:51 +00:00
David Majnemer c8bdd23acf InstCombine: Fix a combine assuming that icmp operands were integers
An icmp may have pointer arguments, it isn't limited to integers or
vectors of integers.

This fixes PR21388.

llvm-svn: 220664
2014-10-27 05:47:49 +00:00
David Majnemer 3cac85e071 InstCombine: mul to shl shouldn't preserve nsw
consider:
mul i32 nsw %x, -2147483648

this instruction will not result in poison if %x is 1

however, if we transform this into:
shl i32 nsw %x, 31

then we will be generating poison because we just shifted into the sign
bit.

This fixes PR21242.

llvm-svn: 219566
2014-10-11 10:19:52 +00:00
Sanjay Patel ad8b666624 Return undef on FP <-> Int conversions that overflow (PR21330).
The LLVM Lang Ref states for signed/unsigned int to float conversions:
"If the value cannot fit in the floating point value, the results are undefined."

And for FP to signed/unsigned int:
"If the value cannot fit in ty2, the results are undefined."

This matches the C definitions.

The existing behavior pins to infinity or a max int value, but that may just
lead to more confusion as seen in:
http://llvm.org/bugs/show_bug.cgi?id=21130

Returning undef will hopefully lead to a less silent failure.

Differential Revision: http://reviews.llvm.org/D5603

llvm-svn: 219542
2014-10-10 23:00:21 +00:00
David Majnemer 49775e0173 InstCombine: Don't unconditionally preserve 'nuw' when shrinking constants
Consider:
  %add = add nuw i32 %a, -16777216
  %and = and i32 %add, 255

Regardless of whether or not we demand the sign bit of %add, we cannot
replace -16777216 with 2130706432 without also removing 'nuw' from the
instruction.

llvm-svn: 216273
2014-08-22 17:11:04 +00:00
David Majnemer 42b83a5e36 InstCombine: Don't unconditionally preserve 'nsw' when shrinking constants
Consider:
  %add = add nsw i32 %a, -16777216
  %and = and i32 %add, 255

Regardless of whether or not we demand the sign bit of %add, we cannot
replace -16777216 with 2130706432 without also removing 'nsw' from the
instruction.

This fixes PR20377.

llvm-svn: 216261
2014-08-22 07:56:32 +00:00
Matt Arsenault 4815f09bbe Allwo bitcast + struct GEP transform to work with addrspacecast
llvm-svn: 215467
2014-08-12 19:46:13 +00:00
Rafael Espindola d1a2c2d905 Add back commit r210029.
The code was actually correct. Sorry for the confusion. I have expanded the
comment saying why the analysis is valid to avoid me misunderstaning it
again in the future.

llvm-svn: 210052
2014-06-02 22:01:04 +00:00
Rafael Espindola 582c890fbe Revert "Add the nsw flag when we detect that an add will not signed overflow."
This reverts commit r210029.

It was not correctly handling cases where LHS and RHS had multiple but different
sign bits.

llvm-svn: 210048
2014-06-02 21:12:19 +00:00
Rafael Espindola 82899febf0 Add the nsw flag when we detect that an add will not signed overflow.
We already had a function for checking this, we were just using it only in
specialized cases.

llvm-svn: 210029
2014-06-02 14:32:58 +00:00
Matt Arsenault aa689f5079 Do more addrspacecast transforms that happen for bitcast.
Makes addrspacecast (gep) do addrspacecast (gep) instead.

llvm-svn: 201376
2014-02-14 00:49:12 +00:00
Matt Arsenault d79f7d9ea1 Teach InstCombine visitGetElementPtr about address spaces
llvm-svn: 188721
2013-08-19 22:17:40 +00:00
Stephen Lin c1c7a1309c 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

llvm-svn: 186268
2013-07-14 01:42:54 +00:00
Benjamin Kramer 14e915f7b4 InstCombine: Don't claim to be able to evaluate any shl in a zexted type.
The shift amount may be larger than the type leading to undefined behavior.
Limit the transform to constant shift amounts. While there update the bits to
clear in the result which may enable additional optimizations.

PR15959.

llvm-svn: 181604
2013-05-10 16:26:37 +00:00
Jakub Staszak a3619d31d8 unHECKify test fixed by Jacob in r159003.
llvm-svn: 170023
2012-12-12 20:58:42 +00:00
Duncan Sands 72c19ed386 Add a testcase that would have noticed the typo fixed in commit 166475.
llvm-svn: 166547
2012-10-24 07:17:20 +00:00
Duncan Sands 533c8ae79f Transform code like this
%V = mul i64 %N, 4
 %t = getelementptr i8* bitcast (i32* %arr to i8*), i32 %V
into
 %t1 = getelementptr i32* %arr, i32 %N
 %t = bitcast i32* %t1 to i8*
incorporating the multiplication into the getelementptr.
This happens all the time in dragonegg, for example for
  int foo(int *A, int N) {
    return A[N];
  }
because gcc turns this into byte pointer arithmetic before it hits the plugin:
  D.1590_2 = (long unsigned int) N_1(D);
  D.1591_3 = D.1590_2 * 4;
  D.1592_5 = A_4(D) + D.1591_3;
  D.1589_6 = *D.1592_5;
  return D.1589_6;
The D.1592_5 line is a POINTER_PLUS_EXPR, which is turned into a getelementptr
on a bitcast of A_4 to i8*, so this becomes exactly the kind of IR that the
transform fires on.

An analogous transform (with no testcases!) already existed for bitcasts of
arrays, so I rewrote it to share code with this one.

llvm-svn: 166474
2012-10-23 08:28:26 +00:00
Eli Friedman e0a64d83fc Fix a minor logic mistake transforming compares in instcombine. PR12514.
llvm-svn: 156600
2012-05-11 01:32:59 +00:00
Jakob Stoklund Olesen 43bcb970e5 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.

llvm-svn: 155362
2012-04-23 17:39:52 +00:00
Jakob Stoklund Olesen 205ee3b389 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.

llvm-svn: 155181
2012-04-20 00:38:45 +00:00
Jakob Stoklund Olesen 6b6c81e6b2 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.

llvm-svn: 155136
2012-04-19 16:46:26 +00:00
Nadav Rotem 5fc81ffbac Fixes following the CR by Chris and Duncan:
Optimize chained bitcasts of the form A->B->A.
Undo r138722 and change isEliminableCastPair to allow this case.

llvm-svn: 138756
2011-08-29 19:58:36 +00:00
Nadav Rotem 52600ee8c3 Bitcasts are transitive. Bitcast-Bitcast-X becomes Bitcast-X.
llvm-svn: 138722
2011-08-28 11:51:08 +00:00
Chris Lattner b90ed2233c manually upgrade a bunch of tests to modern syntax, and remove some that
are either unreduced or only test old syntax.

llvm-svn: 133228
2011-06-17 03:14:27 +00:00
Benjamin Kramer 35159c114c Simplify code. No functionality changes, name changes aside.
llvm-svn: 132896
2011-06-12 22:47:53 +00:00