Commit Graph

25 Commits

Author SHA1 Message Date
Max Kazantsev b9edcbcb1d Re-enable "[IndVars] Canonicalize comparisons between non-negative values and indvars"
The patch was reverted due to a bug. The bug was that if the IV is the 2nd operand of the icmp
instruction, then the "Pred" variable gets swapped and differs from the instruction's predicate.
In this patch we use the original predicate to do the transformation.

Also added a test case that exercises this situation.

Differentian Revision: https://reviews.llvm.org/D35107

llvm-svn: 307477
2017-07-08 17:17:30 +00:00
Max Kazantsev 98838527c6 Revert "Revert "Revert "[IndVars] Canonicalize comparisons between non-negative values and indvars"""
It appears that the problem is still there. Needs more analysis to understand why
SaturatedMultiply test fails.

llvm-svn: 307249
2017-07-06 10:47:13 +00:00
Max Kazantsev c8db20b78c Revert "Revert "[IndVars] Canonicalize comparisons between non-negative values and indvars""
It seems that the patch was reverted by mistake. Clang testing showed failure of the
MathExtras.SaturatingMultiply test, however I was unable to reproduce the issue on the
fresh code base and was able to confirm that the transformation introduced by the change
does not happen in the said test. This gives a strong confidence that the actual reason of
the failure of the initial patch was somewhere else, and that problem now seems to be
fixed. Re-submitting the change to confirm that.

llvm-svn: 307244
2017-07-06 09:57:41 +00:00
Max Kazantsev ebe56283bc Revert "[IndVars] Canonicalize comparisons between non-negative values and indvars"
This patch seems to cause failures of test MathExtras.SaturatingMultiply on
multiple buildbots. Reverting until the reason of that is clarified.

Differential Revision: https://reviews.llvm.org/rL307126

llvm-svn: 307135
2017-07-05 09:44:41 +00:00
Max Kazantsev 80bc4a5554 [IndVars] Canonicalize comparisons between non-negative values and indvars
-If there is a IndVar which is known to be non-negative, and there is a value which is also non-negative,
then signed and unsigned comparisons between them produce the same result. Both of those can be
seen in the same loop. To allow other optimizations to simplify them, we turn all instructions like

  %c = icmp slt i32 %iv, %b
to

  %c = icmp ult i32 %iv, %b

if both %iv and %b are known to be non-negative.

Differential Revision: https://reviews.llvm.org/D34979

llvm-svn: 307126
2017-07-05 06:38:49 +00:00
Sanjoy Das c1a2977fb2 Re-apply r251050 with a for PR25421
The bug: I missed adding break statements in the switch / case.

Original commit message:

[SCEV] Teach SCEV some axioms about non-wrapping arithmetic

Summary:
 - A s<  (A + C)<nsw> if C >  0
 - A s<= (A + C)<nsw> if C >= 0
 - (A + C)<nsw> s<  A if C <  0
 - (A + C)<nsw> s<= A if C <= 0

Right now `C` needs to be a constant, but we can later generalize it to
be a non-constant if needed.

Reviewers: atrick, hfinkel, reames, nlewycky

Subscribers: sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D13686

llvm-svn: 252236
2015-11-05 23:45:38 +00:00
Richard Trieu f8978e1a74 Revert r251050 to fix miscompile when running Clang -O1
See bug for details: https://llvm.org/bugs/show_bug.cgi?id=25421
Some comparisons were incorrectly replaced with a constant value.

llvm-svn: 252231
2015-11-05 23:20:36 +00:00
Sanjoy Das 1740d72867 [SCEV] Remove a test case added in r249168
The test case wasn't testing what it was commented to be testing; and
when I tried to fix the test I noticed that SCEV does not support the
simplification that the test was supposed to test.

This change removes the test case to avoid confusion.

llvm-svn: 251053
2015-10-22 19:57:41 +00:00
Sanjoy Das 6e78b17b43 [SCEV] Opportunistically interpret unsigned constraints as signed
Summary:
An unsigned comparision is equivalent to is corresponding signed version
if both the operands being compared are positive.  Teach SCEV to use
this fact when profitable.

Reviewers: atrick, hfinkel, reames, nlewycky

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D13687

llvm-svn: 251051
2015-10-22 19:57:34 +00:00
Sanjoy Das 1123148d40 [SCEV] Teach SCEV some axioms about non-wrapping arithmetic
Summary:
 - A s<  (A + C)<nsw> if C >  0
 - A s<= (A + C)<nsw> if C >= 0
 - (A + C)<nsw> s<  A if C <  0
 - (A + C)<nsw> s<= A if C <= 0

Right now `C` needs to be a constant, but we can later generalize it to
be a non-constant if needed.

Reviewers: atrick, hfinkel, reames, nlewycky

Subscribers: sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D13686

llvm-svn: 251050
2015-10-22 19:57:29 +00:00
Sanjoy Das 7d910f2b11 [SCEV] Try to prove predicates by splitting them
Summary:
This change teaches SCEV that to prove `A u< B` it is sufficient to
prove each of these facts individually:

 - B >= 0
 - A s< B
 - A >= 0

In practice, SCEV sometimes finds it easier to prove these facts
individually than to prove `A u< B` as one atomic step.

Reviewers: reames, atrick, nlewycky, hfinkel

Subscribers: sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D13042

llvm-svn: 249168
2015-10-02 18:50:30 +00:00
Sanjoy Das b174f9a316 [SCEV] Reapply 'Teach isLoopBackedgeGuardedByCond to exploit trip counts'
Summary:
If the trip count of a specific backedge is `N`, then we know that
backedge is effectively guarded by the condition `{0,+,1} u< N`.  This
change teaches SCEV to use this condition to prove things in
`isLoopBackedgeGuardedByCond`.

Depends on D12948
Depends on D12949

The original checkin, r248608 had to be backed out due to an issue with
a ObjCXX unit test.  That issue is now fixed, so re-landing.

Reviewers: atrick, reames, majnemer, hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12950

llvm-svn: 248638
2015-09-25 23:53:50 +00:00
Sanjoy Das 96709c4854 [SCEV] Reapply 'Exploit A < B => (A+K) < (B+K) when possible'
Summary:

This change teaches SCEV's `isImpliedCond` two new identities:

  A u< B u< -C          =>  (A + C) u< (B + C)
  A s< B s< INT_MIN - C =>  (A + C) s< (B + C)

While these are useful on their own, they're really intended to support
D12950.

The original checkin, r248606 had to be backed out due to an issue with
a ObjCXX unit test.  That issue is now fixed, so re-landing.

Reviewers: atrick, reames, majnemer, nlewycky, hfinkel

Subscribers: aadg, sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D12948

llvm-svn: 248637
2015-09-25 23:53:45 +00:00
Sanjoy Das 4a39b97671 Revert two SCEV changes that caused test failures in clang.
r248606: "[SCEV] Exploit A < B => (A+K) < (B+K) when possible"
r248608: "[SCEV] Teach isLoopBackedgeGuardedByCond to exploit trip counts."
llvm-svn: 248614
2015-09-25 21:16:50 +00:00
Sanjoy Das d706fa8a0c [SCEV] Teach isLoopBackedgeGuardedByCond to exploit trip counts.
Summary:
If the trip count of a specific backedge is `N`, then we know that
backedge is effectively guarded by the condition `{0,+,1} u< N`.  This
change teaches SCEV to use this condition to prove things in
`isLoopBackedgeGuardedByCond`.

Depends on D12948
Depends on D12949

Reviewers: atrick, reames, majnemer, hfinkel

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D12950

llvm-svn: 248608
2015-09-25 19:59:57 +00:00
Sanjoy Das fdec9deb13 [SCEV] Exploit A < B => (A+K) < (B+K) when possible
Summary:

This change teaches SCEV's `isImpliedCond` two new identities:

  A u< B u< -C          =>  (A + C) u< (B + C)
  A s< B s< INT_MIN - C =>  (A + C) s< (B + C)

While these are useful on their own, they're really intended to support
D12950.

Reviewers: atrick, reames, majnemer, nlewycky, hfinkel

Subscribers: aadg, sanjoy, llvm-commits

Differential Revision: http://reviews.llvm.org/D12948

llvm-svn: 248606
2015-09-25 19:59:49 +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
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 ba11a9892c Follow up to 168711: It's safe to base this analysis on the found compare, just return the value for the right predicate.
Thanks to Andy for catching this.

llvm-svn: 168921
2012-11-29 19:07:57 +00:00
Benjamin Kramer e20e124280 SCEV: Even if the latch terminator is foldable we can't deduce the result of an unrelated condition with it.
Fixes PR14432.

llvm-svn: 168711
2012-11-27 18:16:32 +00:00
Dan Gohman e637ff5e9a Remove the Expr member from IVUsers. Instead of remembering the expression,
just ask ScalarEvolution for it on demand. This helps IVUsers be more robust
in the case of expressions changing underneath it. This fixes PR6862.

llvm-svn: 101819
2010-04-19 21:48:58 +00:00
Dan Gohman fa5ad797e3 Re-apply r101000, with a fix: Don't eliminate an icmp which is part of
the loop exit test. This usually doesn't come up for a variety of
reasons, but it isn't impossible, so make IndVarSimplify handle it
conservatively.

llvm-svn: 101008
2010-04-12 02:21:50 +00:00
Dan Gohman c0f1efaf8d Revert 101000, which is breaking self-host builds.
llvm-svn: 101002
2010-04-12 00:17:10 +00:00
Dan Gohman af4ab1b681 Teach IndVarSimplify how to eliminate comparisons involving induction
variables. For example, with code like this:

  for (i=0;i<n;++i)
    if (i<n)
      x[i] = 0;

IndVarSimplify will now recognize that i is always less than n inside
the loop, and eliminate the if.

llvm-svn: 101000
2010-04-11 23:10:12 +00:00