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Commit Graph

8 Commits

Author SHA1 Message Date
Nick Lewycky
baf1d18cf0 Teach SCEV to handle more cases of 'and X, CST', specifically where CST is any number of contiguous 1 bits in a row, with any number of leading and trailing 0 bits.
Unfortunately, this in turn led to some lower quality SCEVs due to some different paths through expression simplification, so add getUDivExactExpr and use it. This fixes all instances of the problems that I found, but we can make that function smarter as necessary.

Merge test "xor-and.ll" into "and-xor.ll" since I needed to update it anyways. Test 'nsw-offset.ll' analyzes a little deeper, %n now gets a scev in terms of %no instead of a SCEVUnknown.

llvm-svn: 200203
2014-01-27 10:04:03 +00:00
Benjamin Kramer
550faddc94 Revert "SCEV: When expanding a GEP the final addition to the base pointer has NUW but not NSW."
This isn't right either, reverting for now.

llvm-svn: 154910
2012-04-17 06:33:57 +00:00
Benjamin Kramer
a690750db9 SCEV: When expanding a GEP the final addition to the base pointer has NUW but not NSW.
Found by inspection.

llvm-svn: 154262
2012-04-07 17:19:26 +00:00
Andrew Trick
5c8b815e5f Propagate SCEV no-wrap flags whenever possible.
This needs review.

llvm-svn: 127638
2011-03-15 00:37:00 +00:00
Dan Gohman
71fc5e8fce -disable-output is no longer needed with -analyze.
llvm-svn: 94574
2010-01-26 19:25:59 +00:00
Dan Gohman
5e06a05a16 Fix the the ceiling-division used in computing the MaxBECount so that it doesn't
have trouble with an intermediate add overflowing. Also, be more conservative
about the case where the induction variable in an SLT loop exit can step past
the RHS of the SLT and overflow in a single step.

Make getSignedRange more aggressive, to recover for some common cases which
the above fixes pessimized.

This addresses rdar://7561161.

llvm-svn: 94512
2010-01-26 04:40:18 +00:00
Dan Gohman
771144e807 Use WriteAsOperand instead of getName() to print loop header names,
so that unnamed blocks are handled.

llvm-svn: 93059
2010-01-09 18:17:45 +00:00
Dan Gohman
723717853b Teach ScalarEvolution how to reason about no-wrap flags on loops
where the induction variable has a non-unit stride, such as {0,+,2}, and
there are expressions such as {1,+,2} inside the loop formed with
or or add nsw operators.

llvm-svn: 82151
2009-09-17 18:05:20 +00:00