Commit Graph

12 Commits

Author SHA1 Message Date
Michael Kuperstein de16b44f74 Port DemandedBits to the new pass manager.
Differential Revision: http://reviews.llvm.org/D18679

llvm-svn: 266699
2016-04-18 23:55:01 +00:00
Mehdi Amini b550cb1750 [NFC] Header cleanup
Removed some unused headers, replaced some headers with forward class declarations.

Found using simple scripts like this one:
clear && ack --cpp -l '#include "llvm/ADT/IndexedMap.h"' | xargs grep -L 'IndexedMap[<]' | xargs grep -n --color=auto 'IndexedMap'

Patch by Eugene Kosov <claprix@yandex.ru>

Differential Revision: http://reviews.llvm.org/D19219

From: Mehdi Amini <mehdi.amini@apple.com>
llvm-svn: 266595
2016-04-18 09:17:29 +00:00
James Molloy 6e518a3b50 [DemandedBits] Revert r249687 due to PR26071
This regresses a test in LoopVectorize, so I'll need to go away and think about how to solve this in a way that isn't broken.

From the writeup in PR26071:

What's happening is that ComputeKnownZeroes is telling us that all bits except the LSB are zero. We're then deciding that only the LSB needs to be demanded from the icmp's inputs.

This is where we're wrong - we're assuming that after simplification the bits that were known zero will continue to be known zero. But they're not - during trivialization the upper bits get changed (because an XOR isn't shrunk), so the icmp fails.

The fault is in demandedbits - its contract does clearly state that a non-demanded bit may either be zero or one.

llvm-svn: 259649
2016-02-03 15:05:06 +00:00
Benjamin Kramer 820f7548a1 Make some headers self-contained, remove unused includes that violate layering.
llvm-svn: 258937
2016-01-27 16:05:37 +00:00
James Molloy 121de0bcfa [DemandedBits] Fix computation of demanded bits for ICmps
The computation of ICmp demanded bits is independent of the individual operand being evaluated. We simply return a mask consisting of the minimum leading zeroes of both operands.

We were incorrectly passing "I" to ComputeKnownBits - this should be "UserI->getOperand(0)". In cases where we were evaluating the 1th operand, we were taking the minimum leading zeroes of it and itself.

This should fix PR26266.

llvm-svn: 258690
2016-01-25 14:49:36 +00:00
James Molloy e9d50dc9f7 Compute demanded bits for icmp instructions
Instead of bailing out when we see an icmp, we can instead at least
say that if the upper bits of both operands are known zero, they are
not demanded. This doesn't help with signed comparisons, but it's at
least better than bailing out.

llvm-svn: 249687
2015-10-08 12:40:06 +00:00
James Molloy bcd7f0ac98 Treat Mul just like Add and Subtract
Like adds and subtracts, muls ripple only to the left so we can use
the same logic.

While we're here, add a print method to DemandedBits so it can be used
with -analyze, which we'll use in the testcase.

llvm-svn: 249686
2015-10-08 12:39:59 +00:00
James Molloy ab9fdb9226 Make demanded bits lazy
The algorithm itself is still eager, but it doesn't get run until a
query function is called. This greatly reduces the compile-time impact
of requiring DemandedBits when at runtime it is not often used.

NFCI.

llvm-svn: 249685
2015-10-08 12:39:50 +00:00
NAKAMURA Takumi 0a7d0ad95f Untabify.
llvm-svn: 248264
2015-09-22 11:15:07 +00:00
NAKAMURA Takumi 84965031a7 Reformat comment lines.
llvm-svn: 248262
2015-09-22 11:14:12 +00:00
NAKAMURA Takumi 70ad98aca4 Reformat.
llvm-svn: 248261
2015-09-22 11:13:55 +00:00
James Molloy 87405c7f66 Separate out BDCE's analysis into a separate DemandedBits analysis.
This allows other areas of the compiler to use BDCE's bit-tracking.
NFCI.

llvm-svn: 245039
2015-08-14 11:09:09 +00:00