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
The problem is that the struct file_status on UNIX systems has two
members called st_dev and st_ino; those are also members of the
struct stat, and they are reserved identifiers which can also be
provided as #define (and this is the case for st_dev on Hurd).
The solution (attached) is to rename them, for example adding a
"fs_" prefix (= file status) to them.
Patch by Pino Toscano
llvm-svn: 155354
The X86 target is editing the selection DAG while isel is selecting
nodes following a topological ordering. When the DAG hacking triggers
CSE, nodes can be deleted and bad things happen.
llvm-svn: 155257
Now that multiple DAGUpdateListeners can be active at the same time,
ISelPosition can become a local variable in DoInstructionSelection.
We simply register an ISelUpdater with CurDAG while ISelPosition exists.
llvm-svn: 155249
Instead of passing listener pointers to RAUW, let SelectionDAG itself
keep a linked list of interested listeners.
This makes it possible to have multiple listeners active at once, like
RAUWUpdateListener was already doing. It also makes it possible to
register listeners up the call stack without controlling all RAUW calls
below.
DAGUpdateListener uses an RAII pattern to add itself to the SelectionDAG
list of active listeners.
llvm-svn: 155248
The <undef> flag on a def operand only applies to partial register
redefinitions. Only print the flag when relevant, and print it as
<def,read-undef> to make it clearer what it means.
llvm-svn: 155239
This nicely handles the most common case of virtual register sets, but
also handles anticipated cases where we will map pointers to IDs.
The goal is not to develop a completely generic SparseSet
template. Instead we want to handle the expected uses within llvm
without any template antics in the client code. I'm adding a bit of
template nastiness here, and some assumption about expected usage in
order to make the client code very clean.
The expected common uses cases I'm designing for:
- integer keys that need to be reindexed, and may map to additional
data
- densely numbered objects where we want pointer keys because no
number->object map exists.
llvm-svn: 155227
Use the new TwoOperandAliasConstraint to handle lots of the two-operand aliases
for NEON instructions. There's still more to go, but this is a good chunk of
them.
llvm-svn: 155210
(load only has one operand) and smuggle in some whitespace changes too
NB: I am obviously testing the water here, and believe that the unguarded
cast is still wrong, but why is the getZExtValue of the load's operand
tested against zero here? Any review is appreciated.
llvm-svn: 155190
Sirish Pande