[mips] [IAS] Inline assemble-time shifting out of createLShiftOri. NFC.
Summary:
Do the assemble-time shifts from createLShiftOri at the source, which groups all the shifting together, closer to the main logic path, and
store the results in concisely-named variables to improve code clarity.
Tim Northover [Tue, 28 Apr 2015 22:03:55 +0000 (22:03 +0000)]
ARM: fix peephole optimisation of TST
We were trying to look through COPY instructions, but only to the next
instruction in a BB and incorrectly anyway. The cases where that would actually
be a good idea are rare enough (and not even tested!) that it's not worth
trying to get right.
This is a compromise: with this simple patch, we should always handle a chain of exactly 3
operations optimally, but we're not generating the optimal balanced binary tree for a longer
sequence.
In general, this transform will reduce the dependency chain for a sequence of instructions
using N operands from a worst case N-1 dependent operations to N/2 dependent operations.
The optimal balanced binary tree would reduce the chain to log2(N).
The trade-off for not dealing with longer sequences is: (1) we have less complexity in the
compiler, (2) we avoid unknown compile-time blowup calculating a balanced tree, and (3) we
don't need to worry about the increased register pressure required to parallelize longer
sequences. It also seems unlikely that we would ever encounter really long strings of
dependent ops like that in the wild, but I'm not sure how to verify that speculation.
FWIW, I see no perf difference for test-suite running on btver2 (x86-64) with -ffast-math
and this patch.
We can extend this patch to cover other associative operations such as fmul, fmax, fmin,
integer add, integer mul.
This is a partial fix for:
https://llvm.org/bugs/show_bug.cgi?id=17305
and if extended:
https://llvm.org/bugs/show_bug.cgi?id=21768
https://llvm.org/bugs/show_bug.cgi?id=23116
The issue also came up in:
http://reviews.llvm.org/D8941
[NVPTX] Handle addrspacecast constant expressions in aggregate initializers
We need to track if an AddrSpaceCast expression was seen when
generating an MCExpr for a ConstantExpr. This change introduces a
custom lowerConstant method to the NVPTX asm printer that will create
NVPTXGenericMCSymbolRefExpr nodes at the appropriate places to encode
the information that a given symbol needs to be casted to a generic
address.
move IR-level optimization flags into their own struct
This is a preliminary step to using the IR-level floating-point fast-math-flags in the SDAG (D8900).
In this patch, we introduce the optimization flags as their own struct. As noted in the TODO comment,
we should eventually share this data between the IR passes and the backend.
We also switch the existing nsw / nuw / exact bit functionality of the BinaryWithFlagsSDNode class to
use the new struct.
The tradeoff is that instead of using the free but limited space of SDNode's SubclassData, we add a
data member to the subclass. This means we don't have to repeat all of the get/set methods per flag,
but we're potentially adding size to all nodes of this subclassi type.
In practice on 64-bit systems (measured on Linux and MacOS X), there is no size difference between an
SDNode and BinaryWithFlagsSDNode after this change: they're both 80 bytes. This means that we had at
least one free byte to play with due to struct alignment.
Reapply r235977 "[DebugInfo] Add debug locations to constant SD nodes"
[DebugInfo] Add debug locations to constant SD nodes
This adds debug location to constant nodes of Selection DAG and updates
all places that create constants to pass debug locations
(see PR13269).
Can't guarantee that all locations are correct, but in a lot of cases choice
is obvious, so most of them should be. At least all tests pass.
Tests for these changes do not cover everything, instead just check it for
SDNodes, ARM and AArch64 where it's easy to get incorrect locations on
constants.
This is not complete fix as FastISel contains workaround for wrong debug
locations, which drops locations from instructions on processing constants,
but there isn't currently a way to use debug locations from constants there
as llvm::Constant doesn't cache it (yet). Although this is a bit different
issue, not directly related to these changes.
[DebugInfo] Add debug locations to constant SD nodes
This adds debug location to constant nodes of Selection DAG and updates
all places that create constants to pass debug locations
(see PR13269).
Can't guarantee that all locations are correct, but in a lot of cases choice
is obvious, so most of them should be. At least all tests pass.
Tests for these changes do not cover everything, instead just check it for
SDNodes, ARM and AArch64 where it's easy to get incorrect locations on
constants.
This is not complete fix as FastISel contains workaround for wrong debug
locations, which drops locations from instructions on processing constants,
but there isn't currently a way to use debug locations from constants there
as llvm::Constant doesn't cache it (yet). Although this is a bit different
issue, not directly related to these changes.
David Blaikie [Tue, 28 Apr 2015 04:30:29 +0000 (04:30 +0000)]
[opaque pointer type] Encode the pointee type in the bitcode for 'cmpxchg'
As a space optimization, this instruction would just encode the pointer
type of the first operand and use the knowledge that the second and
third operands would be of the pointee type of the first. When typed
pointers go away, this assumption will no longer be available - so
encode the type of the second operand explicitly and rely on that for
the third.
Test case added to demonstrate the backwards compatibility concern,
which only comes up when the definition of the second operand comes
after the use (hence the weird basic block sequence) - at which point
the type needs to be explicitly encoded in the bitcode and the record
length changes to accommodate this.
Ahmed Bougacha [Tue, 28 Apr 2015 01:37:11 +0000 (01:37 +0000)]
[MC] Use LShr for constant evaluation of ">>" on ELF/arm64--darwin.
This matches other assemblers and is less unexpected (e.g. PR23227).
On ELF, I tried binutils gas v2.24 and nasm 2.10.09, and they both
agree on LShr. On COFF, I couldn't get my hands on an assembler yet,
so don't change the behavior. For now, don't change it on non-AArch64
Darwin either, as the other assembler is gas v1.38, which does an AShr.
Ahmed Bougacha [Tue, 28 Apr 2015 00:21:32 +0000 (00:21 +0000)]
[MC] Split MCBinaryExpr::Shr into LShr and AShr.
Defaulting to AShr without consulting the target MCAsmInfo isn't OK.
Add a flag to fix that. Keep it off for now: target migrations will
follow in separate commits.
Hans Wennborg [Mon, 27 Apr 2015 23:52:19 +0000 (23:52 +0000)]
Switch lowering: use uint32_t for weights everywhere
I previously thought switch clusters would need to use uint64_t in case
the weights of multiple cases overflowed a 32-bit int. It turns
out that the weights on a terminator instruction are capped to allow for
being added together, so using a uint32_t should be safe.
Reverse libLTO's default behaviour for preserving use-list order in
bitcode, and add API for controlling it. The default setting is now
`false` (don't preserve them), which is consistent with `clang`'s
default behaviour.
Users of libLTO should call `lto_codegen_should_embed_uselists(CG,true)`
prior to calling `lto_codegen_write_merged_modules()` whenever the
output file isn't part of the production workflow in order to reproduce
results with subsequent calls to `llc`.
(I haven't added tests since `llvm-lto` (the test tool for LTO) doesn't
support bitcode output, and even if it did: there isn't actually a good
way to test whether a tool has passed the flag. If the order is already
"natural" (if the order will already round-trip) then no use-list
directives are emitted at all. At some point I'll circle back to add
tests to `llvm-as` (etc.) that they actually respect the flag, at which
point I can somehow add a test here as well.)
Hans Wennborg [Mon, 27 Apr 2015 23:35:22 +0000 (23:35 +0000)]
Switch lowering: Take branch weight into account when ordering for fall-through
Previously, the code would try to put a fall-through case last,
even if that meant moving a case with much higher branch weight
further down the chain.
Ordering by branch weight is most important, putting a fall-through
block last is secondary.
LTO: Correct some doxygen comments about API availability
These look like copy/paste errors, and shouldn't have the "prior to"
qualifier. Each API was introduced at the given values of
`LTO_API_VERSION`. The "prior to" in other doxygen comments is because
I couldn't easily differentiate between versions 1 and 2 when I added
these comments.
Ahmed Bougacha [Mon, 27 Apr 2015 21:43:12 +0000 (21:43 +0000)]
[AArch64] Also combine vector selects fed by non-i1 SETCCs.
After legalization, scalar SETCC has an i32 result type on AArch64.
The i1 requirement seems too conservative, replace it with an assert.
This also means that we now can run after legalization. That should also
be fine, since the ops legalizer runs again after each combine, and
all types created all have the same sizes as the (legal) inputs.
Exposed by r235917; while there, robustize its tests (bsl also uses the
register it defines).
Ahmed Bougacha [Mon, 27 Apr 2015 21:01:20 +0000 (21:01 +0000)]
[AArch64] Don't assert when combining (v3f32 select (setcc f64)).
When the setcc has f64 operands, we can't build a vector setcc mask
to feed a vselect, because f64 doesn't divide v3f32 evenly.
Just bail out when that happens.
Chris Bieneman [Mon, 27 Apr 2015 20:45:35 +0000 (20:45 +0000)]
Fixes a hang that can occur if a signal comes in during malloc calls.
We need to dereference the signals mutex during handler registration so that we force its construction. This is to prevent the first use being during handling an actual signal because you can't safely allocate memory in a signal handler.
David Blaikie [Mon, 27 Apr 2015 19:58:56 +0000 (19:58 +0000)]
[opaque pointer type] encode the pointee type of global variables
Use a few extra bits in the const field (after widening it from a fixed
single bit) to stash the address space which is no longer provided by
the type (and an extra bit in there to specify that we're using that new
encoding).
Bill Schmidt [Mon, 27 Apr 2015 19:57:34 +0000 (19:57 +0000)]
[PPC64LE] Remove unnecessary swaps from lane-insensitive vector computations
This patch adds a new SSA MI pass that runs on little-endian PPC64
code with VSX enabled. Loads and stores of 4x32 and 2x64 vectors
without alignment constraints are accomplished for little-endian using
lxvd2x/xxswapd and xxswapd/stxvd2x. The existence of the additional
xxswapd instructions hurts performance in comparison with big-endian
code, but they are necessary in the general case to support correct
semantics.
However, the general case does not apply to most vector code. Many
vector instructions are lane-insensitive; they do not "care" which
lanes the parallel computations are performed within, provided that
the resulting data is stored into the correct locations. Thus this
pass looks for computations that perform only lane-insensitive
operations, and remove the unnecessary swaps from loads and stores in
such computations.
Future improvements will allow computations using certain
lane-sensitive operations to also be optimized in this manner, by
modifying the lane-sensitive operations to account for the permuted
order of the lanes. However, this patch only adds the infrastructure
to permit this; no lane-sensitive operations are optimized at this
time.
This code is heavily exercised by the various vectorizing applications
in the projects/test-suite tree. For the time being, I have only added
one simple test case to demonstrate what the pass is doing. Although
it is quite simple, it provides coverage for much of the code,
including the special case handling of copies and subreg-to-reg
operations feeding the swaps. I plan to add additional tests in the
future as I fill in more of the "special handling" code.
Two existing tests were affected, because they expected the swaps to
be present, but they are now removed.
[Hexagon] Use constant extenders to fix up hardware loops
Use a loop instruction with a constant extender for a hardware
loop instruction that is too far away from the start of the loop.
This is cheaper than changing the SA register value.
[mips] [IAS] Improve warning for using AT with .set noat.
Summary:
Changed the warning message to show the current value of $at, similar to what clang does for typedef's, and renamed warnIfAssemblerTemporary to a more descriptive name.
I also changed the type of variables which store registers from int to unsigned, updated the relevant test and tried to make the related comments clearer.
Reapply "[mips][FastISel] Implement shift ops for Mips fast-isel.""
This reapplies r235194, which was reverted in r235495 because it was causing a
failure in our out-of-tree buildbots for MIPS. With the sign-extension patch
in r235718, this patch doesn't cause any problem any more.
[MC] [IAS] Add support for the \@ .macro pseudo-variable.
Summary:
When used, it is substituted with the number of .macro instantiations we've done up to that point in time.
So if this is the 1st time we've instantiated a .macro (any .macro, regardless of name), \@ will instantiate to 0, if it's the 2nd .macro instantiation, it will instantiate to 1 etc.
It can only be used inside a .macro definition, an .irp definition or an .irpc definition (those last 2 uses are undocumented).
Constfold insertelement to undef when index is out-of-bounds
Summary:
This patch adds constant folding of insertelement instruction to undef value when index operand is constant and is not less than vector size or is undef.
InstCombine does not support this case, but I'm happy to add it there also if this change is accepted.
Test Plan: Unittests and regression tests for ConstProp pass.
projects / llvm / log