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=21768https://llvm.org/bugs/show_bug.cgi?id=23116
The issue also came up in:
http://reviews.llvm.org/D8941
Differential Revision: http://reviews.llvm.org/D9232
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236031 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236000 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235942 91177308-0d34-0410-b5e6-96231b3b80d8
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).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235922 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235917 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235910 91177308-0d34-0410-b5e6-96231b3b80d8
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.
Differential Revision: http://reviews.llvm.org/D9262
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235882 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235878 91177308-0d34-0410-b5e6-96231b3b80d8
Patch to allow int8 vectors to be multiplied on the SSE unit instead of being scalarized.
The patch sign extends the i8 lanes to i16, uses the SSE2 pmullw multiplication instruction, then packs the lower byte from each result.
Differential Revision: http://reviews.llvm.org/D9115
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235837 91177308-0d34-0410-b5e6-96231b3b80d8
This introduces an intrinsic called llvm.eh.exceptioncode. It is lowered
by copying the EAX value live into whatever basic block it is called
from. Obviously, this only works if you insert it late during codegen,
because otherwise mid-level passes might reschedule it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235768 91177308-0d34-0410-b5e6-96231b3b80d8
Same as r235145 for the call instruction - the justification, tradeoffs,
etc are all the same. The conversion script worked the same without any
false negatives (after replacing 'call' with 'invoke').
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235755 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Fixes a bug in the NVPTX codegen. The code used to miss necessary "generic()"
on aggregates of addrspacecasts.
Test Plan: addrspacecast-gvar.ll
Reviewers: eliben, jholewinski
Reviewed By: jholewinski
Subscribers: jholewinski, llvm-commits
Differential Revision: http://reviews.llvm.org/D9130
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235689 91177308-0d34-0410-b5e6-96231b3b80d8
This enables the rematerialization of some R600 MOV instructions in the
RegisterCoalescer and adds a testcase for r235668.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235675 91177308-0d34-0410-b5e6-96231b3b80d8
So long as the choice between printing msync and sync is not ambiguous, we can
print 'sync 0' and just 'sync'.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235663 91177308-0d34-0410-b5e6-96231b3b80d8
We were asserting on code like this:
extern "C" unsigned long _exception_code();
void might_crash(unsigned long);
void foo() {
__try {
might_crash(0);
} __except(1) {
might_crash(_exception_code());
}
}
Gtest and many other libraries get the exception code from the __except
block. What's supposed to happen here is that EAX is live into the
__except block, and it contains the exception code. Eventually we'll
represent that as a use of the landingpad ehptr value, but for now we
can replace it with undef.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235649 91177308-0d34-0410-b5e6-96231b3b80d8
remove copies that are useful after breaking some hardware dependencies.
In other words, handle this kind of situations conservatively by assuming reg2
is redefined by the undef flag.
reg1 = copy reg2
= inst reg2<undef>
reg2 = copy reg1
Copy propagation used to remove the last copy.
This is incorrect because the undef flag on reg2 in inst, allows next
passes to put whatever trashed value in reg2 that may help.
In practice we end up with this code:
reg1 = copy reg2
reg2 = 0
= inst reg2<undef>
reg2 = copy reg1
This fixes PR21743.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235647 91177308-0d34-0410-b5e6-96231b3b80d8
When the base register index of the vector plus the constant offset
was less than zero, we were passing the wrong base register to the indirect
addressing instruction.
In this case, we need to set the base register to v0 and then add
the computed (negative) index to m0.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235641 91177308-0d34-0410-b5e6-96231b3b80d8
The order in which branches appear in ImmBranches is approximately their
order within the function body. By visiting later branches first, we reduce
the distance between earlier forward branches and their targets, making it
more likely that the cbn?z optimization, which can only apply to forward
branches, will succeed for those earlier branches.
Differential Revision: http://reviews.llvm.org/D9185
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235640 91177308-0d34-0410-b5e6-96231b3b80d8
In particular, this preserves the kill flag, which allows the Thumb2 cbn?z
optimization to be applied in cases where a branch has been re-created after
the live variables analysis pass, e.g. by the machine block placement pass.
This appears to be low risk; a number of other targets seem to already be
doing something similar, e.g. AArch64, PowerPC.
Differential Revision: http://reviews.llvm.org/D9184
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235639 91177308-0d34-0410-b5e6-96231b3b80d8
This appears to have been introduced back in r76698 as part of an unrelated
change. I can find no official ARM documentation stating that Thumb-2 functions
require 4-byte alignment; in fact, ARM documentation appears to contradict
this (see, e.g., ARM Architecture Reference Manual Thumb-2 Supplement,
section 2.6.1: "Thumb-2 enforces 16-bit alignment on all instructions.").
Also remove code that sets alignment for ARM functions, which is redundant
with code in the MachineFunction constructor, and remove the hidden
-arm-align-constant-islands flag, which has been enabled by default since
r146739 (Dec 2011) and has probably received sufficient testing by now.
Differential Revision: http://reviews.llvm.org/D9138
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235636 91177308-0d34-0410-b5e6-96231b3b80d8
TableGen had been nicely generating code to print a number of instructions using
shorter aliases (and PowerPC has plenty of short mnemonics), but we were not
calling it. For some of the aliases we support in the parser, TableGen can't
infer the "inverse" alias relationship, so there is still more to do.
Thus, after some hours of updating test cases...
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235616 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Constant stores of f16 vectors can create NvCast nodes from various
operand types to v4f16 or v8f16 depending on patterns in the stored
constants. This patch adds nvcast rules with v4f16 and v8f16 values.
AArchISelLowering::LowerBUILD_VECTOR has the details on which constant
patterns generate the nvcast nodes.
Reviewers: jmolloy, srhines, ab
Subscribers: rengolin, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D9201
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235610 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Set operation action for SINT_TO_FP and UINT_TO_FP nodes with v4i32,
v8i8, v8i16 inputs to allow promotion of v4f16 results.
Add tests for sitofp and uitofp for vec4, vec8, vec16, and i8, i16, i32,
and i64 vectors. Only missing tests are for v16i8 and v16i16 as the
shift operations are too complicated to write a proper check sequence.
The conversions from v4i64 to v4f16 do not depend on this patch - v4i64
is split and the conversion gets handled while lowering v2i64. I am
adding a test here for completeness.
Reviewers: aemerson, rengolin, ab, jmolloy, srhines
Subscribers: rengolin, aemerson, llvm-commits
Differential Revision: http://reviews.llvm.org/D9166
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235609 91177308-0d34-0410-b5e6-96231b3b80d8
Third time's the charm. The previous commit was reverted as a
reverse for-loop in SelectionDAGBuilder::lowerWorkItem did 'I--'
on an iterator at the beginning of a vector, causing asserts
when using debugging iterators. This commit fixes that.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235608 91177308-0d34-0410-b5e6-96231b3b80d8
Patch to remove extra bitcasts from shuffles, this is often a legacy of XformToShuffleWithZero being used to combine bitmaskings (of float vectors bitcast to integer vectors) into shuffles: bitcast(shuffle(bitcast(s0),bitcast(s1))) -> shuffle(s0,s1)
Differential Revision: http://reviews.llvm.org/D9097
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235578 91177308-0d34-0410-b5e6-96231b3b80d8
