We only really need this to be true for SIFixSGPRCopies.
I'm not sure there's any way this could happen before that point.
Fixes a case where MachineCSE could introduce a cross block
scc use.
llvm-svn: 269391
Summary:
...loop after the last iteration.
This is really hard to do correctly. The core problem is that we need to
model liveness through the induction PHIs from iteration to iteration in
order to get the correct results, and we need to correctly de-duplicate
the common subgraphs of instructions feeding some subset of the
induction PHIs. All of this can be driven either from a side effect at
some iteration or from the loop values used after the loop finishes.
This patch implements this by storing the forward-propagating analysis
of each instruction in a cache to recall whether it was free and whether
it has become live and thus counted toward the total unroll cost. Then,
at each sink for a value in the loop, we recursively walk back through
every value that feeds the sink, including looping back through the
iterations as needed, until we have marked the entire input graph as
live. Because we cache this, we never visit instructions more than twice
-- once when we analyze them and put them into the cache, and once when
we count their cost towards the unrolled loop. Also, because the cache
is only two bits and because we are dealing with relatively small
iteration counts, we can store all of this very densely in memory to
avoid this from becoming an excessively slow analysis.
The code here is still pretty gross. I would appreciate suggestions
about better ways to factor or split this up, I've stared too long at
the algorithmic side to really have a good sense of what the design
should probably look at.
Also, it might seem like we should do all of this bottom-up, but I think
that is a red herring. Specifically, the simplification power is *much*
greater working top-down. We can forward propagate very effectively,
even across strange and interesting recurrances around the backedge.
Because we use data to propagate, this doesn't cause a state space
explosion. Doing this level of constant folding, etc, would be very
expensive to do bottom-up because it wouldn't be until the last moment
that you could collapse everything. The current solution is essentially
a top-down simplification with a bottom-up cost accounting which seems
to get the best of both worlds. It makes the simplification incremental
and powerful while leaving everything dead until we *know* it is needed.
Finally, a core property of this approach is its *monotonicity*. At all
times, the current UnrolledCost is a conservatively low estimate. This
ensures that we will never early-exit from the analysis due to exceeding
a threshold when if we had continued, the cost would have gone back
below the threshold. These kinds of bugs can cause incredibly hard to
track down random changes to behavior.
We could use a techinque similar (but much simpler) within the inliner
as well to avoid considering speculated code in the inline cost.
Reviewers: chandlerc
Subscribers: sanjoy, mzolotukhin, llvm-commits
Differential Revision: http://reviews.llvm.org/D11758
llvm-svn: 269388
Summary:
Currently we consider such instructions as simplified, which is incorrect,
because if their user isn't simplified, we can't actually simplify them too.
This biases our estimates of profitability: for instance the analyzer expects
much more gains from unrolling memcpy loops than there actually are.
Reviewers: hfinkel, chandlerc
Subscribers: mzolotukhin, llvm-commits
Differential Revision: http://reviews.llvm.org/D17365
llvm-svn: 269387
In verbose mode, we emit a warning if the DWOId of a skeleton CU
mismatches the DWOId of the referenced module. This patch updates the
cached DWOId after a module has been loaded to the DWOId of the module
on disk (instead of storing the DWOId we expected to load). This
allows us to correctly emit the mismatch warning for all subsequent
object files that want to import the same module. This patch also
ensures both warnings are only emitted in verbose mode.
rdar://problem/26214027
llvm-svn: 269383
This change implements the transformation in processInstruction() for the
LDR rt, =expression to MOV rt, expression when the expression can be evaluated
and can fit into the immediate field of the MOV or a MVN.
Across the ARM and Thumb instruction sets there are several cases to consider,
each with a different range of representatble constants.
In ARM we have:
* Modified immediate (All ARM architectures)
* MOVW (v6t2 and above)
In Thumb we have:
* Modified immediate (v6t2, v7m and v8m.mainline)
* MOVW (v6t2, v7m, v8.mainline and v8m.baseline)
* Narrow Thumb MOV that can be used in an IT block (non flag-setting)
If the immediate fits any of the available alternatives then we make the transformation.
Fixes 25722.
Patch by Peter Smith.
llvm-svn: 269354
Alter instances in the test-suite that use immediates that can be represented
in the immediate field of a MOV. The reason for doing this is that when the
LDR rt,=imm transformation to MOV rt, imm the existing tests do not need to
be modified.
Required by the patch that fixes PR25722.
Patch by Peter Smith.
llvm-svn: 269353
I've added the reserved field as an "optional" in YAML, but I've added asserts in the yaml2macho code to enforce that the field is present in mach_header_64, but not in mach_header.
llvm-svn: 269320
Summary:
This expands on r269179 to fix an additional case that was not covered by our
tests. The assembler temporary is not needed when the .cprestore offset fits
inside a simm16 and it is not an error to use it inside a '.set noat' in this
case.
Reviewers: emaste, seanbruno, sdardis
Subscribers: dsanders, sdardis, llvm-commits
Differential Revision: http://reviews.llvm.org/D20199
llvm-svn: 269295
As explained in r269196, microMIPS has a special case that is not correctly
implemented in LLVM. If we have a symbol 'foo' which is equivalent to
'.text+0x10'. The value of an R_MICROMIPS_LO16 relocation using 'foo' is
'foo+0x11' and not 'foo+0x10'. The in-place addend should therefore be 0x11.
This commit reverts a little more of the effect of r268900 by keeping the
symbol when the STO_MIPS_MICROMIPS flag is set for R_MIPS_GPREL32 relocations.
This fixes SingleSource/UnitTests/2003-08-11-VaListArg, and
SingleSource/UnitTests/2003-05-07-VarArgs for microMIPS.
I believe there are additional relocations that have the same issue (e.g.
R_MIPS_64, and R_MIPS_GPREL16) but for now I'm focusing on restoring our
internal buildbots back to the green state we had in r268899.
llvm-svn: 269294
For BITREVERSE, bit shifting/masking every bit in a vector element is a very lengthy procedure.
If the input vector type is a whole multiple of bytes wide then we can split this into a BSWAP shuffle stage (to reverse at the byte level) and then a BITREVERSE stage applied to each byte. Most vector capable targets can efficiently BSWAP using shuffles resulting in a considerable reduction in instructions.
With this patch targets would only need to implement a target specific vXi8 BITREVERSE implementation to efficiently reverse most legal vector types.
Differential Revision: http://reviews.llvm.org/D19978
llvm-svn: 269290
Summary:
This eliminates the default case for N64 that was left out of r269047.
The change to R_MIPS_SUB is needed in this patch to make this testable since
%lo(%neg(%gp_rel(foo))) and %hi(%neg(%gp_rel(foo))) remain the only ways to get
a compound relocation from the assembler.
Reviewers: sdardis, rafael
Subscribers: dsanders, llvm-commits, sdardis
Differential Revision: http://reviews.llvm.org/D20097
llvm-svn: 269280
While promoting nodes in PPCTargetLowering::DAGCombineExtBoolTrunc, it is
possible for one of the nodes to be replaced by another. To make sure we do not
visit the deleted nodes, and to make sure we visit the replacement nodes, use a
list of HandleSDNodes to track the to-be-promoted nodes during the promotion
process.
The same fix has been applied to the analogous code in
PPCTargetLowering::DAGCombineTruncBoolExt.
Fixes PR26985.
llvm-svn: 269272
Shifts beyond the bitwidth are undef but SCCP resolved them to zero.
Instead, DTRT and resolve them to undef.
This reimplements the transform which caused PR27712.
llvm-svn: 269269
The promote alloca pass would attempt to promote an alloca with
a select, icmp, or phi user, even though the other operand was
from a non-promotable source, producing a select on two different
pointer types.
Only do this if we know that both operands derive from the same
alloca. In the future we should be able to relax this to an alloca
which will also be promoted.
llvm-svn: 269265
This new verifier rule lets us unambigously pick a calling convention
when creating a new declaration for
`@llvm.experimental.deoptimize.<ty>`. It is also congruent with our
lowering strategy -- since all calls to `@llvm.experimental.deoptimize`
are lowered to calls to `__llvm_deoptimize`, it is reasonable to enforce
a unique calling convention.
Some of the tests that were breaking this verifier rule have had to be
split up into different .ll files.
The inliner was violating this rule as well, and has been fixed to avoid
producing invalid IR.
llvm-svn: 269261
This is to fix the bug in https://llvm.org/bugs/show_bug.cgi?id=27612.
When spill is hoisted to a BB with landingpad successor, and if the VNI
of the spill reg lives into the landingpad successor, the spill should be
inserted before the call which may throw exception. InsertPointAnalysis
is used to compute the safe insert point.
http://reviews.llvm.org/D20027 is a preparing patch for this patch.
Differential Revision: http://reviews.llvm.org/D19884.
llvm-svn: 269249
For narrow stores (e.g., strb, srth) we know the upper bits of the register are
unused/not useful. In some cases we can use this information to eliminate
unnecessary instructions.
For example, without this patch we generate (from the 2nd test case):
ldr w8, [x0]
and w8, w8, #0xfff0
bfxil w8, w2, #16, #4
strh w8, [x1]
and after the patch the 'and' is removed:
ldr w8, [x0]
bfxil w8, w2, #16, #4
strh w8, [x1]
ret
During the lowering of the bitfield insert instruction the 'and' is eliminated
because we know the upper 16-bits that are masked off are unused and the lower
4-bits that are masked off are overwritten by the insert itself. Therefore, the
'and' is unnecessary.
Differential Revision: http://reviews.llvm.org/D20175
llvm-svn: 269226
SCEVExpander::replaceCongruentIVs assumes the backedge value of an
SCEV-analysable PHI to always be an instruction, when this is not
necessarily true. For now address this by bailing out of the
optimization if the backedge value of the PHI is a non-Instruction.
llvm-svn: 269213
`SCEVExpander::replaceCongruentIVs` bypasses `hoistIVInc` if both the
original and the isomorphic increments are PHI nodes. Doing this can
break SSA if the isomorphic increment is not dominated by the original
increment. Get rid of the bypass, and let `hoistIVInc` do the right
thing.
Fixes PR27232 (compile time crash/hang).
llvm-svn: 269212
... for AddRec's in loops for which SCEV is unable to compute a max
tripcount. This is not a problem for "normal" loops[0] that don't have
guards or assumes, but helps in cases where we have guards or assumes in
the loop that can be used to constrain incoming values over the backedge.
This partially fixes PR27691 (we still don't handle the NUW case).
[0]: for "normal" loops, in the cases where we'd be able to prove
no-wrap via isKnownPredicate, we'd also be able to compute a max
tripcount.
llvm-svn: 269211
Equivalent GEP indices with different types are treated as different
indices altogether, leading to an incorrect AA result. Fix the issue
by comparing indices based on their values.
Thanks to Mikael Holmén for reporting the issue!
Differential Revision: http://reviews.llvm.org/D19935
llvm-svn: 269197
microMIPS has a special case that is not correctly implemented in LLVM. If we
have a symbol 'foo' which is equivalent to '.text+0x10'. The value of an
R_MICROMIPS_LO16 relocation using 'foo' is 'foo+0x11' and not 'foo+0x10'. The
in-place addend should therefore be 0x11.
Work around this by partially reverting the effect of r268900 by keeping the
symbol when the STO_MIPS_MICROMIPS flag is set. This fixes
SingleSource/Regression/C/PR640 for microMIPS.
llvm-svn: 269196
When generating .cfi_offset instructions, make sure that the offset is
calculated with respect to the register used to define the CFA (which is
currently always FP+8).
llvm-svn: 269191
Summary:
r268058 unintentionally made the retrieval of the current assembler temporary
unconditional. This was fine for the existing tests but it broke the cases
where the assembler temporary is not needed (N32/N64 or not PIC) and is
unavailable due to a '.set noat' directive.
This fixes FreeBSD's libc.
Reviewers: emaste, sdardis, seanbruno
Subscribers: dsanders, emaste, sdardis, llvm-commits
Differential Revision: http://reviews.llvm.org/D20093
llvm-svn: 269179
Summary: When emitting comparison for fp16, in addition to promote the LHS and RHS to fp32, we need to change the VT as well.
Reviewers: t.p.northover
Subscribers: t.p.northover, aemerson, rengolin, llvm-commits
Differential Revision: http://reviews.llvm.org/D19922
llvm-svn: 269151
Michael Zolotukhin