Per original comment, the intention of this loop
is to go ahead and break the critical edge
(in order to sink this instruction) if there's
reason to believe doing so might "unblock" the
sinking of additional instructions that define
registers used by this one. The idea is that if
we have a few instructions to sink "together"
breaking the edge might be worthwhile.
This commit makes a few small changes
to help better realize this goal:
First, modify the loop to ignore registers
defined by this instruction. We don't
sink definitions of physical registers,
and sinking an SSA definition isn't
going to unblock an upstream instruction.
Second, ignore uses of physical registers.
Instructions that define physical registers are
rejected for sinking, and so moving this one
won't enable moving any defining instructions.
As an added bonus, while virtual register
use-def chains are generally small due
to SSA goodness, iteration over the uses
and definitions (used by hasOneNonDBGUse)
for physical registers like EFLAGS
can be rather expensive in practice.
(This is the original reason for looking at this)
Finally, to keep things simple continue
to only consider this trick for registers that
have a single use (via hasOneNonDBGUse),
but to avoid spuriously breaking critical edges
only do so if the definition resides
in the same MBB and therefore this one directly
blocks it from being sunk as well.
If sinking them together is meant to be,
let the iterative nature of this pass
sink the definition into this block first.
Update tests to accomodate this change,
add new testcase where sinking avoids pipeline stalls.
llvm-svn: 192608
When if converting something like:
true:
... = R0<kill>
false:
... = R0<kill>
then the instructions of the true block must not have a <kill> flag
anymore, as the instruction of the false block follow and do still read
the R0 value.
Specifically this patch determines the set of register live-in in the
false block (possibly after simulating the liveness changes of the
duplicated instructions). Each of these live-in registers mustn't be
killed.
llvm-svn: 192482
This reverts r192454
Apparently FileCheck isn't as smart as I though and does not enforce a
topological order between variable defs+uses.
llvm-svn: 192472
When we had a sequence like:
s1 = VLDRS [r0, 1], Q0<imp-def>
s3 = VLDRS [r0, 2], Q0<imp-use,kill>, Q0<imp-def>
s0 = VLDRS [r0, 0], Q0<imp-use,kill>, Q0<imp-def>
s2 = VLDRS [r0, 4], Q0<imp-use,kill>, Q0<imp-def>
we were gathering the {s0, s1} loads below the s3 load. This is fine,
but confused the verifier since now the s3 load had Q0<imp-use> with
no definition above it.
This should mark such uses <undef> as well. The liveness structure at
the beginning and end of the block is unaffected, and the true sN
definitions should prevent any dodgy reorderings being introduced
elsewhere.
rdar://problem/15124449
llvm-svn: 192344
from struct byval to registers.
We used to pass 0 which means the alignment of PtrVT. Even when the alignment
of the struct is smaller than 4, the LOADs would have alignment of 4, and
further optimizations could combine the LOADs into a ldm, which would
cause crash.
The fix is to pass the alignment of the struct byval.
rdar://problem/15144402
llvm-svn: 192126
optimizeSelect folds (predicated) copy instructions, it must not ignore
the original register class of the operand when replacing the register
with the copies dest register.
llvm-svn: 191963
The jump doesn't really kill the registers, the following call does but
we never get back anyway.
This avoids some verify-machineinstrs problems when TAILJUMPs are
if-converted.
llvm-svn: 191962
This function-attribute modifies the callee-saved register list and function
epilogue (specifically the return instruction) so that a routine is suitable
for use as an interrupt-handler of the specified type without disrupting
user-mode applications.
rdar://problem/14207019
llvm-svn: 191766
Generally, it is desirable to distribute (a + b) * c to a*c + b*c for
ARM with VMLx forwarding, where a, b and c are vectors.
However, for (a + b)*(a + b), distribution will result in one extra
instruction.
With distribution:
x = a + b (add)
y = a * x (mul)
z = y + b * y (mla)
Without distribution:
x = a + b (add)
z = x * x (mul)
This patch checks if a mul is a square of add/sub. If yes, skip
distribution.
llvm-svn: 191410
PEI inserts a save/restore sequence for the link register, according to the
information it gets from the MachineRegisterInfo.
MachineRegisterInfo is populated by the VirtRegMap pass.
This pass was not aware of noreturn calls and was registering the definitions of
these calls the same way as regular operations.
Modify VirtRegPass so that it does not set the isPhysRegUsed information for
registers only defined by noreturn calls.
The rational is that a noreturn call is the "last instruction" of the program
(if it returns the behavior is undefined), so everything that is defined by it
cannot be used and will not interfere with anything else. Therefore, it is
pointless to account for then.
llvm-svn: 191349
This is being disabled because it is no longer needed for
performance. It is only used by postRAscheduler which is also planned
for removal, and it is implemented with an out-dated view of register
liveness. It consideres aliases instead of register units, assumes
valid kill flags, and assumes implicit uses on partial register
defs. Kill flags and implicit operands are error prone and impossible
to verify. We should gradually eliminate dependence on them in the
postRA phases.
Targets that still benefit from this should move to the MI
scheduler. If that doesn't solve the problem, then we should add a
hook to regalloc to optimize reload placement.
llvm-svn: 191348
When a truncate node defines a legal vector type but uses an illegal
vector type, the legalization process was splitting the vector until
<1 x vector> type, but then it was failing to scalarize the node because
it did not know how to handle TRUNCATE.
<rdar://problem/14989896>
llvm-svn: 190830
Field 2 of DIType (Context), field 9 of DIDerivedType (TypeDerivedFrom),
field 12 of DICompositeType (ContainingType), fields 2, 7, 12 of DISubprogram
(Context, Type, ContainingType).
llvm-svn: 190205
Solution is not sufficient to prevent 'mov pc, lr' being emitted for jump table code.
Test case doesn't trigger the added functionality.
llvm-svn: 190047
This improves code generation for jump tables by avoiding the emission of "mov pc, lr" which could fool the processor into believing this is a return from a function causing mispredicts. The code generation logic for jump tables uses ADR to materialize the address of the jump target.
Patch by Daniel Stewart!
llvm-svn: 190043
'Force' values in registers using the calling convention. Now, we only depend on
the calling convention and that the allocator performs copy coalescing.
llvm-svn: 189985
This reverts commit r189648.
Fixes for the previously failing clang-side arm_neon_intrinsics test
cases will be checked in separately.
llvm-svn: 189841
What we really want is to enable Swift by default for *v7s triples (and there already seems to be some logic which attempts to do that). In that case the iOS version doesn't matter.
llvm-svn: 189763
In addition to recognizing when the multiply's second argument is
coming from an explicit VDUPLANE, also look for a plain scalar
f32 reference and reference it via the corresponding vector
lane.
rdar://14870054
llvm-svn: 189619
The vqdmlal and vqdmlls instructions are really just a fused pair consisting of
a vqdmull.sN and a vqadd.sN. This adds patterns to LLVM so that we can switch
Clang's CodeGen over to generating these instead of the special vqdmlal
intrinsics.
llvm-svn: 189480
