frame index. eliminateFrameIndex will replace these instructions with
(LDWSP|STWSP|LDAWSP) or (LDW|STW|LDAWF) if a frame pointer is in use.
This fixes PR 3324. Previously we used LDWSP, STWSP, LDAWSP before frame
pointer elimination. However since they were marked as implicitly using
SP they could not be rematerialised.
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my earlier patch to this file.
The issue there was that all uses of an IV inside a loop
are actually references to Base[IV*2], and there was one
use outside that was the same but LSR didn't see the base
or the scaling because it didn't recurse into uses outside
the loop; thus, it used base+IV*scale mode inside the loop
instead of pulling base out of the loop. This was extra bad
because register pressure later forced both base and IV into
memory. Doing that recursion, at least enough
to figure out addressing modes, is a good idea in general;
the change in AddUsersIfInteresting does this. However,
there were side effects....
It is also possible for recursing outside the loop to
introduce another IV where there was only 1 before (if
the refs inside are not scaled and the ref outside is).
I don't think this is a common case, but it's in the testsuite.
It is right to be very aggressive about getting rid of
such introduced IVs (CheckForIVReuse and the handling of
nonzero RewriteFactor in StrengthReduceStridedIVUsers).
In the testcase in question the new IV produced this way
has both a nonconstant stride and a nonzero base, neither
of which was handled before. And when inserting
new code that feeds into a PHI, it's right to put such
code at the original location rather than in the PHI's
immediate predecessor(s) when the original location is outside
the loop (a case that couldn't happen before)
(RewriteInstructionToUseNewBase); better to avoid making
multiple copies of it in this case.
Also, the mechanism for keeping SCEV's corresponding to GEP's
no longer works, as the GEP might change after its SCEV
is remembered, invalidating the SCEV, and we might get a bad
SCEV value when looking up the GEP again for a later loop.
This also couldn't happen before, as we weren't recursing
into GEP's outside the loop.
Also, when we build an expression that involves a (possibly
non-affine) IV from a different loop as well as an IV from
the one we're interested in (containsAddRecFromDifferentLoop),
don't recurse into that. We can't do much with it and will
get in trouble if we try to create new non-affine IVs or something.
More testcases are coming.
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vector and extraneous loop over it, 2) not delete globals used by
phis/selects etc which could actually be useful. This fixes PR3321.
Many thanks to Duncan for narrowing this down.
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to Eli for pointing out that these forms don't ignore the high bits of
their index operands, and as such are not immediately suitable for use
by isel.
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scheduling dependencies. Add assertion checks to help catch
this.
It appears the Mips target defaults to list-td, and it has a
regression test that uses a physreg dependence. Such code was
liable to be miscompiled, and now evokes an assertion failure.
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been modified, to avoid trouble in the (unlikely) scenario that
D is a reference to an element in one of those arrays.
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via two paths, process it once not twice, d'oh!
Analysis, testcase and original patch thanks to
Mon Ping Wang.
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Note, multiple compile unit support is not well tested (it did not work correctly until now anyway.)
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