and extern_weak_odr. These are the same as the non-odr versions,
except that they indicate that the global will only be overridden
by an *equivalent* global. In C, a function with weak linkage can
be overridden by a function which behaves completely differently.
This means that IP passes have to skip weak functions, since any
deductions made from the function definition might be wrong, since
the definition could be replaced by something completely different
at link time. This is not allowed in C++, thanks to the ODR
(One-Definition-Rule): if a function is replaced by another at
link-time, then the new function must be the same as the original
function. If a language knows that a function or other global can
only be overridden by an equivalent global, it can give it the
weak_odr linkage type, and the optimizers will understand that it
is alright to make deductions based on the function body. The
code generators on the other hand map weak and weak_odr linkage
to the same thing.
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to find a tiny mouse hole to squeeze through, it struck
me that globals without a name can be considered internal
since they can't be referenced from outside the current
module. This patch makes GlobalOpt give them internal
linkage. Also done for aliases even though they always
have names, since in my opinion anonymous aliases should
be allowed for consistency with global variables and
functions. So if that happens one day, this code is ready!
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@66267 91177308-0d34-0410-b5e6-96231b3b80d8
If non constant local GV named A is used by a constant local GV named B (e.g. llvm.dbg.variable) and B is not used by anyone else then eliminate A as well as B.
In other words, debug info should not interfere in removal of unused GV.
--This life, and those below, will be ignored--
M test/Transforms/GlobalOpt/2009-03-03-dbg.ll
M lib/Transforms/IPO/GlobalOpt.cpp
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use, check also for the case where it has two uses,
the other being a llvm.dbg.declare. This is needed so
debug info doesn't affect codegen.
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info with it.
Don't count debug info insns against the scan maximum
in FindAvailableLoadedValue (lest they affect codegen).
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to more accurately describe what it does. Expand its doxygen comment
to describe what the backedge-taken count is and how it differs
from the actual iteration count of the loop. Adjust names and
comments in associated code accordingly.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65382 91177308-0d34-0410-b5e6-96231b3b80d8
ashr instcombine to help expose this code. And apply the fix to
SelectionDAG's copy of this code too.
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trip counts that use signed comparisons. It's not obviously the best
approach for preserving trip count information, and at any rate there
isn't anything in the tree right now that makes use of that, so for
now always using zero-extensions is preferable.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65347 91177308-0d34-0410-b5e6-96231b3b80d8
so that ScalarEvolution doesn't hang onto a dangling Loop*, which
could be a problem if another Loop happens to get allocated at the
same address.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65323 91177308-0d34-0410-b5e6-96231b3b80d8
-std-compile-opts sequence, this avoids the need for ScalarEvolution to
be rerun before LoopDeletion.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65318 91177308-0d34-0410-b5e6-96231b3b80d8
memcpy to match the alignment of the destination. It isn't necessary
for making loads and stores handled like the SSE loadu/storeu
intrinsics, and it was causing a performance regression in
MultiSource/Applications/JM/lencod.
The problem appears to have been a memcpy that copies from some
highly aligned array into an alloca; the alloca was then being
assigned a large alignment, which required codegen to perform
dynamic stack-pointer re-alignment, which forced the enclosing
function to have a frame pointer, which led to increased spilling.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65289 91177308-0d34-0410-b5e6-96231b3b80d8
as legality. Make load sinking and gep sinking more careful: we only
do it when it won't pessimize loads from the stack. This has the added
benefit of not producing code that is unanalyzable to SROA.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65209 91177308-0d34-0410-b5e6-96231b3b80d8
addresses, part 1. This fixes an obvious logic bug. Previously if the only
in-loop use is a PHI, it would return AllUsesAreAddresses as true.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65178 91177308-0d34-0410-b5e6-96231b3b80d8
Currently this pass will delete the variable declaration info,
and keep the line number info. But the kept line number info is not updated,
and some is redundant or not correct, this patch just updates those info.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@65123 91177308-0d34-0410-b5e6-96231b3b80d8
reduction of address calculations down to basic pointer arithmetic.
This is currently off by default, as it needs a few other features
before it becomes generally useful. And even when enabled, full
strength reduction is only performed when it doesn't increase
register pressure, and when several other conditions are true.
This also factors out a bunch of exisiting LSR code out of
StrengthReduceStridedIVUsers into separate functions, and tidies
up IV insertion. This actually decreases register pressure even
in non-superhero mode. The change in iv-users-in-other-loops.ll
is an example of this; there are two more adds because there are
two fewer leas, and there is less spilling.
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here. Since we only do the transform if there is
one use, strip off any such users in the hope of
making the transform fire more often.
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trip count value when the original loop iteration condition is
signed and the canonical induction variable won't undergo signed
overflow. This isn't required for correctness; it just preserves
more information about original loop iteration values.
Add a getTruncateOrSignExtend method to ScalarEvolution,
following getTruncateOrZeroExtend.
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are multiple IV's in a loop, some of them may under go signed
or unsigned wrapping even if the IV that's used in the loop
exit condition doesn't. Restrict sign-extension-elimination
and zero-extension-elimination to only those that operate on
the original loop-controlling IV.
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modified in a way that may effect the trip count calculation. Change
IndVars to use this method when it rewrites pointer or floating-point
induction variables instead of using a doInitialization method to
sneak these changes in before ScalarEvolution has a chance to see
the loop. This eliminates the need for LoopPass to depend on
ScalarEvolution.
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eliminate all the extensions and all but the one required truncate
from the testcase, but the or/and/shift stuff still isn't zapped.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64809 91177308-0d34-0410-b5e6-96231b3b80d8
Enhance instcombine to use the preferred field of
GetOrEnforceKnownAlignment in more cases, so that regular IR operations are
optimized in the same way that the intrinsics currently are.
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when I was looking at functions used by python.
Highlights include, better largefile support (64-bit file sizes on 32-bit
systems), fputs string is nocapture, popen/pclose added (popen being noalias
return), modf and frexp and friends. Also added some missing 'break' statements
and combined identical sections.
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alias can be morphed into the target. Implement this
transform, and fix a crash in the existing transform at
the same time.
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- Test for signed and unsigned wrapping conditions, instead of just
testing for non-negative induction ranges.
- Handle loops with GT comparisons, in addition to LT comparisons.
- Support more cases of induction variables that don't start at 0.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64532 91177308-0d34-0410-b5e6-96231b3b80d8
addrec in a different loop to check the value being added to
the accumulated Start value, not the Start value before it has
the new value added to it. This prevents LSR from going crazy
on the included testcase. Dale, please review.
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after sorting by stride value. This prevents it from missing
IV reuse opportunities in a host-sensitive manner.
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loop induction on LP64 targets. When the induction variable is
used in addressing, IndVars now is usually able to inserst a
64-bit induction variable and eliminates the sign-extending cast.
This is also useful for code using C "short" types for
induction variables on targets with 32-bit addressing.
Inserting a wider induction variable is easy; the tricky part is
determining when trunc(sext(i)) expressions are no-ops. This
requires range analysis of the loop trip count. A common case is
when the original loop iteration starts at 0 and exits when the
induction variable is signed-less-than a fixed value; this case
is now handled.
This replaces IndVarSimplify's OptimizeCanonicalIVType. It was
doing the same optimization, but it was limited to loops with
constant trip counts, because it was running after the loop
rewrite, and the information about the original induction
variable is lost by that point.
Rename ScalarEvolution's executesAtLeastOnce to
isLoopGuardedByCond, generalize it to be able to test for
ICMP_NE conditions, and move it to be a public function so that
IndVars can use it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64407 91177308-0d34-0410-b5e6-96231b3b80d8
calls with the tail marker when inlining them through an invoke. Patch,
testcase, and perfect analysis by Jay Foad!
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accessed at least once as a vector. This prevents it from
compiling the example in not-a-vector into:
define double @test(double %A, double %B) {
%tmp4 = insertelement <7 x double> undef, double %A, i32 0
%tmp = insertelement <7 x double> %tmp4, double %B, i32 4
%tmp2 = extractelement <7 x double> %tmp, i32 4
ret double %tmp2
}
instead, producing the integer code. Producing vectors when they
aren't otherwise in the program is dangerous because a lot of other
code treats them carefully and doesn't want to break them down.
OTOH, many things want to break down tasty i448's.
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With the new world order, it can handle cases where the first
store into the alloca is an element of the vector, instead of
requiring the first analyzed store to have the vector type
itself. This allows us to un-xfail
test/CodeGen/X86/vec_ins_extract.ll.
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turn icmp eq a+x, b+x into icmp eq a, b if a+x or b+x has other uses. This
may have been increasing register pressure leading to the bzip2 slowdown.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@63487 91177308-0d34-0410-b5e6-96231b3b80d8
improvements to the EvaluateInDifferentType code. This code works
by just inserted a bunch of new code and then seeing if it is
useful. Instcombine is not allowed to do this: it can only insert
new code if it is useful, and only when it is converging to a more
canonical fixed point. Now that we iterate when DCE makes progress,
this causes an infinite loop when the code ends up not being used.
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simplifydemandedbits to simplify instructions with *multiple
uses* in contexts where it can get away with it. This allows
it to simplify the code in multi-use-or.ll into a single 'add
double'.
This change is particularly interesting because it will cover
up for some common codegen bugs with large integers created due
to the recent SROA patch. When working on fixing those bugs,
this should be disabled.
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Now, if it detects that "V" is the same as some other value,
SimplifyDemandedBits returns the new value instead of RAUW'ing it immediately.
This has two benefits:
1) simpler code in the recursive SimplifyDemandedBits routine.
2) it allows future fun stuff in instcombine where an operation has multiple
uses and can be simplified in one context, but not all.
#2 isn't implemented yet, this patch should have no functionality change.
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not doing so prevents it from properly iterating and prevents it
from deleting the entire body of dce-iterate.ll
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be able to handle *ANY* alloca that is poked by loads and stores of
bitcasts and GEPs with constant offsets. Before the code had a number
of annoying limitations and caused it to miss cases such as storing into
holes in structs and complex casts (as in bitfield-sroa) where we had
unions of bitfields etc. This also handles a number of important cases
that are exposed due to the ABI lowering stuff we do to pass stuff by
value.
One case that is pretty great is that we compile
2006-11-07-InvalidArrayPromote.ll into:
define i32 @func(<4 x float> %v0, <4 x float> %v1) nounwind {
%tmp10 = call <4 x i32> @llvm.x86.sse2.cvttps2dq(<4 x float> %v1)
%tmp105 = bitcast <4 x i32> %tmp10 to i128
%tmp1056 = zext i128 %tmp105 to i256
%tmp.upgrd.43 = lshr i256 %tmp1056, 96
%tmp.upgrd.44 = trunc i256 %tmp.upgrd.43 to i32
ret i32 %tmp.upgrd.44
}
which turns into:
_func:
subl $28, %esp
cvttps2dq %xmm1, %xmm0
movaps %xmm0, (%esp)
movl 12(%esp), %eax
addl $28, %esp
ret
Which is pretty good code all things considering :).
One effect of this is that SROA will start generating arbitrary bitwidth
integers that are a multiple of 8 bits. In the case above, we got a
256 bit integer, but the codegen guys assure me that it can handle the
simple and/or/shift/zext stuff that we're doing on these operations.
This addresses rdar://6532315
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Thus we need to check whether the struct is empty before trying to index into
it. This fixes PR3381.
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handling the case in Transforms/InstCombine/cast-store-gep.ll, which
is a heavily reduced testcase from Clang on x86-64.
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There is now a direct way from value-use-iterator to incoming block in PHINode's API.
This way we avoid the iterator->index->iterator trip, and especially the costly
getOperandNo() invocation. Additionally there is now an assertion that the iterator
really refers to one of the PHI's Uses.
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Besides APFloat, this involved removing code
from two places that thought they knew the
result of frem(0., x) but were wrong.
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we assumed a CFG structure that would be valid when all code in
the function is reachable, but not all code is necessarily
reachable. Do a simple, but horrible, CFG walk to check for this
case.
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because of dead code, a phi could use the speculated instruction
that was not in "BB2". Make this check explicit and tighten up
some other corners. This fixes PR3292. No testcase becauase this
depends entirely on visitation order of blocks and requires a
sequence of 8 passes to repro.
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doing very similar pointer capture analysis.
Factor out the common logic. The new version
is from FunctionAttrs since it does a better
job than the version in BasicAliasAnalysis
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putc, puts, perror, vscanf and vsscanf from getting annotations.
Add annotations for eight printf functions, memalign, pread and pwrite.
On Linux, llvm-gcc sometimes renames strdup, getc, putc, strtok_r, scanf and
sscanf. Match the alternate function names.
Fix a crash annotating opendir.
Don't mark fsetpos's second parameter as nocapture. It's supposed to be
captured.
Do mark fopen's path and mode strings as nocapture. Mark ferror as readonly,
but not fileno which may set errno.
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- Looking at the number of sign bits of the a sext instruction to determine whether new trunc + sext pair should be added when its source is being evaluated in a different type.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@62263 91177308-0d34-0410-b5e6-96231b3b80d8
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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compensation for turning off gcc's inliner. This gets
us closer to the amount of inlining we were getting before.
It is not a win on everything, of course, but seems to
gain overall.
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canonicalization transform based on duncan's comments:
1) improve the comment about %.
2) within our index loop make sure the offset stays
within the *type size*, instead of within the *abi size*.
This allows us to reason explicitly about landing in tail
padding and means that issues like non-zero offsets into
[0 x foo] types don't occur anymore.
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functions that don't already have a (dynamic) alloca.
Dynamic allocas cause inefficient codegen and we shouldn't
propagate this (behavior follows gcc). Two existing tests
assumed such inlining would be done; they are hacked by
adding an alloca in the caller, preserving the point of
the tests.
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loads from allocas that cover the entire aggregate. This handles
some memcpy/byval cases that are produced by llvm-gcc. This triggers
a few times in kc++ (with std::pair<std::_Rb_tree_const_iterator
<kc::impl_abstract_phylum*>,bool>) and once in 176.gcc (with %struct..0anon).
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was it not very helpful, it was also wrong! The problem
is shown in the testcase: the alloca might be passed to
a nocapture callee which dereferences it and returns the
original pointer. But because it was a nocapture call we
think we don't need to track its uses, but we do.
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integer to a (transitive) bitcast the alloca and if that integer
has the full size of the alloca, then it clobbers the whole thing.
Handle this by extracting pieces out of the stored integer and
filing them away in the SROA'd elements.
This triggers fairly frequently because the CFE uses integers to
pass small structs by value and the inliner exposes these. For
example, in kimwitu++, I see a bunch of these with i64 stores to
"%struct.std::pair<std::_Rb_tree_const_iterator<kc::impl_abstract_phylum*>,bool>"
In 176.gcc I see a few i32 stores to "%struct..0anon".
In the testcase, this is a difference between compiling test1 to:
_test1:
subl $12, %esp
movl 20(%esp), %eax
movl %eax, 4(%esp)
movl 16(%esp), %eax
movl %eax, (%esp)
movl (%esp), %eax
addl 4(%esp), %eax
addl $12, %esp
ret
vs:
_test1:
movl 8(%esp), %eax
addl 4(%esp), %eax
ret
The second half of this will be to handle loads of the same form.
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as template arguments instead of as instance variables, exposing more
optimization opportunities to the compiler earlier.
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In fact this also deletes those with linkonce linkage,
however this is currently dead because for the moment
aliases aren't allowed to have this linkage type.
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Finalization occurs after all the FunctionPasses in the group have run, which
is clearly not what we want.
This also means that we have to make sure that we apply the right param
attributes when creating a new function.
Also, add a missed optimization: strdup and strndup. NoCapture and
NoAlias return!
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not have pointer type. In particular, it may
be the condition argument for a select or a GEP
index. While I was unable to construct a testcase
for which some bits of the original pointer are
captured due to one of these, it's very very close
to being possible - so play safe and exclude these
possibilities.
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the argument to be stored to an alloca by tracking uses
of the alloca. This occurs 4 times (out of 7121, 0.05%)
in MultiSource/Applications, so may not be worth it. On
the other hand, it is easy to do and fairly cheap. The
functions it helps are: W_addcom and W_addlit in spiff;
process_args (argv) in d (make_dparser); ercPixConcealIMB
in JM/ldecod.
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functions that don't write can't leak a pointer except through
the return value, so a void readonly function is implicitly nocapture.
Test these, and add a test that verifies that f1 calling f2 with an
otherwise dead pointer gets both of them marked nocapture.
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to work out (in a very simplistic way) which function
arguments (pointer arguments only) are only dereferenced
and so do not escape. Mark such arguments 'nocapture'.
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and select instructions doesn't buy anything here
except extra complexity: the only difference in
the entire testsuite was that a readonly function
became readnone in MiBench/consumer-typeset. Add
a comment about this.
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constants, since doing so is irrelevant for aliasing
purposes. While this doesn't increase the total number
of functions marked readonly or readnone in MultiSource/
Applications (3089), it does result in 12 functions being
marked readnone rather than readonly.
Before:
readnone: 820
readonly: 2269
After:
readnone: 832
readonly: 2257
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other SPEC breakage. I'll be reverting all recent
changes shortly, this checking is mostly so this
change doesn't get lost.
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my last 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.
I owe some testcases for this, want to get it in for nightly runs.
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- Use SplitBlockPredecessors to factor out common predecessors of the critical edge destination. This is disabled for now due to some regressions.
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