The problematic part of this patch is that we were out of attribute bits,
requiring some fancy bit hacking to make it fit (by shrinking alignment)
without breaking existing users or the file format.
This change will require users to rebuild llvm-gcc to match llvm.
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parallel, allowing it to decide that P/Q must alias if A/B
must alias in things like:
P = gep A, 0, i, 1
Q = gep B, 0, i, 1
This allows GVN to delete 62 more instructions out of 403.gcc.
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indicate functions that allocate, such as operator new, or list::insert. The
actual definition is slightly less strict (for now).
No changes to the bitcode reader/writer, asm printer or verifier were needed.
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Use it to safely handle less-than-or-equals-to exit conditions in loops. These
also occur when the loop exit branch is exit on true because SCEV inverses the
icmp predicate.
Use it again to handle non-zero strides, but only with an unsigned comparison
in the exit condition.
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If this patch causes a performance regression for anyone, please let me know,
and it can be fixed in a different way with much more effort.
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Unfortunately this means removing one regression test
of GlobalsModRef because I couldn't work out how to
perform it without MarkModRef.
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can get the readnone/readonly attributes, and gives them it.
The plan is to remove markmodref (which did the same thing
by querying GlobalsModRef) and delete the analogous
functionality from GlobalsModRef.
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description says it does), not just when -analyze is
used as well. This means printing to stderr, so adjust
some tests.
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its callers to emit a space character before calling it when a
space is needed.
This fixes several spurious whitespace issues in
ScalarEvolution's debug dumps. See the test changes for
examples.
This also fixes odd space-after-tab indentation in the output
for switch statements, and changes calls from being printed like
this:
call void @foo( i32 %x )
to this:
call void @foo(i32 %x)
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(1) code left over from the days of ConstantPointerRef:
if a use of a function is a GlobalValue then that is
not considered a reason to add an edge from the external
node, even though the use may be as an initializer for
an externally visible global! There might be some point
to this behaviour when the use is by an alias (though the
code predated aliases by some centuries), but I think
PR2782 is a better way of handling that. (2) If function
F calls function G, and also G is a parameter to the
call, then an F->G edge is not added to the callgraph.
While this doesn't seem to matter much, adding such an
edge makes the callgraph more regular.
In addition, the new code should be faster as well as
simpler.
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doesNotAccessMemory, check doesNotAccessMemory
first, since otherwise functions may be
marked readonly rather than readnone.
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callgraph, when one member of a SCC calls another
then the analysis would drop to mod-ref because
there is (usually) no function info for the callee
yet; fix this. Teach the analysis about function
attributes, in particular the readonly attribute
(which requires being careful about globals).
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continue past the first conditional branch when looking for a
relevant test. This helps it avoid using MAX expressions in
loop trip counts in more cases.
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version uses a new algorithm for evaluating the binomial coefficients
which is significantly more efficient for AddRecs of more than 2 terms
(see the comments in the code for details on how the algorithm works).
It also fixes some bugs: it removes the arbitrary length restriction for
AddRecs, it fixes the silent generation of incorrect code for AddRecs
which require a wide calculation width, and it fixes an issue where we
were incorrectly truncating the iteration count too far when evaluating
an AddRec expression narrower than the induction variable.
There are still a few related issues I know of: I think there's
still an issue with the SCEVExpander expansion of AddRec in terms of
the width of the induction variable used. The hack to avoid generating
too-wide integers shouldn't be necessary; instead, the callers should be
considering the cost of the expansion before expanding it (in addition
to not expanding too-wide integers, we might not want to expand
expressions that are really expensive, especially when optimizing for
size; calculating an length-17 32-bit AddRec currently generates about 250
instructions of straight-line code on X86). Also, for long 32-bit
AddRecs on X86, CodeGen really sucks at scheduling the code. I'm planning on
filing follow-up PRs for these issues.
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time applying to the implicit comparison in smin expressions. The
correct way to transform an inequality into the opposite
inequality, either signed or unsigned, is with a not expression.
I looked through the SCEV code, and I don't think there are any more
occurrences of this issue.
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SGT exit condition. Essentially, the correct way to flip an inequality
in 2's complement is the not operator, not the negation operator.
That said, the difference only affects cases involving INT_MIN.
Also, enhance the pre-test search logic to be a bit smarter about
inequalities flipped with a not operator, so it can eliminate the smax
from the iteration count for simple loops.
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force evaluation (ComputeIterationCountExhaustively) should be turned off.
It doesn't apply to trip-count2.ll because this file tests the brute force
evaluation.
The test for PR2364 (2008-05-25-NegativeStepToZero.ll) currently fails
showing that the patch for this bug doesn't work. I'll fix it in a few hours
with a patch for PR2088.
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pointer derived from a local allocation, if the local allocation
never escapes, the pointers can't alias. This implements PR2436
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with code that was expecting different bit widths for different values.
Make getTruncateOrZeroExtend a method on ScalarEvolution, and use it.
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is longer than the second one) should stop after finding one. Added break
instruction guarantees it. It also changes difference between offsets to
absolute value of this difference in the condition.
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