introduce no-return or unreachable heuristics.
The return heuristics from the Ball and Larus paper don't work well in
practice as they pessimize early return paths. The only good hitrate
return heuristics are those for:
- NULL return
- Constant return
- negative integer return
Only the last of these three can possibly require significant code for
the returning block, and even the last is fairly rare and usually also
a constant. As a consequence, even for the cold return paths, there is
little code on that return path, and so little code density to be gained
by sinking it. The places where sinking these blocks is valuable (inner
loops) will already be weighted appropriately as the edge is a loop-exit
branch.
All of this aside, early returns are nearly as common as all three of
these return categories, and should actually be predicted as taken!
Rather than muddy the waters of the static predictions, just remain
silent on returns and let the CFG itself dictate any layout or other
issues.
However, the return heuristic was flagging one very important case:
unreachable. Unfortunately it still gave a 1/4 chance of the
branch-to-unreachable occuring. It also didn't do a rigorous job of
finding those blocks which post-dominate an unreachable block.
This patch builds a more powerful analysis that should flag all branches
to blocks known to then reach unreachable. It also has better worst-case
runtime complexity by not looping through successors for each block. The
previous code would perform an N^2 walk in the event of a single entry
block branching to N successors with a switch where each successor falls
through to the next and they finally fall through to a return.
Test case added for noreturn heuristics. Also doxygen comments improved
along the way.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142793 91177308-0d34-0410-b5e6-96231b3b80d8
Assertion `i_nocapture < OperandTraits<PHINode>::operands(this) && "getOperand() out of range!"' failed.
coming out of indvars.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142786 91177308-0d34-0410-b5e6-96231b3b80d8
to bring it under direct test instead of merely indirectly testing it in
the BlockFrequencyInfo pass.
The next step is to start adding tests for the various heuristics
employed, and to start fixing those heuristics once they're under test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142778 91177308-0d34-0410-b5e6-96231b3b80d8
able to constant fold load instructions where the argument is a constant.
Second, we should be able to watch multiple PHI nodes through the loop; this
patch only supports PHIs in loop headers, more can be done here.
With this patch, we now constant evaluate:
static const int arr[] = {1, 2, 3, 4, 5};
int test() {
int sum = 0;
for (int i = 0; i < 5; ++i) sum += arr[i];
return sum;
}
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142731 91177308-0d34-0410-b5e6-96231b3b80d8
and switches, with arbitrary numbers of successors. Still optimized for
the common case of 2 successors for a conditional branch.
Add a test case for switch metadata showing up in the BlockFrequencyInfo pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142493 91177308-0d34-0410-b5e6-96231b3b80d8
encoding of probabilities. In the absense of metadata, it continues to
fall back on static heuristics.
This allows __builtin_expect, after lowering through llvm.expect
a branch instruction's metadata, to actually enter the branch
probability model. This is one component of resolving PR2577.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142492 91177308-0d34-0410-b5e6-96231b3b80d8
layer already had support for printing the results of this analysis, but
the wiring was missing.
Now that printing the analysis works, actually bring some of this
analysis, and the BranchProbabilityInfo analysis that it wraps, under
test! I'm planning on fixing some bugs and doing other work here, so
having a nice place to add regression tests and a way to observe the
results is really useful.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142491 91177308-0d34-0410-b5e6-96231b3b80d8
for pre-2.9 bitcode files. We keep x86 unaligned loads, movnt, crc32, and the
target indep prefetch change.
As usual, updating the testsuite is a PITA.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@133337 91177308-0d34-0410-b5e6-96231b3b80d8
queries in the case of a DAG, where a query reaches a node
visited earlier, but it's not on a cycle. This avoids
MayAlias results in cases where BasicAA is expected to
return MustAlias or PartialAlias in order to protect TBAA.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@132609 91177308-0d34-0410-b5e6-96231b3b80d8
after checking for a GEP, so that it matches what GetUnderlyingObject
does. This fixes an obscure bug turned up by bugpoint in the testcase
for PR9931.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131971 91177308-0d34-0410-b5e6-96231b3b80d8
Original log message:
When BasicAA can determine that two pointers have the same base but
differ by a dynamic offset, return PartialAlias instead of MayAlias.
See the comment in the code for details. This fixes PR9971.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131809 91177308-0d34-0410-b5e6-96231b3b80d8
differ by a dynamic offset, return PartialAlias instead of MayAlias.
See the comment in the code for details. This fixes PR9971.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131781 91177308-0d34-0410-b5e6-96231b3b80d8
only check arguments with pointer types. Update the documentation
of IntrReadArgMem reflect this.
While here, add support for TBAA tags on intrinsic calls.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130317 91177308-0d34-0410-b5e6-96231b3b80d8
is equivalent to any other relevant value; it isn't true in general.
If it is equivalent, the LoopPromoter will tell the AST the equivalence.
Also, delete the PreheaderLoad if it is unused.
Chris, since you were the last one to make major changes here, can you check
that this is sane?
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129049 91177308-0d34-0410-b5e6-96231b3b80d8
When ExactBECount is a constant, use it for MaxBECount.
When MaxBECount cannot be computed, replace it with ExactBECount.
Fixes PR9424.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127342 91177308-0d34-0410-b5e6-96231b3b80d8
This fixes a FIXME in scev-aa.ll (allowing a new no-alias result) and
generally makes things more precise.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125449 91177308-0d34-0410-b5e6-96231b3b80d8
unsigned overflow (e.g. "gep P, -1"), and while they can have
signed wrap in theoretical situations, modelling an AddRec as
not having signed wrap is going enough for any case we can
think of today. In the future if this isn't enough, we can
revisit this. Modeling them as having NUW isn't causing any
known problems either FWIW.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125410 91177308-0d34-0410-b5e6-96231b3b80d8
The PassManager did not implement the transitivity of requiredTransitive. This
was unnoticed since 2006.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123942 91177308-0d34-0410-b5e6-96231b3b80d8
by indvars through the scev expander.
trunc(add x, y) --> add(trunc x, y). Currently SCEV largely folds the other way
which is probably wrong, but preserved to minimize churn. Instcombine doesn't
do this fold either, demonstrating a missed optz'n opportunity on code doing
add+trunc+add.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123838 91177308-0d34-0410-b5e6-96231b3b80d8
are pointing to the same object, one pointer is accessing the entire
object, and the other is access has a non-zero size. This prevents
TBAA from kicking in and saying NoAlias in such cases.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123775 91177308-0d34-0410-b5e6-96231b3b80d8
does normal initialization and normal chaining. Change the default
AliasAnalysis implementation to NoAlias.
Update StandardCompileOpts.h and friends to explicitly request
BasicAliasAnalysis.
Update tests to explicitly request -basicaa.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116720 91177308-0d34-0410-b5e6-96231b3b80d8
make any assumptions about when the two conditions will agree on when
to permit the loop to exit. This fixes PR7845.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110758 91177308-0d34-0410-b5e6-96231b3b80d8
of BasicAA::getModRefInfo. This allows BasicAA to say that two
memset calls to non-aliasing memory locations don't interfere.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110393 91177308-0d34-0410-b5e6-96231b3b80d8
response from getModRefInfo is not useful here. Instead, check for identical
calls only in the NoModRef case.
Reapply r110270, and strengthen it to compensate for the memdep changes.
When both calls are readonly, there is no dependence between them.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110382 91177308-0d34-0410-b5e6-96231b3b80d8
one is a suffix of the other, and FileCheck accepts superstrings.
Adjust the output to avoid this problem.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110280 91177308-0d34-0410-b5e6-96231b3b80d8
to return Ref if the left callsite only reads memory read or written
by the right callsite; fix BasicAliasAnalysis to implement this.
Add AliasAnalysisEvaluator support for testing the two-callsite
form of getModRefInfo.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110270 91177308-0d34-0410-b5e6-96231b3b80d8
The RegionInfo pass detects single entry single exit regions in a function,
where a region is defined as any subgraph that is connected to the remaining
graph at only two spots.
Furthermore an hierarchical region tree is built.
Use it by calling "opt -regions analyze" or "opt -view-regions".
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109089 91177308-0d34-0410-b5e6-96231b3b80d8
interface needs implementations to be consistent, so any code which
wants to support different semantics must use a different interface.
It's not currently worthwhile to add a new interface for this new
concept.
Document that AliasAnalysis doesn't support cross-function queries.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107776 91177308-0d34-0410-b5e6-96231b3b80d8
properly handles instructions and arguments defined in different
functions, or across recursive function iterations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107109 91177308-0d34-0410-b5e6-96231b3b80d8
assuming that loops are in canonical form, as ScalarEvolution doesn't
depend on LoopSimplify itself. Also, with indirectbr not all loops can
be simplified. This fixes PR7416.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106389 91177308-0d34-0410-b5e6-96231b3b80d8
scrounging through SCEVUnknown contents and SCEVNAryExpr operands;
instead just do a simple deterministic comparison of the precomputed
hash data.
Also, since this is more precise, it eliminates the need for the slow
N^2 duplicate detection code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@105540 91177308-0d34-0410-b5e6-96231b3b80d8
Also, generalize ScalarEvolutions's min and max recognition to handle
some new forms of min and max that this change makes more common.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@102234 91177308-0d34-0410-b5e6-96231b3b80d8
Added support for address spaces and added a isVolatile field to memcpy, memmove, and memset,
e.g., llvm.memcpy.i32(i8*, i8*, i32, i32) -> llvm.memcpy.p0i8.p0i8.i32(i8*, i8*, i32, i32, i1)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100304 91177308-0d34-0410-b5e6-96231b3b80d8
Added support for address spaces and added a isVolatile field to memcpy, memmove, and memset,
e.g., llvm.memcpy.i32(i8*, i8*, i32, i32) -> llvm.memcpy.p0i8.p0i8.i32(i8*, i8*, i32, i32, i1)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@100191 91177308-0d34-0410-b5e6-96231b3b80d8
e.g., llvm.memcpy.i32(i8*, i8*, i32, i32) -> llvm.memcpy.p0i8.p0i8.i32(i8*, i8*, i32, i32, i1)
A update of langref will occur in a subsequent checkin.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@99928 91177308-0d34-0410-b5e6-96231b3b80d8
true or false as its exit condition. These are usually eliminated by
SimplifyCFG, but the may be left around during a pass which wishes
to preserve the CFG.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96683 91177308-0d34-0410-b5e6-96231b3b80d8
have trouble with an intermediate add overflowing. Also, be more conservative
about the case where the induction variable in an SLT loop exit can step past
the RHS of the SLT and overflow in a single step.
Make getSignedRange more aggressive, to recover for some common cases which
the above fixes pessimized.
This addresses rdar://7561161.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94512 91177308-0d34-0410-b5e6-96231b3b80d8
Nodes that had children outside of the post dominator tree (infinite loops)
where removed from the post dominator tree. This seems to be wrong. Leave them
in the tree.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@93633 91177308-0d34-0410-b5e6-96231b3b80d8
first expression as P+4+4*i which we considered to possibly alias
P+4*j. Now we correctly analyze the former one as P+1+4*i.
@test10 is a sanity test that verfies that we know that P+4+4*i != P+4*i.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@89960 91177308-0d34-0410-b5e6-96231b3b80d8
Here is the original commit message:
This commit updates malloc optimizations to operate on malloc calls that have constant int size arguments.
Update CreateMalloc so that its callers specify the size to allocate:
MallocInst-autoupgrade users use non-TargetData-computed allocation sizes.
Optimization uses use TargetData to compute the allocation size.
Now that malloc calls can have constant sizes, update isArrayMallocHelper() to use TargetData to determine the size of the malloced type and the size of malloced arrays.
Extend getMallocType() to support malloc calls that have non-bitcast uses.
Update OptimizeGlobalAddressOfMalloc() to optimize malloc calls that have non-bitcast uses. The bitcast use of a malloc call has to be treated specially here because the uses of the bitcast need to be replaced and the bitcast needs to be erased (just like the malloc call) for OptimizeGlobalAddressOfMalloc() to work correctly.
Update PerformHeapAllocSRoA() to optimize malloc calls that have non-bitcast uses. The bitcast use of the malloc is not handled specially here because ReplaceUsesOfMallocWithGlobal replaces through the bitcast use.
Update OptimizeOnceStoredGlobal() to not care about the malloc calls' bitcast use.
Update all globalopt malloc tests to not rely on autoupgraded-MallocInsts, but instead use explicit malloc calls with correct allocation sizes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86311 91177308-0d34-0410-b5e6-96231b3b80d8
MallocInst-autoupgrade users use non-TargetData-computed allocation sizes.
Optimization uses use TargetData to compute the allocation size.
Now that malloc calls can have constant sizes, update isArrayMallocHelper() to use TargetData to determine the size of the malloced type and the size of malloced arrays.
Extend getMallocType() to support malloc calls that have non-bitcast uses.
Update OptimizeGlobalAddressOfMalloc() to optimize malloc calls that have non-bitcast uses. The bitcast use of a malloc call has to be treated specially here because the uses of the bitcast need to be replaced and the bitcast needs to be erased (just like the malloc call) for OptimizeGlobalAddressOfMalloc() to work correctly.
Update PerformHeapAllocSRoA() to optimize malloc calls that have non-bitcast uses. The bitcast use of the malloc is not handled specially here because ReplaceUsesOfMallocWithGlobal replaces through the bitcast use.
Update OptimizeOnceStoredGlobal() to not care about the malloc calls' bitcast use.
Update all globalopt malloc tests to not rely on autoupgraded-MallocInsts, but instead use explicit malloc calls with correct allocation sizes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86077 91177308-0d34-0410-b5e6-96231b3b80d8
cannot alias the GEP. GEP pointer alias rule states this clearly:
A pointer value formed from a getelementptr instruction is associated with the
addresses associated with the first operand of the getelementptr.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84079 91177308-0d34-0410-b5e6-96231b3b80d8
where the induction variable has a non-unit stride, such as {0,+,2}, and
there are expressions such as {1,+,2} inside the loop formed with
or or add nsw operators.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@82151 91177308-0d34-0410-b5e6-96231b3b80d8
input filename so that opt doesn't print the input filename in the
output so that grep lines in the tests don't unintentionally match
strings in the input filename.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81537 91177308-0d34-0410-b5e6-96231b3b80d8
D test/Analysis/Profiling
--- Reverse-merging r80907 into '.':
U lib/Analysis/ProfileInfoLoaderPass.cpp
Attempt to remove failure in the self-hosting build bot.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80966 91177308-0d34-0410-b5e6-96231b3b80d8
on a self-hosted build (although it seems to work on non-self hosted). I'll work
with Andreas to figure this out.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80947 91177308-0d34-0410-b5e6-96231b3b80d8
edge-profiling, this is more useful since the loading of the
optimal-edge-profiling is more complicated.
The edge-profiling is tested in edge-profiling.ll where only the
instrumentation is tested.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80791 91177308-0d34-0410-b5e6-96231b3b80d8
make check in a non-clean directory causes it to fail (for example when running
make check twice), since execution counts will differ.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80362 91177308-0d34-0410-b5e6-96231b3b80d8
This is a simple AliasAnalysis implementation which works by making
ScalarEvolution queries. ScalarEvolution has a more complete understanding
of arithmetic than BasicAA's collection of ad-hoc checks, so it handles
some cases that BasicAA misses, for example p[i] and p[i+1] within the
same iteration of a loop.
This is currently experimental. It may be that the main use for this pass
will be to help find cases where BasicAA can be profitably extended, or
to help in the development of the overall AliasAnalysis infrastructure,
however it's also possible that it could grow up to become a directly
useful pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@80098 91177308-0d34-0410-b5e6-96231b3b80d8
