Currently, the ASan executables built with -O0 are unnecessarily slow.
The main reason is that ASan instrumentation pass inserts redundant
checks around promotable allocas. These allocas do not get instrumented
under -O1 because they get converted to virtual registered by mem2reg.
With this patch, ASan instrumentation pass will only instrument non
promotable allocas, giving us a speedup of 39% on a collection of
benchmarks with -O0. (There is no measurable speedup at -O1.)
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InstCombine has long had logic to convert aligned Altivec load/store intrinsics
into regular loads and stores. This mirrors that functionality for QPX vector
load/store intrinsics.
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IRCE can now split the iteration space for loops like:
for (i = n; i >= 0; i--)
a[i + k] = 42; // bounds check on access
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Use the IRBuilder helpers for gc.statepoint and gc.result, instead of
coding the construction by hand. Note that the gc.statepoint IRBuilder
handles only CallInst, not InvokeInst; retain that part of hand-coding.
Differential Revision: http://reviews.llvm.org/D7518
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This symbol exists only to pull in the required pieces of the runtime,
so nothing ever needs to refer to it. Making it hidden avoids the
potential for issues with duplicate symbols when linking profiled
libraries together.
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This is a follow-on to r227491 which tightens the check for propagating FP
values. If a non-constant value happens to be a zero, we would hit the same
bug as before.
Bug noted and patch suggested by Eli Friedman.
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Summary: SROA generates code that isn't quite as easy to optimize and contains unusual-sized shuffles, but that code is generally correct. As discussed in D7487 the right place to clean things up is InstCombine, which will pick up the type-punning pattern and transform it into a more obvious bitcast+extractelement, while leaving the other patterns SROA encounters as-is.
Test Plan: make check
Reviewers: jvoung, chandlerc
Subscribers: llvm-commits
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This change aligns globals to the next highest power of 2 bytes, up to a
maximum of 128. This makes it more likely that we will be able to compress
bit sets with a greater alignment. In many more cases, we can now take
advantage of a new optimization also introduced in this patch that removes
bit set checks if the bit set is all ones.
The 128 byte maximum was found to provide the best tradeoff between instruction
overhead and data overhead in a recent build of Chromium. It allows us to
remove ~2.4MB of instructions at the cost of ~250KB of data.
Differential Revision: http://reviews.llvm.org/D7873
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Summary:
This change fixes the FIXME that you recently added when you committed
(a modified version of) my patch. When `InstCombine` combines a load and
store of an pointer to those of an equivalently-sized integer, it currently
drops any `!nonnull` metadata that might be present. This change replaces
`!nonnull` metadata with `!range !{ 1, -1 }` metadata instead.
Reviewers: chandlerc
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D7621
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The builder is based on a layout algorithm that tries to keep members of
small bit sets together. The new layout compresses Chromium's bit sets to
around 15% of their original size.
Differential Revision: http://reviews.llvm.org/D7796
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When AddressSanitizer only a single dynamic alloca and no static allocas, due to an early exit from FunctionStackPoisoner::poisonStack we forget to unpoison the dynamic alloca. This patch fixes that.
Reviewed at http://reviews.llvm.org/D7810
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This case is interesting because ScalarEvolutionExpander lowers min(a,
b) as ~max(~a,~b). I think the profitability heuristics can be made
more clever/aggressive, but this is a start.
Differential Revision: http://reviews.llvm.org/D7821
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This patch adds the isProfitableToHoist API. For AArch64, we want to prevent a
fmul from being hoisted in cases where it is more profitable to form a
fmsub/fmadd.
Phabricator Review: http://reviews.llvm.org/D7299
Patch by Lawrence Hu <lawrence@codeaurora.org>
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This refactors the core functionality of LICM: HoistRegion, SinkRegion and
PromoteAliasSet (renamed to promoteLoopAccessesToScalars) as utility functions
in LoopUtils. This will enable other transformations to make use of them
directly.
Patch by Ashutosh Nema.
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work with a non-canonical induction variable.
This is currently a non-functional change because we only ever call
computeSafeIterationSpace on a canonical induction variable; but the
generalization will be useful in a later commit.
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calculations. Semantically non-functional change.
This gets rid of some of the SCEV -> Value -> SCEV round tripping and
the Construct(SMin|SMax)Of and MaybeSimplify helper routines.
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Previously, this pass ran over every function in the Module if added to the pass order. With this change, it runs only over those with a GC attribute where the GC explicitly opts in. A GC can also choose which of entry safepoint polls, backedge safepoint polls, and call safepoints it wants. I hope to get these exposed as checks on the GCStrategy at some point, but for now, the checks are manual string comparisons.
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These are internal options. I need to go through, evaluate which are worth keeping and which not. Many of them should probably be renamed as well. Until I have time to do that, we can at least stop poluting the standard opt -help output.
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This should be the last cleanup on non-llvm preferred data structures. I left one use of std::set in an assertion; DenseSet didn't seem to have a tombstone for CallSite defined. That might be worth fixing, but wasn't worth it for a debug only use.
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I'd done the work of extracting the typedef in a previous commit, but didn't actually change it. Hopefully this will make any subtle changes easier to isolate.
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Use llvm_unreachable where appropriate, use SmallVector where easy to do so, introduce typedefs for planned type migrations.
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The notion of a range of inserted safepoint related code is no longer really applicable. This survived over from an earlier implementation. Just saving the inserted gc.statepoint and working from that is far clearer given the current code structure. Particularly when invokable statepoints get involved.
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Yet another chapter in the endless story. While this looks like we leave
the loop in a non-canonical state this replicates the logic in
LoopSimplify so it doesn't diverge from the canonical form in any way.
PR21968
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This patch introduces a new mechanism that allows IR modules to co-operatively
build pointer sets corresponding to addresses within a given set of
globals. One particular use case for this is to allow a C++ program to
efficiently verify (at each call site) that a vtable pointer is in the set
of valid vtable pointers for the class or its derived classes. One way of
doing this is for a toolchain component to build, for each class, a bit set
that maps to the memory region allocated for the vtables, such that each 1
bit in the bit set maps to a valid vtable for that class, and lay out the
vtables next to each other, to minimize the total size of the bit sets.
The patch introduces a metadata format for representing pointer sets, an
'@llvm.bitset.test' intrinsic and an LTO lowering pass that lays out the globals
and builds the bitsets, and documents the new feature.
Differential Revision: http://reviews.llvm.org/D7288
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When doing style cleanup, I noticed a minor bug in this code. If we have a pointer that we think is unused after a statepoint and thus doesn't need relocation, we store a null pointer into the alloca we're about to promote. This helps turn a mistake in liveness analysis into an easily debuggable crash. It turned out this code had never been updated to handle invoke statepoints.
There's no test for this. Without a bug in liveness, it appears impossible to make this trigger in a way which is visible in the resulting IR. We might store the null, but when promoting the alloca, there will be no uses and thus nothing to test against. Suggestions on how to test are very welcome.
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Starting to update variable naming and types to match LLVM style. This will be an incremental process to minimize the chance of breakage as I work. Step one, rename member variables to LLVM CamelCase and use llvm's ADT. Much more to come.
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Before calling Function::getGC to test for enablement, we need to make sure there's actually a GC at all via Function::hasGC. Otherwise, we'd crash on functions without a GC. Thankfully, this only mattered if you manually scheduled the pass, but still, oops. :(
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This change addresses a deficiency pointed out in PR22629. To copy from the bug
report:
[from the bug report]
Consider this code:
int f(int x) {
int a[] = {12};
return a[x];
}
GCC knows to optimize this to
movl $12, %eax
ret
The code generated by recent Clang at -O3 is:
movslq %edi, %rax
movl .L_ZZ1fiE1a(,%rax,4), %eax
retq
.L_ZZ1fiE1a:
.long 12 # 0xc
[end from the bug report]
This definitely seems worth fixing. I've also seen this kind of code before (as
the base case of generic vector wrapper templates with one element).
The general idea is to look at the GEP feeding a load or a store, which has
some variable as its first non-zero index, and determine if that index must be
zero (or else an out-of-bounds access would occur). We can do this for allocas
and globals with constant initializers where we know the maximum size of the
underlying object. When we find such a GEP, we create a new one for the memory
access with that first variable index replaced with a constant zero.
Even if we can't eliminate the memory access (and sometimes we can't), it is
still useful because it removes unnecessary indexing calculations.
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When back merging the changes in 229945 I noticed that I forgot to mark the test cases with the appropriate GC. We want the rewriting to be off by default (even when manually added to the pass order), not on-by default. To keep the current test working, mark them as using the statepoint-example GC and whitelist that GC.
Longer term, we need a better selection mechanism here for both actual usage and testing. As I migrate more tests to the in tree version of this pass, I will probably need to update the enable/disable logic as well.
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This patch consists of a single pass whose only purpose is to visit previous inserted gc.statepoints which do not have gc.relocates inserted yet, and insert them. This can be used either immediately after IR generation to perform 'early safepoint insertion' or late in the pass order to perform 'late insertion'.
This patch is setting the stage for work to continue in tree. In particular, there are known naming and style violations in the current patch. I'll try to get those resolved over the next week or so. As I touch each area to make style changes, I need to make sure we have adequate testing in place. As part of the cleanup, I will be cleaning up a collection of test cases we have out of tree and submitting them upstream. The tests included in this change are very basic and mostly to provide examples of usage.
The pass has several main subproblems it needs to address:
- First, it has identify any live pointers. In the current code, the use of address spaces to distinguish pointers to GC managed objects is hard coded, but this will become parametrizable in the near future. Note that the current change doesn't actually contain a useful liveness analysis. It was seperated into a followup change as the code wasn't ready to be shared. Instead, the current implementation just considers any dominating def of appropriate pointer type to be live.
- Second, it has to identify base pointers for each live pointer. This is a fairly straight forward data flow algorithm.
- Third, the information in the previous steps is used to actually introduce rewrites. Rather than trying to do this by hand, we simply re-purpose the code behind Mem2Reg to do this for us.
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