| Commit message (Collapse) | Author | Age | Files | Lines |
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This turned out to be surprisingly effective. I was originally doing this just for completeness sake, but it seems like there are a lot of cases where SCEV's exit count reasoning is stronger than it's isKnownPredicate reasoning.
Once this is in, I'm thinking about trying to build on the same infrastructure to eliminate provably untaken checks. There may be something generally interesting here.
Differential Revision: https://reviews.llvm.org/D63618
llvm-svn: 364135
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The limit for the pointer case is incorrect.
llvm-svn: 364128
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This reverts r364084 (git commit 5698921be2d567f6abf925479ac9f5a376d6d74f)
It caused crashes while compiling a file in Chrome. Reduction
forthcoming.
llvm-svn: 364111
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This patch introduces a new heuristic for guiding operand reordering. The new "look-ahead" heuristic can look beyond the immediate predecessors. This helps break ties when the immediate predecessors have identical opcodes (see lit test for an example).
Committed on behalf of @vporpo (Vasileios Porpodas)
Differential Revision: https://reviews.llvm.org/D60897
llvm-svn: 364084
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llvm-svn: 364083
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llvm-svn: 364082
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Summary:
```
%a = sub i32 31, %x
%r = shl i32 1, %a
=>
%d = shl i32 1, 31
%r = lshr i32 %d, %x
Done: 1
Optimization is correct!
```
https://rise4fun.com/Alive/btZm
Reviewers: spatel, lebedev.ri, nikic
Reviewed By: lebedev.ri
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63652
llvm-svn: 364073
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llvm-svn: 364069
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Summary: Signedness does not change number of trailing zeros.
Reviewers: spatel, lebedev.ri, nikic
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D63546
llvm-svn: 364064
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Patch based on suggestion by James Molloy (@jmolloy) in:
https://bugs.llvm.org/show_bug.cgi?id=42346
llvm-svn: 364062
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llvm-svn: 364060
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Summary:
The motivation for this was to propagate fast-math flags like nnan and
ninf on vector floating point operations to the corresponding scalar
operations to take advantage of follow-on optimizations. But I think
the same argument applies to all of our IR flags: if they apply to the
vector operation then they also apply to all the individual scalar
operations, and they might enable follow-on optimizations.
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63593
llvm-svn: 364051
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Summary:
LLVM Allows Targets to provide information that guides optimisations
made to LLVM IR. This is done with callbacks on a TargetTransformInfo object.
This patch adds a TargetTransformInfo class for RISC-V. This will allow us to
implement RISC-V specific callbacks as they become necessary.
This commit also adds the getIntImmCost callbacks, and tests them with a simple
constant hoisting test. Our immediate costs are on the conservative side, for
the moment, but we prevent hoisting in most circumstances anyway.
Previous review was on D63007
Reviewers: asb, luismarques
Reviewed By: asb
Subscribers: ributzka, MaskRay, llvm-commits, Jim, benna, psnobl, jocewei, PkmX, rkruppe, the_o, brucehoult, MartinMosbeck, rogfer01, edward-jones, zzheng, jrtc27, shiva0217, kito-cheng, niosHD, sabuasal, apazos, simoncook, johnrusso, rbar, hiraditya, mgorny
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63433
llvm-svn: 364046
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Also, add a FIXME for the unsafe transform on a unary FNeg. A unary FNeg can only be transformed to a FMul by -1.0 when the nnan flag is present. The unary FNeg project is a WIP, so the unsafe transformation is acceptable until that work is complete.
The bogus assert with introduced in D63445.
llvm-svn: 363998
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As discussed in PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314
Improving the canonicalization for these patterns:
rL363956
...means we should adjust/enhance the related simplification.
https://rise4fun.com/Alive/w1cp
Name: isPow2 or zero
%x = and i32 %xx, 2048
%a = add i32 %x, -1
%r = and i32 %a, %x
=>
%r = i32 0
llvm-svn: 363997
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Summary:
The getClobberingMemoryAccess API checks for clobbering accesses in a loop by walking the backedge. This may check if a memory access is being
clobbered by the loop in a previous iteration, depending how smart AA got over the course of the updates in MemorySSA (it does not occur when built from scratch).
If no clobbering access is found inside the loop, it will optimize to an access outside the loop. This however does not mean that access is safe to sink.
Given:
```
for i
load a[i]
store a[i]
```
The access corresponding to the load can be optimized to outside the loop, and the load can be hoisted. But it is incorrect to sink it.
In order to sink the load, we'd need to check no Def clobbers the Use in the same iteration. With this patch we currently restrict sinking to either
Defs not existing in the loop, or Defs preceding the load in the same block. An easy extension is to ensure the load (Use) post-dominates all Defs.
Caught by PR42294.
This issue also shed light on the converse problem: hoisting stores in this same scenario would be illegal. With this patch we restrict
hoisting of stores to the case when their corresponding Defs are dominating all Uses in the loop.
Reviewers: george.burgess.iv
Subscribers: jlebar, Prazek, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63582
llvm-svn: 363982
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I added a canonicalization to create this general pattern in:
rL363956
But as noted in PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314#c11
...we have a (potentially expensive) simplification for the version
of the code that we just canonicalized away from, so we should
add/adjust that code to match.
llvm-svn: 363981
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llvm-svn: 363978
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llvm-svn: 363967
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The form that compares against 0 is better because:
1. It removes a use of the input value.
2. It's the more standard form for this pattern: https://graphics.stanford.edu/~seander/bithacks.html#DetermineIfPowerOf2
3. It results in equal or better codegen (tested with x86, AArch64, ARM, PowerPC, MIPS).
This is a root cause for PR42314, but probably doesn't completely answer the codegen request:
https://bugs.llvm.org/show_bug.cgi?id=42314
Alive proof:
https://rise4fun.com/Alive/9kG
Name: is power-of-2
%neg = sub i32 0, %x
%a = and i32 %neg, %x
%r = icmp eq i32 %a, %x
=>
%dec = add i32 %x, -1
%a2 = and i32 %dec, %x
%r = icmp eq i32 %a2, 0
Name: is not power-of-2
%neg = sub i32 0, %x
%a = and i32 %neg, %x
%r = icmp ne i32 %a, %x
=>
%dec = add i32 %x, -1
%a2 = and i32 %dec, %x
%r = icmp ne i32 %a2, 0
llvm-svn: 363956
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Thought of this case while working on something else. We appear to get it right in all of the variations I tried, but that's by accident. So, add a test which would catch the potential bug.
llvm-svn: 363953
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Summary: Signedness does not change number of trailing zeros.
Reviewers: spatel, lebedev.ri, nikic
Reviewed By: spatel
Subscribers: llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63534
llvm-svn: 363951
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llvm-svn: 363945
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llvm-svn: 363938
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llvm-svn: 363937
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llvm-svn: 363925
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Teach IndVarSimply's LinearFunctionTestReplace transform to handle multiple exit loops. LFTR does two key things 1) it rewrites (all) exit tests in terms of a common IV potentially eliminating one in the process and 2) it moves any offset/indexing/f(i) style logic out of the loop.
This turns out to actually be pretty easy to implement. SCEV already has all the information we need to know what the backedge taken count is for each individual exit. (We use that when computing the BE taken count for the loop as a whole.) We basically just need to iterate through the exiting blocks and apply the existing logic with the exit specific BE taken count. (The previously landed NFC makes this super obvious.)
I chose to go ahead and apply this to all loop exits instead of only latch exits as originally proposed. After reviewing other passes, the only case I could find where LFTR form was harmful was LoopPredication. I've fixed the latch case, and guards aren't LFTRed anyways. We'll have some more work to do on the way towards widenable_conditions, but that's easily deferred.
I do want to note that I added one bit after the review. When running tests, I saw a new failure (no idea why didn't see previously) which pointed out LFTR can rewrite a constant condition back to a loop varying one. This was theoretically possible with a single exit, but the zero case covered it in practice. With multiple exits, we saw this happening in practice for the eliminate-comparison.ll test case because we'd compute a ExitCount for one of the exits which was guaranteed to never actually be reached. Since LFTR ran after simplifyAndExtend, we'd immediately turn around and undo the simplication work we'd just done. The solution seemed obvious, so I didn't bother with another round of review.
Differential Revision: https://reviews.llvm.org/D62625
llvm-svn: 363883
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llvm-svn: 363882
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Summary:
To generate simplified IR, make sure fold
```
(X & signbit) ==/!= 0) -> X s>=/s< 0;
```
is scheduled before fold
```
((X << Y) & C) == 0 -> (X & (C >> Y)) == 0.
```
https://rise4fun.com/Alive/fbdh
Reviewers: lebedev.ri, efriedma, spatel, craig.topper
Reviewed By: lebedev.ri
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63026
llvm-svn: 363845
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D63489 proposes to change this behavior, but there's no
direct -instsimplify test to verify that the transform exists.
llvm-svn: 363842
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greater-than-sign is not a BRE special character.
POSIX.1-2017 XBD Section 9.3.2 indicates that the interpretation of `\>`
is undefined. This patch replaces the pattern.
llvm-svn: 363828
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Differential Revision: https://reviews.llvm.org/D63445
llvm-svn: 363813
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llvm-svn: 363796
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llvm-svn: 363795
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loop even after completion
Summary:
Bug: https://bugs.llvm.org/show_bug.cgi?id=39024
The bug reports that a vectorized loop is stepped through 4 times and each step through the loop seemed to show a different path. I found two problems here:
A) An incorrect line number on a preheader block (for.body.preheader) instruction causes a step into the loop before it begins.
B) Instructions in the middle block have different line numbers which give the impression of another iteration.
In this patch I give all of the middle block instructions the line number of the scalar loop latch terminator branch. This seems to provide the smoothest debugging experience because the vectorized loops will always end on this line before dropping into the scalar loop. To solve problem A I have altered llvm::SplitBlockPredecessors to accommodate loop header blocks.
I have set up a separate review D61933 for a fix which is required for this patch.
Reviewers: samsonov, vsk, aprantl, probinson, anemet, hfinkel, jmorse
Reviewed By: hfinkel, jmorse
Subscribers: jmorse, javed.absar, eraman, kcc, bjope, jmellorcrummey, hfinkel, gbedwell, hiraditya, zzheng, llvm-commits
Tags: #llvm, #debug-info
Differential Revision: https://reviews.llvm.org/D60831
> llvm-svn: 363046
llvm-svn: 363786
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Summary:
The test case does an (out of bounds) load from a global constant with
type <3 x float>. InstSimplify tried to turn this into an integer load
of the whole alloc size of the vector, which is 128 bits due to
alignment padding, and then bitcast this to <3 x vector> which failed
an assertion due to the type size mismatch.
The fix is to do an integer load of the normal size of the vector, with
no alignment padding.
Reviewers: tpr, arsenm, majnemer, dstuttard
Reviewed By: arsenm
Subscribers: hfinkel, wdng, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63375
llvm-svn: 363784
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[SROA] Enhance SROA to handle `addrspacecast`ed allocas
- Fix typo in original change
- Add additional handling to ensure all return pointers are properly
casted.
Summary:
- After `addrspacecast` is allowed to be eliminated in SROA, the
adjusting of storage pointer (from `alloca) needs to handle the
potential different address spaces between the storage pointer (from
alloca) and the pointer being used.
Reviewers: arsenm
Subscribers: wdng, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63501
llvm-svn: 363743
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D39417
llvm-svn: 363741
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llvm-svn: 363730
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This reverts r363711 (git commit 76a149ef8187310a60fd20481fdb2a10c8ba968e)
This causes stage2 build failures, e.g.:
http://lab.llvm.org:8011/builders/clang-x64-windows-msvc/builds/132/steps/stage%202%20build/logs/stdio
http://lab.llvm.org:8011/builders/ppc64le-lld-multistage-test/builds/87/steps/build-stage2-unified-tree/logs/stdio
llvm-svn: 363718
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Summary:
- After `addrspacecast` is allowed to be eliminated in SROA, the
adjusting of storage pointer (from `alloca) needs to handle the
potential different address spaces between the storage pointer (from
alloca) and the pointer being used.
Reviewers: arsenm
Subscribers: wdng, hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63501
llvm-svn: 363711
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w/taken backedges
This patch really contains two pieces:
Teach SCEV how to fold a phi in the header of a loop to the value on the backedge when a) the backedge is known to execute at least once, and b) the value is safe to use globally within the scope dominated by the original phi.
Teach IndVarSimplify's rewriteLoopExitValues to allow loop invariant expressions which already exist (and thus don't need new computation inserted) even in loops where we can't optimize away other uses.
Differential Revision: https://reviews.llvm.org/D63224
llvm-svn: 363619
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Recommit r363289 with a bug fix for crash identified in pr42279. Issue was that a loop exit test does not have to be an icmp, leading to a null dereference crash when new logic was exercised for that case. Test case previously committed in r363601.
Original commit comment follows:
This contains fixes for two cases where we might invalidate inbounds and leave it stale in the IR (a miscompile). Case 1 is when switching to an IV with no dynamically live uses, and case 2 is when doing pre-to-post conversion on the same pointer type IV.
The basic scheme used is to prove that using the given IV (pre or post increment forms) would have to already trigger UB on the path to the test we're modifying. As such, our potential UB triggering use does not change the semantics of the original program.
As was pointed out in the review thread by Nikita, this is defending against a separate issue from the hasConcreteDef case. This is about poison, that's about undef. Unfortunately, the two are different, see Nikita's comment for a fuller explanation, he explains it well.
(Note: I'm going to address Nikita's last style comment in a separate commit just to minimize chance of subtle bugs being introduced due to typos.)
Differential Revision: https://reviews.llvm.org/D62939
llvm-svn: 363613
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llvm-svn: 363601
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Summary:
Update compare normalization in SimpleValue hashing to break ties (when
the same value is being compared to itself) by switching to the swapped
predicate if it has a lower numerical value. This brings the hashing in
line with isEqual, which already recognizes the self-compares with
swapped predicates as equal.
Fixes PR 42280.
Reviewers: spatel, efriedma, nikic, fhahn, uabelho
Reviewed By: nikic
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D63349
llvm-svn: 363598
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llvm-svn: 363587
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When considering a loop containing nontemporal stores or loads for
vectorization, suppress the vectorization if the corresponding
vectorized store or load with the aligment of the original scaler
memory op is not supported with the nontemporal hint on the target.
This adds two new functions:
bool isLegalNTStore(Type *DataType, unsigned Alignment) const;
bool isLegalNTLoad(Type *DataType, unsigned Alignment) const;
to TTI, leaving the target independent default implementation as
returning true, but with overriding implementations for X86 that
check the legality based on available Subtarget features.
This fixes https://llvm.org/PR40759
Differential Revision: https://reviews.llvm.org/D61764
llvm-svn: 363581
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If an addrspacecast needed to be inserted again, this was creating a
clone of the original cast for each user. Just use the original, which
also saves losing the value name.
llvm-svn: 363562
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Even if the target doesn't have flat instructions, addrspace(0) is
still flat. It just happens to not work.
llvm-svn: 363561
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Should also be marked writeonly, but I think that would require
splitting the version with done set to a separate intrinsic
Test change is only from renumbering the attribute group numbers,
which for some reason the generated check lines consider.
llvm-svn: 363560
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