We were handling some vectors in foldSelectIntoOp, but not if the operand of the bin op was any kind of vector constant. This patch fixes it to treat vector splats the same as scalars.
Differential Revision: https://reviews.llvm.org/D37232
llvm-svn: 311940
This canonicalization was suggested in D33172 as a way to make InstCombine behavior more uniform.
We have this transform for icmp+br, so unless there's some reason that icmp+select should be
treated differently, we should do the same thing here.
The benefit comes from increasing the chances of creating identical instructions. This is shown in
the tests in logical-select.ll (PR32791). InstCombine doesn't fold those directly, but EarlyCSE
can simplify the identical cmps, and then InstCombine can fold the selects together.
The possible regression for the tests in select.ll raises questions about poison/undef:
http://lists.llvm.org/pipermail/llvm-dev/2017-May/113261.html
...but that transform is just as likely to be triggered by this canonicalization as it is to be
missed, so we're just pointing out a commutation deficiency in the pattern matching:
https://reviews.llvm.org/rL228409
Differential Revision: https://reviews.llvm.org/D34242
llvm-svn: 306435
As discussed in:
https://bugs.llvm.org/show_bug.cgi?id=32486
...the canonicalization of vector select to shufflevector does not hold up
when undef elements are present in the condition vector.
Try to make the undef handling clear in the code and the LangRef.
Differential Revision: https://reviews.llvm.org/D31980
llvm-svn: 300092
This is part of trying to clean up our handling of min/max patterns in IR.
By converting these to canonical form, we're more likely to recognize them
because there are various places in InstCombine that don't use
matchSelectPattern or m_SMax and friends.
The backend fixups referenced in the now deleted TODO comment were added with:
https://reviews.llvm.org/rL291392https://reviews.llvm.org/rL289738
If there's any codegen fallout from this change, we should be able to address
it in DAGCombiner or target-specific lowering.
llvm-svn: 295758
The code comments didn't match the code logic, and we didn't actually distinguish the fake unary (not/neg/fneg)
operators from arguments. Adding another level to the weighting scheme provides more structure and can help
simplify the pattern matching in InstCombine and other places.
I fixed regressions that would have shown up from this change in:
rL290067
rL290127
But that doesn't mean there are no pattern-matching logic holes left; some combines may just be missing regression tests.
Should fix:
https://llvm.org/bugs/show_bug.cgi?id=28296
Differential Revision: https://reviews.llvm.org/D27933
llvm-svn: 294049
Also, add the corresponding match to the AssumptionCache's 'Affected Values' list.
Differential Revision: https://reviews.llvm.org/D28485
llvm-svn: 292239
I think the former 'test50' had a typo making it functionally equivalent
to the former 'test49'; changed the predicate to provide more coverage.
llvm-svn: 285706
Try harder to detect obfuscated min/max patterns: the initial pattern was added with D9352 / rL236202.
There was a bug fix for PR27137 at rL264996, but I think we can do better by folding the corresponding
smax pattern and commuted variants.
The codegen tests demonstrate the effect of ValueTracking on the backend via SelectionDAGBuilder. We
can't expose these differences minimally in IR because we don't have smin/smax intrinsics for IR.
Differential Revision: https://reviews.llvm.org/D26091
llvm-svn: 285499
The motivating example for this transform is similar to D20774 where bitcasts interfere
with a single cmp/select sequence, but in this case we have 2 uses of each bitcast to
produce min and max ops:
define void @minmax_bc_store(<4 x float> %a, <4 x float> %b, <4 x float>* %ptr1, <4 x float>* %ptr2) {
%cmp = fcmp olt <4 x float> %a, %b
%bc1 = bitcast <4 x float> %a to <4 x i32>
%bc2 = bitcast <4 x float> %b to <4 x i32>
%sel1 = select <4 x i1> %cmp, <4 x i32> %bc1, <4 x i32> %bc2
%sel2 = select <4 x i1> %cmp, <4 x i32> %bc2, <4 x i32> %bc1
%bc3 = bitcast <4 x float>* %ptr1 to <4 x i32>*
store <4 x i32> %sel1, <4 x i32>* %bc3
%bc4 = bitcast <4 x float>* %ptr2 to <4 x i32>*
store <4 x i32> %sel2, <4 x i32>* %bc4
ret void
}
With this patch, we move the selects up to use the input args which allows getting rid of
all of the bitcasts:
define void @minmax_bc_store(<4 x float> %a, <4 x float> %b, <4 x float>* %ptr1, <4 x float>* %ptr2) {
%cmp = fcmp olt <4 x float> %a, %b
%sel1.v = select <4 x i1> %cmp, <4 x float> %a, <4 x float> %b
%sel2.v = select <4 x i1> %cmp, <4 x float> %b, <4 x float> %a
store <4 x float> %sel1.v, <4 x float>* %ptr1, align 16
store <4 x float> %sel2.v, <4 x float>* %ptr2, align 16
ret void
}
The asm for x86 SSE then improves from:
movaps %xmm0, %xmm2
cmpltps %xmm1, %xmm2
movaps %xmm2, %xmm3
andnps %xmm1, %xmm3
movaps %xmm2, %xmm4
andnps %xmm0, %xmm4
andps %xmm2, %xmm0
orps %xmm3, %xmm0
andps %xmm1, %xmm2
orps %xmm4, %xmm2
movaps %xmm0, (%rdi)
movaps %xmm2, (%rsi)
To:
movaps %xmm0, %xmm2
minps %xmm1, %xmm2
maxps %xmm0, %xmm1
movaps %xmm2, (%rdi)
movaps %xmm1, (%rsi)
The TODO comments show that we're limiting this transform only to vectors and only to bitcasts
because we need to improve other transforms or risk creating worse codegen.
Differential Revision: http://reviews.llvm.org/D21190
llvm-svn: 273011
The original change broke clang side tests. I will be submitting those momentarily. This change includes post commit feedback on the original change from from Pete Cooper.
Original Submission comments:
If a parameter to a function is known non-null, use the existing parameter attributes to record that fact at the call site. This has no optimization benefit by itself - that I know of - but is an enabling change for http://reviews.llvm.org/D9129.
Differential Revision: http://reviews.llvm.org/D9132
llvm-svn: 239849
If a parameter to a function is known non-null, use the existing parameter attributes to record that fact at the call site. This has no optimization benefit by itself - that I know of - but is an enabling change for http://reviews.llvm.org/D9129.
Differential Revision: http://reviews.llvm.org/D9132
llvm-svn: 239795
If we have (select a, b, c), it is sometimes valid to simplify this to a
single select operand. However, doing so is only valid if the
computation doesn't inject poison into the computation.
It might be helpful to consider the following example:
(select (icmp ne %i, INT_MAX), (add nsw %i, 1), INT_MIN)
The select is equivalent to (add %i, 1) but not (add nsw %i, 1).
Self hosting on x86_64 revealed that this occurs very, very rarely so
bailing out is hopefully pretty reasonable.
llvm-svn: 239215
This reverts commit r239141. This commit was an attempt to reintroduce
a previous patch that broke many self-hosting bots with clang timeouts,
but it still has slowdown issues, at least on ARM, increasing the
compilation time (stage 2, clang's) by 5x.
llvm-svn: 239175
I don't have the IR which is causing the build bot breakage but I can
postulate as to why they are timing out:
1. SimplifyWithOpReplaced was stripping flags from the simplified value.
2. visitSelectInstWithICmp was overriding SimplifyWithOpReplaced because
it's simplification wasn't correct.
3. InstCombine would revisit the add instruction and note that it can
rederive the flags.
4. By modifying the value, we chose to revisit instructions which reuse
the value. One of the instructions is the original select, causing
LLVM to never reach fixpoint.
Instead, strip the flags only when we are sure we are going to perform
the simplification.
llvm-svn: 239141
We cleverly handle cases where computation done in one argument of a select
instruction is suitable for the other operand, thus obviating the need
of the select and the comparison. However, the other operand cannot
have flags.
This fixes PR23757.
llvm-svn: 239115
Summary:
After this change `MatchSelectPattern` recognizes the following form
of SMIN:
Y >s C ? ~Y : ~C == ~Y <s ~C ? ~Y : ~C = SMIN(~Y, ~C)
Reviewers: majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D9352
llvm-svn: 236202
Change `llc` and `opt` to run `verifyModule()`. This ensures that we
check the full module before `FunctionPass::doInitialization()` ever
gets called (I was getting crashes in `DwarfDebug` instead of verifier
failures when testing a WIP patch that checks operands of compile
units). In `opt`, also move up debug-info-stripping so that it still
runs before verification.
There was a fair bit of broken code that was sitting in tree.
Interestingly, some were cases of a `select` that referred to itself in
`-instcombine` tests (apparently an intermediate result). I split them
off to `*-noverify.ll` tests with RUN lines like this:
opt < %s -S -disable-verify -instcombine | opt -S | FileCheck %s
This avoids verifying the input file (so we can get the broken code into
`-instcombine), but still verifies the output with a second call to
`opt` (to verify that `-instcombine` will clean it up like it should).
llvm-svn: 233432
Essentially the same as the GEP change in r230786.
A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)
import fileinput
import sys
import re
pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")
for line in sys.stdin:
sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))
Reviewers: rafael, dexonsmith, grosser
Differential Revision: http://reviews.llvm.org/D7649
llvm-svn: 230794
Normalize
select(C0, select(C1, a, b), b) -> select((C0 & C1), a, b)
select(C0, a, select(C1, a, b)) -> select((C0 | C1), a, b)
This normal form may enable further combines on the And/Or and shortens
paths for the values. Many targets prefer the other but can go back
easily in CodeGen.
Differential Revision: http://reviews.llvm.org/D7399
llvm-svn: 228409
This patches fixes a miscompile where we were assuming that loading from null is undefined and thus we could assume it doesn't happen. This transform is perfectly legal in address space 0, but is not neccessarily legal in other address spaces.
We really should introduce a hook to control this property on a per target per address space basis. We may be loosing valuable optimizations in some address spaces by being too conservative.
Original patch by Thomas P Raoux (submitted to llvm-commits), tests and formatting fixes by me.
llvm-svn: 224961
This restores our ability to optimize:
(X & C) ? X & ~C : X into X & ~C
(X & C) ? X : X & ~C into X
(X & C) ? X | C : X into X
(X & C) ? X : X | C into X | C
llvm-svn: 222868
This reverts commit r210006, it miscompiled libapr which is used in who
knows how many projects.
A test has been added to ensure that we don't regress again.
I'll work on a rewrite of what the optimization was trying to do later.
llvm-svn: 222856
stored rather than the pointer type.
This change is analogous to r220138 which changed the canonicalization
for loads. The rationale is the same: memory does not have a type,
operations (and thus the values they produce) have a type. We should
match that type as closely as possible rather than reading some form of
semantics into the pointer type.
With this change, loads and stores should no longer be made with
nonsensical types for the values that tehy load and store. This is
particularly important when trying to match specific loaded and stored
types in the process of doing other instcombines, which is what led me
down this twisty maze of miscanonicalization.
I've put quite some effort into looking through IR to find places where
LLVM's optimizer was being unreasonably conservative in the face of
mismatched load and store types, however it is possible (let's say,
likely!) I have missed some. If you see regressions here, or from
r220138, the likely cause is some part of LLVM failing to cope with load
and store types differing. Test cases appreciated, it is important that
we root all of these out of LLVM.
llvm-svn: 222748
