Summary:
If we have the code like this:
```
float a, b;
a = std::max(a ,b);
```
it is converted into something like this:
```
%call = call dereferenceable(4) float* @_ZSt3maxIfERKT_S2_S2_(float* nonnull dereferenceable(4) %a.addr, float* nonnull dereferenceable(4) %b.addr)
%1 = bitcast float* %call to i32*
%2 = load i32, i32* %1, align 4
%3 = bitcast float* %a.addr to i32*
store i32 %2, i32* %3, align 4
```
After inlinning this code is converted to the next:
```
%1 = load float, float* %a.addr
%2 = load float, float* %b.addr
%cmp.i = fcmp fast olt float %1, %2
%__b.__a.i = select i1 %cmp.i, float* %a.addr, float* %b.addr
%3 = bitcast float* %__b.__a.i to i32*
%4 = load i32, i32* %3, align 4
%5 = bitcast float* %arrayidx to i32*
store i32 %4, i32* %5, align 4
```
This pattern is not recognized as minmax pattern.
Patch solves this problem by converting sequence
```
store (bitcast, (load bitcast (select ((cmp V1, V2), &V1, &V2))))
```
to a sequence
```
store (,load (select((cmp V1, V2), &V1, &V2)))
```
After this the code is recognized as minmax pattern.
Reviewers: RKSimon, spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D40304
llvm-svn: 320157
Follow-up of r316824. This patch supports the vector type for both current and
previous index when factoring out the current one into the previous one.
Differential Revision: https://reviews.llvm.org/D39556
llvm-svn: 319683
As the first test shows, we could transform an llvm intrinsic which never sets errno
into a libcall which could set errno (even though it's marked readnone?), so that's
not ideal.
It's possible that we can also transform a libcall which could set errno to an
intrinsic given the fast-math-flags constraint, but that's deferred to determine
exactly which set of FMF are needed.
Differential Revision: https://reviews.llvm.org/D40150
llvm-svn: 318628
// trunc (binop X, C) --> binop (trunc X, C')
// trunc (binop (ext X), Y) --> binop X, (trunc Y)
I'm grouping sub with the other binops because that makes the code simpler
and the transforms are valid:
https://rise4fun.com/Alive/UeF
...so even though we don't expect a sub with constant Op1 or any of the
other opcodes with constant Op0 due to canonicalization rules, we might as
well handle those situations if non-canonical code somehow reaches this
point (it should just make instcombine more efficient in reaching its
end goal).
This should solve the problem that later manifests in the vectorizers in
PR35295:
https://bugs.llvm.org/show_bug.cgi?id=35295
llvm-svn: 318404
Note that one-use and shouldChangeType() are checked ahead of the switch.
Without the narrowing folds, we can produce inferior vector code as shown in PR35299:
https://bugs.llvm.org/show_bug.cgi?id=35299
llvm-svn: 318323
InstCombine salvages debug info for every instruction it erases from its
worklist, but it wasn't doing it during its initial DCE when populating
its worklist. This fixes that.
This should help improve availability of 'this' in optimized debug info
when casts are necessary.
llvm-svn: 318320
Summary:
This patch optimizes a binop sandwiched between 2 selects with the same condition. Since we know its only used by the select we can propagate the appropriate input value from the earlier select.
As I'm writing this I realize I may need to avoid doing this for division in case the select was protecting a divide by zero?
Reviewers: spatel, majnemer
Reviewed By: majnemer
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D39999
llvm-svn: 318267
Summary:
Instcombine (and probably other passes) sometimes want to change the
type of an alloca. To do this, they generally create a new alloca with
the desired type, create a bitcast to make the new pointer type match
the old pointer type, replace all uses with the cast, and then simplify
the casts. We already knew how to salvage dbg.value instructions when
removing casts, but we can extend it to cover dbg.addr and dbg.declare.
Fixes a debug info quality issue uncovered in Chromium in
http://crbug.com/784609
Reviewers: aprantl, vsk
Subscribers: hiraditya, llvm-commits
Differential Revision: https://reviews.llvm.org/D40042
llvm-svn: 318203
Summary:
This patch adds an early out to visitICmpInst if we are looking at a compare as part of an integer absolute value idiom. Similar is already done for min/max.
In the particular case I observed in a benchmark we had an absolute value of a load from an indexed global. We simplified the compare using foldCmpLoadFromIndexedGlobal into a magic bit vector, a shift, and an and. But the load result was still used for the select and the negate part of the absolute valute idiom. So we overcomplicated the code and lost the ability to recognize it as an absolute value.
I've chosen a simpler case for the test here.
Reviewers: spatel, davide, majnemer
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D39766
llvm-svn: 317994
This patch implements Chandler's idea [0] for supporting languages that
require support for infinite loops with side effects, such as Rust, providing
part of a solution to bug 965 [1].
Specifically, it adds an `llvm.sideeffect()` intrinsic, which has no actual
effect, but which appears to optimization passes to have obscure side effects,
such that they don't optimize away loops containing it. It also teaches
several optimization passes to ignore this intrinsic, so that it doesn't
significantly impact optimization in most cases.
As discussed on llvm-dev [2], this patch is the first of two major parts.
The second part, to change LLVM's semantics to have defined behavior
on infinite loops by default, with a function attribute for opting into
potential-undefined-behavior, will be implemented and posted for review in
a separate patch.
[0] http://lists.llvm.org/pipermail/llvm-dev/2015-July/088103.html
[1] https://bugs.llvm.org/show_bug.cgi?id=965
[2] http://lists.llvm.org/pipermail/llvm-dev/2017-October/118632.html
Differential Revision: https://reviews.llvm.org/D38336
llvm-svn: 317729
The hexagon test should be fixed now.
Original commit message:
This pulls shifts through a select+binop with a constant where the select conditionally executes the binop. We already do this for just the binop, but not with the select.
This can allow us to get the select closer to other selects to enable removing one.
Differential Revision: https://reviews.llvm.org/D39222
llvm-svn: 317600
This broke the CodeGen/Hexagon/loop-idiom/pmpy-mod.ll test on a bunch of buildbots.
> This pulls shifts through a select+binop with a constant where the select conditionally executes the binop. We already do this for just the binop, but not with the select.
>
> This can allow us to get the select closer to other selects to enable removing one.
>
> Differential Revision: https://reviews.llvm.org/D39222
>
> git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@317510 91177308-0d34-0410-b5e6-96231b3b80d8
llvm-svn: 317518
This pulls shifts through a select+binop with a constant where the select conditionally executes the binop. We already do this for just the binop, but not with the select.
This can allow us to get the select closer to other selects to enable removing one.
Differential Revision: https://reviews.llvm.org/D39222
llvm-svn: 317510
If a select instruction tests the returned flag of a cmpxchg instruction and
selects between the returned value of the cmpxchg instruction and its compare
operand, the result of the select will always be equal to its false value.
Differential Revision: https://reviews.llvm.org/D39383
llvm-svn: 316994
LLVM crashes when factoring out an out-of-bound index into preceding dimension
and the preceding dimension uses vector index. Simply bail out now when this
case happens.
Differential Revision: https://reviews.llvm.org/D38677
llvm-svn: 316824
Summary:
ValueTracking was recognizing not all variations of clamp. Swapping of
true value and false value of select was added to fix this problem. The
first patch was reverted because it caused miscompile in NVPTX target.
Added corresponding test cases.
Reviewers: spatel, majnemer, efriedma, reames
Subscribers: llvm-commits, jholewinski
Differential Revision: https://reviews.llvm.org/D39240
llvm-svn: 316795
Summary:
Kill the thread if operand 0 == false.
llvm.amdgcn.wqm.vote can be applied to the operand.
Also allow kill in all shader stages.
Reviewers: arsenm, nhaehnle
Subscribers: kzhuravl, wdng, yaxunl, dstuttard, tpr, t-tye, llvm-commits
Differential Revision: https://reviews.llvm.org/D38544
llvm-svn: 316427
Summary:
It's unclear if this is the only thing we can do but at least this is consistent with the check
of address space agreement in `isBitCastable`.
The code is used at least in both instcombine and jumpthreading though
I could only find a way to trigger the invalid cast in instcombine.
Reviewers: loladiro, sanjoy, majnemer
Reviewed By: sanjoy
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D34335
llvm-svn: 316302
Summary:
When we have the following case:
%cond = cmp iN %x, CmpConst
%tr = trunc iN %x to iK
%narrowsel = select i1 %cond, iK %t, iK C
We could possibly match only min/max pattern after looking through cast.
So it is more profitable if widened C constant will be equal CmpConst.
That is why just set widened C constant equal to CmpConst, because there
is a further check in this function that trunc CmpConst == C.
Also description for lookTroughCast function was added.
Reviewers: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38536
Patch by: Artur Gainullin <artur.gainullin@intel.com>
llvm-svn: 316070
Summary:
ValueTracking was recognizing not all variations of clamp. Swapping of
true value and false value of select was added to fix this problem. This
change breaks the canonical form of cmp inside the matchMinMax function,
that is why additional checks for compare predicates is needed. Added
corresponding test cases.
Reviewers: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38531
Patch by: Artur Gainullin <artur.gainullin@intel.com>
llvm-svn: 315992
Summary:
The following transformation for cmp instruction:
icmp smin(x, PositiveValue), 0 -> icmp x, 0
should only be done after checking for min/max to prevent infinite
looping caused by a reverse canonicalization. That is why this
transformation was moved to place after the mentioned check.
Reviewers: spatel, efriedma
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D38934
Patch by: Artur Gainullin <artur.gainullin@intel.com>
llvm-svn: 315895
Alexey Bataev