Reduced from oss-fuzz #5032 test case

llvm-svn: 322078

Reduced from oss-fuzz #4871 test case

llvm-svn: 321748

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

Differential Revision: https://reviews.llvm.org/D36743

llvm-svn: 310949

Narrow ops are better for bit-tracking, and in the case of vectors,
may enable better codegen.

As the trunc test shows, this can allow follow-on simplifications.

There's a block of code in visitTrunc that deals with shifted ops
with FIXME comments. It may be possible to remove some of that now,
but I want to make sure there are no problems with this step first.

http://rise4fun.com/Alive/Y3a

Name: hoist_ashr_ahead_of_sext_1
  %s = sext i8 %x to i32
  %r = ashr i32 %s, 3  ; shift value is < than source bit width
  =>
  %a = ashr i8 %x, 3
  %r = sext i8 %a to i32
  
Name: hoist_ashr_ahead_of_sext_2
  %s = sext i8 %x to i32
  %r = ashr i32 %s, 8  ; shift value is >= than source bit width
  =>
  %a = ashr i8 %x, 7   ; so clamp this shift value
  %r = sext i8 %a to i32
  
Name: junc_the_trunc  
  %a = sext i16 %v to i32
  %s = ashr i32 %a, 18
  %t = trunc i32 %s to i16
  =>
  %t = ashr i16 %v, 15
llvm-svn: 310942

We already support pulling through an add with constant RHS. We can do the same for subtract.

Differential Revision: https://reviews.llvm.org/D36443

llvm-svn: 310407

[InstCombine] Teach the code that pulls logical operators through constant shifts to handle vector splats too.

llvm-svn: 310185

Avoids unused variable warnings in Release builds. No functional change.

llvm-svn: 310064

Name: narrow_shift
Pre: C1 < 8
%zx = zext i8 %x to i32
%l = lshr i32 %zx, C1
  =>  
%narrowC = trunc i32 C1 to i8
%ns = lshr i8 %x, %narrowC
%l = zext i8 %ns to i32

http://rise4fun.com/Alive/jIV

This isn't directly applicable to PR34046 as written, but we
need to have more narrowing folds like this to be sure that
rotate patterns are recognized.

llvm-svn: 310060

Previously the InstCombiner class contained a pointer to an IR builder that had been passed to the constructor. Sometimes this would be passed to helper functions as either a pointer or the pointer would be dereferenced to be passed by reference.

This patch makes it a reference everywhere including the InstCombiner class itself so there is more inconsistency. This a large, but mechanical patch. I've done very minimal formatting changes on it despite what clang-format wanted to do.

llvm-svn: 307451

llvm-svn: 306205

This is a follow-up to https://reviews.llvm.org/D33879 / https://reviews.llvm.org/rL304939 ,
and was discussed in https://reviews.llvm.org/D33338.

We prefer this form because a narrower shift may be cheaper, and we can more easily fold a
zext than a sext.

http://rise4fun.com/Alive/slVe

Name: shz
%s = sext i8 %x to i12
%r = lshr i12 %s, 4
=>
%a = ashr i8 %x, 4
%r = zext i8 %a to i12 

llvm-svn: 305190

Summary: This matches the behavior we already had for compares and makes us consistent everywhere.

Reviewers: dberlin, hfinkel, spatel

Reviewed By: dberlin

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D33604

llvm-svn: 305049

This was discussed in D33338. We have larger pattern-matching ending in a truncate that 
we can reduce or remove by handling these smaller patterns first. Further motivation is 
that narrower shift ops are easier for value tracking and zext is better than sext.

http://rise4fun.com/Alive/rhh

Name: boolshift
%sext = sext i1 %x to i8
%r = lshr i8 %sext, 7

=>

%r = zext i1 %x to i8

Name: noboolshift
%sext = sext i3 %x to i8
%r = lshr i8 %sext, 7

=>

%sh = lshr i3 %x, 2
%r = zext i3 %sh to i8

Differential Revision: https://reviews.llvm.org/D33879

llvm-svn: 304939

[InstCombine] Pass the DominatorTree, AssumptionCache, and context instruction to a few calls to isKnownPositive, isKnownNegative, and isKnownNonZero

Every other place in InstCombine that uses these methods in ValueTracking already pass this information. This makes the remaining sites consistent.

Differential Revision: https://reviews.llvm.org/D33567

llvm-svn: 304018

InstCombine: Use the new SimplifyQuery versions of Simplify*. Use AssumptionCache, DominatorTree, TargetLibraryInfo everywhere.

llvm-svn: 301464

getSignBit is a static function that creates an APInt with only the sign bit set. getSignMask seems like a better name to convey its functionality. In fact several places use it and then store in an APInt named SignMask.

Differential Revision: https://reviews.llvm.org/D32108

llvm-svn: 300856

This patch uses lshrInPlace to replace code where the object that lshr is called on is being overwritten with the result.

This adds an lshrInPlace(const APInt &) version as well.

Differential Revision: https://reviews.llvm.org/D32155

llvm-svn: 300566

This fold already existed for vectors but only when 'C1' was a splat
constant (but 'C2' could be any constant). 

There were no tests for any vector constants, so I'm adding a test
that shows non-splat constants for both operands.  

llvm-svn: 294650

Although this is 'no-functional-change-intended', I'm adding tests
for shl-shl and lshr-lshr pairs because there is no existing test 
coverage for those folds.

It seems like we should be able to remove some code from foldShiftedShift()
at this point because we're handling those patterns on the general path.

llvm-svn: 293814

llvm-svn: 293570

llvm-svn: 293562

llvm-svn: 293524

llvm-svn: 293508

llvm-svn: 293507

The original shift is bigger, so this may qualify as 'obvious', 
but here's an attempt at an Alive-based proof:

Name: exact
Pre: (C1 u< C2)
%a = shl i8 %x, C1
%b = lshr exact i8 %a, C2 
  =>
%c = lshr exact i8 %x, C2 - C1
%b = and i8 %c, ((1 << width(C1)) - 1) u>> C2

Optimization is correct!

llvm-svn: 293498

llvm-svn: 293489

llvm-svn: 293435

We already have this fold when the lshr has one use, but it doesn't need that
restriction. We may be able to remove some code from foldShiftedShift().

Also, move the similar:
(X << C) >>u C --> X & (-1 >>u C)
...directly into visitLShr to help clean up foldShiftByConstOfShiftByConst().

That whole function seems questionable since it is called by commonShiftTransforms(),
but there's really not much in common if we're checking the shift opcodes for every
fold.

llvm-svn: 293215

llvm-svn: 293208

We may be able to assert that no shl-shl or lshr-lshr pairs ever get here
because we should have already handled those in foldShiftedShift().

llvm-svn: 292726

llvm-svn: 292230

llvm-svn: 292164

It's not clear what 'First' and 'Second' mean, so use 'Inner' and 'Outer'
to match foldShiftedShift() and add comments with formulas, so it's easier
to see what's going on.

llvm-svn: 292153

Some existing 'FIXME' tests are still not folded because of splat holes in value tracking.

llvm-svn: 292151

Reduces code duplication and makes it easier to extend these folds for vectors.

llvm-svn: 292145

llvm-svn: 292073

llvm-svn: 292064