Commit Graph

9 Commits

Author SHA1 Message Date
Sanjay Patel 8dd99dce6c [DAG] vector div/rem with any zero element in divisor is undef
This is the backend counterpart to:
https://reviews.llvm.org/rL297390
https://reviews.llvm.org/rL297409
and follow-up to:
https://reviews.llvm.org/rL297384

It surprised me that we need to duplicate the check in FoldConstantArithmetic and FoldConstantVectorArithmetic, 
but one or the other doesn't catch all of the test cases. There is an existing code comment about merging those 
someday.

Differential Revision: https://reviews.llvm.org/D30826

llvm-svn: 297762
2017-03-14 18:06:28 +00:00
Sanjay Patel 7f7947bf41 [DAGCombiner] simplify div/rem-by-0
Refactoring of duplicated code and more fixes to follow.

This is motivated by the post-commit comments for r296699:
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20170306/435182.html

Ie, we can crash if we're missing obvious simplifications like this that
exist in the IR simplifier or if these occur later than expected.

The x86 change for non-splat division shows a potential opportunity to improve
vector codegen: we assumed that since only one lane had meaningful results, we
should do the math in scalar. But that means moving back and forth from vector
registers.

llvm-svn: 297026
2017-03-06 16:36:42 +00:00
Simon Pilgrim 1b14082488 [X86][SSE] Regenerated vector sdiv to shifts tests
Added SSE + AVX1 tests as well as AVX2

llvm-svn: 265169
2016-04-01 18:18:40 +00:00
Michael Kuperstein 9fe42604aa [X86] Do not lower scalar sdiv/udiv to a shifts + mul sequence when optimizing for minsize
There are some cases where the mul sequence is smaller, but for the most part,
using a div is preferable. This does not apply to vectors, since x86 doesn't
have vector idiv, and a vector mul/shifts sequence ought to be smaller than a
scalarized division.

Differential Revision: http://reviews.llvm.org/D12082

llvm-svn: 245431
2015-08-19 11:21:43 +00:00
Stephen Lin f799e3f944 Convert CodeGen/*/*.ll tests to use the new CHECK-LABEL for easier debugging. No functionality change and all tests pass after conversion.
This was done with the following sed invocation to catch label lines demarking function boundaries:
    sed -i '' "s/^;\( *\)\([A-Z0-9_]*\):\( *\)test\([A-Za-z0-9_-]*\):\( *\)$/;\1\2-LABEL:\3test\4:\5/g" test/CodeGen/*/*.ll
which was written conservatively to avoid false positives rather than false negatives. I scanned through all the changes and everything looks correct.

llvm-svn: 186258
2013-07-13 20:38:47 +00:00
Elena Demikhovsky 6769c50d9e Optimized integer vector multiplication operation by replacing it with shift/xor/sub when it is possible. Fixed a bug in SDIV, where the const operand is not a splat constant vector.
llvm-svn: 184931
2013-06-26 10:55:03 +00:00
Benjamin Kramer 01b75cc0f2 Test case hygiene.
llvm-svn: 176772
2013-03-09 18:25:40 +00:00
Nadav Rotem 3f5825c6c1 add -march to the test
llvm-svn: 171956
2013-01-09 07:04:23 +00:00
Nadav Rotem 977e0be4a0 Efficient lowering of vector sdiv when the divisor is a splatted power of two constant.
PR 14848. The lowered sequence is based on the existing sequence the target-independent
DAG Combiner creates for the scalar case.

Patch by Zvi Rackover.

llvm-svn: 171953
2013-01-09 05:14:33 +00:00