Arnold Schwaighofer 08a0e8f8db LoopVectorizer: integer division is not a reduction operation ...

Don't classify idiv/udiv as a reduction operation. Integer division is lossy.
For example : (1 / 2) * 4 != 4/2.

Example:

int a[] = { 2, 5, 2, 2}
int x = 80;

for()
  x /= a[i];

Scalar:
  x /= 2 // = 40
  x /= 5 // = 8
  x /= 2 // = 4
  x /= 2 // = 2

Vectorized:

 <80, 1> / <2,5> //= <40,0>
 <40, 0> / <2,2> //= <20,0>

 20*0 = 0

radar://13640654

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179381 91177308-0d34-0410-b5e6-96231b3b80d8

2013-04-12 15:15:19 +00:00

..

BBVectorize.cpp

BBVectorize: Fixup debugging statements

2013-03-10 20:57:42 +00:00

CMakeLists.txt

Add support for bottom-up SLP vectorization infrastructure.

2013-04-09 19:44:35 +00:00

LLVMBuild.txt

…

LoopVectorize.cpp

LoopVectorizer: integer division is not a reduction operation

2013-04-12 15:15:19 +00:00

Makefile

…

SLPVectorizer.cpp

Make the SLP store-merger less paranoid about function calls. We check for function calls when we check if it is safe to sink instructions.

2013-04-10 19:41:36 +00:00

Vectorize.cpp

Rename the C function to create a SLPVectorizerPass to something sane and expose it in the header file.

2013-04-11 11:36:36 +00:00

VecUtils.cpp

We require DataLayout for analyzing the size of stores.

2013-04-10 18:57:27 +00:00

VecUtils.h

Add support for bottom-up SLP vectorization infrastructure.

2013-04-09 19:44:35 +00:00