[Vectorizer] Add a new 'OperandValueKind' in TargetTransformInfo called

'OK_NonUniformConstValue' to identify operands which are constants but
not constant splats.

The cost model now allows returning 'OK_NonUniformConstValue'
for non splat operands that are instances of ConstantVector or
ConstantDataVector.

With this change, targets are now able to compute different costs
for instructions with non-uniform constant operands.
For example, On X86 the cost of a vector shift may vary depending on whether
the second operand is a uniform or non-uniform constant.

This patch applies the following changes:
 - The cost model computation now takes into account non-uniform constants;
 - The cost of vector shift instructions has been improved in
   X86TargetTransformInfo analysis pass;
 - BBVectorize, SLPVectorizer and LoopVectorize now know how to distinguish
   between non-uniform and uniform constant operands.

Added a new test to verify that the output of opt
'-cost-model -analyze' is valid in the following configurations: SSE2,
SSE4.1, AVX, AVX2.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201272 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 1 deletions

diff --git a/lib/Transforms/Vectorize/LoopVectorize.cpp b/lib/Transforms/Vectorize/LoopVectorize.cpp
index b52970119a..ecbab63acf 100644
--- a/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -5491,9 +5491,20 @@ LoopVectorizationCostModel::getInstructionCost(Instruction *I, unsigned VF) {
       TargetTransformInfo::OK_AnyValue;
     TargetTransformInfo::OperandValueKind Op2VK =
       TargetTransformInfo::OK_AnyValue;
+    Value *Op2 = I->getOperand(1);
 
-    if (isa<ConstantInt>(I->getOperand(1)))
+    // Check for a splat of a constant or for a non uniform vector of constants.
+    if (isa<ConstantInt>(Op2))
       Op2VK = TargetTransformInfo::OK_UniformConstantValue;
+    else if (ConstantDataVector *CDV = dyn_cast<ConstantDataVector>(Op2)) {
+      Op2VK = TargetTransformInfo::OK_NonUniformConstantValue;
+      if (CDV->getSplatValue() != NULL)
+        Op2VK = TargetTransformInfo::OK_UniformConstantValue;
+    } else if (ConstantVector *CV = dyn_cast<ConstantVector>(Op2)) {
+      Op2VK = TargetTransformInfo::OK_NonUniformConstantValue;
+      if (CV->getSplatValue() != NULL)
+        Op2VK = TargetTransformInfo::OK_UniformConstantValue;
+    }
 
     return TTI.getArithmeticInstrCost(I->getOpcode(), VectorTy, Op1VK, Op2VK);
   }