Add support for bottom-up SLP vectorization infrastructure.

This commit adds the infrastructure for performing bottom-up SLP vectorization (and other optimizations) on parallel computations.
The infrastructure has three potential users:

  1. The loop vectorizer needs to be able to vectorize AOS data structures such as (sum += A[i] + A[i+1]).

  2. The BB-vectorizer needs this infrastructure for bottom-up SLP vectorization, because bottom-up vectorization is faster to compute.

  3. A loop-roller needs to be able to analyze consecutive chains and roll them into a loop, in order to reduce code size. A loop roller does not need to create vector instructions, and this infrastructure separates the chain analysis from the vectorization.

This patch also includes a simple (100 LOC) bottom up SLP vectorizer that uses the infrastructure, and can vectorize this code:

void SAXPY(int *x, int *y, int a, int i) {
  x[i]   = a * x[i]   + y[i];
  x[i+1] = a * x[i+1] + y[i+1];
  x[i+2] = a * x[i+2] + y[i+2];
  x[i+3] = a * x[i+3] + y[i+3];
}



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179117 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 5 insertions, 0 deletions

diff --git a/lib/Transforms/Vectorize/Vectorize.cpp b/lib/Transforms/Vectorize/Vectorize.cpp
index 19eefd2f87..3aff6366a6 100644
--- a/lib/Transforms/Vectorize/Vectorize.cpp
+++ b/lib/Transforms/Vectorize/Vectorize.cpp
@@ -28,6 +28,7 @@ using namespace llvm;
 void llvm::initializeVectorization(PassRegistry &Registry) {
   initializeBBVectorizePass(Registry);
   initializeLoopVectorizePass(Registry);
+  initializeSLPVectorizerPass(Registry);
 }
 
 void LLVMInitializeVectorization(LLVMPassRegistryRef R) {
@@ -41,3 +42,7 @@ void LLVMAddBBVectorizePass(LLVMPassManagerRef PM) {
 void LLVMAddLoopVectorizePass(LLVMPassManagerRef PM) {
   unwrap(PM)->add(createLoopVectorizePass());
 }
+
+void LLVMAddLoopRollerPass(LLVMPassManagerRef PM) {
+  unwrap(PM)->add(createSLPVectorizerPass());
+}