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];
}

llvm-svn: 179117

3 files changed, 8 insertions, 0 deletions

diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index 9cc194b4248..5b2cd603c3f 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -271,6 +271,7 @@ void initializeInstSimplifierPass(PassRegistry&);
 void initializeUnpackMachineBundlesPass(PassRegistry&);
 void initializeFinalizeMachineBundlesPass(PassRegistry&);
 void initializeLoopVectorizePass(PassRegistry&);
+void initializeSLPVectorizerPass(PassRegistry&);
 void initializeBBVectorizePass(PassRegistry&);
 void initializeMachineFunctionPrinterPassPass(PassRegistry&);
 }
diff --git a/llvm/include/llvm/LinkAllPasses.h b/llvm/include/llvm/LinkAllPasses.h
index 1f017e471de..ca1c13924e9 100644
--- a/llvm/include/llvm/LinkAllPasses.h
+++ b/llvm/include/llvm/LinkAllPasses.h
@@ -161,6 +161,7 @@ namespace {
       (void) llvm::createMemDepPrinter();
       (void) llvm::createInstructionSimplifierPass();
       (void) llvm::createLoopVectorizePass();
+      (void) llvm::createSLPVectorizerPass();
       (void) llvm::createBBVectorizePass();
 
       (void)new llvm::IntervalPartition();
diff --git a/llvm/include/llvm/Transforms/Vectorize.h b/llvm/include/llvm/Transforms/Vectorize.h
index d205dbdede2..8d0db161160 100644
--- a/llvm/include/llvm/Transforms/Vectorize.h
+++ b/llvm/include/llvm/Transforms/Vectorize.h
@@ -117,6 +117,12 @@ createBBVectorizePass(const VectorizeConfig &C = VectorizeConfig());
 Pass *createLoopVectorizePass();
 
 //===----------------------------------------------------------------------===//
+//
+// SLPVectorizer - Create a bottom-up SLP vectorizer pass.
+//
+Pass *createSLPVectorizerPass();
+
+//===----------------------------------------------------------------------===//
 /// @brief Vectorize the BasicBlock.
 ///
 /// @param BB The BasicBlock to be vectorized