Add PM extension point EP_VectorizerStart

This extension point allows passes to be executed right before the vectorizer
and other highly target specific optimizations are run.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@242389 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Transforms/IPO/PassManagerBuilder.h

@@ -81,6 +81,11 @@ class PassManagerBuilder {
     /// run after everything else.
     EP_OptimizerLast,
 
+    /// EP_VectorizerStart - This extension point allows adding optimization
+    /// passes before the vectorizer and other highly target specific
+    /// optimization passes are executed.
+    EP_VectorizerStart,
+
     /// EP_EnabledOnOptLevel0 - This extension point allows adding passes that
     /// should not be disabled by O0 optimization level. The passes will be
     /// inserted after the inlining pass.

lib/Transforms/IPO/PassManagerBuilder.cpp

@@ -318,6 +318,8 @@ void PassManagerBuilder::populateModulePassManager(
   if (RunFloat2Int)
     MPM.add(createFloat2IntPass());
 
+  addExtensionsToPM(EP_VectorizerStart, MPM);
+
   // Re-rotate loops in all our loop nests. These may have fallout out of
   // rotated form due to GVN or other transformations, and the vectorizer relies
   // on the rotated form. Disable header duplication at -Oz.