LTO: respect command-line options that disable vectorization.

[jfb]

Summary

Patches 202051 and 208013 added calls to LTO's PassManager which unconditionally add LoopVectorizePass and SLPVectorizerPass instead of following the logic in PassManagerBuilder::populateModulePassManager and honoring the -vectorize-loops -run-slp-after-loop-vectorization flags.

[aschwaighofer]

LGTM.

[jfb]

Closed by commit rL220345 (authored by @jfb).

lib/Transforms/IPO/PassManagerBuilder.cpp

void PassManagerBuilder::addLTOOptimizationPasses(PassManagerBase &PM) {
   PM.add(createMemCpyOptPass());            // Remove dead memcpys.
 
   // Nuke dead stores.
   PM.add(createDeadStoreEliminationPass());
 
   // More loops are countable; try to optimize them.
   PM.add(createIndVarSimplifyPass());
   PM.add(createLoopDeletionPass());
-  PM.add(createLoopVectorizePass(true, true));
+  PM.add(createLoopVectorizePass(DisableUnrollLoops, LoopVectorize));
 
   // More scalar chains could be vectorized due to more alias information
+  if (RunSLPAfterLoopVectorization)
+    if (SLPVectorize)
       PM.add(createSLPVectorizerPass()); // Vectorize parallel scalar chains.
 
   // After vectorization, assume intrinsics may tell us more about pointer
   // alignments.
   PM.add(createAlignmentFromAssumptionsPass());
 
   if (LoadCombine)
     PM.add(createLoadCombinePass());