[LV] Run loop-simplify and LCSSA explicitly instead of "requiring" them

This changes the vectorizer to explicitly use the loopsimplify and lcssa utils,
instead of "requiring" the transformations as if they were analyses.

This is not NFC, since it changes the LCSSA behavior - we no longer run LCSSA
for all loops, but rather only for the loops we expect to modify.

Differential Revision: https://reviews.llvm.org/D28868

llvm-svn: 292456

1 files changed, 13 insertions, 5 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 18cfef026fb..71424b2bac2 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -92,6 +92,7 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
+#include "llvm/Transforms/Utils/LoopSimplify.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 #include "llvm/Transforms/Utils/LoopVersioning.h"
 #include "llvm/Transforms/Vectorize.h"
@@ -2134,8 +2135,6 @@ struct LoopVectorize : public FunctionPass {
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<AssumptionCacheTracker>();
-    AU.addRequiredID(LoopSimplifyID);
-    AU.addRequiredID(LCSSAID);
     AU.addRequired<BlockFrequencyInfoWrapperPass>();
     AU.addRequired<DominatorTreeWrapperPass>();
     AU.addRequired<LoopInfoWrapperPass>();
@@ -7169,9 +7168,7 @@ INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
 INITIALIZE_PASS_DEPENDENCY(BlockFrequencyInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(LCSSAWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
-INITIALIZE_PASS_DEPENDENCY(LoopSimplify)
 INITIALIZE_PASS_DEPENDENCY(LoopAccessLegacyAnalysis)
 INITIALIZE_PASS_DEPENDENCY(DemandedBitsWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)
@@ -7543,6 +7540,8 @@ bool LoopVectorizePass::processLoop(Loop *L) {
     DEBUG(dbgs() << "LV: Interleave Count is " << IC << '\n');
   }
 
+  formLCSSARecursively(*L, *DT, LI, SE);
+
   using namespace ore;
   if (!VectorizeLoop) {
     assert(IC > 1 && "interleave count should not be 1 or 0");
@@ -7618,6 +7617,16 @@ bool LoopVectorizePass::runImpl(
   if (!TTI->getNumberOfRegisters(true) && TTI->getMaxInterleaveFactor(1) < 2)
     return false;
 
+  bool Changed = false;
+
+  // The vectorizer requires loops to be in simplified form.
+  // Since simplification may add new inner loops, it has to run before the
+  // legality and profitability checks. This means running the loop vectorizer
+  // will simplify all loops, regardless of whether anything end up being
+  // vectorized.
+  for (auto &L : *LI)
+    Changed |= simplifyLoop(L, DT, LI, SE, AC, false /* PreserveLCSSA */);
+
   // Build up a worklist of inner-loops to vectorize. This is necessary as
   // the act of vectorizing or partially unrolling a loop creates new loops
   // and can invalidate iterators across the loops.
@@ -7629,7 +7638,6 @@ bool LoopVectorizePass::runImpl(
   LoopsAnalyzed += Worklist.size();
 
   // Now walk the identified inner loops.
-  bool Changed = false;
   while (!Worklist.empty())
     Changed |= processLoop(Worklist.pop_back_val());