[llvm] fa58847 - [GVN] Always require LoopInfo

[Nikita Popov via llvm-commits]

Author: Nikita Popov
Date: 2023-10-11T11:28:26+02:00
New Revision: fa5884770ab240139f33a8b2be801673ca21b9c0

URL: https://github.com/llvm/llvm-project/commit/fa5884770ab240139f33a8b2be801673ca21b9c0
DIFF: https://github.com/llvm/llvm-project/commit/fa5884770ab240139f33a8b2be801673ca21b9c0.diff

LOG: [GVN] Always require LoopInfo

GVN behavior depends on LoopInfo in multiple ways, most notably
as a dependency for loop load PRE. As this is not a preserved-only
analysis, using a cached analysis is inappropriate.

In the actual optimization pipeline LoopInfo is always available
at the point GVN runs, but this will ensure it stays this way
even if the pipeline changes.

Added: 
    

Modified: 
    llvm/include/llvm/Transforms/Scalar/GVN.h
    llvm/lib/Transforms/Scalar/GVN.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Transforms/Scalar/GVN.h b/llvm/include/llvm/Transforms/Scalar/GVN.h
index 0a00e3af03d2fd0..4ba9b74ccb005d4 100644
--- a/llvm/include/llvm/Transforms/Scalar/GVN.h
+++ b/llvm/include/llvm/Transforms/Scalar/GVN.h
@@ -261,7 +261,7 @@ class GVNPass : public PassInfoMixin<GVNPass> {
 
   bool runImpl(Function &F, AssumptionCache &RunAC, DominatorTree &RunDT,
                const TargetLibraryInfo &RunTLI, AAResults &RunAA,
-               MemoryDependenceResults *RunMD, LoopInfo *LI,
+               MemoryDependenceResults *RunMD, LoopInfo &LI,
                OptimizationRemarkEmitter *ORE, MemorySSA *MSSA = nullptr);
 
   /// Push a new Value to the LeaderTable onto the list for its value number.

diff  --git a/llvm/lib/Transforms/Scalar/GVN.cpp b/llvm/lib/Transforms/Scalar/GVN.cpp
index f419d03c0ce3837..6619ed780e77557 100644
--- a/llvm/lib/Transforms/Scalar/GVN.cpp
+++ b/llvm/lib/Transforms/Scalar/GVN.cpp
@@ -760,7 +760,7 @@ PreservedAnalyses GVNPass::run(Function &F, FunctionAnalysisManager &AM) {
   auto &AA = AM.getResult<AAManager>(F);
   auto *MemDep =
       isMemDepEnabled() ? &AM.getResult<MemoryDependenceAnalysis>(F) : nullptr;
-  auto *LI = AM.getCachedResult<LoopAnalysis>(F);
+  auto &LI = AM.getResult<LoopAnalysis>(F);
   auto *MSSA = AM.getCachedResult<MemorySSAAnalysis>(F);
   auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
   bool Changed = runImpl(F, AC, DT, TLI, AA, MemDep, LI, &ORE,
@@ -772,8 +772,7 @@ PreservedAnalyses GVNPass::run(Function &F, FunctionAnalysisManager &AM) {
   PA.preserve<TargetLibraryAnalysis>();
   if (MSSA)
     PA.preserve<MemorySSAAnalysis>();
-  if (LI)
-    PA.preserve<LoopAnalysis>();
+  PA.preserve<LoopAnalysis>();
   return PA;
 }
 
@@ -1434,8 +1433,7 @@ void GVNPass::eliminatePartiallyRedundantLoad(
     if (auto *RangeMD = Load->getMetadata(LLVMContext::MD_range))
       NewLoad->setMetadata(LLVMContext::MD_range, RangeMD);
     if (auto *AccessMD = Load->getMetadata(LLVMContext::MD_access_group))
-      if (LI &&
-          LI->getLoopFor(Load->getParent()) == LI->getLoopFor(UnavailableBlock))
+      if (LI->getLoopFor(Load->getParent()) == LI->getLoopFor(UnavailableBlock))
         NewLoad->setMetadata(LLVMContext::MD_access_group, AccessMD);
 
     // We do not propagate the old load's debug location, because the new
@@ -1743,9 +1741,6 @@ bool GVNPass::PerformLoadPRE(LoadInst *Load, AvailValInBlkVect &ValuesPerBlock,
 bool GVNPass::performLoopLoadPRE(LoadInst *Load,
                                  AvailValInBlkVect &ValuesPerBlock,
                                  UnavailBlkVect &UnavailableBlocks) {
-  if (!LI)
-    return false;
-
   const Loop *L = LI->getLoopFor(Load->getParent());
   // TODO: Generalize to other loop blocks that dominate the latch.
   if (!L || L->getHeader() != Load->getParent())
@@ -1914,7 +1909,7 @@ bool GVNPass::processNonLocalLoad(LoadInst *Load) {
   // Step 4: Eliminate partial redundancy.
   if (!isPREEnabled() || !isLoadPREEnabled())
     return Changed;
-  if (!isLoadInLoopPREEnabled() && LI && LI->getLoopFor(Load->getParent()))
+  if (!isLoadInLoopPREEnabled() && LI->getLoopFor(Load->getParent()))
     return Changed;
 
   if (performLoopLoadPRE(Load, ValuesPerBlock, UnavailableBlocks) ||
@@ -2686,7 +2681,7 @@ bool GVNPass::processInstruction(Instruction *I) {
 /// runOnFunction - This is the main transformation entry point for a function.
 bool GVNPass::runImpl(Function &F, AssumptionCache &RunAC, DominatorTree &RunDT,
                       const TargetLibraryInfo &RunTLI, AAResults &RunAA,
-                      MemoryDependenceResults *RunMD, LoopInfo *LI,
+                      MemoryDependenceResults *RunMD, LoopInfo &LI,
                       OptimizationRemarkEmitter *RunORE, MemorySSA *MSSA) {
   AC = &RunAC;
   DT = &RunDT;
@@ -2696,7 +2691,7 @@ bool GVNPass::runImpl(Function &F, AssumptionCache &RunAC, DominatorTree &RunDT,
   MD = RunMD;
   ImplicitControlFlowTracking ImplicitCFT;
   ICF = &ImplicitCFT;
-  this->LI = LI;
+  this->LI = &LI;
   VN.setMemDep(MD);
   ORE = RunORE;
   InvalidBlockRPONumbers = true;
@@ -2710,7 +2705,7 @@ bool GVNPass::runImpl(Function &F, AssumptionCache &RunAC, DominatorTree &RunDT,
   // Merge unconditional branches, allowing PRE to catch more
   // optimization opportunities.
   for (BasicBlock &BB : llvm::make_early_inc_range(F)) {
-    bool removedBlock = MergeBlockIntoPredecessor(&BB, &DTU, LI, MSSAU, MD);
+    bool removedBlock = MergeBlockIntoPredecessor(&BB, &DTU, &LI, MSSAU, MD);
     if (removedBlock)
       ++NumGVNBlocks;
 
@@ -3286,8 +3281,6 @@ class llvm::gvn::GVNLegacyPass : public FunctionPass {
     if (skipFunction(F))
       return false;
 
-    auto &LIWP = getAnalysis<LoopInfoWrapperPass>();
-
     auto *MSSAWP = getAnalysisIfAvailable<MemorySSAWrapperPass>();
     return Impl.runImpl(
         F, getAnalysis<AssumptionCacheTracker>().getAssumptionCache(F),
@@ -3297,7 +3290,7 @@ class llvm::gvn::GVNLegacyPass : public FunctionPass {
         Impl.isMemDepEnabled()
             ? &getAnalysis<MemoryDependenceWrapperPass>().getMemDep()
             : nullptr,
-        &LIWP.getLoopInfo(),
+        getAnalysis<LoopInfoWrapperPass>().getLoopInfo(),
         &getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE(),
         MSSAWP ? &MSSAWP->getMSSA() : nullptr);
   }