[AssumeBundles] preserve information in NewGVN

[jdoerfert]

LGTM!

llvm/lib/Transforms/Scalar/NewGVN.cpp

 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/DebugCounter.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/PointerLikeTypeTraits.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Scalar/GVNExpression.h"
+#include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/PredicateInfo.h"
 #include "llvm/Transforms/Utils/VNCoercion.h"
 #include <algorithm>
 #include <cassert>
 #include <cstdint>
 #include <iterator>
 #include <map>

 
 class NewGVN {
   Function &F;
   DominatorTree *DT = nullptr;
   const TargetLibraryInfo *TLI = nullptr;
   AliasAnalysis *AA = nullptr;
   MemorySSA *MSSA = nullptr;
   MemorySSAWalker *MSSAWalker = nullptr;
+  AssumptionCache *AC = nullptr;
   const DataLayout &DL;
   std::unique_ptr<PredicateInfo> PredInfo;
 
   // These are the only two things the create* functions should have
   // side-effects on due to allocating memory.
   mutable BumpPtrAllocator ExpressionAllocator;
   mutable ArrayRecycler<Value *> ArgRecycler;
   mutable TarjanSCC SCCFinder;
#endif
 
   // Deletion info.
   SmallPtrSet<Instruction *, 8> InstructionsToErase;
 
 public:
   NewGVN(Function &F, DominatorTree *DT, AssumptionCache *AC,
          TargetLibraryInfo *TLI, AliasAnalysis *AA, MemorySSA *MSSA,
          const DataLayout &DL)
-      : F(F), DT(DT), TLI(TLI), AA(AA), MSSA(MSSA), DL(DL),
+      : F(F), DT(DT), TLI(TLI), AA(AA), MSSA(MSSA), AC(AC), DL(DL),
         PredInfo(std::make_unique<PredicateInfo>(F, *DT, *AC)),
         SQ(DL, TLI, DT, AC, /*CtxI=*/nullptr, /*UseInstrInfo=*/false) {}
 
   bool runGVN();
 
 private:
   // Expression handling.
   const Expression *createExpression(Instruction *) const;
void NewGVN::deleteInstructionsInBlock(BasicBlock *BB) {
   // Note that we explicitly recalculate BB->rend() on each iteration,
   // as it may change when we remove the first instruction.
   for (BasicBlock::reverse_iterator I(StartPoint); I != BB->rend();) {
     Instruction &Inst = *I++;
     if (!Inst.use_empty())
       Inst.replaceAllUsesWith(UndefValue::get(Inst.getType()));
     if (isa<LandingPadInst>(Inst))
       continue;
+    salvageKnowledge(&Inst, AC);
 
     Inst.eraseFromParent();
     ++NumGVNInstrDeleted;
   }
   // Now insert something that simplifycfg will turn into an unreachable.
   Type *Int8Ty = Type::getInt8Ty(BB->getContext());
   new StoreInst(UndefValue::get(Int8Ty),
                 Constant::getNullValue(Int8Ty->getPointerTo()),

llvm/test/Transforms/NewGVN/2007-07-26-PhiErasure.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt < %s -newgvn -S | FileCheck %s
+; RUN: opt < %s -newgvn -S | FileCheck %s --check-prefixes=CHECK,NO_ASSUME
+; RUN: opt < %s -newgvn --enable-knowledge-retention -S | FileCheck %s --check-prefixes=CHECK,USE_ASSUME
 
   %struct..0anon = type { i32 }
   %struct.FILE = type { i8*, i32, i32, i16, i16, %struct.__sbuf, i32, i8*, i32 (i8*)*, i32 (i8*, i8*, i32)*, i64 (i8*, i64, i32)*, i32 (i8*, i8*, i32)*, %struct.__sbuf, %struct.__sFILEX*, i32, [3 x i8], [1 x i8], %struct.__sbuf, i32, i64 }
   %struct.__sFILEX = type opaque
   %struct.__sbuf = type { i8*, i32 }
   %struct.rtx_def = type { i16, i8, i8, [1 x %struct..0anon] }
 @n_spills = external global i32   ; <i32*> [#uses=2]
 
 define i32 @reload(%struct.rtx_def* %first, i32 %global, %struct.FILE* %dumpfile) {
-; CHECK-LABEL: @reload(
-; CHECK-NEXT:  cond_next2835.1:
-; CHECK-NEXT:    br label [[BB2928:%.*]]
-; CHECK:       bb2928:
-; CHECK-NEXT:    br i1 false, label [[COND_NEXT2943:%.*]], label [[COND_TRUE2935:%.*]]
-; CHECK:       cond_true2935:
-; CHECK-NEXT:    br label [[COND_NEXT2943]]
-; CHECK:       cond_next2943:
-; CHECK-NEXT:    br i1 false, label [[BB2982_PREHEADER:%.*]], label [[BB2928]]
-; CHECK:       bb2982.preheader:
-; CHECK-NEXT:    store i8 undef, i8* null
-; CHECK-NEXT:    ret i32 undef
+; NO_ASSUME-LABEL: @reload(
+; NO_ASSUME-NEXT:  cond_next2835.1:
+; NO_ASSUME-NEXT:    br label [[BB2928:%.*]]
+; NO_ASSUME:       bb2928:
+; NO_ASSUME-NEXT:    br i1 false, label [[COND_NEXT2943:%.*]], label [[COND_TRUE2935:%.*]]
+; NO_ASSUME:       cond_true2935:
+; NO_ASSUME-NEXT:    br label [[COND_NEXT2943]]
+; NO_ASSUME:       cond_next2943:
+; NO_ASSUME-NEXT:    br i1 false, label [[BB2982_PREHEADER:%.*]], label [[BB2928]]
+; NO_ASSUME:       bb2982.preheader:
+; NO_ASSUME-NEXT:    store i8 undef, i8* null
+; NO_ASSUME-NEXT:    ret i32 undef
+;
+; USE_ASSUME-LABEL: @reload(
+; USE_ASSUME-NEXT:  cond_next2835.1:
+; USE_ASSUME-NEXT:    br label [[BB2928:%.*]]
+; USE_ASSUME:       bb2928:
+; USE_ASSUME-NEXT:    br i1 false, label [[COND_NEXT2943:%.*]], label [[COND_TRUE2935:%.*]]
+; USE_ASSUME:       cond_true2935:
+; USE_ASSUME-NEXT:    br label [[COND_NEXT2943]]
+; USE_ASSUME:       cond_next2943:
+; USE_ASSUME-NEXT:    br i1 false, label [[BB2982_PREHEADER:%.*]], label [[BB2928]]
+; USE_ASSUME:       bb2982.preheader:
+; USE_ASSUME-NEXT:    call void @llvm.assume(i1 true) [ "align"(i32* @n_spills, i64 4), "dereferenceable"(i32* @n_spills, i64 4), "nonnull"(i32* @n_spills) ]
+; USE_ASSUME-NEXT:    store i8 undef, i8* null
+; USE_ASSUME-NEXT:    ret i32 undef
 ;
 cond_next2835.1:    ; preds = %cond_next2861
   %tmp2922 = load i32, i32* @n_spills, align 4    ; <i32> [#uses=0]
   br label %bb2928
 
 bb2928:   ; preds = %cond_next2835.1, %cond_next2943
   br i1 false, label %cond_next2943, label %cond_true2935