Revert "[GlobalISel] LegalizationArtifactCombiner: Elide redundant G_AND"

This reverts commit 3686a0b.
This seems to have broken some sanitizer tests:
https://lab.llvm.org/buildbot/#/builders/184/builds/7721

Author: tobias-stadler

llvm/include/llvm/CodeGen/GlobalISel/GISelKnownBits.h

@@ -118,7 +118,11 @@ class GISelKnownBitsAnalysis : public MachineFunctionPass {
   GISelKnownBitsAnalysis() : MachineFunctionPass(ID) {
     initializeGISelKnownBitsAnalysisPass(*PassRegistry::getPassRegistry());
   }
-  GISelKnownBits &get(MachineFunction &MF);
+  GISelKnownBits &get(MachineFunction &MF) {
+    if (!Info)
+      Info = std::make_unique<GISelKnownBits>(MF);
+    return *Info.get();
+  }
   void getAnalysisUsage(AnalysisUsage &AU) const override;
   bool runOnMachineFunction(MachineFunction &MF) override;
   void releaseMemory() override { Info.reset(); }

llvm/include/llvm/CodeGen/GlobalISel/LegalizationArtifactCombiner.h

@@ -35,7 +35,6 @@ class LegalizationArtifactCombiner {
   MachineIRBuilder &Builder;
   MachineRegisterInfo &MRI;
   const LegalizerInfo &LI;
-  GISelKnownBits *KB;
 
   static bool isArtifactCast(unsigned Opc) {
     switch (Opc) {
@@ -51,9 +50,8 @@ class LegalizationArtifactCombiner {
 
 public:
   LegalizationArtifactCombiner(MachineIRBuilder &B, MachineRegisterInfo &MRI,
-                               const LegalizerInfo &LI,
-                               GISelKnownBits *KB = nullptr)
-      : Builder(B), MRI(MRI), LI(LI), KB(KB) {}
+                    const LegalizerInfo &LI)
+      : Builder(B), MRI(MRI), LI(LI) {}
 
   bool tryCombineAnyExt(MachineInstr &MI,
                         SmallVectorImpl<MachineInstr *> &DeadInsts,
@@ -133,26 +131,13 @@ class LegalizationArtifactCombiner {
       LLVM_DEBUG(dbgs() << ".. Combine MI: " << MI;);
       LLT SrcTy = MRI.getType(SrcReg);
       APInt MaskVal = APInt::getAllOnes(SrcTy.getScalarSizeInBits());
+      auto Mask = Builder.buildConstant(
+        DstTy, MaskVal.zext(DstTy.getScalarSizeInBits()));
       if (SextSrc && (DstTy != MRI.getType(SextSrc)))
         SextSrc = Builder.buildSExtOrTrunc(DstTy, SextSrc).getReg(0);
       if (TruncSrc && (DstTy != MRI.getType(TruncSrc)))
         TruncSrc = Builder.buildAnyExtOrTrunc(DstTy, TruncSrc).getReg(0);
-      APInt ExtMaskVal = MaskVal.zext(DstTy.getScalarSizeInBits());
-      Register AndSrc = SextSrc ? SextSrc : TruncSrc;
-      // Elide G_AND and mask constant if possible.
-      // The G_AND would also be removed by the post-legalize redundant_and
-      // combine, but in this very common case, eliding early and regardless of
-      // OptLevel results in significant compile-time and O0 code-size
-      // improvements. Inserting unnecessary instructions between a boolean def
-      // and use can also hinder ISel to detect e.g. that reloading a flags
-      // register is unnecessary.
-      if (KB && (KB->getKnownZeroes(AndSrc) | ExtMaskVal).isAllOnes()) {
-        replaceRegOrBuildCopy(DstReg, AndSrc, MRI, Builder, UpdatedDefs,
-                              Observer);
-      } else {
-        auto Mask = Builder.buildConstant(DstTy, ExtMaskVal);
-        Builder.buildAnd(DstReg, AndSrc, Mask);
-      }
+      Builder.buildAnd(DstReg, SextSrc ? SextSrc : TruncSrc, Mask);
       markInstAndDefDead(MI, *MRI.getVRegDef(SrcReg), DeadInsts);
       return true;
     }

llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp

@@ -19,7 +19,6 @@
 #include "llvm/CodeGen/TargetLowering.h"
 #include "llvm/CodeGen/TargetOpcodes.h"
 #include "llvm/IR/Module.h"
-#include "llvm/Target/TargetMachine.h"
 
 #define DEBUG_TYPE "gisel-known-bits"
 
@@ -774,12 +773,3 @@ void GISelKnownBitsAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
 bool GISelKnownBitsAnalysis::runOnMachineFunction(MachineFunction &MF) {
   return false;
 }
-
-GISelKnownBits &GISelKnownBitsAnalysis::get(MachineFunction &MF) {
-  if (!Info) {
-    unsigned MaxDepth =
-        MF.getTarget().getOptLevel() == CodeGenOptLevel::None ? 2 : 6;
-    Info = std::make_unique<GISelKnownBits>(MF, MaxDepth);
-  }
-  return *Info.get();
-}

llvm/lib/CodeGen/GlobalISel/Legalizer.cpp

@@ -218,7 +218,7 @@ Legalizer::legalizeMachineFunction(MachineFunction &MF, const LegalizerInfo &LI,
   // This will keep all the observers notified about new insertions/deletions.
   RAIIMFObsDelInstaller Installer(MF, WrapperObserver);
   LegalizerHelper Helper(MF, LI, WrapperObserver, MIRBuilder, KB);
-  LegalizationArtifactCombiner ArtCombiner(MIRBuilder, MRI, LI, KB);
+  LegalizationArtifactCombiner ArtCombiner(MIRBuilder, MRI, LI);
   bool Changed = false;
   SmallVector<MachineInstr *, 128> RetryList;
   do {