Remove icmp BPF builtin

llvm/lib/Target/SBF/SBFAdjustOpt.cpp

@@ -15,13 +15,11 @@
 #include "SBFTargetMachine.h"
 #include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
-#include "llvm/IR/IntrinsicsBPF.h" // TODO: jle.
 #include "llvm/IR/Module.h"
 #include "llvm/IR/PatternMatch.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/User.h"
 #include "llvm/IR/Value.h"
-#include "llvm/Pass.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 
 #define DEBUG_TYPE "sbf-adjust-opt"
@@ -59,7 +57,6 @@ class SBFAdjustOptImpl {
   Module *M;
   SmallVector<PassThroughInfo, 16> PassThroughs;
 
-  bool adjustICmpToBuiltin();
   void adjustBasicBlock(BasicBlock &BB);
   bool serializeICMPCrossBB(BasicBlock &BB);
   void adjustInst(Instruction &I);
@@ -71,72 +68,13 @@ class SBFAdjustOptImpl {
 } // End anonymous namespace
 
 bool SBFAdjustOptImpl::run() {
-  bool Changed = adjustICmpToBuiltin();
-
   for (Function &F : *M)
     for (auto &BB : F) {
       adjustBasicBlock(BB);
       for (auto &I : BB)
         adjustInst(I);
     }
-  return insertPassThrough() || Changed;
-}
-
-// Commit acabad9ff6bf ("[InstCombine] try to canonicalize icmp with
-// trunc op into mask and cmp") added a transformation to
-// convert "(conv)a < power_2_const" to "a & <const>" in certain
-// cases and bpf kernel verifier has to handle the resulted code
-// conservatively and this may reject otherwise legitimate program.
-// Here, we change related icmp code to a builtin which will
-// be restored to original icmp code later to prevent that
-// InstCombine transformatin.
-bool SBFAdjustOptImpl::adjustICmpToBuiltin() {
-  bool Changed = false;
-  ICmpInst *ToBeDeleted = nullptr;
-  for (Function &F : *M)
-    for (auto &BB : F)
-      for (auto &I : BB) {
-        if (ToBeDeleted) {
-          ToBeDeleted->eraseFromParent();
-          ToBeDeleted = nullptr;
-        }
-
-        auto *Icmp = dyn_cast<ICmpInst>(&I);
-        if (!Icmp)
-          continue;
-
-        Value *Op0 = Icmp->getOperand(0);
-        if (!isa<TruncInst>(Op0))
-          continue;
-
-        auto ConstOp1 = dyn_cast<ConstantInt>(Icmp->getOperand(1));
-        if (!ConstOp1)
-          continue;
-
-        auto ConstOp1Val = ConstOp1->getValue().getZExtValue();
-        auto Op = Icmp->getPredicate();
-        if (Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_UGE) {
-          if ((ConstOp1Val - 1) & ConstOp1Val)
-            continue;
-        } else if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_UGT) {
-          if (ConstOp1Val & (ConstOp1Val + 1))
-            continue;
-        } else {
-          continue;
-        }
-
-        Constant *Opcode =
-            ConstantInt::get(Type::getInt32Ty(BB.getContext()), Op);
-        Function *Fn = Intrinsic::getDeclaration(
-            M, Intrinsic::bpf_compare, {Op0->getType(), ConstOp1->getType()});
-        auto *NewInst = CallInst::Create(Fn, {Opcode, Op0, ConstOp1});
-        NewInst->insertBefore(&I);
-        Icmp->replaceAllUsesWith(NewInst);
-        Changed = true;
-        ToBeDeleted = Icmp;
-      }
-
-  return Changed;
+  return insertPassThrough();
 }
 
 bool SBFAdjustOptImpl::insertPassThrough() {

llvm/lib/Target/SBF/SBFCheckAndAdjustIR.cpp

@@ -20,14 +20,10 @@
 #include "SBFTargetMachine.h"
 #include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/GlobalVariable.h"
-#include "llvm/IR/Instruction.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Module.h"
-#include "llvm/IR/Type.h"
-#include "llvm/IR/User.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Pass.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
 
 #define DEBUG_TYPE "sbf-check-and-opt-ir"
 
@@ -46,7 +42,6 @@ class SBFCheckAndAdjustIR final : public ModulePass {
   void checkIR(Module &M);
   bool adjustIR(Module &M);
   bool removePassThroughBuiltin(Module &M);
-  bool removeCompareBuiltin(Module &M);
 };
 } // End anonymous namespace
 
@@ -121,50 +116,8 @@ bool SBFCheckAndAdjustIR::removePassThroughBuiltin(Module &M) {
   return Changed;
 }
 
-bool SBFCheckAndAdjustIR::removeCompareBuiltin(Module &M) {
-  // Remove __builtin_bpf_compare()'s which are used to prevent
-  // certain IR optimizations. Now major IR optimizations are done,
-  // remove them.
-  bool Changed = false;
-  CallInst *ToBeDeleted = nullptr;
-  for (Function &F : M)
-    for (auto &BB : F)
-      for (auto &I : BB) {
-        if (ToBeDeleted) {
-          ToBeDeleted->eraseFromParent();
-          ToBeDeleted = nullptr;
-        }
-
-        auto *Call = dyn_cast<CallInst>(&I);
-        if (!Call)
-          continue;
-        auto *GV = dyn_cast<GlobalValue>(Call->getCalledOperand());
-        if (!GV)
-          continue;
-        if (!GV->getName().startswith("llvm.bpf.compare"))
-          continue;
-
-        Changed = true;
-        Value *Arg0 = Call->getArgOperand(0);
-        Value *Arg1 = Call->getArgOperand(1);
-        Value *Arg2 = Call->getArgOperand(2);
-
-        auto OpVal = cast<ConstantInt>(Arg0)->getValue().getZExtValue();
-        CmpInst::Predicate Opcode = (CmpInst::Predicate)OpVal;
-
-        auto *ICmp = new ICmpInst(Opcode, Arg1, Arg2);
-        ICmp->insertBefore(Call);
-
-        Call->replaceAllUsesWith(ICmp);
-        ToBeDeleted = Call;
-      }
-  return Changed;
-}
-
 bool SBFCheckAndAdjustIR::adjustIR(Module &M) {
-  bool Changed = removePassThroughBuiltin(M);
-  Changed = removeCompareBuiltin(M) || Changed;
-  return Changed;
+  return removePassThroughBuiltin(M);
 }
 
 bool SBFCheckAndAdjustIR::runOnModule(Module &M) {