[PATCH] D140666: [InstCombine] combine intersection for inequality icmps

[chenglin.bi via Phabricator via llvm-commits]

bcl5980 added inline comments.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:628
 
-  if (Mask & BMask_Mixed) {
+  if (Mask & BMask_Mixed || Mask & BMask_NotMixed) {
+    // (icmp eq (A & B), C) &/| (icmp eq (A & D), E)
----------------
Is `Mask & (BMask_Mixed | BMask_NotMixed)` better?


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:682
+
+    if ((~*ConstB & ConstC) != 0 || (~*ConstD & ConstE) != 0)
+      return nullptr;
----------------
I think this code can be shared by both BMask_Mixed and BMask_NotMixed also.


================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:686
+    // If there is a conflict, we still have to check both sides.
     if (((*ConstB & *ConstD) & (ConstC ^ ConstE)).getBoolValue())
+      return nullptr;
----------------
Is this condition the same to line 660 ? Can we add some code like:

```
if (((*ConstB & *ConstD) & (ConstC ^ ConstE)).getBoolValue())
  return isMixed ? ConstantInt::get(LHS->getType(), !IsAnd) : nullptr
```




================
Comment at: llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:689
 
-    Value *NewOr1 = Builder.CreateOr(B, D);
-    Value *NewAnd = Builder.CreateAnd(A, NewOr1);
-    Constant *NewOr2 = ConstantInt::get(A->getType(), ConstC | ConstE);
-    return Builder.CreateICmp(NewCC, NewAnd, NewOr2);
+    Value *NewAnd1 = Builder.CreateAnd(A, ConstT);
+    Value *NewAnd2 = ConstantInt::get(A->getType(), ConstC & ConstE);
----------------
This also can be shared by select like:

```
Value *ICmpLHS = Builder.CreateBinOp(isMixed ? Instruction::Or : Instruction::And);
Value * ICmpRHS = ConstantInt::get(A->getType(), isMixed ? (ConstC | ConstE) : (ConstC & ConstE));
```

Or you can check isMixed at first:

```
Instruction::BinaryOps ICmpLHSOpcode;
APInt ICmpRHSAP;
Value* ICmpAndConflictBailout;
if (isMixed) {
  ICmpLHSOpcode = Instruction::Or;
  ICmpRHSAP = ConstC | ConstE;
  ICmpAndConflictBailout = ConstantInt::get(LHS->getType(), !IsAnd);
} else {
  ICmpLHSOpcode = Instruction::And;
  ICmpRHSAP = ConstC & ConstE;
  ICmpAndConflictBailout = ConstantInt::get(LHS->getType(), !IsAnd);
}
```




Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D140666/new/

https://reviews.llvm.org/D140666