[llvm] [InstSimplify] Simplify select if it combinated `and/or/xor` (PR #73362)

[via llvm-commits]

================
@@ -4585,6 +4585,57 @@ static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS,
                                Pred == ICmpInst::ICMP_EQ);
 }
 
+/// Try to simplify the Select instruction consisting of add/or/xor.
+static Value *simplifySpecificBitOp(Value *CmpLHS, Value *CmpRHS,
+                                    Value *TrueVal, Value *FalseVal) {
+  Value *X, *Y;
+  // (X & Y) == 0 ? X | Y : X ^ Y   --> X ^ Y
+  // (X & Y) == 0 ? X ^ Y : X | Y   --> X | Y
+  // (X & Y) != 0 ? X | Y : X ^ Y   --> X | Y
+  // (X & Y) != 0 ? X ^ Y : X | Y   --> X ^ Y
+  if (match(CmpLHS, m_And(m_Value(X), m_Value(Y))) && match(CmpRHS, m_Zero())) {
+    if ((match(TrueVal, m_c_Or(m_Specific(X), m_Specific(Y))) &&
+         match(FalseVal, m_c_Xor(m_Specific(X), m_Specific(Y)))) ||
+        (match(FalseVal, m_c_Or(m_Specific(X), m_Specific(Y))) &&
+         match(TrueVal, m_c_Xor(m_Specific(X), m_Specific(Y)))))
+      return FalseVal;
+  }
+  // (X | Y) == 0 ? X & Y : X ^ Y   --> X ^ Y
+  // (X | Y) == 0 ? X ^ Y : X & Y   --> X & Y
+  // (X | Y) != 0 ? X & Y : X ^ Y   --> X & Y
+  // (X | Y) != 0 ? X ^ Y : X & Y   --> X ^ Y
+  if (match(CmpLHS, m_Or(m_Value(X), m_Value(Y))) && match(CmpRHS, m_Zero())) {
+    if ((match(TrueVal, m_c_And(m_Specific(X), m_Specific(Y))) &&
+         match(FalseVal, m_c_Xor(m_Specific(X), m_Specific(Y)))) ||
+        (match(FalseVal, m_c_And(m_Specific(X), m_Specific(Y))) &&
+         match(TrueVal, m_c_Xor(m_Specific(X), m_Specific(Y)))))
+      return FalseVal;
+  }
+  // (X ^ Y) == 0 ? X | Y : X & Y   --> X & Y
+  // (X ^ Y) == 0 ? X & Y : X | Y   --> X | Y
+  // (X ^ Y) != 0 ? X | Y : X & Y   --> X | Y
+  // (X ^ Y) != 0 ? X & Y : X | Y   --> X & Y
+  if (match(CmpLHS, m_Xor(m_Value(X), m_Value(Y))) && match(CmpRHS, m_Zero())) {
+    if ((match(TrueVal, m_c_And(m_Specific(X), m_Specific(Y))) &&
+         match(FalseVal, m_c_Or(m_Specific(X), m_Specific(Y)))) ||
+        (match(FalseVal, m_c_And(m_Specific(X), m_Specific(Y))) &&
+         match(TrueVal, m_c_Or(m_Specific(X), m_Specific(Y)))))
+      return FalseVal;
+  }
+
+  // (X ^ Y) == 0 could be transformed to X == Y
+  // (X ^ Y) != 0 could be transformed to X != Y
+  if (match(CmpLHS, m_Value(X)) && match(CmpRHS, m_Value(Y))) {
+    if ((match(TrueVal, m_c_And(m_Specific(X), m_Specific(Y))) &&
+         match(FalseVal, m_c_Or(m_Specific(X), m_Specific(Y)))) ||
+        (match(FalseVal, m_c_And(m_Specific(X), m_Specific(Y))) &&
+         match(TrueVal, m_c_Or(m_Specific(X), m_Specific(Y)))))
+      return FalseVal;
+  }
----------------
ParkHanbum wrote:

I think it is necessary. because Select ICmp is must be "X (comp) Y". here is example:
```
define i32 @src_select_xor_max_positive_int(i32 %x, i32 %y) {
; CHECK-LABEL: @src_select_xor_max_positive_int(
; CHECK-NEXT:    [[XOR:%.*]] = xor i32 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT:    [[XOR0:%.*]] = icmp eq i32 [[XOR]], 2147483647
; CHECK-NEXT:    [[AND:%.*]] = and i32 [[X]], [[Y]]
; CHECK-NEXT:    [[OR:%.*]] = or i32 [[X]], [[Y]]
; CHECK-NEXT:    [[COND:%.*]] = select i1 [[XOR0]], i32 [[AND]], i32 [[OR]]
; CHECK-NEXT:    ret i32 [[COND]]
;
  %xor = xor i32 %x, %y
  %xor0 = icmp eq i32 %xor, 2147483647
  %and = and i32 %x, %y
  %or = or i32 %x, %y
  %cond = select i1 %xor0, i32 %and, i32 %or
  ret i32 %cond
}
```
without `if (match(CmpLHS, m_Value(X)) && match(CmpRHS, m_Value(Y))) {`  condition then 
`  %and = and i32 %x, %y
  %or = or i32 %x, %y`
will match case. 

am I right?

https://github.com/llvm/llvm-project/pull/73362