[PATCH] D138815: [InstSimplify] Fold (X || Y) ? X : Y --> X

[chenglin.bi via Phabricator via llvm-commits]

bcl5980 added inline comments.


================
Comment at: llvm/lib/Analysis/InstructionSimplify.cpp:4558
 
+    // (X || Y) ? X : Y --> X (commuted 2 ways)
+    if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Specific(FalseVal))))
----------------
Hi @spatel , which way do you think is better here?


```
    // (X || Y) ? X : Y --> X (commuted 2 ways)
    if (match(Cond, m_c_LogicalOr(m_Specific(TrueVal), m_Specific(FalseVal))))
      return TrueVal;

    // (X || Y) ? false : X --> false (commuted 2 ways)
    if (match(Cond, m_c_LogicalOr(m_Specific(FalseVal), m_Value())) &&
        match(TrueVal, m_ZeroInt()))
      return ConstantInt::getFalse(Cond->getType());
```
or

```
    if (match(Cond, m_LogicalOr(m_Value(X), m_Value(Y)))) {
      // (X || Y) ? X : Y --> X
      if ((X == TrueVal && Y == FalseVal) || (X == FalseVal && Y == TrueVal))
        return TrueVal;

      // (X || Y) ? false : X --> false (commuted 2 ways)
      if (match(TrueVal, m_ZeroInt()) && (X == FalseVal || Y == FalseVal))
        return ConstantInt::getFalse(Cond->getType());
    }


```


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  https://reviews.llvm.org/D138815/new/

https://reviews.llvm.org/D138815