[PATCH] D138853: [InstSimplify] Fold !(X || Y) && X --> false

[Sanjay Patel via Phabricator via llvm-commits]

spatel added inline comments.


================
Comment at: llvm/lib/Analysis/InstructionSimplify.cpp:4567-4568
+      // !(X || Y) && X --> false (commuted 2 ways)
+      if (match(Cond, m_Not(m_LogicalOr(m_Value(X), m_Value(Y)))) &&
+          (TrueVal == X || TrueVal == Y))
+        return ConstantInt::getFalse(Cond->getType());
----------------
Shorten:
      if (match(Cond, m_Not(m_c_LogicalOr(m_Specific(TrueVal), m_Value()))))



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Comment at: llvm/test/Transforms/InstSimplify/select-logical.ll:190
 
 define i1 @logical_or_not_and_comute_or(i1 %x, i1 %y) {
 ; CHECK-LABEL: @logical_or_not_and_comute_or(
----------------
typo: comute -> commute


================
Comment at: llvm/test/Transforms/InstSimplify/select-logical.ll:223
   %not = xor <3 x i1> %l.and, <i1 true, i1 true, i1 true>
   %r = select <3 x i1> %not, <3 x i1> %x, <3 x i1> <i1 true, i1 false, i1 false>
   ret <3 x i1> %r
----------------
The FalseVal of `%r` is not zero, so this is not showing what the comment describes. This might need a TODO if we don't match the first select as logical-or?


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D138853/new/

https://reviews.llvm.org/D138853