[PATCH] D49229: [InstCombine] Fold redundant masking operations of shifted value

[Diogo N. Sampaio via Phabricator via llvm-commits]

dnsampaio marked 2 inline comments as done.
dnsampaio added inline comments.


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Comment at: lib/Transforms/InstCombine/InstCombineAndOrXor.cpp:2026-2036
+  // 1st: Check for desired pattern
+  if (match(&I, m_c_Or(m_And(m_OneUse(m_Shift(m_Value(X), m_APInt(ShftAmt))),
+                             m_APInt(ShAndC)),
+                       m_And(m_Deferred(X), m_APInt(AndC))))) {
+    // 2nd: Find out which AND is which
+    BinaryOperator *And = cast<BinaryOperator>(A), *Shift, *ShtAnd;
+    if (And->getOperand(0) != X) {
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lebedev.ri wrote:
> See `m_CombineAnd()`.
Nice one, it took me some time to understand that I could match and then capture. Thanks. :)


https://reviews.llvm.org/D49229