[llvm] [DAG] Add SDPatternMatch m_ZExtOrSelf/m_SExtOrSelf/m_AExtOrSelf/m_TruncOrSelf matchers (PR #85480)

[Simon Pilgrim via llvm-commits]

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@@ -737,6 +737,39 @@ template <typename ValTy>
 inline BinaryOpc_match<ValTy, SpecificInt_match, true> m_Not(const ValTy &V) {
   return m_Xor(V, m_AllOnes());
 }
+
+/// Match a zext or identity
+/// Allows to peek through optional extensions
+template <typename Opnd>
+inline Or<UnaryOpc_match<Opnd>, Opnd> m_ZExtOrSelf(Opnd &&Op) {
+  return Or<UnaryOpc_match<Opnd>, Opnd>(m_ZExt(std::forward<Opnd>(Op)),
+                                        std::forward<Opnd>(Op));
+}
+
+/// Match a sext or identity
+/// Allows to peek through optional extensions
+template <typename Opnd>
+inline Or<UnaryOpc_match<Opnd>, Opnd> m_SExtOrSelf(Opnd &&Op) {
+  return Or<UnaryOpc_match<Opnd>, Opnd>(m_SExt(std::forward<Opnd>(Op)),
+                                        std::forward<Opnd>(Op));
+}
+
+/// Match a aext or identity
+/// Allows to peek through optional extensions
+template <typename Opnd>
+inline Or<UnaryOpc_match<Opnd>, Opnd> m_AExtOrSelf(Opnd &&Op) {
+  return Or<UnaryOpc_match<Opnd>, Opnd>(m_AnyExt(std::forward<Opnd>(Op)),
+                                        std::forward<Opnd>(Op));
+}
+
+/// Match a trunc or identity
+/// Allows to peek through optional truncations
+template <typename Opnd>
+inline Or<UnaryOpc_match<Opnd>, Opnd> m_TruncOrSelf(Opnd &&Op) {
+  return Or<UnaryOpc_match<Opnd>, Opnd>(m_Trunc(std::forward<Opnd>(Op)),
+                                        std::forward<Opnd>(Op));
+}
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RKSimon wrote:

(pedantic) but would it be possible to move these next to the other m_*ext/m_Trunc variants?

https://github.com/llvm/llvm-project/pull/85480