[llvm] [X86] Extend `combinei64TruncSrlAdd` to handle patterns with `or` and `xor` (PR #128435)

[Phoebe Wang via llvm-commits]

=?utf-8?q?João?= Gouveia <jtalonegouveia at gmail.com>,
=?utf-8?q?João?= Gouveia <jtalonegouveia at gmail.com>,
=?utf-8?q?João?= Gouveia <jtalonegouveia at gmail.com>,
=?utf-8?q?João?= Gouveia <jtalonegouveia at gmail.com>,
=?utf-8?q?João?= Gouveia <jtalonegouveia at gmail.com>
Message-ID:
In-Reply-To: <llvm.org/llvm/llvm-project/pull/128435 at github.com>


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@@ -53733,36 +53733,47 @@ static SDValue combineLRINT_LLRINT(SDNode *N, SelectionDAG &DAG,
   return DAG.getNode(X86ISD::CVTP2SI, DL, VT, Src);
 }
 
-// Attempt to fold some (truncate (srl (add X, C1), C2)) patterns to
-// (add (truncate (srl X, C2)), C1'). C1' will be smaller than C1 so we are able
-// to avoid generating code with MOVABS and large constants in certain cases.
-static SDValue combinei64TruncSrlAdd(SDValue N, EVT VT, SelectionDAG &DAG,
-                                     const SDLoc &DL) {
-  using namespace llvm::SDPatternMatch;
+// Attempt to fold some (truncate (srl (add/or/xor X, C1), C2)) patterns to
+// (add/or/xor (truncate (srl X, C2)), C1'). C1' will be smaller than C1 so we
+// are able to avoid generating code with MOVABS and large constants in certain
+// cases.
+static SDValue combinei64TruncSrlConstant(SDValue N, EVT VT, SelectionDAG &DAG,
+                                          const SDLoc &DL) {
 
-  SDValue AddLhs;
-  APInt AddConst, SrlConst;
-  if (VT != MVT::i32 ||
-      !sd_match(N, m_AllOf(m_SpecificVT(MVT::i64),
-                           m_Srl(m_OneUse(m_Add(m_Value(AddLhs),
-                                                m_ConstInt(AddConst))),
-                                 m_ConstInt(SrlConst)))))
-    return SDValue();
+  SDValue Op = N.getOperand(0);
+  APInt OpConst = Op.getConstantOperandAPInt(1);
+  APInt SrlConst = N.getConstantOperandAPInt(1);
+  unsigned Opcode = Op.getOpcode();
 
-  if (SrlConst.ule(32) || AddConst.countr_zero() < SrlConst.getZExtValue())
+  switch (Opcode) {
----------------
phoebewang wrote:

No need to use switch since we have limit to ADD/OR/XOR in `combineTruncatedArithmetic`.

https://github.com/llvm/llvm-project/pull/128435