[llvm] [LLVM][ISel][SVE] Remove redundant merging fp patterns. (PR #101351)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-aarch64

Author: Paul Walker (paulwalker-arm)

<details>
<summary>Changes</summary>

Since "vselect cond, (binop, x, y), x" became the canonical form the equivalent PatFrags for "binop x, (vselect cond, y, 0)" are no longer required.

---
Full diff: https://github.com/llvm/llvm-project/pull/101351.diff


3 Files Affected:

- (modified) llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp (-12) 
- (modified) llvm/lib/Target/AArch64/AArch64SVEInstrInfo.td (+2-14) 
- (modified) llvm/lib/Target/AArch64/SVEInstrFormats.td (-1) 


``````````diff
diff --git a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
index 55cc106c08b95..a3db3628c0686 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelDAGToDAG.cpp
@@ -239,18 +239,6 @@ class AArch64DAGToDAGISel : public SelectionDAGISel {
     return false;
   }
 
-  bool SelectDupNegativeZero(SDValue N) {
-    switch(N->getOpcode()) {
-    case AArch64ISD::DUP:
-    case ISD::SPLAT_VECTOR: {
-      ConstantFPSDNode *Const = dyn_cast<ConstantFPSDNode>(N->getOperand(0));
-      return Const && Const->isZero() && Const->isNegative();
-    }
-    }
-
-    return false;
-  }
-
   template<MVT::SimpleValueType VT>
   bool SelectSVEAddSubImm(SDValue N, SDValue &Imm, SDValue &Shift) {
     return SelectSVEAddSubImm(N, VT, Imm, Shift);
diff --git a/llvm/lib/Target/AArch64/AArch64SVEInstrInfo.td b/llvm/lib/Target/AArch64/AArch64SVEInstrInfo.td
index a3c41f2e052cd..19c03011e07b2 100644
--- a/llvm/lib/Target/AArch64/AArch64SVEInstrInfo.td
+++ b/llvm/lib/Target/AArch64/AArch64SVEInstrInfo.td
@@ -213,18 +213,10 @@ def AArch64fadd_p_contract : PatFrag<(ops node:$op1, node:$op2, node:$op3),
                                      (AArch64fadd_p node:$op1, node:$op2, node:$op3), [{
   return N->getFlags().hasAllowContract();
 }]>;
-def AArch64fadd_p_nsz : PatFrag<(ops node:$op1, node:$op2, node:$op3),
-                                (AArch64fadd_p node:$op1, node:$op2, node:$op3), [{
-  return N->getFlags().hasNoSignedZeros();
-}]>;
 def AArch64fsub_p_contract : PatFrag<(ops node:$op1, node:$op2, node:$op3),
                                      (AArch64fsub_p node:$op1, node:$op2, node:$op3), [{
   return N->getFlags().hasAllowContract();
 }]>;
-def AArch64fsub_p_nsz : PatFrag<(ops node:$op1, node:$op2, node:$op3),
-                                (AArch64fsub_p node:$op1, node:$op2, node:$op3), [{
-  return N->getFlags().hasNoSignedZeros();
-}]>;
 
 def SDT_AArch64Arith_Imm : SDTypeProfile<1, 3, [
   SDTCisVec<0>, SDTCisVec<1>, SDTCisVec<2>, SDTCisVT<3,i32>,
@@ -281,15 +273,11 @@ def AArch64not_mt  : PatFrags<(ops node:$pg, node:$op, node:$pt), [(int_aarch64_
 def AArch64fmul_m1 : VSelectPredOrPassthruPatFrags<int_aarch64_sve_fmul, AArch64fmul_p>;
 def AArch64fadd_m1 : PatFrags<(ops node:$pg, node:$op1, node:$op2), [
     (int_aarch64_sve_fadd node:$pg, node:$op1, node:$op2),
-    (vselect node:$pg, (AArch64fadd_p (SVEAllActive), node:$op1, node:$op2), node:$op1),
-    (AArch64fadd_p_nsz (SVEAllActive), node:$op1, (vselect node:$pg, node:$op2, (SVEDup0))),
-    (AArch64fadd_p (SVEAllActive), node:$op1, (vselect node:$pg, node:$op2, (SVEDupNeg0)))
+    (vselect node:$pg, (AArch64fadd_p (SVEAllActive), node:$op1, node:$op2), node:$op1)
 ]>;
 def AArch64fsub_m1 : PatFrags<(ops node:$pg, node:$op1, node:$op2), [
     (int_aarch64_sve_fsub node:$pg, node:$op1, node:$op2),
-    (vselect node:$pg, (AArch64fsub_p (SVEAllActive), node:$op1, node:$op2), node:$op1),
-    (AArch64fsub_p (SVEAllActive), node:$op1, (vselect node:$pg, node:$op2, (SVEDup0))),
-    (AArch64fsub_p_nsz (SVEAllActive), node:$op1, (vselect node:$pg, node:$op2, (SVEDupNeg0)))
+    (vselect node:$pg, (AArch64fsub_p (SVEAllActive), node:$op1, node:$op2), node:$op1)
 ]>;
 
 def AArch64shadd : PatFrags<(ops node:$pg, node:$op1, node:$op2),
diff --git a/llvm/lib/Target/AArch64/SVEInstrFormats.td b/llvm/lib/Target/AArch64/SVEInstrFormats.td
index fc7d3cdda4acd..482d3a0664d72 100644
--- a/llvm/lib/Target/AArch64/SVEInstrFormats.td
+++ b/llvm/lib/Target/AArch64/SVEInstrFormats.td
@@ -446,7 +446,6 @@ multiclass SVE_1_Op_PassthruUndef_Round_Pat<ValueType vtd, SDPatternOperator op,
 }
 
 def SVEDup0 : ComplexPattern<vAny, 0, "SelectDupZero", []>;
-def SVEDupNeg0 : ComplexPattern<vAny, 0, "SelectDupNegativeZero", []>;
 
 class SVE_1_Op_PassthruZero_Pat<ValueType vtd, SDPatternOperator op, ValueType vt1,
                    ValueType vt2, Instruction inst>

``````````

</details>


https://github.com/llvm/llvm-project/pull/101351