[llvm] [X86] Remove redundant code in X86 (PR #157687)

[via llvm-commits]

https://github.com/AZero13 updated https://github.com/llvm/llvm-project/pull/157687

>From 1129f0ab4a4122065e5cd6c541d2de45f878cb9a Mon Sep 17 00:00:00 2001
From: AZero13 <gfunni234 at gmail.com>
Date: Tue, 9 Sep 2025 11:08:21 -0400
Subject: [PATCH 1/2] [X86] Remove redundant code in X86

These transforms are now handled in DAGCombine, so enable hasAndNotCompare for the same cases for X86, and remove the platform-specific code that does the same thing.
---
 llvm/lib/Target/X86/X86ISelLowering.cpp | 52 +------------------------
 1 file changed, 2 insertions(+), 50 deletions(-)

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 08ae0d52d795e..f4df70206105e 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -3489,19 +3489,8 @@ bool X86TargetLowering::isMaskAndCmp0FoldingBeneficial(
 }
 
 bool X86TargetLowering::hasAndNotCompare(SDValue Y) const {
-  EVT VT = Y.getValueType();
-
-  if (VT.isVector())
-    return false;
-
-  if (!Subtarget.hasBMI())
-    return false;
-
-  // There are only 32-bit and 64-bit forms for 'andn'.
-  if (VT != MVT::i32 && VT != MVT::i64)
-    return false;
-
-  return !isa<ConstantSDNode>(Y) || cast<ConstantSDNode>(Y)->isOpaque();
+  // Can use andn for any scalar integer.
+  return Y.getValueType().isScalarInteger();
 }
 
 bool X86TargetLowering::hasAndNot(SDValue Y) const {
@@ -3511,7 +3500,6 @@ bool X86TargetLowering::hasAndNot(SDValue Y) const {
     return hasAndNotCompare(Y);
 
   // Vector.
-
   if (!Subtarget.hasSSE1() || VT.getSizeInBits() < 128)
     return false;
 
@@ -56333,42 +56321,6 @@ static SDValue combineSetCC(SDNode *N, SelectionDAG &DAG,
 
   if (CC == ISD::SETNE || CC == ISD::SETEQ) {
     if (OpVT.isScalarInteger()) {
-      // cmpeq(or(X,Y),X) --> cmpeq(and(~X,Y),0)
-      // cmpne(or(X,Y),X) --> cmpne(and(~X,Y),0)
-      auto MatchOrCmpEq = [&](SDValue N0, SDValue N1) {
-        if (N0.getOpcode() == ISD::OR && N0->hasOneUse()) {
-          if (N0.getOperand(0) == N1)
-            return DAG.getNode(ISD::AND, DL, OpVT, DAG.getNOT(DL, N1, OpVT),
-                               N0.getOperand(1));
-          if (N0.getOperand(1) == N1)
-            return DAG.getNode(ISD::AND, DL, OpVT, DAG.getNOT(DL, N1, OpVT),
-                               N0.getOperand(0));
-        }
-        return SDValue();
-      };
-      if (SDValue AndN = MatchOrCmpEq(LHS, RHS))
-        return DAG.getSetCC(DL, VT, AndN, DAG.getConstant(0, DL, OpVT), CC);
-      if (SDValue AndN = MatchOrCmpEq(RHS, LHS))
-        return DAG.getSetCC(DL, VT, AndN, DAG.getConstant(0, DL, OpVT), CC);
-
-      // cmpeq(and(X,Y),Y) --> cmpeq(and(~X,Y),0)
-      // cmpne(and(X,Y),Y) --> cmpne(and(~X,Y),0)
-      auto MatchAndCmpEq = [&](SDValue N0, SDValue N1) {
-        if (N0.getOpcode() == ISD::AND && N0->hasOneUse()) {
-          if (N0.getOperand(0) == N1)
-            return DAG.getNode(ISD::AND, DL, OpVT, N1,
-                               DAG.getNOT(DL, N0.getOperand(1), OpVT));
-          if (N0.getOperand(1) == N1)
-            return DAG.getNode(ISD::AND, DL, OpVT, N1,
-                               DAG.getNOT(DL, N0.getOperand(0), OpVT));
-        }
-        return SDValue();
-      };
-      if (SDValue AndN = MatchAndCmpEq(LHS, RHS))
-        return DAG.getSetCC(DL, VT, AndN, DAG.getConstant(0, DL, OpVT), CC);
-      if (SDValue AndN = MatchAndCmpEq(RHS, LHS))
-        return DAG.getSetCC(DL, VT, AndN, DAG.getConstant(0, DL, OpVT), CC);
-
       // cmpeq(trunc(x),C) --> cmpeq(x,C)
       // cmpne(trunc(x),C) --> cmpne(x,C)
       // iff x upper bits are zero.

>From a453f8ba2b547fcee9751c1a76e9d8b98d990b3a Mon Sep 17 00:00:00 2001
From: AZero13 <gfunni234 at gmail.com>
Date: Tue, 9 Sep 2025 11:28:17 -0400
Subject: [PATCH 2/2] Update X86ISelLowering.cpp

---
 llvm/lib/Target/X86/X86ISelLowering.cpp | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index f4df70206105e..d3752c7a84a3e 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -3496,8 +3496,9 @@ bool X86TargetLowering::hasAndNotCompare(SDValue Y) const {
 bool X86TargetLowering::hasAndNot(SDValue Y) const {
   EVT VT = Y.getValueType();
 
-  if (!VT.isVector())
-    return hasAndNotCompare(Y);
+  if (!VT.isVector()) {
+    return !isa<ConstantSDNode>(Y) || cast<ConstantSDNode>(Y)->isOpaque();
+  }
 
   // Vector.
   if (!Subtarget.hasSSE1() || VT.getSizeInBits() < 128)