Remove pointless use of GTF_ZSF_SET

It doesn't make sense to ContainCheckBinary and others set GTF_ZSF_SET on all nodes. There are far more ADD/SUB/AND/OR/XOR nodes than relop nodes that may reuse the flags set by the previous node.

Author: mikedn

src/jit/compiler.cpp

@@ -9781,11 +9781,11 @@ int cTreeFlagsIR(Compiler* comp, GenTree* tree)
         {
             chars += printf("[SPILLED_OP2]");
         }
-#endif
         if (tree->gtFlags & GTF_ZSF_SET)
         {
             chars += printf("[ZSF_SET]");
         }
+#endif
 #if FEATURE_SET_FLAGS
         if (tree->gtFlags & GTF_SET_FLAGS)
         {

src/jit/gentree.h

@@ -856,11 +856,11 @@ struct GenTree
 #ifdef LEGACY_BACKEND
 #define GTF_SPILLED_OPER 0x00000100 // op1 has been spilled
 #define GTF_SPILLED_OP2  0x00000200 // op2 has been spilled
+#define GTF_ZSF_SET      0x00000400 // the zero(ZF) and sign(SF) flags set to the operand
 #else  // !LEGACY_BACKEND
 #define GTF_NOREG_AT_USE 0x00000100 // tree node is in memory at the point of use
 #endif // !LEGACY_BACKEND
 
-#define GTF_ZSF_SET     0x00000400 // the zero(ZF) and sign(SF) flags set to the operand
 #define GTF_SET_FLAGS   0x00000800 // Requires that codegen for this node set the flags. Use gtSetFlags() to check this flag.
 #define GTF_USE_FLAGS   0x00001000 // Indicates that this node uses the flags bits.
 
@@ -2123,12 +2123,14 @@ struct GenTree
     bool gtSetFlags() const;
     bool gtRequestSetFlags();
 
+#ifdef LEGACY_BACKEND
     // Returns true if the codegen of this tree node
     // sets ZF and SF flags.
     bool gtSetZSFlags() const
     {
         return (gtFlags & GTF_ZSF_SET) != 0;
     }
+#endif
 
 #ifdef DEBUG
     bool       gtIsValid64RsltMul();

src/jit/lower.cpp

@@ -142,16 +142,6 @@ GenTree* Lowering::LowerNode(GenTree* node)
             ContainCheckBinary(node->AsOp());
             break;
 
-#ifdef _TARGET_XARCH_
-        case GT_NEG:
-            // Codegen of this tree node sets ZF and SF flags.
-            if (!varTypeIsFloating(node))
-            {
-                node->gtFlags |= GTF_ZSF_SET;
-            }
-            break;
-#endif // _TARGET_XARCH_
-
         case GT_MUL:
         case GT_MULHI:
 #if defined(_TARGET_X86_) && !defined(LEGACY_BACKEND)
@@ -2618,8 +2608,8 @@ GenTree* Lowering::LowerCompare(GenTree* cmp)
         GenTree* op2 = cmp->gtGetOp2();
         LIR::Use cmpUse;
 
-        if (op1->gtSetZSFlags() && op2->IsIntegralConst(0) && (op1->gtNext == op2) && (op2->gtNext == cmp) &&
-            BlockRange().TryGetUse(cmp, &cmpUse))
+        if (op1->OperIs(GT_AND, GT_OR, GT_XOR, GT_ADD, GT_SUB, GT_NEG) && op2->IsIntegralConst(0) &&
+            (op1->gtNext == op2) && (op2->gtNext == cmp) && BlockRange().TryGetUse(cmp, &cmpUse))
         {
             genTreeOps condition = cmp->OperGet();
             GenTree*   next      = cmp->gtNext;
@@ -5402,16 +5392,6 @@ void Lowering::ContainCheckNode(GenTree* node)
             ContainCheckBinary(node->AsOp());
             break;
 
-#ifdef _TARGET_XARCH_
-        case GT_NEG:
-            // Codegen of this tree node sets ZF and SF flags.
-            if (!varTypeIsFloating(node))
-            {
-                node->gtFlags |= GTF_ZSF_SET;
-            }
-            break;
-#endif // _TARGET_XARCH_
-
 #if defined(_TARGET_X86_)
         case GT_MUL_LONG:
 #endif

src/jit/lowerxarch.cpp

@@ -2010,9 +2010,6 @@ void Lowering::ContainCheckBinary(GenTreeOp* node)
         return;
     }
 
-    // Codegen of these tree nodes sets ZF and SF flags.
-    node->gtFlags |= GTF_ZSF_SET;
-
     // We're not marking a constant hanging on the left of an add
     // as containable so we assign it to a register having CQ impact.
     // TODO-XArch-CQ: Detect this case and support both generating a single instruction