JIT: Remove FEATURE_SET_FLAGS, clean up arm32 flags (#104778)

- Remove `FEATURE_SET_FLAGS`
- Remove `GenTree::gtRequestSetFlags`
- Remove all manipulation of `GTF_SET_FLAGS` from morph
- Switch arm32 to be similar to other backends: only set
  `GTF_SET_FLAGS`  on IR nodes that need to set flags that upcoming
  nodes may use. Do not set it for IR nodes whose internal codegen sets
  and uses flags.

src/coreclr/jit/compiler.cpp

@@ -10391,15 +10391,10 @@ JITDBGAPI void __cdecl cTreeFlags(Compiler* comp, GenTree* tree)
         {
             chars += printf("[SPILLED_OPER]");
         }
-#if FEATURE_SET_FLAGS
         if (tree->gtFlags & GTF_SET_FLAGS)
         {
-            if ((op != GT_IND) && (op != GT_STOREIND))
-            {
-                chars += printf("[ZSF_SET_FLAGS]");
-            }
+            chars += printf("[SET_FLAGS]");
         }
-#endif
         if (tree->gtFlags & GTF_IND_NONFAULTING)
         {
             if (tree->OperIsIndirOrArrMetaData())

src/coreclr/jit/gentree.cpp

@@ -9961,81 +9961,7 @@ void Compiler::gtUpdateNodeSideEffects(GenTree* tree)
 
 bool GenTree::gtSetFlags() const
 {
-    //
-    // When FEATURE_SET_FLAGS (TARGET_ARM) is active the method returns true
-    //    when the gtFlags has the flag GTF_SET_FLAGS set
-    // otherwise the architecture will be have instructions that typically set
-    //    the flags and this method will return true.
-    //
-    //    Exceptions: GT_IND (load/store) is not allowed to set the flags
-    //                and on XARCH the GT_MUL/GT_DIV and all overflow instructions
-    //                do not set the condition flags
-    //
-    // Precondition we have a GTK_SMPOP
-    //
-    if (!varTypeIsIntegralOrI(TypeGet()) && (TypeGet() != TYP_VOID))
-    {
-        return false;
-    }
-
-    if (((gtFlags & GTF_SET_FLAGS) != 0) && (gtOper != GT_IND))
-    {
-        // GTF_SET_FLAGS is not valid on GT_IND and is overlaid with GTF_NONFAULTING_IND
-        return true;
-    }
-    else
-    {
-        return false;
-    }
-}
-
-bool GenTree::gtRequestSetFlags()
-{
-    bool result = false;
-
-#if FEATURE_SET_FLAGS
-    // This method is a Nop unless FEATURE_SET_FLAGS is defined
-
-    // In order to set GTF_SET_FLAGS
-    //              we must have a GTK_SMPOP
-    //          and we have a integer or machine size type (not floating point or TYP_LONG on 32-bit)
-    //
-    if (!OperIsSimple())
-        return false;
-
-    if (!varTypeIsIntegralOrI(TypeGet()))
-        return false;
-
-    switch (gtOper)
-    {
-        case GT_IND:
-        case GT_ARR_LENGTH:
-        case GT_MDARR_LENGTH:
-        case GT_MDARR_LOWER_BOUND:
-            // These will turn into simple load from memory instructions
-            // and we can't force the setting of the flags on load from memory
-            break;
-
-        case GT_MUL:
-        case GT_DIV:
-            // These instructions don't set the flags (on x86/x64)
-            //
-            break;
-
-        default:
-            // Otherwise we can set the flags for this gtOper
-            // and codegen must set the condition flags.
-            //
-            gtFlags |= GTF_SET_FLAGS;
-            result = true;
-            break;
-    }
-#endif // FEATURE_SET_FLAGS
-
-    // Codegen for this tree must set the condition flags if
-    // this method returns true.
-    //
-    return result;
+    return (gtFlags & GTF_SET_FLAGS) != 0;
 }
 
 GenTreeUseEdgeIterator::GenTreeUseEdgeIterator()
@@ -10680,10 +10606,6 @@ bool GenTree::HandleKindDataIsInvariant(GenTreeFlags flags)
                                             : '-'); // H is for Hoist this expr
     printf("%c", (flags & GTF_REVERSE_OPS) ? 'R' : '-');
     printf("%c", (flags & GTF_UNSIGNED) ? 'U' : (flags & GTF_BOOLEAN) ? 'B' : '-');
-#if FEATURE_SET_FLAGS
-    printf("%c", (flags & GTF_SET_FLAGS) ? 'S' : '-');
-    ++charsDisplayed;
-#endif
 
     // Both GTF_SPILL and GTF_SPILLED: '#'
     //               Only GTF_SPILLED: 'z'
@@ -13281,10 +13203,6 @@ void Compiler::gtDispLIRNode(GenTree* node, const char* prefixMsg /* = nullptr *
 
         // 60 spaces for alignment
         printf("%-60s", "");
-#if FEATURE_SET_FLAGS
-        // additional flag enlarges the flag field by one character
-        printf(" ");
-#endif
 
         indentStack.Push(operandArc);
         indentStack.print();

src/coreclr/jit/gentree.h

@@ -2271,7 +2271,6 @@ struct GenTree
     bool gtOverflow() const;
     bool gtOverflowEx() const;
     bool gtSetFlags() const;
-    bool gtRequestSetFlags();
 
 #ifdef DEBUG
     static int         gtDispFlags(GenTreeFlags flags, GenTreeDebugFlags debugFlags);

src/coreclr/jit/lowerarmarch.cpp

@@ -75,7 +75,7 @@ bool Lowering::IsContainableImmed(GenTree* parentNode, GenTree* childNode) const
         emitAttr       attr   = emitActualTypeSize(childNode->TypeGet());
         emitAttr       size   = EA_SIZE(attr);
 #ifdef TARGET_ARM
-        insFlags flags = parentNode->gtSetFlags() ? INS_FLAGS_SET : INS_FLAGS_DONT_CARE;
+        insFlags flags = (parentNode->gtOverflowEx() || parentNode->gtSetFlags()) ? INS_FLAGS_SET : INS_FLAGS_DONT_CARE;
 #endif
 
         switch (parentNode->OperGet())

src/coreclr/jit/morph.cpp

@@ -7610,14 +7610,6 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac, bool* optA
 
                 /* We also mark it as DONT_CSE, as we don't handle QMARKs with nonRELOP op1s */
                 op1->gtFlags |= (GTF_RELOP_JMP_USED | GTF_DONT_CSE);
-
-                // Request that the codegen for op1 sets the condition flags
-                // when it generates the code for op1.
-                //
-                // Codegen for op1 must set the condition flags if
-                // this method returns true.
-                //
-                op1->gtRequestSetFlags();
             }
             else
             {
@@ -8311,23 +8303,6 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac, bool* optA
     op1 = tree->AsOp()->gtOp1;
     op2 = tree->gtGetOp2IfPresent();
 
-    // Do we have an integer compare operation?
-    //
-    if (tree->OperIsCompare() && varTypeIsIntegralOrI(tree->TypeGet()))
-    {
-        // Are we comparing against zero?
-        //
-        if (op2->IsIntegralConst(0))
-        {
-            // Request that the codegen for op1 sets the condition flags
-            // when it generates the code for op1.
-            //
-            // Codegen for op1 must set the condition flags if
-            // this method returns true.
-            //
-            op1->gtRequestSetFlags();
-        }
-    }
     /*-------------------------------------------------------------------------
      * Perform the required oper-specific postorder morphing
      */
@@ -8619,8 +8594,6 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac, bool* optA
         CM_OVF_OP:
             if (tree->gtOverflow())
             {
-                tree->gtRequestSetFlags();
-
                 // Add the excptn-throwing basic block to jump to on overflow
 
                 fgAddCodeRef(compCurBB, SCK_OVERFLOW);

src/coreclr/jit/optimizebools.cpp

@@ -1273,30 +1273,6 @@ void OptBoolsDsc::optOptimizeBoolsUpdateTrees()
         --m_comp->fgReturnCount;
     }
 
-#if FEATURE_SET_FLAGS
-    // For comparisons against zero we will have the GTF_SET_FLAGS set
-    // and this can cause an assert to fire in fgMoveOpsLeft(GenTree* tree)
-    // during the CSE phase.
-    //
-    // So make sure to clear any GTF_SET_FLAGS bit on these operations
-    // as they are no longer feeding directly into a comparisons against zero
-
-    // Make sure that the GTF_SET_FLAGS bit is cleared.
-    // Fix 388436 ARM JitStress WP7
-    m_c1->gtFlags &= ~GTF_SET_FLAGS;
-    m_c2->gtFlags &= ~GTF_SET_FLAGS;
-
-    // The new top level node that we just created does feed directly into
-    // a comparison against zero, so set the GTF_SET_FLAGS bit so that
-    // we generate an instruction that sets the flags, which allows us
-    // to omit the cmp with zero instruction.
-
-    // Request that the codegen for cmpOp1 sets the condition flags
-    // when it generates the code for cmpOp1.
-    //
-    cmpOp1->gtRequestSetFlags();
-#endif
-
     // Recost/rethread the tree if necessary
     //
     if (m_comp->fgNodeThreading != NodeThreading::None)

src/coreclr/jit/targetamd64.h

@@ -29,7 +29,6 @@
   #define FEATURE_STRUCTPROMOTE    1       // JIT Optimization to promote fields of structs into registers
   #define FEATURE_FASTTAILCALL     1       // Tail calls made as epilog+jmp
   #define FEATURE_TAILCALL_OPT     1       // opportunistic Tail calls (i.e. without ".tail" prefix) made as fast tail calls.
-  #define FEATURE_SET_FLAGS        0       // Set to true to force the JIT to mark the trees with GTF_SET_FLAGS when the flags need to be set
   #define MAX_PASS_SINGLEREG_BYTES      8  // Maximum size of a struct passed in a single register (double).
 #ifdef    UNIX_AMD64_ABI
   #define FEATURE_IMPLICIT_BYREFS       1  // Support for struct parameters passed via pointers to shadow copies

src/coreclr/jit/targetarm.h

@@ -19,7 +19,6 @@
   #define FEATURE_MULTIREG_STRUCT_PROMOTE  0  // True when we want to promote fields of a multireg struct into registers
   #define FEATURE_FASTTAILCALL     1       // Tail calls made as epilog+jmp
   #define FEATURE_TAILCALL_OPT     1       // opportunistic Tail calls (i.e. without ".tail" prefix) made as fast tail calls.
-  #define FEATURE_SET_FLAGS        1       // Set to true to force the JIT to mark the trees with GTF_SET_FLAGS when the flags need to be set
   #define FEATURE_IMPLICIT_BYREFS       0  // Support for struct parameters passed via pointers to shadow copies
   #define FEATURE_MULTIREG_ARGS_OR_RET  1  // Support for passing and/or returning single values in more than one register (including HFA support)
   #define FEATURE_MULTIREG_ARGS         1  // Support for passing a single argument in more than one register (including passing HFAs)

src/coreclr/jit/targetarm64.h

@@ -21,7 +21,6 @@
   #define FEATURE_MULTIREG_STRUCT_PROMOTE 1  // True when we want to promote fields of a multireg struct into registers
   #define FEATURE_FASTTAILCALL     1       // Tail calls made as epilog+jmp
   #define FEATURE_TAILCALL_OPT     1       // opportunistic Tail calls (i.e. without ".tail" prefix) made as fast tail calls.
-  #define FEATURE_SET_FLAGS        0       // Set to true to force the JIT to mark the trees with GTF_SET_FLAGS when the flags need to be set
   #define FEATURE_IMPLICIT_BYREFS       1  // Support for struct parameters passed via pointers to shadow copies
   #define FEATURE_MULTIREG_ARGS_OR_RET  1  // Support for passing and/or returning single values in more than one register
   #define FEATURE_MULTIREG_ARGS         1  // Support for passing a single argument in more than one register

src/coreclr/jit/targetloongarch64.h

@@ -27,7 +27,6 @@
   #define FEATURE_MULTIREG_STRUCT_PROMOTE 1  // True when we want to promote fields of a multireg struct into registers
   #define FEATURE_FASTTAILCALL     1       // Tail calls made as epilog+jmp
   #define FEATURE_TAILCALL_OPT     1       // opportunistic Tail calls (i.e. without ".tail" prefix) made as fast tail calls.
-  #define FEATURE_SET_FLAGS        0       // Set to true to force the JIT to mark the trees with GTF_SET_FLAGS when the flags need to be set
   #define FEATURE_IMPLICIT_BYREFS       1  // Support for struct parameters passed via pointers to shadow copies
   #define FEATURE_MULTIREG_ARGS_OR_RET  1  // Support for passing and/or returning single values in more than one register
   #define FEATURE_MULTIREG_ARGS         1  // Support for passing a single argument in more than one register

src/coreclr/jit/targetriscv64.h

@@ -22,7 +22,6 @@
   #define FEATURE_MULTIREG_STRUCT_PROMOTE 1  // True when we want to promote fields of a multireg struct into registers
   #define FEATURE_FASTTAILCALL     1       // Tail calls made as epilog+jmp
   #define FEATURE_TAILCALL_OPT     1       // opportunistic Tail calls (i.e. without ".tail" prefix) made as fast tail calls.
-  #define FEATURE_SET_FLAGS        0       // Set to true to force the JIT to mark the trees with GTF_SET_FLAGS when the flags need to be set
   #define FEATURE_IMPLICIT_BYREFS       1  // Support for struct parameters passed via pointers to shadow copies
   #define FEATURE_MULTIREG_ARGS_OR_RET  1  // Support for passing and/or returning single values in more than one register
   #define FEATURE_MULTIREG_ARGS         1  // Support for passing a single argument in more than one register

src/coreclr/jit/targetx86.h

@@ -24,7 +24,6 @@
   #define FEATURE_MULTIREG_STRUCT_PROMOTE  0  // True when we want to promote fields of a multireg struct into registers
   #define FEATURE_FASTTAILCALL     0       // Tail calls made as epilog+jmp
   #define FEATURE_TAILCALL_OPT     0       // opportunistic Tail calls (without ".tail" prefix) made as fast tail calls.
-  #define FEATURE_SET_FLAGS        0       // Set to true to force the JIT to mark the trees with GTF_SET_FLAGS when
                                            // the flags need to be set
   #define FEATURE_IMPLICIT_BYREFS       0  // Support for struct parameters passed via pointers to shadow copies
   #define FEATURE_MULTIREG_ARGS_OR_RET  1  // Support for passing and/or returning single values in more than one register