JIT: Remove JTRUE(relop) invariant in the backend

src/coreclr/jit/codegen.h

@@ -1610,6 +1610,7 @@ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
 
     void genCodeForJcc(GenTreeCC* tree);
     void genCodeForSetcc(GenTreeCC* setcc);
+    void genCodeForJTrue(GenTreeOp* jtrue);
 #endif // !TARGET_LOONGARCH64
 };
 

src/coreclr/jit/codegenarm.cpp

@@ -1274,6 +1274,22 @@ void CodeGen::genCodeForCompare(GenTreeOp* tree)
     }
 }
 
+//------------------------------------------------------------------------
+// genCodeForJTrue: Produce code for a GT_JTRUE node.
+//
+// Arguments:
+//    jtrue - the node
+//
+void CodeGen::genCodeForJTrue(GenTreeOp* jtrue)
+{
+    assert(compiler->compCurBB->bbJumpKind == BBJ_COND);
+
+    GenTree*  op  = jtrue->gtGetOp1();
+    regNumber reg = genConsumeReg(op);
+    inst_RV_RV(INS_tst, reg, reg, genActualType(op));
+    inst_JMP(EJ_ne, compiler->compCurBB->bbJumpDest);
+}
+
 //------------------------------------------------------------------------
 // genCodeForReturnTrap: Produce code for a GT_RETURNTRAP node.
 //

src/coreclr/jit/codegenarm64.cpp

@@ -4564,6 +4564,21 @@ void CodeGen::genCodeForCompare(GenTreeOp* tree)
     }
 }
 
+//------------------------------------------------------------------------
+// genCodeForJTrue: Produce code for a GT_JTRUE node.
+//
+// Arguments:
+//    jtrue - the node
+//
+void CodeGen::genCodeForJTrue(GenTreeOp* jtrue)
+{
+    assert(compiler->compCurBB->bbJumpKind == BBJ_COND);
+
+    GenTree*  op  = jtrue->gtGetOp1();
+    regNumber reg = genConsumeReg(op);
+    GetEmitter()->emitIns_J_R(INS_cbnz, emitActualTypeSize(op), compiler->compCurBB->bbJumpDest, reg);
+}
+
 //------------------------------------------------------------------------
 // genCodeForConditionalCompare: Produce code for a compare that's dependent on a previous compare.
 //

src/coreclr/jit/codegenarmarch.cpp

@@ -377,6 +377,10 @@ void CodeGen::genCodeForTreeNode(GenTree* treeNode)
             break;
 #endif // TARGET_ARM64
 
+        case GT_JTRUE:
+            genCodeForJTrue(treeNode->AsOp());
+            break;
+
         case GT_JCC:
             genCodeForJcc(treeNode->AsCC());
             break;

src/coreclr/jit/codegenxarch.cpp

@@ -1304,6 +1304,22 @@ void CodeGen::genCodeForCompare(GenTreeOp* tree)
     }
 }
 
+//------------------------------------------------------------------------
+// genCodeForJTrue: Produce code for a GT_JTRUE node.
+//
+// Arguments:
+//    jtrue - the node
+//
+void CodeGen::genCodeForJTrue(GenTreeOp* jtrue)
+{
+    assert(compiler->compCurBB->bbJumpKind == BBJ_COND);
+
+    GenTree*  op  = jtrue->gtGetOp1();
+    regNumber reg = genConsumeReg(op);
+    inst_RV_RV(INS_test, reg, reg, genActualType(op));
+    inst_JMP(EJ_jne, compiler->compCurBB->bbJumpDest);
+}
+
 //------------------------------------------------------------------------
 // JumpKindToCmov:
 //   Convert an emitJumpKind to the corresponding cmov instruction.
@@ -1836,6 +1852,10 @@ void CodeGen::genCodeForTreeNode(GenTree* treeNode)
             genCodeForCompare(treeNode->AsOp());
             break;
 
+        case GT_JTRUE:
+            genCodeForJTrue(treeNode->AsOp());
+            break;
+
         case GT_JCC:
             genCodeForJcc(treeNode->AsCC());
             break;

src/coreclr/jit/gentree.cpp

@@ -12740,8 +12740,9 @@ void Compiler::gtDispRange(LIR::ReadOnlyRange const& range)
 //
 void Compiler::gtDispTreeRange(LIR::Range& containingRange, GenTree* tree)
 {
-    bool unused;
-    gtDispRange(containingRange.GetTreeRange(tree, &unused));
+    bool     closed;
+    unsigned sideEffects;
+    gtDispRange(containingRange.GetTreeRangeWithFlags(tree, &closed, &sideEffects));
 }
 
 //------------------------------------------------------------------------

src/coreclr/jit/lir.cpp

@@ -1131,9 +1131,9 @@ bool LIR::Range::TryGetUse(GenTree* node, Use* use)
 }
 
 //------------------------------------------------------------------------
-// LIR::Range::GetTreeRange: Computes the subrange that includes all nodes
-//                           in the dataflow trees rooted at a particular
-//                           set of nodes.
+// LIR::Range::GetMarkedRange:
+//   Computes the subrange that includes all nodes in the dataflow trees rooted
+//   at a particular set of nodes.
 //
 // This method logically uses the following algorithm to compute the
 // range:
@@ -1164,14 +1164,29 @@ bool LIR::Range::TryGetUse(GenTree* node, Use* use)
 // occurring before uses).
 //
 // Arguments:
-//    root        - The root of the dataflow tree.
-//    isClosed    - An output parameter that is set to true if the returned
-//                  range contains only nodes in the dataflow tree and false
-//                  otherwise.
+//    markCount         - The number of marks initially set on nodes before the
+//                        start node.
+//    start             - The node to start looking backwards from.
+//    isClosed          - [out] Set to true if the returned range contains only
+//                        nodes in the dataflow tree and false otherwise.
+//    sideEffects       - [out] Combined side effect flags for all nodes in the
+//                        returned range.
+//
+// Template arguments:
+//    markFlagsOperands - Whether the dataflow algorithm should also try to
+//                        mark operands that are defining flags. For example,
+//                        GT_JCC implicitly consumes the flags defined by the
+//                        previous node in linear order. If this argument is
+//                        true, then the algorithm will also include the flags
+//                        definition (which is e.g. a CMP node) in the returned
+//                        range.
+//                        This works on a best-effort basis; the user should not
+//                        rely on all flags defs to be found.
 //
 // Returns:
 //    The computed subrange.
 //
+template <bool     markFlagsOperands>
 LIR::ReadOnlyRange LIR::Range::GetMarkedRange(unsigned  markCount,
                                               GenTree*  start,
                                               bool*     isClosed,
@@ -1182,6 +1197,12 @@ LIR::ReadOnlyRange LIR::Range::GetMarkedRange(unsigned  markCount,
     assert(isClosed != nullptr);
     assert(sideEffects != nullptr);
 
+#ifndef DEBUG
+    // The treatment of flags definitions is on a best-effort basis; it should
+    // be used for debug purposes only.
+    static_assert_no_msg(!markFlagsOperands);
+#endif
+
     bool     sawUnmarkedNode    = false;
     unsigned sideEffectsInRange = 0;
 
@@ -1203,6 +1224,17 @@ LIR::ReadOnlyRange LIR::Range::GetMarkedRange(unsigned  markCount,
                 return GenTree::VisitResult::Continue;
             });
 
+            if (markFlagsOperands && firstNode->OperConsumesFlags())
+            {
+                GenTree* prev = firstNode->gtPrev;
+                if ((prev != nullptr) && ((prev->gtFlags & GTF_SET_FLAGS) != 0) &&
+                    ((prev->gtLIRFlags & LIR::Flags::Mark) == 0))
+                {
+                    prev->gtLIRFlags |= LIR::Flags::Mark;
+                    markCount++;
+                }
+            }
+
             // Unmark the node and update `firstNode`
             firstNode->gtLIRFlags &= ~LIR::Flags::Mark;
             markCount--;
@@ -1282,6 +1314,34 @@ LIR::ReadOnlyRange LIR::Range::GetTreeRange(GenTree* root, bool* isClosed, unsig
     return GetMarkedRange(markCount, root, isClosed, sideEffects);
 }
 
+#ifdef DEBUG
+//------------------------------------------------------------------------
+// LIR::Range::GetTreeRangeWithFlags:
+// Computes the subrange that includes all nodes in the dataflow tree rooted at
+// a particular node, taking into account that the nodes may also implicitly
+// consume flags defined by non-operands.
+//
+// Arguments:
+//    root        - The root of the dataflow tree range of nodes.
+//    isClosed    - An output parameter that is set to true if the returned
+//                  range contains only nodes in the dataflow tree and false
+//                  otherwise.
+//    sideEffects - An output parameter that summarizes the side effects
+//                  contained in the returned range.
+//
+// Returns:
+//    The computed subrange.
+LIR::ReadOnlyRange LIR::Range::GetTreeRangeWithFlags(GenTree* root, bool* isClosed, unsigned* sideEffects) const
+{
+    assert(root != nullptr);
+
+    unsigned markCount = 1;
+    root->gtLIRFlags |= LIR::Flags::Mark;
+
+    return GetMarkedRange<true>(markCount, root, isClosed, sideEffects);
+}
+#endif
+
 //------------------------------------------------------------------------
 // LIR::Range::GetTreeRange: Computes the subrange that includes all nodes
 //                           in the dataflow trees rooted by the operands

src/coreclr/jit/lir.h

@@ -248,6 +248,7 @@ class LIR final
         Range(const Range& other) = delete;
         Range& operator=(const Range& other) = delete;
 
+        template <bool markFlagsOperands = false>
         ReadOnlyRange GetMarkedRange(unsigned markCount, GenTree* start, bool* isClosed, unsigned* sideEffects) const;
 
         void FinishInsertBefore(GenTree* insertionPoint, GenTree* first, GenTree* last);
@@ -291,6 +292,9 @@ class LIR final
 
         ReadOnlyRange GetTreeRange(GenTree* root, bool* isClosed) const;
         ReadOnlyRange GetTreeRange(GenTree* root, bool* isClosed, unsigned* sideEffects) const;
+#ifdef DEBUG
+        ReadOnlyRange GetTreeRangeWithFlags(GenTree* root, bool* isClosed, unsigned* sideEffects) const;
+#endif
         ReadOnlyRange GetRangeOfOperandTrees(GenTree* root, bool* isClosed, unsigned* sideEffects) const;
 
 #ifdef DEBUG