[JIT] ARM64 - Combine 'neg' and 'cmp' to 'cmn'

src/coreclr/jit/codegenarm64.cpp

@@ -3369,13 +3369,40 @@ void CodeGen::genCodeForNegNot(GenTree* tree)
     // The src must be a register.
     if (tree->OperIs(GT_NEG) && operand->isContained())
     {
-        ins          = INS_mneg;
-        GenTree* op1 = tree->gtGetOp1();
-        GenTree* a   = op1->gtGetOp1();
-        GenTree* b   = op1->gtGetOp2();
-        genConsumeRegs(op1);
-        assert(op1->OperGet() == GT_MUL);
-        GetEmitter()->emitIns_R_R_R(ins, emitActualTypeSize(tree), targetReg, a->GetRegNum(), b->GetRegNum());
+        genTreeOps oper = operand->OperGet();
+        switch (oper)
+        {
+            case GT_MUL:
+            {
+                ins          = INS_mneg;
+                GenTree* op1 = tree->gtGetOp1();
+                GenTree* a   = op1->gtGetOp1();
+                GenTree* b   = op1->gtGetOp2();
+                genConsumeRegs(op1);
+                GetEmitter()->emitIns_R_R_R(ins, emitActualTypeSize(tree), targetReg, a->GetRegNum(), b->GetRegNum());
+            }
+            break;
+
+            case GT_LSH:
+            case GT_RSH:
+            case GT_RSZ:
+            {
+                assert(ins == INS_neg || ins == INS_negs);
+                assert(operand->gtGetOp2()->IsCnsIntOrI());
+                assert(operand->gtGetOp2()->isContained());
+
+                GenTree* op1 = tree->gtGetOp1();
+                GenTree* a   = op1->gtGetOp1();
+                GenTree* b   = op1->gtGetOp2();
+                genConsumeRegs(op1);
+                GetEmitter()->emitIns_R_R_I(ins, emitActualTypeSize(tree), targetReg, a->GetRegNum(),
+                                            b->AsIntConCommon()->IntegralValue(), ShiftOpToInsOpts(oper));
+            }
+            break;
+
+            default:
+                unreached();
+        }
     }
     else
     {
@@ -4534,12 +4561,53 @@ void CodeGen::genCodeForCompare(GenTreeOp* tree)
         }
         else if (op2->isContained())
         {
-            assert(op2->OperIs(GT_LSH, GT_RSH, GT_RSZ));
-            assert(op2->gtGetOp2()->IsCnsIntOrI());
-            assert(op2->gtGetOp2()->isContained());
+            genTreeOps oper = op2->OperGet();
+            switch (oper)
+            {
+                case GT_NEG:
+                    assert(ins == INS_cmp);
+
+                    ins  = INS_cmn;
+                    oper = op2->gtGetOp1()->OperGet();
+                    switch (oper)
+                    {
+                        case GT_LSH:
+                        case GT_RSH:
+                        case GT_RSZ:
+                        {
+                            GenTree* shiftOp1 = op2->gtGetOp1()->gtGetOp1();
+                            GenTree* shiftOp2 = op2->gtGetOp1()->gtGetOp2();
+
+                            assert(op2->gtGetOp1()->isContained());
+                            assert(shiftOp2->IsCnsIntOrI());
+                            assert(shiftOp2->isContained());
+
+                            emit->emitIns_R_R_I(ins, cmpSize, op1->GetRegNum(), shiftOp1->GetRegNum(),
+                                                shiftOp2->AsIntConCommon()->IntegralValue(), ShiftOpToInsOpts(oper));
+                        }
+                        break;
+
+                        default:
+                            assert(!op2->gtGetOp1()->isContained());
+
+                            emit->emitIns_R_R(ins, cmpSize, op1->GetRegNum(), op2->gtGetOp1()->GetRegNum());
+                            break;
+                    }
+                    break;
+
+                case GT_LSH:
+                case GT_RSH:
+                case GT_RSZ:
+                    assert(op2->gtGetOp2()->IsCnsIntOrI());
+                    assert(op2->gtGetOp2()->isContained());
+
+                    emit->emitIns_R_R_I(ins, cmpSize, op1->GetRegNum(), op2->gtGetOp1()->GetRegNum(),
+                                        op2->gtGetOp2()->AsIntConCommon()->IntegralValue(), ShiftOpToInsOpts(oper));
+                    break;
 
-            emit->emitIns_R_R_I(ins, cmpSize, op1->GetRegNum(), op2->gtGetOp1()->GetRegNum(),
-                                op2->gtGetOp2()->AsIntConCommon()->IntegralValue(), ShiftOpToInsOpts(op2->gtOper));
+                default:
+                    unreached();
+            }
         }
         else
         {

src/coreclr/jit/lower.cpp

@@ -3775,7 +3775,7 @@ GenTree* Lowering::LowerJTrue(GenTreeOp* jtrue)
         jtrue->AsCC()->gtCondition = condCode;
     }
 
-    JITDUMP("Result:\n");
+    JITDUMP("Lowering JTRUE Result:\n");
     DISPTREERANGE(BlockRange(), jtrue);
     JITDUMP("\n");
 
@@ -3876,6 +3876,10 @@ GenTree* Lowering::LowerSelect(GenTreeConditional* select)
 //
 bool Lowering::TryLowerConditionToFlagsNode(GenTree* parent, GenTree* condition, GenCondition* cond)
 {
+    JITDUMP("Lowering condition:\n");
+    DISPTREERANGE(BlockRange(), condition);
+    JITDUMP("\n");
+
     if (condition->OperIsCompare())
     {
         if (!IsInvariantInRange(condition, parent))

src/coreclr/jit/lower.h

@@ -474,7 +474,7 @@ class Lowering final : public Phase
     }
 
 #ifdef TARGET_ARM64
-    bool IsContainableBinaryOp(GenTree* parentNode, GenTree* childNode) const;
+    bool IsContainableUnaryOrBinaryOp(GenTree* parentNode, GenTree* childNode) const;
 #endif // TARGET_ARM64
 
 #if defined(FEATURE_HW_INTRINSICS)

src/coreclr/jit/lowerarmarch.cpp

@@ -148,18 +148,28 @@ bool Lowering::IsContainableImmed(GenTree* parentNode, GenTree* childNode) const
 
 #ifdef TARGET_ARM64
 //------------------------------------------------------------------------
-// IsContainableBinaryOp: Is the child node a binary op that is containable from the parent node?
+// IsContainableUnaryOrBinaryOp: Is the child node a unary/binary op that is containable from the parent node?
 //
 // Return Value:
 //    True if the child node can be contained.
 //
 // Notes:
 //    This can handle the decision to emit 'madd' or 'msub'.
 //
-bool Lowering::IsContainableBinaryOp(GenTree* parentNode, GenTree* childNode) const
+bool Lowering::IsContainableUnaryOrBinaryOp(GenTree* parentNode, GenTree* childNode) const
 {
+#ifdef DEBUG
     // The node we're checking should be one of the two child nodes
-    assert((parentNode->gtGetOp1() == childNode) || (parentNode->gtGetOp2() == childNode));
+    if (parentNode->OperIsBinary())
+    {
+        assert((parentNode->gtGetOp1() == childNode) || (parentNode->gtGetOp2() == childNode));
+    }
+    else
+    {
+        assert(parentNode->OperIsUnary());
+        assert((parentNode->gtGetOp1() == childNode));
+    }
+#endif // DEBUG
 
     // We cannot contain if the parent node
     // * is contained
@@ -173,7 +183,7 @@ bool Lowering::IsContainableBinaryOp(GenTree* parentNode, GenTree* childNode) co
     if (!varTypeIsIntegral(parentNode))
         return false;
 
-    if (parentNode->gtGetOp1()->isContained() || parentNode->gtGetOp2()->isContained())
+    if (parentNode->gtGetOp1()->isContained() || (parentNode->OperIsBinary() && parentNode->gtGetOp2()->isContained()))
         return false;
 
     if (parentNode->OperMayOverflow() && parentNode->gtOverflow())
@@ -252,7 +262,7 @@ bool Lowering::IsContainableBinaryOp(GenTree* parentNode, GenTree* childNode) co
             return false;
         }
 
-        if (parentNode->OperIs(GT_ADD, GT_SUB, GT_AND))
+        if (parentNode->OperIs(GT_ADD, GT_SUB, GT_AND, GT_NEG))
         {
             // These operations can still report flags
 
@@ -282,6 +292,32 @@ bool Lowering::IsContainableBinaryOp(GenTree* parentNode, GenTree* childNode) co
         return false;
     }
 
+    if (childNode->OperIs(GT_NEG))
+    {
+        // If we have a contained LSH, RSH or RSZ, we can still contain NEG if the parent is a CMP or comparison op.
+        if (childNode->gtGetOp1()->isContained() && !childNode->gtGetOp1()->OperIs(GT_LSH, GT_RSH, GT_RSZ))
+        {
+            // Cannot contain if the childs op1 is already contained
+            return false;
+        }
+
+        if ((parentNode->gtFlags & GTF_SET_FLAGS) != 0)
+        {
+            // Cannot contain if the parent operation needs to set flags
+            return false;
+        }
+
+        if (parentNode->OperIs(GT_CMP) || parentNode->OperIsCompare())
+        {
+            if (IsInvariantInRange(childNode, parentNode))
+            {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
     if (childNode->OperIs(GT_CAST))
     {
         // Find "a op cast(b)"
@@ -2027,7 +2063,7 @@ void Lowering::ContainCheckBinary(GenTreeOp* node)
 #ifdef TARGET_ARM64
     if (comp->opts.OptimizationEnabled())
     {
-        if (IsContainableBinaryOp(node, op2))
+        if (IsContainableUnaryOrBinaryOp(node, op2))
         {
             if (op2->OperIs(GT_CAST))
             {
@@ -2039,7 +2075,7 @@ void Lowering::ContainCheckBinary(GenTreeOp* node)
             return;
         }
 
-        if (node->OperIsCommutative() && IsContainableBinaryOp(node, op1))
+        if (node->OperIsCommutative() && IsContainableUnaryOrBinaryOp(node, op1))
         {
             if (op1->OperIs(GT_CAST))
             {
@@ -2259,19 +2295,22 @@ void Lowering::ContainCheckCompare(GenTreeOp* cmp)
     }
 
 #ifdef TARGET_ARM64
-    if (comp->opts.OptimizationEnabled() && cmp->OperIsCompare())
+    if (comp->opts.OptimizationEnabled() && (cmp->OperIsCompare() || cmp->OperIs(GT_CMP)))
     {
-        if (IsContainableBinaryOp(cmp, op2))
+        if (IsContainableUnaryOrBinaryOp(cmp, op2))
         {
             MakeSrcContained(cmp, op2);
             return;
         }
 
-        if (IsContainableBinaryOp(cmp, op1))
+        if (IsContainableUnaryOrBinaryOp(cmp, op1))
         {
             MakeSrcContained(cmp, op1);
             std::swap(cmp->gtOp1, cmp->gtOp2);
-            cmp->SetOper(cmp->SwapRelop(cmp->gtOper));
+            if (cmp->OperIsCompare())
+            {
+                cmp->SetOper(cmp->SwapRelop(cmp->gtOper));
+            }
             return;
         }
     }
@@ -2501,6 +2540,11 @@ void Lowering::ContainCheckNeg(GenTreeOp* neg)
             MakeSrcContained(neg, childNode);
         }
     }
+    else if (comp->opts.OptimizationEnabled() && childNode->OperIs(GT_LSH, GT_RSH, GT_RSZ) &&
+             IsContainableUnaryOrBinaryOp(neg, childNode))
+    {
+        MakeSrcContained(neg, childNode);
+    }
 }
 
 //----------------------------------------------------------------------------------------------