Solve most of the regressions

In morph, when narrowing the AND operand, only insert casts if necessary - prefer to use "optNarrowTree". Otherwise we end up with redundant register shuffling.
dotnet · Jun 22, 2021 · 3b61c12 · 3b61c12
1 parent d2dd580
commit 3b61c12
Showing 1 changed file with 37 additions and 27 deletions.
diff --git a/src/coreclr/jit/morph.cpp b/src/coreclr/jit/morph.cpp
@@ -13789,44 +13789,54 @@ GenTree* Compiler::fgMorphSmpOp(GenTree* tree, MorphAddrContext* mac)
 
             noway_assert(op1->TypeGet() == TYP_LONG && op1->OperGet() == GT_AND);
 
-            /* Is the result of the mask effectively an INT ? */
-
-            GenTree* andMask;
-            andMask = op1->AsOp()->gtOp2;
-            if (andMask->gtOper != GT_CNS_NATIVELONG)
-            {
-                goto COMPARE;
-            }
-            if ((andMask->AsIntConCommon()->LngValue() >> 32) != 0)
+            // The transform below cannot preserve VNs.
+            if (fgGlobalMorph)
             {
-                goto COMPARE;
-            }
+                // Is the result of the mask effectively an INT ?
 
-            /* Now we know that we can cast AsOp()->gtOp1 of AND to int */
+                GenTree* andMask = op1->AsOp()->gtOp2;
+
+                if (andMask->gtOper != GT_CNS_NATIVELONG)
+                {
+                    goto COMPARE;
+                }
+                if ((andMask->AsIntConCommon()->LngValue() >> 32) != 0)
+                {
+                    goto COMPARE;
+                }
 
-            op1->AsOp()->gtOp1 = gtNewCastNode(TYP_INT, op1->AsOp()->gtOp1, false, TYP_INT);
+                // Now we narrow AsOp()->gtOp1 of AND to int.
+                if (optNarrowTree(op1->AsOp()->gtGetOp1(), TYP_LONG, TYP_INT, ValueNumPair(), false))
+                {
+                    optNarrowTree(op1->AsOp()->gtGetOp1(), TYP_LONG, TYP_INT, ValueNumPair(), true);
+                }
+                else
+                {
+                    op1->AsOp()->gtOp1 = gtNewCastNode(TYP_INT, op1->AsOp()->gtGetOp1(), false, TYP_INT);
+                }
 
-            /* now replace the mask node (AsOp()->gtOp2 of AND node) */
+                // now replace the mask node (AsOp()->gtOp2 of AND node).
 
-            noway_assert(andMask == op1->AsOp()->gtOp2);
+                noway_assert(andMask == op1->AsOp()->gtOp2);
 
-            ival1 = (int)andMask->AsIntConCommon()->LngValue();
-            andMask->SetOper(GT_CNS_INT);
-            andMask->gtType                = TYP_INT;
-            andMask->AsIntCon()->gtIconVal = ival1;
+                ival1 = (int)andMask->AsIntConCommon()->LngValue();
+                andMask->SetOper(GT_CNS_INT);
+                andMask->gtType                = TYP_INT;
+                andMask->AsIntCon()->gtIconVal = ival1;
 
-            /* now change the type of the AND node */
+                // now change the type of the AND node.
 
-            op1->gtType = TYP_INT;
+                op1->gtType = TYP_INT;
 
-            /* finally we replace the comparand */
+                // finally we replace the comparand.
 
-            ival2 = (int)cns2->AsIntConCommon()->LngValue();
-            cns2->SetOper(GT_CNS_INT);
-            cns2->gtType = TYP_INT;
+                ival2 = (int)cns2->AsIntConCommon()->LngValue();
+                cns2->SetOper(GT_CNS_INT);
+                cns2->gtType = TYP_INT;
 
-            noway_assert(cns2 == op2);
-            cns2->AsIntCon()->gtIconVal = ival2;
+                noway_assert(cns2 == op2);
+                cns2->AsIntCon()->gtIconVal = ival2;
+            }
 
             goto COMPARE;