Reserve return reg for cross-reg-file copy (dotnet#37863)

Fix dotnet#37829
DzmitryKN · Jun 16, 2020 · 382dce3 · 382dce3
1 parent 9929c07
commit 382dce3
Showing 1 changed file with 30 additions and 2 deletions.
diff --git a/src/coreclr/src/jit/lsrabuild.cpp b/src/coreclr/src/jit/lsrabuild.cpp
@@ -3485,12 +3485,36 @@ int LinearScan::BuildReturn(GenTree* tree)
                            retTypeDesc.GetReturnRegCount());
                 }
                 srcCount = pRetTypeDesc->GetReturnRegCount();
+                // For any source that's coming from a different register file, we need to ensure that
+                // we reserve the specific ABI register we need.
+                bool hasMismatchedRegTypes = false;
+                if (op1->IsMultiRegLclVar())
+                {
+                    for (int i = 0; i < srcCount; i++)
+                    {
+                        RegisterType srcType = regType(op1->AsLclVar()->GetFieldTypeByIndex(compiler, i));
+                        RegisterType dstType = regType(pRetTypeDesc->GetReturnRegType(i));
+                        if (srcType != dstType)
+                        {
+                            hasMismatchedRegTypes = true;
+                            regMaskTP dstRegMask  = genRegMask(pRetTypeDesc->GetABIReturnReg(i));
+                            if (varTypeIsFloating(dstType))
+                            {
+                                buildInternalFloatRegisterDefForNode(tree, dstRegMask);
+                            }
+                            else
+                            {
+                                buildInternalIntRegisterDefForNode(tree, dstRegMask);
+                            }
+                        }
+                    }
+                }
                 for (int i = 0; i < srcCount; i++)
                 {
                     // We will build uses of the type of the operand registers/fields, and the codegen
                     // for return will move as needed.
-                    if (!op1->OperIs(GT_LCL_VAR) || (regType(op1->AsLclVar()->GetFieldTypeByIndex(compiler, i)) ==
-                                                     regType(pRetTypeDesc->GetReturnRegType(i))))
+                    if (!hasMismatchedRegTypes || (regType(op1->AsLclVar()->GetFieldTypeByIndex(compiler, i)) ==
+                                                   regType(pRetTypeDesc->GetReturnRegType(i))))
                     {
                         BuildUse(op1, genRegMask(pRetTypeDesc->GetABIReturnReg(i)), i);
                     }
@@ -3499,6 +3523,10 @@ int LinearScan::BuildReturn(GenTree* tree)
                         BuildUse(op1, RBM_NONE, i);
                     }
                 }
+                if (hasMismatchedRegTypes)
+                {
+                    buildInternalRegisterUses();
+                }
                 return srcCount;
             }
         }