Migration Rules

Intel® DPC++ Compatibility Tool Developer Guide and Reference

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ID 768918

Date 3/22/2024

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Migration Rules

Intel® DPC++ Compatibility Tool uses migration rules to migrate CUDA* code to SYCL* code. There are three categories of migration rules used by the tool:

Default migration rules. A set of built-in migration rules used by the tool for all migrations.
Optional predefined migration rules. A set of predefined migration rules that can optionally be used for migration. Available predefined migration rules are in the extensions/opt_rules folder on the installation path of the tool.
User-defined migration rules. Custom migration rules defined by the user. User-defined migration rules extend the migration capability of Intel® DPC++ Compatibility Tool and can be used to target the migration of specific CUDA syntax to specific SYCL syntax.

Specify Migration Rule Files

To specify a predefined or user-defined migration rule file for use in migration, use the –rule-file command line option with your migration command.

The –rule-file option can be used multiple times with a single command to specify multiple migration rule files. For example:

dpct sample.cu --rule-file=rule_file1.YAML --rule-file=rule_file2.YAML

See the Command Line Options Reference for additional information.

Write User-defined Migration Rules

Migration rules are specified in YAML files. A single rule file may contain multiple migration rules. To define a rule, use the following <key>: <value> pairs:

Key	Value	Description
Rule	String value	Required. Specifies the unique name of the rule.
Priority	`Takeover` \| `Default` \| `Fallback`	Required. Specifies the priority of the rule: `Takeover` > `Default` > `Fallback`. When there are rule conflicts, the rule with higher priority will take precedence.
Kind	`Macro` \| `API` \| `Header` \| `Type` \| `Class` \| `Enum` \| `DisableAPIMigration` \| `PatternRewriter` \| `CMakeRule`	Required. Specifies the rule type.
CmakeSyntax	String value	Required. Specify the CMake syntax name that will be migrated. Use the unique name for the CMake syntax.
MatchMode	`Partial` \| `Full`	Required. Specify the match mode with full word match or partial word match. If not specified, partial match mode will be used.
In	String value	Required. Specifies the target name in the input source code.
Out	String value	Required. Specifies the final format in the output source code.
Includes	List of header files	Required. Specifies the header files which should be included in the output source code. The value can be an empty list.
EnumName	String value	Specifies the name of an enum for an Enum rule type.
Fields	String value	Specifies the migration rule of fields in a Class rule type.
Methods	String value	Specifies the migration rule of methods in a Class rule type.
Prefix	String value	Specifies the prefix of a Header rule type. For example: `#ifdef ...`
Postfix	String value	Specifies the postfix of a Header rule type. For example: `#endif ...`
Subrules	String value	Specifies the subrules for the PatternRewriter rule type.

For example, the following user-defined migration rule file demonstrates different rule types. The behavior of each rule is explained in the corresponding comment:

---                                   # [YAML syntax] Begin the document
- Rule: rule_forceinline              # Rule to migrate "__forceinline__" to "inline"
  Kind: Macro                         # Rule type
  Priority: Takeover                  # Rule priority
  In: __forceinline__                 # Target macro name in the input source code
  Out: inline                         # Name of migrated macro in the output source code
  Includes: ["header1.h", "\"header2.h\""]  # List of header file names which the new macro
                                            # depends on
- Rule: rule_foo                      # Rule to migrate "foo(a,b)" to "int *new_ptr=bar(*b)"
  Kind: API
  Priority: Takeover
  In: foo                             # Target function name in the input source code
  Out: $type_name_of($2) *new_ptr = bar($deref($1))  # Format of the migrated result in the
                                                     # output source code
  Includes: ["<header3>"]
- Rule: rule_cmath                    # Rule to migrate "include<cmath>" to "#include<mymath>"
  Kind: Header
  Priority: Takeover
  In: cmath
  Out: mymath
  Prefix: "#ifdef USE_MYMATH\n"       # Add prefix before "#include<mymath>"
  Postfix: "#endif\n"                 # Add postfix after "#include<mymath>"
  Includes: [""]
- Rule: rule_classA                   # Rule to migrate "classA" to "classB"
  Kind: Class
  Priority: Takeover
  In: classA
  Out: classB
  Includes: []
  Fields:                             # Specify the migration rule of fields of classA
    - In: fieldA                      # Migrate classA.fieldA to getter and setter
      OutGetter: get_a                # Migrate value reference of classA.fieldA to
                                      # classB.get_a()
      OutSetter: set_a                # Migrate value assignment of classA.fieldA to
                                      # classB.set_a()
    - In: fieldC
      Out: fieldD                     # Migrate classA.fieldC to classB.fieldD
  Methods:
    - In: methodA
      Out: a.methodB($2)              # Migrate classA.methodA(x,y) to a.methodB(y)
- Rule: rule_Fruit                    # Rule to migrate "Fruit:apple" to "Fruit:pineapple"
  Kind: Enum
  Priority: Takeover
  EnumName: Fruit
  In: apple
  Out: pineapple
  Includes: ["fruit.h"]
- Rule: type_rule                     # Migrate "OldType" to "NewType"
  Kind: Type
  Priority: Takeover
  In: OldType
  Out: NewType
  Includes: []
- Rule: disable_rule                  # Disable the migration of an API
  Kind: DisableAPIMigration
  Priority: Takeover
  In: foo                             # Disable the migration of foo
  Out: ""
  Includes: []
- Rule: post_migration_rewriter_rule  # Post-migration pattern rewrite rule which uses nested
                                      # string pattern search and replace to find and update
                                      # strings in the migrated code
  Kind: PatternRewriter
  Priority: Takeover
  In: my_max(${args});                # Match pattern "my_max(...);" and save the arbitrary
                                      # arbitrary string between "my_max(" and ");" as ${args}.
                                      # "args" can be a user-defined name which will be
                                      # referenced by "Out" and "Subrules"
  Out: my_min(${args});               # Replace the pattern string to "my_min(${args});"
  Includes: []
  Subrules:
    args:                             # Specify the subrule to apply to ${args}, where "args"
                                      # is the user-defined name which is defined in "In".
      In: a                           # Match pattern "a" in ${args}
      Out: b                          # Replace the pattern string to "b" in ${args}
...                                   # [YAML syntax] End the document

Grammar for Out Key in a User-defined API Migration Rule

To describe the value format for the Out key in a migration rule of Kind: API, use the following Backus-Naur form grammar:

OutValue::= Token | Token OutValue       # OutValue is the value for the "out" key
Token::= AnyString | Keyword             # AnyString is a string provided by the user
Keyword::= ArgIndex
   | $queue                              # Represents the queue string
   | $context                            # Represents the context string
   | $device                             # Represents the device string
   | $deref(ArgIndex)                    # The dereferenced value of the argument
   | $type_name_of(ArgIndex)             # The type name of the argument
   | $deref_type(ArgIndex)               # The dereferenced type name of the argument
   | $addr_of(ArgIndex)                  # The address of the argument
ArgIndex::= $Int                         # Int should be a greater than zero integer

The following scenario describes how the tool makes use of a user-defined migration rule that uses this grammar to migrate code.

Consider the following user-defined API migration rule:

- Rule: rule_foo
  Kind: API
  Priority: Takeover
  In: foo
  Out: $type_name_of($2) new_ptr = bar($deref($1), $3)
  Includes: ["<header3>"]

If the input source code contains a function call that matches the rule, the tool parses the value of the In and Out keys and builds a keyword mapping between the input and output source code. For example, with input source code:

int *ptr, *ptr2;
foo(ptr, ptr2, 30);

The tool creates the following mapping:

Keyword	Input Source Code Match	Migration Result
`$1`	`ptr`	`ptr`
`$2`	`ptr2`	`ptr2`
`$3`	`30`	`30`
`$type_name_of($2)`	N/A	`int*`
`$deref($1)`	N/A	`*ptr`

Using this mapping, the tool migrates the input source code into the following output source code:

int *ptr, *ptr2;
int * new_ptr = bar(*ptr, 30);

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Intel® DPC++ Compatibility Tool Developer Guide and Reference

Migration Rules

Specify Migration Rule Files

Write User-defined Migration Rules

Grammar for Out Key in a User-defined API Migration Rule