[_CDCSL_93-16_]<1>Cedar>release>C2C>C2CIntCodeUtils.mesa

C2CIntCodeUtils.mesa

Christian Jacobi, 1987

Christian Jacobi, January 25, 1993 9:57 am PST

DIRECTORY

C2CBasics, C2CTarget, IntCodeDefs;

C2CIntCodeUtils: CEDAR DEFINITIONS =

BEGIN OPEN IntCodeDefs;

NewVariableId: PROC [] RETURNS [id: VariableId];

--makes up a new unique VariableId

CountNodes: PROC [nodes: NodeList] RETURNS [INT];

--count nodes in list

NodeHasCode: PROC [node: Node] RETURNS [BOOL];

--returns whether node generates some code [is not only comment]

AnyNodeHasCode: PROC [nodes: NodeList] RETURNS [BOOL];

--returns whether nodes generates some code [are not only comments]

LastNodeWithCode: PROC [nodes: NodeList] RETURNS [node: Node];

--returns last node in list which generates some code [is not only comment]

CheckArgCount: PROC [args: NodeList, n: INT];

--Raises an error if args has not n elements

IsSimpleConst: PROC [node: Node] RETURNS [is: BOOL, val: CARD];

--checks whether node is simple, numeric constant

--which fits in a single word

IsFieldVar: PROC [node: Node] RETURNS [BOOL];

--checks whether node is field variable

GenConst: PROC [value: INT, bits: INT ¬ C2CTarget.bitsPerWord] RETURNS [ConstNode];

--generates a node for a constant [with value which fits into an int]

UseTemporaryIfReused: PROC [arg: Node, addr: BOOL ¬ FALSE] RETURNS [BOOL];

--Checks whether duplication of arg should be done by using a temporary variable.

--This is particularly true if arg has side effects (but not errors).

--addr: If true means return if use of addr of arg should have a temporary.

--If no side effects, tries to figure out whether duplication or use of temporary is faster.

--IF USAGE GENERATES STATEMENT-CODE FIX THE FOLLOWING (UsingTemporaryWhichGeneratesStatementCode) PROC TO SAY SO.

UsingTemporaryWhichGeneratesStatementCode: PROC [arg: Node] RETURNS [BOOL];

StatementCode: PROC [node: Node] RETURNS [BOOL];

--Checks whether node contains a label, goto, need for temporary, deep in tree.

--To detect statement code which is not ok in conditional expressions

--This is the stronger test

--Caveat

--Fails to recognize cases of lHSMaskNShift; but that case wont occur unbounded by

--assignment node. [Which is assumed to generate statement code anyway]. Check

--at each application of StatementCode whether lHSMaskNShift might occur...

StatementJumps: PROC [node: Node] RETURNS [BOOL];

--Checks whether node contains a label, goto, shallow in tree

--Does not care about assignments in statement part.

--For detection of the so called block assignments

SizeIsProvableOk: PROC [node: Node] RETURNS [BOOL];

--nasty problem: the intermediate code gives wrong size information where it is not used

--finds out whether this can't happen for a particular node

HasLabel: PROC [node: Node] RETURNS [BOOL];

--Determines whether control flow might enter node

--If node has no label and its predecessor is not live, node can be skipped

END.