Method and apparatus for ordered predicate phi in static single assignment form
US6898787B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 22, 2001 |
| Grant date | May 24, 2005 |
| Priority date | — |
| Expiry date | Dec 15, 2022 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F8/433
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A Φ function provides a mechanism for static single assignment in the presence of predicated code. Guards placed on each source operand of the Φ function indicate the condition under which the corresponding source operand is live and provide correct materialization of the Φ functions after code reordering. For control functions Φc representing a confluence of live reaching definitions at a join point in the control flow graph, the guards indicate the basic block which is the source of the edge associated with the source operand. The Φc operands are paired with the source basic block of the incoming edge(s) along which they are live. The operands are also ordered according to a topological ordering of their associated block. This ordering is maintained through subsequent code transformations. In the topological ordering, the source of the edge from which the definition was passed is defined. A predicate Φ function Φp, represents the confluence of definitions in a straight line of code in which some of the definitions have been predicated. For Φp, the guards on the source operands indicate the predicate under which the corresponding operand is live. The order of the operands is such …
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