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SSA

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SSA is an IntermediateLanguage, translated from SXML by ClosureConvert, optimized by SSASimplify, and translated by ToSSA2 to SSA2.

## Description

SSA is a FirstOrder, SimplyTyped IntermediateLanguage. It is the main IntermediateLanguage used for optimizations.

An SSA program consists of a collection of datatype declarations, a sequence of global statements, and a collection of functions, along with a distinguished "main" function. Each function consists of a collection of basic blocks, where each basic block is a sequence of statements ending with some control transfer.

## Implementation

ssa.sig ssa.fun
ssa-tree.sig ssa-tree.fun

## Type Checking

Type checking of a SSA program verifies the following:

- no duplicate definitions (tycons, cons, vars, labels, funcs)

- no out of scope references (tycons, cons, vars, labels, funcs)

- variable definitions dominate variable uses

- case transfers are exhaustive and irredundant

- `Enter`/`Leave` profile statements match

- "traditional" well-typedness

type-check.sig type-check.fun

## Details and Notes

SSA is an abbreviation for Static Single Assignment.

Last edited on 2006-11-02 17:31:56 by MatthewFluet.