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diff --git a/chapter01/README.md b/chapter01/README.md index e5b79493..69a09328 100644 --- a/chapter01/README.md +++ b/chapter01/README.md @@ -71,34 +71,39 @@ at very little cost (nearly always small constant time) because all dependencies ### Unique Node ID -Each node is assigned a unique dense integer Node ID when created. This ID is useful for debugging and e.g. as -an index into a bit vector, which in turn is used to efficiently visit a (possibly cyclic) graph. -The ID is also used to efficiently compute equality of nodes; a subject that we discuss in Chapter 8 Global Value Numbering. +Each node is assigned a unique dense integer Node ID when created. This ID is +useful for debugging, efficiently computing equality and e.g. as an index into +a bit vector, which in turn is used to efficiently visit a (possibly cyclic) +graph. We discuss Node equality in Chapter 8 Global Value Numbering. ### Start Node -The Start node represents the start of the function. For now, we do not have any values in the Start node, this is because our function does not -yet accept parameters. When we add parameters, the value of the Start node will be a tuple, and will require Projection nodes to extract the values. +The Start node represents the start of the function. For now, we do not have any inputs to Start because our function does not +yet accept parameters. When we add parameters the value of Start will be a tuple, and will require Projections to extract the values. We discuss this in detail in Chapter 9: Functions and Calls. ### Constant Node -The Constant node represents a constant value. At present, the only constants that we allow are integer literals; therefore the Constant node contains -an integer value. As we add other types of constants, we will need to refactor how we represent Constant nodes. +A Constant node represents a constant value. At present, the only constants +that we allow are integer literals; therefore Constants contain an integer +value. As we add other types of constants, we refactor how we represent +Constants. -The Constant node has no inputs. However, we set the Start node as an input to the Constant node to enable forward graph walk. This edge carries no semantic meaning, -it is present _solely_ to allow visitation. +Constants have no semantic inputs. However, we set Start as an input to +Constants to enable a forward graph walk. This edge carries no semantic +meaning, and it is present _solely_ to allow visitation. -The Constant node's output is the value stored in it. +The Constant's value is the value stored in it. ### Return Node -The Return node has two inputs. The first input is a control node. The second input is the data node that supplies the return value. +The Return node has two inputs. The first input is a control node and the +second is the data node that supplies the return value. -In this presentation, the Return node functions as the Stop node, since we are compiling a single unnamed function. -A separate Stop node is not necessary. Compiling multiple functions is covered in Chapter 9: Functions and Calls. +In this presentation, Return functions as a Stop node, since we are compiling a single unnamed function. +A separate Stop is not necessary. Compiling multiple functions is covered in Chapter 9: Functions and Calls. -The output of the Return node is the value it obtained from the data node. +The Return's output is the value from the data node. ### Representation @@ -111,4 +116,4 @@ return 1;  * Control nodes appear as square boxes -* Control edges are in bold red
\ No newline at end of file +* Control edges are in bold red |