cmd/compile/internal/noder: format grammar

This just wraps column width to 72 and indents production definitions
so they are easier to distinguish from prose.

Change-Id: I386b122b4f617db4b182ebb549fbee4f35a0122c
Reviewed-on: https://go-review.googlesource.com/c/go/+/673536
TryBot-Bypass: Mark Freeman <mark@golang.org>
Reviewed-by: Robert Griesemer <gri@google.com>
Auto-Submit: Mark Freeman <mark@golang.org>

src/cmd/compile/internal/noder/doc.go

@@ -5,7 +5,8 @@
 /*
 The Unified IR (UIR) format is implicitly defined by the package noder.
 
-At the highest level, a package encoded in UIR follows the grammar below.
+At the highest level, a package encoded in UIR follows the grammar
+below.
 
     File        = Header Payload fingerprint .
     Header      = version [ flags ] sectionEnds elementEnds .
@@ -16,8 +17,8 @@ sectionEnds = [10]uint32 . // defines section boundaries
     elementEnds = []uint32 .   // defines element boundaries
     fingerprint = [8]byte .    // sha256 fingerprint
 
-The payload is a series of sections. Each section has a kind which determines
+The payload is a series of sections. Each section has a kind which
-its index in the series.
+determines its index in the series.
 
     SectionKind = Uint64 .
     Payload     = SectionString
@@ -33,29 +34,30 @@ Payload     = SectionString
                   .
 
 # Sections
-A section is a series of elements of a type determined by the section's kind.
+A section is a series of elements of a type determined by the section's
-Go constructs are mapped onto (potentially multiple) elements. Elements are
+kind. Go constructs are mapped onto (potentially multiple) elements.
-accessed using an index relative to the start of the section.
+Elements are accessed using an index relative to the start of the
+section.
 
     // TODO(markfreeman): Rename to SectionIndex.
     RelIndex = Uint64 .
 
 ## String Section
-String values are stored as elements in the string section. Elements outside
+String values are stored as elements in the string section. Elements
-the string section access string values by reference.
+outside the string section access string values by reference.
 
     SectionString = { String } .
 
 ## Meta Section
-The meta section provides fundamental information for a package. It contains
+The meta section provides fundamental information for a package. It
-exactly two elements — a public root and a private root.
+contains exactly two elements — a public root and a private root.
 
     SectionMeta = PublicRoot
                   PrivateRoot     // TODO(markfreeman): Define.
                   .
 
-The public root element identifies the package and provides references for all
+The public root element identifies the package and provides references
-exported objects it contains.
+for all exported objects it contains.
 
     PublicRoot  = Relocs
                   [ SyncPublic ] // TODO(markfreeman): Define.
@@ -64,8 +66,8 @@ PublicRoot  = Relocs
                   ObjectRefCount // TODO(markfreeman): Define.
                   { ObjectRef }  // TODO(markfreeman): Define.
                   .
-HasInit     = Bool .          // Whether the package uses any initialization
+    HasInit     = Bool .         // Whether the package uses any
-                              // functions.
+                                 // initialization functions.
 
 ## PosBase Section
 This section provides position information. It is a series of PosBase
@@ -80,7 +82,7 @@ constant for file bases and hence not encoded.
     PosBase = Relocs
               [ SyncPosBase ] // TODO(markfreeman): Define.
               StringRef       // the (absolute) file name for the base
-          Bool            // true if it is a file base, else a line base
+              Bool            // true if a file base, else a line base
               // The below is ommitted for file bases.
               [ Pos
                 Uint64        // line
@@ -100,8 +102,9 @@ Pos     = [ SyncPos ]      // TODO(markfreeman): Define.
               .
 
 # References
-A reference table precedes every element. Each entry in the table contains a
+A reference table precedes every element. Each entry in the table
-section / index pair denoting the location of the referenced element.
+contains a section / index pair denoting the location of the referenced
+element.
 
     // TODO(markfreeman): Rename to RefTable.
     Relocs   = [ SyncRelocs ]   // TODO(markfreeman): Define.
@@ -116,8 +119,8 @@ Reloc      = [ SyncReloc ]    // TODO(markfreeman): Define.
                RelIndex
                .
 
-Elements encode references to other elements as an index in the reference
+Elements encode references to other elements as an index in the
-table — not the location of the referenced element directly.
+reference table — not the location of the referenced element directly.
 
     // TODO(markfreeman): Rename to RefUse.
     UseReloc = [ SyncUseReloc ] // TODO(markfreeman): Define.
@@ -125,8 +128,8 @@ UseReloc   = [ SyncUseReloc ] // TODO(markfreeman): Define.
                .
 
 # Primitives
-Primitive encoding is handled separately by the pkgbits package. Check there
+Primitive encoding is handled separately by the pkgbits package. Check
-for definitions of the below productions.
+there for definitions of the below productions.
 
     * Bool
     * Int64