commit fb742ec0e4d8992a9f55bbf40920bd173dde41db
parent 6cd97975738db196ff86ae3b9c98a961177818c3
Author: Quentin Carbonneaux <quentin@c9x.me>
Date: Wed, 11 May 2022 10:14:24 +0200
document spacing in il reference
Diffstat:
| M | doc/il.txt | | | 44 | ++++++++++++++++++++++++++++++-------------- |
1 file changed, 30 insertions(+), 14 deletions(-)
diff --git a/doc/il.txt b/doc/il.txt
@@ -11,6 +11,7 @@
* <@ Input Files >
* <@ BNF Notation >
* <@ Sigils >
+ * <@ Spaces >
2. <@ Types >
* <@ Simple Types >
* <@ Subtyping >
@@ -105,6 +106,16 @@ scope and nature of identifiers.
In this BNF syntax, we use `?IDENT` to designate an identifier
starting with the sigil `?`.
+~ Spaces
+~~~~~~~~
+
+Individual tokens in IL files must be separated by one or
+more spacing characters. Both spaces and tabs are recognized
+as spacing characters. In data and type definitions, newlines
+can also be used as spaces to prevent overly long lines. When
+exactly one of two consecutive tokens is a symbol (for example
+`,` or `=` or `{`), space may be omitted.
+
- 2. Types
----------
@@ -202,9 +213,9 @@ constants by the linker.
`bnf
LINKAGE :=
- 'export'
- | 'section' SECNAME
- | 'section' SECNAME SECFLAGS
+ 'export' '\n'*
+ | 'section' SECNAME '\n'*
+ | 'section' SECNAME SECFLAGS '\n'*
SECNAME := '"' .... '"'
SECFLAGS := '"' .... '"'
@@ -296,7 +307,8 @@ their size between curly braces.
`bnf
DATADEF :=
- LINKAGE* 'data' $IDENT '=' ['align' NUMBER]
+ LINKAGE*
+ 'data' $IDENT '=' ['align' NUMBER]
'{'
( EXTTY DATAITEM+
| 'z' NUMBER ),
@@ -354,8 +366,9 @@ Here are various examples of data definitions.
`bnf
FUNCDEF :=
- LINKAGE* 'function' [ABITY] $IDENT '(' (PARAM), ')'
- '{'
+ LINKAGE*
+ 'function' [ABITY] $IDENT '(' (PARAM), ')' '\n'*
+ '{' '\n'+
BLOCK+
'}'
@@ -440,25 +453,28 @@ connected using jump instructions.
`bnf
BLOCK :=
- @IDENT # Block label
- PHI* # Phi instructions
- INST* # Regular instructions
- JUMP # Jump or return
+ @IDENT '\n'+ # Block label
+ PHILINE* # Phi instructions
+ INSTLINE* # Regular instructions
+ JUMP '\n'+ # Jump or return
+
+ PHILINE := PHI '\n'+
+ INSTLINE := INST '\n'+
All blocks have a name that is specified by a label at
their beginning. Then follows a sequence of instructions
that have "fall-through" flow. Finally one jump terminates
the block. The jump can either transfer control to another
-block of the same function or return; they are described
+block of the same function or return; jumps are described
further below.
The first block in a function must not be the target of
-any jump in the program. If this is really needed,
-the frontend could insert an empty prelude block
+any jump in the program. If a jump to the function start
+is needed, the frontend must insert an empty prelude block
at the beginning of the function.
When one block jumps to the next block in the IL file,
-it is not necessary to give the jump instruction, it
+it is not necessary to write the jump instruction, it
will be automatically added by the parser. For example
the start block in the example below jumps directly
to the loop block.
