commit fbbd2252aa3a25c045353d8b5210fc48d935a709
parent 3ea138853dfc00560e078d6879469c6b83a74236
Author: Quentin Carbonneaux <quentin.carbonneaux@yale.edu>
Date: Tue, 29 Mar 2016 17:35:37 -0400
typos in il.txt, thanks Robert Ransom
Diffstat:
| M | doc/il.txt | | | 46 | ++++++++++++++++++++++++---------------------- |
1 file changed, 24 insertions(+), 22 deletions(-)
diff --git a/doc/il.txt b/doc/il.txt
@@ -82,7 +82,7 @@ are listed below.
* `[ ... ]` marks some syntax as optional;
* `( ... ),` designates a comma-separated list of the
enclosed syntax;
- * `...*` and `...+` as used for arbitrary and
+ * `...*` and `...+` are used for arbitrary and
at-least-once repetition.
~ Sigils
@@ -114,13 +114,13 @@ starting with the sigil `?`.
The IL makes very minimal use of types. By design, the types
used are restricted to what is necessary for unambiguous
compilation to machine code and C interfacing. Unlike LLVM,
-QBE is not using types as a mean to safety, they are only
-here for semantics purposes.
+QBE is not using types as a means to safety; they are only
+here for semantic purposes.
The four base types are `w` (word), `l` (long), `s` (single),
-and `d` (double), they stand respectively for 32 bits and
-64 bits integers, and 32 bits and 64 bits floating points.
-There are no pointer types available, pointers are typed
+and `d` (double), they stand respectively for 32-bit and
+64-bit integers, and 32-bit and 64-bit floating-point numbers.
+There are no pointer types available; pointers are typed
by an integer type sufficiently wide to represent all memory
addresses (e.g. `l` on x64). Temporaries in the IL can only
have a basic type.
@@ -138,8 +138,8 @@ section.
~~~~~~~~~~~
The IL has a minimal subtyping feature for integer types.
-Any value of type `l` can be used in a `w` context. When that
-happens only the 32 least significant bits of the word value
+Any value of type `l` can be used in a `w` context. In that
+case, only the 32 least significant bits of the word value
are used.
Make note that it is the inverse of the usual subtyping on
@@ -165,21 +165,21 @@ that they can be used directly in instructions; there is
no need for a "load constant" instruction.
The representation of integers is two's complement.
-Floating point numbers are represented using the
+Floating-point numbers are represented using the
single-precision and double-precision formats of the
-EEE 754 standard.
+IEEE 754 standard.
-Consants specify a sequence of bits and are untyped.
-They are always parsed as 64 bits blobs. Depending on
-the context surrounding one constant, only some of its
+Constants specify a sequence of bits and are untyped.
+They are always parsed as 64-bit blobs. Depending on
+the context surrounding a constant, only some of its
bits are used. For example, in the program below, the
-two variables defined have the same value since the fist
+two variables defined have the same value since the first
operand of the substraction is a word (32 bits) context.
%x =w sub -1, 0
%y =w sub 4294967295, 0
-Because specifying floating point constants by their bits
+Because specifying floating-point constants by their bits
makes the code less readable, syntactic sugar is provided
to express them. Standard scientific notation is used with
a prefix of `s_` for single and `d_` for double-precision
@@ -189,8 +189,8 @@ the same double-precision constant.
%x =d add d_0, d_-1
%y =d add d_0, -4616189618054758400
-Global symbols can also be used directly as constants,
-they will be resolved and turned to actual numeric
+Global symbols can also be used directly as constants;
+they will be resolved and turned into actual numeric
constants by the linker.
- 4. Definitions
@@ -218,26 +218,28 @@ using the `export` keyword.
'type' :IDENT '=' 'align' NUMBER '{' NUMBER '}'
Aggregate type definitions start with the `type` keyword.
-They have file scope but types must be defined before their
+They have file scope, but types must be defined before their
first use. The inner structure of a type is expressed by a
-comma separated list of <@ Simple Types> enclosed in curly
+comma-separated list of <@ Simple Types> enclosed in curly
braces.
type :fourfloats = { s, s, d, d }
For ease of generation, a trailing comma is tolerated by
the parser. In case many items of the same type are
-sequenced (like in a C array), the sorter array syntax
+sequenced (like in a C array), the shorter array syntax
can be used.
type :abyteandmanywords = { b, w 100 }
By default, the alignment of an aggregate type is the
maximum alignment of its members. The alignment can be
-explicitely specified by the programmer
+explicitly specified by the programmer.
+
+ type :cryptovector = align 16 { w 4 }
Opaque types are used when the inner structure of an
-aggregate cannot be specified, the alignment for opaque
+aggregate cannot be specified; the alignment for opaque
types is mandatory. They are defined by simply enclosing
their size between curly braces.
