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Say "IR" instead of "IL".

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While the specifics of these terms are debatable, "IR" generally
isn't incorrect in this context, and is the more widely recognized
term at this time.

See also the discussion in #267.

Fixes #267.
This commit is contained in:
Dan Gohman
2018-03-28 14:15:01 -07:00
parent a297465c25
commit 57cd69d8b4
45 changed files with 106 additions and 119 deletions
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20
cranelift/docs/compare-llvm.rst
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@@ -16,8 +16,8 @@ highlighting some of the differences and similarities. Both projects:
- Use an ISA-agnostic input language in order to mostly abstract away the
differences between target instruction set architectures.
- Depend extensively on SSA form.
- Have both textual and in-memory forms of their primary intermediate language.
(LLVM also has a binary bitcode format; Cretonne doesn't.)
- Have both textual and in-memory forms of their primary intermediate
representation. (LLVM also has a binary bitcode format; Cretonne doesn't.)
- Can target multiple ISAs.
- Can cross-compile by default without rebuilding the code generator.
@@ -41,8 +41,8 @@ LLVM uses multiple intermediate representations as it translates a program to
binary machine code:
`LLVM IR <https://llvm.org/docs/LangRef.html>`_
This is the primary intermediate language which has textual, binary, and
in-memory representations. It serves two main purposes:
This is the primary intermediate representation which has textual, binary, and
in-memory forms. It serves two main purposes:
- An ISA-agnostic, stable(ish) input language that front ends can generate
easily.
@@ -89,9 +89,9 @@ representation. Some target ISAs have a fast instruction selector that can
translate simple code directly to MachineInstrs, bypassing SelectionDAG when
possible.
:doc:`Cretonne <langref>` uses a single intermediate language to cover these
levels of abstraction. This is possible in part because of Cretonne's smaller
scope.
:doc:`Cretonne <langref>` uses a single intermediate representation to cover
these levels of abstraction. This is possible in part because of Cretonne's
smaller scope.
- Cretonne does not provide assemblers and disassemblers, so it is not
necessary to be able to represent every weird instruction in an ISA. Only
@@ -102,7 +102,7 @@ scope.
- SSA form is preserved throughout. After register allocation, each SSA value
is annotated with an assigned ISA register or stack slot.
The Cretonne intermediate language is similar to LLVM IR, but at a slightly
The Cretonne intermediate representation is similar to LLVM IR, but at a slightly
lower level of abstraction.
Program structure
@@ -112,12 +112,12 @@ In LLVM IR, the largest representable unit is the *module* which corresponds
more or less to a C translation unit. It is a collection of functions and
global variables that may contain references to external symbols too.
In Cretonne IL, the largest representable unit is the *function*. This is so
In Cretonne IR, the largest representable unit is the *function*. This is so
that functions can easily be compiled in parallel without worrying about
references to shared data structures. Cretonne does not have any
inter-procedural optimizations like inlining.
An LLVM IR function is a graph of *basic blocks*. A Cretonne IL function is a
An LLVM IR function is a graph of *basic blocks*. A Cretonne IR function is a
graph of *extended basic blocks* that may contain internal branch instructions.
The main difference is that an LLVM conditional branch instruction has two
target basic blocks---a true and a false edge. A Cretonne branch instruction