| Age | Commit message (Collapse) | Author |
|---|
|
This big diff does multiple changes to allow
the addition of new targets to qbe. The
changes are listed below in decreasing order
of impact.
1. Add a new Target structure.
To add support for a given target, one has to
implement all the members of the Target
structure. All the source files where changed
to use this interface where needed.
2. Single out amd64-specific code.
In this commit, the amd64 target T_amd64_sysv
is the only target available, it is implemented
in the amd64/ directory. All the non-static
items in this directory are prefixed with either
amd64_ or amd64_sysv (for items that are
specific to the System V ABI).
3. Centralize Ops information.
There is now a file 'ops.h' that must be used to
store all the available operations together with
their metadata. The various targets will only
select what they need; but it is beneficial that
there is only *one* place to change to add a new
instruction.
One good side effect of this change is that any
operation 'xyz' in the IL now as a corresponding
'Oxyz' in the code.
4. Misc fixes.
One notable change is that instruction selection
now generates generic comparison operations and
the lowering to the target's comparisons is done
in the emitter.
GAS directives for data are the same for many
targets, so data emission was extracted in a
file 'gas.c'.
5. Modularize the Makefile.
The Makefile now has a list of C files that
are target-independent (SRC), and one list
of C files per target. Each target can also
use its own 'all.h' header (for example to
define registers).
|
|
|
|
Compiling languages with closures often requires passing
an extra environment parameter to the called function.
One solution is to use a convention, and reserve, say,
the first argument for that purpose. However, that
makes binding to C a little less smooth.
Alternatively, QBE now provides a way to remain fully
ABI compatible with C by having a "hidden" environment
argument (marked with the keyword 'env'). Calling a
function expecting an environment from C will make the
contents of the environment undefined, but the normal
arguments will be passed without alteration. Conversely,
calling a C function like it is a closure by passing
it an environemnt will work smoothly.
|
|
|
|
This change is backward compatible, calls to
"variadic" functions (like printf) must now be
annotated (with ...).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
I found it by compiling -O2 and seeing the ABI code
fail. Further investigation revealed GCC trimmed
away the last iteration of the loop because I was
accessing the third element of an array of size two.
This is undefined behavior, so GCC "proved" that the
last iteration was never run.
|
|
|
|
A struct of size 0 is now marked as passed in memory.
All the ABI code assumes structs passed in registers
have size at least 8. This could have an impact on
the alignment in the stack, but eh, I guess they are
rare.
|
|
|
|
|
|
|
|
Abi lowering does not need use counts, but
they are needed for instruction selection.
I changed main to call filluse() between
these two passes.
|
|
|
