Hi!
I've attached my first week of work as a patchset for review. This is
also available on Github [1].
By next Monday I intend to (more or less) finish up the preliminary
parts concerning the codegen; and start working on the runtime (so that
I can do a basic sanity check).
[1] https://github.com/sanjoy/llvm/tree/segmented-stacks
0001-Adds-relevant-command-line-options.patch (2.2 KB)
0002-Adds-a-new-StackSegmenter-pass.patch (6.78 KB)
0003-Implements-prologue-for-X86.patch (7.69 KB)
0004-Adds-some-basic-documentation.patch (2.96 KB)
Hi!
I've attached my first week of work as a patchset for review. This is
also available on Github [1].
By next Monday I intend to (more or less) finish up the preliminary
parts concerning the codegen; and start working on the runtime (so that
I can do a basic sanity check).
Thanks!. Some quick notes
*) Maybe you could add the description you used for the GSoC to the segmented-stacks document too? Maybe at the end and under a "not yet implemented" section, but having it all in one place is probably useful.
*) You use "stack block" in some places and stacklets in others.
*) You mention that variable sized alloca's are handled by using the heap. This is an interesting idea, but you have to be careful to avoid leaks if exceptions are enabled.
*) If I remember correctly, you wanted to fold the red zone in the "do I need more stack" check, but I seed that you have a !EnableSegmentedStacks in the Red Zone check. Have you decided not to do it?
*) You intend for the runtime to be compatible with the gcc one? Their stack allocating function is called __morestack...
[1] https://github.com/sanjoy/llvm/tree/segmented-stacks
Cheers,
Rafael
Hi!
I've attached my first week of work as a patchset for review. This is
also available on Github [1].
By next Monday I intend to (more or less) finish up the preliminary
parts concerning the codegen; and start working on the runtime (so that
I can do a basic sanity check).
Thanks!. Some quick notes
*) Maybe you could add the description you used for the GSoC to the
segmented-stacks document too? Maybe at the end and under a "not yet
implemented" section, but having it all in one place is probably useful.
Okay, will do.
*) You use "stack block" in some places and stacklets in others.
Will fix.
*) You mention that variable sized alloca's are handled by using the
heap. This is an interesting idea, but you have to be careful to avoid
leaks if exceptions are enabled.
*) If I remember correctly, you wanted to fold the red zone in the "do I
need more stack" check, but I seed that you have a
!EnableSegmentedStacks in the Red Zone check. Have you decided not to do
it?
I want to get an rough version working ASAP (hopefully by next Monday);
after which I'll go on to implement support for the red zone.
About heap allocating allocas: I guessed we could just have the stacklet
cleanup function free all the alloca blocks associated with the stacklet
it is freeing (the stacklet will have a list of heap-allocated alloca
blocks). While this would not ensure that all such allocas are freed as
soon as possible; it will ensure that they are freed eventually so we
don't have a leak. Perhaps, at a later stage, code can be added that
frees the relevant alloca-heap blocks as the function returns; and only
if an exception was thrown will the "backup" mechanism of the cleanup
function freeing the blocks will be used.
*) You intend for the runtime to be compatible with the gcc one? Their
stack allocating function is called __morestack...
I'm not sure. Does it make sense to have a initial version that
generates calls the libgcc rather than compiler-rt?