diff options
Diffstat (limited to 'src/rt/rust_task.cpp')
| -rw-r--r-- | src/rt/rust_task.cpp | 70 |
1 files changed, 48 insertions, 22 deletions
diff --git a/src/rt/rust_task.cpp b/src/rt/rust_task.cpp index 1afbfdd6..febfd851 100644 --- a/src/rt/rust_task.cpp +++ b/src/rt/rust_task.cpp @@ -58,6 +58,21 @@ align_down(uintptr_t sp) return sp & ~(16 - 1); } +static uintptr_t* +align_down(uintptr_t* sp) +{ + return (uintptr_t*) align_down((uintptr_t)sp); +} + + +static void +make_aligned_room_for_bytes(uintptr_t*& sp, size_t n) +{ + uintptr_t tmp = (uintptr_t) sp; + tmp = align_down(tmp - n) + n; + sp = (uintptr_t*) tmp; +} + rust_task::rust_task(rust_dom *dom, rust_task_list *state, rust_task *spawner, const char *name) : @@ -131,9 +146,15 @@ rust_task::start(uintptr_t exit_task_glue, dom->logptr("exit-task glue", exit_task_glue); dom->logptr("from spawnee", spawnee_fn); - // Set sp to last uintptr_t-sized cell of segment and align down. + // Set sp to last uintptr_t-sized cell of segment rust_sp -= sizeof(uintptr_t); - rust_sp = align_down(rust_sp); + + // NB: Darwin needs "16-byte aligned" stacks *at the point of the call + // instruction in the caller*. This means that the address at which a + // retpc is pushed must always be 16-byte aligned. + // + // see: "Mac OS X ABI Function Call Guide" + // Begin synthesizing frames. There are two: a "fully formed" // exit-task frame at the top of the stack -- that pretends to be @@ -145,10 +166,13 @@ rust_task::start(uintptr_t exit_task_glue, // frame when it's done, and exit. uintptr_t *spp = (uintptr_t *)rust_sp; + // The exit_task_glue frame we synthesize above the frame we activate: + make_aligned_room_for_bytes(spp, 3 * sizeof(uintptr_t)); *spp-- = (uintptr_t) 0; // closure-or-obj *spp-- = (uintptr_t) this; // task *spp-- = (uintptr_t) 0x0; // output + I(dom, spp == align_down(spp)); *spp-- = (uintptr_t) 0x0; // retpc uintptr_t exit_task_frame_base; @@ -172,27 +196,28 @@ rust_task::start(uintptr_t exit_task_glue, *spp-- = (uintptr_t) 0; // frame_glue_fns } + I(dom, args); + if (spawnee_abi == ABI_X86_RUSTBOOT_CDECL) + make_aligned_room_for_bytes(spp, callsz); + else + make_aligned_room_for_bytes(spp, callsz - 2 * sizeof(uintptr_t)); + // Copy args from spawner to spawnee. - if (args) { - uintptr_t *src = (uintptr_t *)args; - src += 1; // spawn-call output slot - src += 1; // spawn-call task slot - src += 1; // spawn-call closure-or-obj slot - - // Undo previous sp-- so we're pointing at the last word pushed. - ++spp; - - // Memcpy all but the task, output and env pointers - callsz -= (3 * sizeof(uintptr_t)); - spp = (uintptr_t*) (((uintptr_t)spp) - callsz); - memcpy(spp, src, callsz); - - // Move sp down to point to last implicit-arg cell (env). - spp--; - } else { - // We're at root, starting up. - I(dom, callsz==0); - } + uintptr_t *src = (uintptr_t *)args; + src += 1; // spawn-call output slot + src += 1; // spawn-call task slot + src += 1; // spawn-call closure-or-obj slot + + // Undo previous sp-- so we're pointing at the last word pushed. + ++spp; + + // Memcpy all but the task, output and env pointers + callsz -= (3 * sizeof(uintptr_t)); + spp = (uintptr_t*) (((uintptr_t)spp) - callsz); + memcpy(spp, src, callsz); + + // Move sp down to point to last implicit-arg cell (env). + spp--; // The *implicit* incoming args to the spawnee frame we're // activating: @@ -208,6 +233,7 @@ rust_task::start(uintptr_t exit_task_glue, I(dom, spawnee_abi == ABI_X86_RUSTC_FASTCALL); } + I(dom, spp == align_down(spp)); *spp-- = (uintptr_t) exit_task_glue; // retpc // The context the activate_glue needs to switch stack. |