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add fenv cache to task struct #51288

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merged 3 commits into from
Oct 16, 2024
Merged

add fenv cache to task struct #51288

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51429b6
add fenv cache to task struct
simonbyrne Sep 13, 2023
eb91a2e
Update task.c
vtjnash Feb 1, 2024
4405cf1
Merge branch 'master' into sb/task-fenv
simonbyrne Oct 16, 2024
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4 changes: 4 additions & 0 deletions src/julia.h
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,7 @@
#include "libsupport.h"
#include <stdint.h>
#include <string.h>
#include <fenv.h>

#include "htable.h"
#include "arraylist.h"
Expand Down Expand Up @@ -2282,6 +2283,9 @@ typedef struct _jl_task_t {
uint16_t priority;

// hidden state:
// cached floating point environment
// only updated at task switch
fenv_t fenv;

// id of owning thread - does not need to be defined until the task runs
_Atomic(int16_t) tid;
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4 changes: 4 additions & 0 deletions src/task.c
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Expand Up @@ -534,6 +534,7 @@ JL_NO_ASAN static void ctx_switch(jl_task_t *lastt)
jl_set_pgcstack(&t->gcstack);
jl_signal_fence();
lastt->ptls = NULL;
fegetenv(&lastt->fenv);
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This should come before the task switch, as some task switch implementations will clobber it

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Where specifically should it go?

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Or rather, it looks like the fesetenv is the one that needed to move

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Where should it go?

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Feel free to push to this branch

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Already done. I don't know about the propagating behavior though. I think we might want to start every task with a call to set fesetenv(FE_DFL_ENV)?

#ifdef MIGRATE_TASKS
ptls->previous_task = lastt;
#endif
Expand Down Expand Up @@ -726,6 +727,7 @@ JL_DLLEXPORT void jl_switch(void) JL_NOTSAFEPOINT_LEAVE JL_NOTSAFEPOINT_ENTER
0 == ptls->finalizers_inhibited);
ptls->finalizers_inhibited = finalizers_inhibited;
jl_timing_block_task_enter(ct, ptls, blk); (void)blk;
fesetenv(&ct->fenv);

sig_atomic_t other_defer_signal = ptls->defer_signal;
ptls->defer_signal = defer_signal;
Expand Down Expand Up @@ -1138,6 +1140,7 @@ JL_DLLEXPORT jl_task_t *jl_new_task(jl_function_t *start, jl_value_t *completion
t->excstack = NULL;
t->ctx.started = 0;
t->priority = 0;
fegetenv(&t->fenv);
jl_atomic_store_relaxed(&t->tid, -1);
t->threadpoolid = ct->threadpoolid;
t->ptls = NULL;
Expand Down Expand Up @@ -1239,6 +1242,7 @@ CFI_NORETURN
if (!pt->sticky && !pt->ctx.copy_stack)
jl_atomic_store_release(&pt->tid, -1);
#endif
fesetenv(&ct->fenv);

ct->ctx.started = 1;
JL_PROBE_RT_START_TASK(ct);
Expand Down