From 64aa1de7df2f03e1f9e2c6135644c8fb97e0e98d Mon Sep 17 00:00:00 2001
From: Simon Byrne <simonbyrne@gmail.com>
Date: Tue, 12 Sep 2023 22:12:46 -0700
Subject: [PATCH] add fenv cache to task struct

Fixes #51277
---
 src/julia.h | 4 ++++
 src/task.c  | 3 +++
 2 files changed, 7 insertions(+)

diff --git a/src/julia.h b/src/julia.h
index 92c383ccc5525..b8e392fa8a9bb 100644
--- a/src/julia.h
+++ b/src/julia.h
@@ -19,6 +19,7 @@
 #include "libsupport.h"
 #include <stdint.h>
 #include <string.h>
+#include <fenv.h>
 
 #include "htable.h"
 #include "arraylist.h"
@@ -2050,6 +2051,9 @@ typedef struct _jl_task_t {
     uint16_t priority;
 
 // hidden state:
+    // cached floating point environment
+    // only updated at task switch
+    fenv_t fenv;
 
 #ifdef USE_TRACY
     const char *name;
diff --git a/src/task.c b/src/task.c
index 73d9033f0cb50..7d1c1c82840b3 100644
--- a/src/task.c
+++ b/src/task.c
@@ -503,6 +503,8 @@ 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);
+    fesetenv(&t->fenv);
 #ifdef MIGRATE_TASKS
     ptls->previous_task = lastt;
 #endif
@@ -1079,6 +1081,7 @@ JL_DLLEXPORT jl_task_t *jl_new_task(jl_function_t *start, jl_value_t *completion
     t->excstack = NULL;
     t->started = 0;
     t->priority = 0;
+    fegetenv(&t->fenv);
     jl_atomic_store_relaxed(&t->tid, t->copy_stack ? jl_atomic_load_relaxed(&ct->tid) : -1); // copy_stacks are always pinned since they can't be moved
     t->threadpoolid = ct->threadpoolid;
     t->ptls = NULL;