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Async exceptions implementation for arm64 #2450

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Merged
merged 2 commits into from
Apr 22, 2024
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Merged

Async exceptions implementation for arm64 #2450

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d57c1ed
Async exns for arm64: runtime5
mshinwell Apr 15, 2024
1128f5e
Async exns for arm64: runtime4
mshinwell Apr 15, 2024
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14 changes: 12 additions & 2 deletions ocaml/runtime/arm64.S
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Original file line number Diff line number Diff line change
Expand Up @@ -203,6 +203,7 @@ G(name):
#define Cstack_sp(reg) [reg, #8]
#define Cstack_sp_offset 8
#define Cstack_prev(reg) [reg, #16]
#define Cstack_async_exn_handler(reg) [reg, #24]

/* struct stack_handler */
#define Handler_value(reg) [reg]
Expand Down Expand Up @@ -352,7 +353,7 @@ FUNCTION(caml_call_realloc_stack)
ldp x29, x30, [sp], 16
add sp, sp, 16 /* pop argument */
ADDRGLOBAL(x0, caml_exn_Stack_overflow)
b G(caml_raise_exn)
b G(caml_raise_async)
CFI_ENDPROC
END_FUNCTION(caml_call_realloc_stack)

Expand Down Expand Up @@ -543,7 +544,9 @@ L(jump_to_caml):
ldr ALLOC_PTR, Caml_state(young_ptr)
/* Build (16-byte aligned) struct c_stack_link on the C stack */
ldr x8, Caml_state(c_stack)
stp x8, xzr, [sp, -16]! /* C_stack_prev, pad */
ldr x9, Caml_state(async_exn_handler)
stp x8, x9, [sp, -16]!
/* C_stack_prev, C_stack_async_exn_handler */
CFI_ADJUST(16)
stp xzr, xzr, [sp, -16]! /* C_stack_stack, C_stack_sp */
CFI_ADJUST(16)
Expand All @@ -563,6 +566,10 @@ L(jump_to_caml):
adr x10, L(trap_handler)
stp x9, x10, [x8, -16]!
mov TRAP_PTR, x8
/* Note that the async exception handler chain always goes through
Caml_state, unlike the normal exception handler chain, which goes
through the TRAP_PTR register. */
str x8, Caml_state(async_exn_handler)
/* Switch stacks and call the OCaml code */
mov sp, x8
#ifdef ASM_CFI_SUPPORTED
Expand Down Expand Up @@ -598,6 +605,9 @@ L(return_result):
ldr x9, Caml_state(c_stack)
mov sp, x9
CFI_RESTORE_STATE
/* Restore saved async exception pointer */
ldr x8, Cstack_async_exn_handler(sp)
str x8, Caml_state(async_exn_handler)
/* Pop the struct c_stack_link */
ldr x8, Cstack_prev(sp)
add sp, sp, 32
Expand Down
15 changes: 10 additions & 5 deletions ocaml/runtime4/arm64.S
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Original file line number Diff line number Diff line change
Expand Up @@ -401,8 +401,6 @@ FUNCTION(caml_start_program)
/* Address of OCaml code to call is in TMP2 */
/* Arguments to the OCaml code are in x0...x7 */

/* CR mshinwell: asynchronous exceptions are not yet implemented here */

L(jump_to_caml):
/* Set up stack frame and save callee-save registers */
CFI_OFFSET(29, -160)
Expand All @@ -425,15 +423,19 @@ L(jump_to_caml):
ldr x8, Caml_state(bottom_of_stack)
ldr x9, Caml_state(last_return_address)
ldr x10, Caml_state(gc_regs)
ldr x11, Caml_state(async_exception_pointer)
stp x8, x9, [sp, -32]! /* 16-byte alignment */
CFI_ADJUST(32)
str x10, [sp, 16]
str x11, [sp, 24]
/* Setup a trap frame to catch exceptions escaping the OCaml code */
ldr x8, Caml_state(exn_handler)
adr x9, L(trap_handler)
stp x8, x9, [sp, -16]!
CFI_ADJUST(16)
add TRAP_PTR, sp, #0
/* Store the async exception pointer */
str TRAP_PTR, Caml_state(async_exception_pointer)
/* Reload allocation pointer */
ldr ALLOC_PTR, Caml_state(young_ptr)
/* Call the OCaml code */
Expand All @@ -445,12 +447,14 @@ L(caml_retaddr):
str x8, Caml_state(exn_handler)
/* Pop the callback link, restoring the global variables */
L(return_result):
ldr x11, [sp, 24]
ldr x10, [sp, 16]
ldp x8, x9, [sp], 32
CFI_ADJUST(-32)
str x8, Caml_state(bottom_of_stack)
str x9, Caml_state(last_return_address)
str x10, Caml_state(gc_regs)
str x11, Caml_state(async_exception_pointer)
/* Update allocation pointer */
str ALLOC_PTR, Caml_state(young_ptr)
/* Reload callee-save registers and return address */
Expand Down Expand Up @@ -556,9 +560,10 @@ FUNCTION(caml_raise_exception)
FUNCTION(caml_stack_overflow)
/* Load the exception bucket */
ADDRGLOBAL(x0, caml_exn_Stack_overflow)
/* Cut stack at current trap handler */
mov sp, TRAP_PTR
/* Pop previous handler and jump to it */
/* Cut stack at current async exn trap handler */
ldr TMP, Caml_state(async_exception_pointer)
mov sp, TMP
/* Pop handler and jump to it */
ldr TMP, [sp, 8]
ldr TRAP_PTR, [sp], 16
br TMP
Expand Down
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