From 08aa8ffdfb59fd9bdec686d416357958167dad8f Mon Sep 17 00:00:00 2001
From: Kaz Kylheku <kaz@kylheku.com>
Date: Fri, 7 Feb 2025 19:16:43 -0800
Subject: vm: missed cases of signal check in backwards branch
Only the JMP instruction is checking for a backwards branch
and calling sig_check_fast() so that a loop can be interrupted
by Ctrl-C. The compiler can optimize that so that a backwards
jump is performed by an instruction in the IF family.
* vm.c (vm_if, vm_ifq, vm_ifql): Check for a backwards
branch and call sig_check_fast. Also, eliminate the redundant
call to vm_insn_bigop, which is just a masking macro.
The ip variable is already the result of vm_insn_bigop.
---
vm.c | 21 +++++++++++++++------
1 file changed, 15 insertions(+), 6 deletions(-)
(limited to 'vm.c')
diff --git a/vm.c b/vm.c
index c8d0e6fa..63a8d1a7 100644
--- a/vm.c
+++ b/vm.c
@@ -733,8 +733,11 @@ NOINLINE static void vm_if(struct vm *vm, vm_word_t insn)
vm_word_t arg = vm->code[vm->ip++];
val test = vm_get(vm->dspl, vm_arg_operand_lo(arg));
- if (!test)
- vm->ip = vm_insn_bigop(ip);
+ if (!test) {
+ if (ip < vm->ip)
+ sig_check_fast();
+ vm->ip = ip;
+ }
}
NOINLINE static void vm_ifq(struct vm *vm, vm_word_t insn)
@@ -744,8 +747,11 @@ NOINLINE static void vm_ifq(struct vm *vm, vm_word_t insn)
val a = vm_get(vm->dspl, vm_arg_operand_lo(arg));
val b = vm_get(vm->dspl, vm_arg_operand_hi(arg));
- if (a != b)
- vm->ip = vm_insn_bigop(ip);
+ if (a != b) {
+ if (ip < vm->ip)
+ sig_check_fast();
+ vm->ip = ip;
+ }
}
NOINLINE static void vm_ifql(struct vm *vm, vm_word_t insn)
@@ -755,8 +761,11 @@ NOINLINE static void vm_ifql(struct vm *vm, vm_word_t insn)
val a = vm_get(vm->dspl, vm_arg_operand_lo(arg));
val b = vm_get(vm->dspl, vm_arg_operand_hi(arg));
- if (!eql(a, b))
- vm->ip = vm_insn_bigop(ip);
+ if (!eql(a, b)) {
+ if (ip < vm->ip)
+ sig_check_fast();
+ vm->ip = ip;
+ }
}
NOINLINE static void vm_swtch(struct vm *vm, vm_word_t insn)
--
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