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TAILLCALL VM: Do not return in ZEND_VM_ENTER_EX, ZEND_VM_LEAVE #21475

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TAILLCALL VM: Do not return in ZEND_VM_ENTER_EX, ZEND_VM_LEAVE #21475

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TAILLCALL VM: Do not return in ZEND_VM_ENTER_EX, ZEND_VM_LEAVE
arnaud-lb Mar 20, 2026
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arnaud-lb Mar 20, 2026
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ZEND_VM_INTERRUPT_CHECK
arnaud-lb Mar 23, 2026
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4 changes: 4 additions & 0 deletions Zend/zend_vm_execute.h
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4 changes: 4 additions & 0 deletions Zend/zend_vm_gen.php
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Original file line number Diff line number Diff line change
Expand Up @@ -2126,6 +2126,8 @@ function gen_executor($f, $skl, $spec, $kind, $executor_name, $initializer_name)
out($f,"# undef ZEND_VM_RETURN\n");
out($f,"# undef ZEND_VM_DISPATCH_TO_HELPER\n");
out($f,"# undef ZEND_VM_INTERRUPT\n");
out($f,"# undef ZEND_VM_ENTER_EX\n");
out($f,"# undef ZEND_VM_LEAVE\n");
out($f,"\n");
out($f,"# define ZEND_VM_TAIL_CALL(call) ZEND_MUSTTAIL return call\n");
out($f,"# define ZEND_VM_CONTINUE() ZEND_VM_TAIL_CALL(opline->handler(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU))\n");
Expand All @@ -2137,6 +2139,8 @@ function gen_executor($f, $skl, $spec, $kind, $executor_name, $initializer_name)
out($f," } while (0)\n");
out($f,"# define ZEND_VM_DISPATCH_TO_LEAVE_HELPER(helper) opline = &call_leave_op; SAVE_OPLINE(); ZEND_VM_CONTINUE()\n");
out($f,"# define ZEND_VM_INTERRUPT() ZEND_VM_TAIL_CALL(zend_interrupt_helper".($spec?"_SPEC":"")."_TAILCALL(ZEND_OPCODE_HANDLER_ARGS_PASSTHRU))\n");
out($f,"# define ZEND_VM_ENTER_EX() ZEND_VM_CONTINUE()\n");
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@dstogov dstogov Mar 23, 2026

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This misses ZEND_VM_INTERRUPT_CHECK();, otherwise a deeply recursive function couldn't be interrupted.

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@arnaud-lb arnaud-lb Mar 23, 2026

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Thank you, I forgot about this. In the CALL VM, ZEND_VM_ENTER_EX() relies on the interpreter loop to check for interrupts. Here we need to check interrupts in ZEND_VM_ENTER_EX() since we don't return to the loop anymore.

I've added ZEND_VM_INTERRUPT_CHECK(). Performance numbers are not impacted meaningfully.

out($f,"# define ZEND_VM_LEAVE() ZEND_VM_CONTINUE()\n");
out($f,"\n");
out($f,"static ZEND_OPCODE_HANDLER_RET ZEND_OPCODE_HANDLER_CCONV zend_interrupt_helper".($spec?"_SPEC":"")."_TAILCALL(ZEND_OPCODE_HANDLER_ARGS);\n");
out($f,"static ZEND_OPCODE_HANDLER_RET ZEND_OPCODE_HANDLER_CCONV ZEND_NULL_TAILCALL_HANDLER(ZEND_OPCODE_HANDLER_ARGS);\n");
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