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Add comments for cryptic functions in iseq.c

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This commit is contained in:
Takashi Kokubun 2025-04-28 11:45:53 -07:00
parent 58e3aa0224
commit 9996d692f4
1 changed files with 16 additions and 3 deletions
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19
iseq.c
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@ -2377,6 +2377,8 @@ rb_iseq_event_flags(const rb_iseq_t *iseq, size_t pos)
}
}
// Clear tracing event flags and turn off tracing for a given instruction as needed.
// This is currently used after updating a one-shot line coverage for the current instruction.
void
rb_iseq_clear_event_flags(const rb_iseq_t *iseq, size_t pos, rb_event_flag_t reset)
{
@ -3767,6 +3769,8 @@ rb_free_encoded_insn_data(void)
st_free_table(encoded_insn_data);
}
// Initialize a table to decode bare, trace, and zjit instructions.
// This function also determines which instructions are used when TracePoint is enabled.
void
rb_vm_encoded_insn_data_table_init(void)
{
@ -3783,7 +3787,8 @@ rb_vm_encoded_insn_data_table_init(void)
insn_data[insn].insn_len = insn_len(insn);
// When tracing :return events, we convert opt_invokebuiltin_delegate_leave + leave into
// opt_invokebuiltin_delegate + trace_leave. https://github.com/ruby/ruby/pull/3256
// opt_invokebuiltin_delegate + trace_leave, presumably because we don't want to fire
// :return events before invokebuiltin. https://github.com/ruby/ruby/pull/3256
int notrace_insn = (insn != BIN(opt_invokebuiltin_delegate_leave)) ? insn : BIN(opt_invokebuiltin_delegate);
insn_data[insn].notrace_encoded_insn = (void *)INSN_CODE(notrace_insn);
insn_data[insn].trace_encoded_insn = (void *)INSN_CODE(notrace_insn + VM_BARE_INSTRUCTION_SIZE);
@ -3806,6 +3811,9 @@ rb_vm_encoded_insn_data_table_init(void)
}
}
// Decode an insn address to an insn. This returns bare instructions
// even if they're trace/zjit instructions. Use rb_vm_insn_addr2opcode
// to decode trace/zjit instructions as is.
int
rb_vm_insn_addr2insn(const void *addr)
{
@ -3820,7 +3828,8 @@ rb_vm_insn_addr2insn(const void *addr)
rb_bug("rb_vm_insn_addr2insn: invalid insn address: %p", addr);
}
// Unlike rb_vm_insn_addr2insn, this function can return trace opcode variants.
// Decode an insn address to an insn. Unlike rb_vm_insn_addr2insn,
// this function can return trace/zjit opcode variants.
int
rb_vm_insn_addr2opcode(const void *addr)
{
@ -3844,7 +3853,9 @@ rb_vm_insn_addr2opcode(const void *addr)
rb_bug("rb_vm_insn_addr2opcode: invalid insn address: %p", addr);
}
// Decode `ISEQ_BODY(iseq)->iseq_encoded[i]` to an insn.
// Decode `ISEQ_BODY(iseq)->iseq_encoded[i]` to an insn. This returns
// bare instructions even if they're trace/zjit instructions. Use
// rb_vm_insn_addr2opcode to decode trace/zjit instructions as is.
int
rb_vm_insn_decode(const VALUE encoded)
{
@ -3856,6 +3867,7 @@ rb_vm_insn_decode(const VALUE encoded)
return insn;
}
// Turn on or off tracing for a given instruction address
static inline int
encoded_iseq_trace_instrument(VALUE *iseq_encoded_insn, rb_event_flag_t turnon, bool remain_current_trace)
{
@ -3874,6 +3886,7 @@ encoded_iseq_trace_instrument(VALUE *iseq_encoded_insn, rb_event_flag_t turnon,
rb_bug("trace_instrument: invalid insn address: %p", (void *)*iseq_encoded_insn);
}
// Turn off tracing for an instruction at pos after tracing event flags are cleared
void
rb_iseq_trace_flag_cleared(const rb_iseq_t *iseq, size_t pos)
{