mirrors/Odin
1
0
Fork 0
mirror of https://github.com/odin-lang/Odin.git synced 2026-08-27 23:41:31 +00:00
Code Issues Packages Projects Releases Wiki Activity

Check for infinite cycles in the CFG and report if the procedure is not marketed as diverging

Browse Source
This commit is contained in:
gingerBill
2026-08-25 09:55:48 +01:00
parent 6f65d775c2
commit c200bfc189
1 changed files with 51 additions and 9 deletions
Download Patch File Download Diff File Expand all files Collapse all files

60
src/check_asm_cfg.cpp
View File

@@ -1,6 +1,8 @@
struct AsmBlock {
i32 first, last;
Array<i32> succs;
i32 first; // instruction index
i32 last;
Array<i32> succs;
u16 in_defs;
u16 out_defs;
@@ -33,7 +35,7 @@ struct AsmInstructionFacts {
bool is_terminal;
Entity *branch_target;
i32 block_id;
i32 block_id;
};
struct AsmCfg {
@@ -325,7 +327,7 @@ gb_internal void check_asm_cfg_analyse(AsmCtx *asm_ctx, AsmCfg *cfg, CheckerCont
if (cfg->blocks.count == 0) {
// With an empty body, the CFG cannot really do nothing
if (diverging && !cfg->saw_any_instructions) {
error(entity->token, "This asm template is declared as diverging (-> !) but its body is empty and cannot diverge");
error(entity->token, "This 'asm' template is declared as diverging (-> !) but its body is empty and cannot diverge");
}
return;
}
@@ -584,9 +586,6 @@ gb_internal void check_asm_cfg_analyse(AsmCtx *asm_ctx, AsmCfg *cfg, CheckerCont
break;
}
}
gb_printf_err("RBW-ERROR site=<label> pe='%.*s' run_pm-bit-defined=%d\n",
LIT(pe->token.string),
(map_get(&cfg->entity_to_index, pe) ? ((run_pm >> *map_get(&cfg->entity_to_index, pe)) & 1) : -1));
error(loc, "'%.*s' reads '%.*s' before it is assigned; its initial value is undefined", LIT(f->name), LIT(pe->token.string));
ptr_set_add(&reported_params, pe);
}
@@ -660,10 +659,53 @@ gb_internal void check_asm_cfg_analyse(AsmCtx *asm_ctx, AsmCfg *cfg, CheckerCont
}
if (any_leak) {
error(entity->token,
"This asm template is declared diverging (-> !) but a reachable path can fall through the end; "
"This 'asm' template is declared diverging (-> !) but a reachable path can fall through the end; "
"end every path with an unconditional jump, return, or halt");
}
}
} else {
// Not declared diverging: no reachable block leaves => control never returns
bool any_exit = false;
for_array(bi, cfg->blocks) {
auto const &block = cfg->blocks[bi];
if (block.reachable && check_asm_cfg_block_leaves(cfg, cast(i32)bi)) {
any_exit = true;
break;
}
}
if (!any_exit) {
// Distinguish an unconditional self-loop (jmp to own block, no other exit edge)
// from the general no-returning-path case.
i32 self_loop_bi = -1;
for_array(bi, cfg->blocks) {
AsmBlock const &b = cfg->blocks[bi];
if (!b.reachable) {
continue;
}
bool loops_to_self = false;
for (i32 s : b.succs) {
if (s == cast(i32)bi) {
loops_to_self = true;
break;
}
}
if (loops_to_self && b.succs.count == 1) {
self_loop_bi = cast(i32)bi;
break;
}
}
if (self_loop_bi >= 0) {
AstAsmInstruction *first = cfg->insts[cfg->blocks[self_loop_bi].first];
error(first->name,
"This asm instruction forms an unconditional self-loop and can never exit; "
"if the template is meant never to return, declare it diverging (-> !)");
} else {
error(entity->token,
"This 'asm' template has no reachable path that returns or falls through the end; "
"if this is intended, declare it diverging (-> !)");
}
}
}
}
// Backward liveness: a value is live at a point if some path from there reads it before overwriting it.