hang in ir_sccp

[sgraham]

I'm running into a hang in ir_sccp() on Windows amd64, ir_builder repro below.

It seems to get stuck in this loop, ir_sccp.c:~2232 but I'm not sure what invariant has been violated.

	while ((i = ir_bitqueue_pop(&worklist)) >= 0) {

The hang only happens in this repro if there's 8 CALLs, if I e.g. remove the last one, it works as expected. (Of course it also works at with optimizations disable as ir_sccp() is skipped).

#include <stdlib.h>
#include "ir.h"
#include "ir_builder.h"

#include <stdio.h>

void printer(int32_t value) {
  printf("%d\n", value);
}

void gen_myfunc(ir_ctx* ctx) {
  ir_START();

  ir_ref a = ir_VAR(IR_I32, "a");
  ir_VSTORE(a, ir_CONST_I32(1));

  ir_ref b = ir_VAR(IR_I32, "b");
  ir_VSTORE(b, ir_CONST_I32(2));

  ir_ref c = ir_VAR(IR_I32, "c");
  ir_VSTORE(c, ir_CONST_I32(3));

  ir_ref d = ir_VAR(IR_I32, "d");
  ir_VSTORE(d, ir_CONST_I32(4));

  ir_ref e = ir_VAR(IR_I32, "e");
  ir_VSTORE(e, ir_CONST_I32(5));

  ir_ref f = ir_VAR(IR_I32, "f");
  ir_VSTORE(f, ir_CONST_I32(6));

  ir_ref g = ir_VAR(IR_I32, "g");
  ir_VSTORE(g, ir_CONST_I32(7));

  ir_ref h = ir_VAR(IR_I32, "h");
  ir_VSTORE(h, ir_CONST_I32(8));

  ir_ref print_addr = ir_CONST_ADDR(printer);
  ir_CALL_1(IR_VOID, print_addr, ir_VLOAD(IR_I32, a));
  ir_CALL_1(IR_VOID, print_addr, ir_VLOAD(IR_I32, b));
  ir_CALL_1(IR_VOID, print_addr, ir_VLOAD(IR_I32, c));
  ir_CALL_1(IR_VOID, print_addr, ir_VLOAD(IR_I32, d));
  ir_CALL_1(IR_VOID, print_addr, ir_VLOAD(IR_I32, e));
  ir_CALL_1(IR_VOID, print_addr, ir_VLOAD(IR_I32, f));
  ir_CALL_1(IR_VOID, print_addr, ir_VLOAD(IR_I32, g));
  ir_CALL_1(IR_VOID, print_addr, ir_VLOAD(IR_I32, h));

  ir_RETURN(IR_UNUSED);
}

int main(int argc, char** argv) {
  ir_ctx ctx;

  ir_consistency_check();

  ir_init(&ctx, IR_FUNCTION | IR_OPT_FOLDING, IR_CONSTS_LIMIT_MIN, IR_INSNS_LIMIT_MIN);
  ctx.ret_type = IR_VOID;

  gen_myfunc(&ctx);

  size_t size;
  void* entry = ir_jit_compile(&ctx, 2, &size);
  if (entry) {
    ((void (*)())entry)();
  }

  ir_free(&ctx);

  return 0;
}