fix #3651, codegen was missing some gc roots when boxing objects

src/codegen.cpp

@@ -1326,16 +1326,12 @@ static Value *emit_known_call(jl_value_t *ff, jl_value_t **args, size_t nargs,
  }
 
  int last_depth = ctx->argDepth;
- // we only get a GC root per-argument, so we can't allocate the
- // tuple before evaluating one argument. so eval the first argument
- // first, then do hand-over-hand to track the tuple.
- bool needroots = false;
- for(i=0; i < nargs; i++) {
- needroots |= might_need_root(args[i+1]);
- }
- Value *arg1 = boxed(emit_expr(args[1], ctx));
- if (needroots)
+ // eval the first argument first, then do hand-over-hand to track the tuple.
+ Value *arg1val = emit_expr(args[1], ctx);
+ Value *arg1 = boxed(arg1val);
+ if (arg1val->getType() != jl_pvalue_llvmt || might_need_root(args[1]))
  make_gcroot(arg1, ctx);
+ bool rooted = false;
 #ifdef OVERLAP_TUPLE_LEN
  size_t nwords = nargs+1;
 #else
@@ -1350,8 +1346,6 @@ static Value *emit_known_call(jl_value_t *ff, jl_value_t **args, size_t nargs,
  builder.CreateStore(arg1, emit_nthptr_addr(tup, 2));
 #endif
  ctx->argDepth = last_depth;
- if (needroots)
- make_gcroot(tup, ctx);
 #ifdef OVERLAP_TUPLE_LEN
  builder.
  CreateStore(builder.
@@ -1375,8 +1369,17 @@ static Value *emit_known_call(jl_value_t *ff, jl_value_t **args, size_t nargs,
  emit_nthptr_addr(tup, i+offs));
  }
  for(i=1; i < nargs; i++) {
- builder.CreateStore(boxed(emit_expr(args[i+1], ctx)),
- emit_nthptr_addr(tup, i+offs));
+ if (might_need_root(args[i+1]) && !rooted) {
+ make_gcroot(tup, ctx);
+ rooted = true;
+ }
+ Value *argval = emit_expr(args[i+1], ctx);
+ if (argval->getType() != jl_pvalue_llvmt && !rooted) {
+ make_gcroot(tup, ctx);
+ rooted = true;
+ }
+ Value *argi = boxed(argval);
+ builder.CreateStore(argi, emit_nthptr_addr(tup, i+offs));
  }
  ctx->argDepth = last_depth;
  JL_GC_POP();
@@ -2115,9 +2118,10 @@ static Value *emit_expr(jl_value_t *expr, jl_codectx_t *ctx, bool isboxed,
  // a couple store instructions. avoids initializing
  // the first field to NULL, and sometimes the GC root
  // for the new struct.
- f1 = boxed(emit_expr(args[1],ctx));
+ Value *fval = emit_expr(args[1],ctx);
+ f1 = boxed(fval);
  j++;
- if (might_need_root(args[1]))
+ if (might_need_root(args[1]) || fval->getType() != jl_pvalue_llvmt)
  make_gcroot(f1, ctx);
  }
  Value *strct =
@@ -2141,8 +2145,15 @@ static Value *emit_expr(jl_value_t *expr, jl_codectx_t *ctx, bool isboxed,
  }
  }
  for(size_t i=j+1; i < nargs; i++) {
- emit_setfield(sty, strct, i-1, emit_expr(args[i],ctx), ctx,
- false);
+ Value *rhs = emit_expr(args[i],ctx);
+ if (sty->fields[i].isptr && rhs->getType() != jl_pvalue_llvmt &&
+ !needroots) {
+ // if this struct element needs boxing and we haven't rooted
+ // the struct, root it now.
+ make_gcroot(strct, ctx);
+ needroots = true;
+ }
+ emit_setfield(sty, strct, i-1, rhs, ctx, false);
  }
  ctx->argDepth = fieldStart;
  return strct;