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[PATCH] eval.c (evaluate_subexp_standard): Add some comments.
- From: Doug Evans <dje at google dot com>
- To: gdb-patches at sourceware dot org
- Date: Thu, 17 Apr 2014 13:15:12 -0700
- Subject: [PATCH] eval.c (evaluate_subexp_standard): Add some comments.
- Authentication-results: sourceware.org; auth=none
Hi.
Reading this part of evaluate_subexp_standard was harder than
it could be (for me anyway).
2014-04-17 Doug Evans <dje@google.com>
* eval.c (evaluate_subexp_standard): Add some comments.
diff --git a/gdb/eval.c b/gdb/eval.c
index 3e62ead..8cc923d 100644
--- a/gdb/eval.c
+++ b/gdb/eval.c
@@ -1363,7 +1363,7 @@ evaluate_subexp_standard (struct type *expect_type,
op = exp->elts[*pos].opcode;
nargs = longest_to_int (exp->elts[pc + 1].longconst);
/* Allocate arg vector, including space for the function to be
- called in argvec[0] and a terminating NULL. */
+ called in argvec[0], a potential `this', and a terminating NULL. */
argvec = (struct value **)
alloca (sizeof (struct value *) * (nargs + 3));
if (op == STRUCTOP_MEMBER || op == STRUCTOP_MPTR)
@@ -1514,6 +1514,7 @@ evaluate_subexp_standard (struct type *expect_type,
name, TYPE_TAG_NAME (type));
tem = 1;
+ /* arg2 is left as NULL on purpose. */
}
else
{
@@ -1521,6 +1522,8 @@ evaluate_subexp_standard (struct type *expect_type,
|| TYPE_CODE (type) == TYPE_CODE_UNION);
function_name = name;
+ /* We need a properly typed value for method lookup. For
+ static methods arg2 is otherwise unused. */
arg2 = value_zero (type, lval_memory);
++nargs;
tem = 2;
@@ -1570,7 +1573,8 @@ evaluate_subexp_standard (struct type *expect_type,
}
}
- /* Evaluate arguments. */
+ /* Evaluate arguments (if not already done, e.g., namespace::func()
+ and overload-resolution is off). */
for (; tem <= nargs; tem++)
{
/* Ensure that array expressions are coerced into pointer
@@ -1580,6 +1584,7 @@ evaluate_subexp_standard (struct type *expect_type,
/* Signal end of arglist. */
argvec[tem] = 0;
+
if (op == OP_ADL_FUNC)
{
struct symbol *symp;
@@ -1609,7 +1614,8 @@ evaluate_subexp_standard (struct type *expect_type,
int static_memfuncp;
char *tstr;
- /* Method invocation : stuff "this" as first parameter. */
+ /* Method invocation: stuff "this" as first parameter.
+ If the method turns out to be static we undo this below. */
argvec[1] = arg2;
if (op != OP_SCOPE)
@@ -1663,6 +1669,7 @@ evaluate_subexp_standard (struct type *expect_type,
argvec[1] = arg2; /* the ``this'' pointer */
}
+ /* Take out `this' if needed. */
if (static_memfuncp)
{
argvec[1] = argvec[0];