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and applies them to the use of cgraph_node, varpool_node, and symtab_node.
The functions are:
bool is_a <TYPE> (pointer)
Tests whether the pointer actually points to a more derived TYPE.
TYPE *as_a <TYPE> (pointer)
Converts pointer to a TYPE*.
TYPE *dyn_cast <TYPE> (pointer)
Converts pointer to TYPE* if and only if "is_a <TYPE> pointer".
Otherwise, returns NULL.
This function is essentially a checked down cast.
These functions reduce compile time and increase type safety when treating a
generic item as a more specific item. In essence, the code change is from
if (symtab_function_p (node))
{
struct cgraph_node *cnode = cgraph (node);
....
}
to
if (cgraph_node *cnode = dyn_cast <cgraph_node> (node))
{
....
}
The necessary conditional test defines a variable that holds a known good
pointer to the specific item and avoids subsequent conversion calls and
the assertion checks that may come with them.
When, the property test is embedded within a larger condition, the variable
declaration gets pulled out of the condition. (This leaves some room for
using the variable inappropriately.)
if (symtab_variable_p (node)
&& varpool (node)->finalized)
varpool_analyze_node (varpool (node));
becomes
varpool_node *vnode = dyn_cast <varpool_node> (node);
if (vnode && vnode->finalized)
varpool_analyze_node (vnode);
Note that we have converted two sets of assertions in the calls to varpool
into safe and efficient use of a variable.
There are remaining calls to symtab_function_p and symtab_variable_p that
do not involve a pointer to a more specific type. These have been converted
to calls to a functions is_a <cgraph_node> and is_a <varpool_node>. The
original predicate functions have been removed.
The cgraph.h header defined both a struct and a function with the name
varpool_node. This name overloading can cause some unintuitive error messages
when, as is common in C++, one omits the struct keyword when using the type.
I have renamed the function to varpool_node_for_decl.
Tested on x86_64.
Index: gcc/ChangeLog
2012-10-31 Lawrence Crowl <crowl@google.com>
* is-a.h: New.
(is_a <T> (U*)): New. Test for is-a relationship.
(as_a <T> (U*)): New. Treat as a derived type.
(dyn_cast <T> (U*)): New. Conditionally cast based on is_a.
* cgraph.h (varpool_node): Rename to varpool_node_for_decl.
Adjust callers to match.
(is_a_helper <cgraph_node>::test (symtab_node_def *)): New.
(is_a_helper <varpool_node>::test (symtab_node_def *)): New.
(symtab_node_def::try_function): New. Change most calls to
symtab_function_p with calls to dyn_cast <cgraph_node> (p).
(symtab_node_def::try_variable): New. Change most calls to
symtab_variable_p with calls to dyn_cast <varpool_node> (p).
(symtab_function_p): Remove. Change callers to use
is_a <cgraph_node> (p) instead.
(symtab_variable_p): Remove. Change callers to use
is_a <varpool_node> (p) instead.
* cgraph.c (cgraph_node_for_asm): Remove redundant call to
symtab_node_for_asm.
* cgraphunit.c (symbol_finalized_and_needed): New.
(symbol_finalized): New.
(cgraph_analyze_functions): Split complicated conditionals out into
above new functions.
* Makefile.in (CGRAPH_H): Add is-a.h as used by cgraph.h.
From-SVN: r193051
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