https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83423
Bug ID: 83423
Summary: default_static_chain is sorry for non-nested functions
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: vries at gcc dot gnu.org
Target Milestone: ---
The default_static_chain hook has implemented a sorry if both
STATIC_CHAIN_INCOMING_REGNUM and STATIC_CHAIN_REGNUM are undefined:
...
rtx
default_static_chain (const_tree ARG_UNUSED (fndecl_or_type), bool incoming_p)
{
if (incoming_p)
{
#ifdef STATIC_CHAIN_INCOMING_REGNUM
return gen_rtx_REG (Pmode, STATIC_CHAIN_INCOMING_REGNUM);
#endif
}
#ifdef STATIC_CHAIN_REGNUM
return gen_rtx_REG (Pmode, STATIC_CHAIN_REGNUM);
#endif
{
static bool issued_error;
if (!issued_error)
{
issued_error = true;
sorry ("nested functions not supported on this target");
}
/* It really doesn't matter what we return here, so long at it
doesn't cause the rest of the compiler to crash. */
return gen_rtx_MEM (Pmode, stack_pointer_rtx);
}
}
...
However, we also call this hook when compiling normal, non-nested functions, so
the sorry is effective for both nested and non-nested functions.
The i386 port has a bit that returns NULL for non-nested functions:
...
static rtx
ix86_static_chain (const_tree fndecl_or_type, bool incoming_p)
{
unsigned regno;
/* While this function won't be called by the middle-end when a static
chain isn't needed, it's also used throughout the backend so it's
easiest to keep this check centralized. */
if (DECL_P (fndecl_or_type) && !DECL_STATIC_CHAIN (fndecl_or_type))
return NULL;
...
Using the same code in default_static_chain fixes the problem.
There are two ways to fix this:
- conservative: we add the test before the sorry, such that it's only effective
for targets that do not define STATIC_CHAIN_INCOMING_REGNUM and
STATIC_CHAIN_REGNUM (typically, this situation happens during bringup of a
target. I'm not certain this triggers for any current trunk target)
- optimal: we add the test at the start of the function, such that it's
effective for all targets that use it (all but i386, moxie, xtensa)
