[PATCH] [MSP430] PR78838: Do not add section name prefixes when section name is .lowtext

[Martin Sebor]

On 05/18/2017 10:14 AM, Jozef Lawrynowicz wrote:
> A patch for this bug was originally posted here:
> https://gcc.gnu.org/ml/gcc-patches/2017-02/msg01054.html
> There were some issues with that patch which I've now fixed.
>
> The MSP430 target supports the automatic placement of functions and
> data in different memory regions when passing the
> "-mdata-region=either" and "-mcode-region=either" options.
> MSP430x devices support the large memory model, "-mlarge", which
> enables 20 bit pointers, however the vector table across all MSP430
> targets only accepts 16-bit pointers. To prevent the use of 20-bit
> pointers in the vector table when the large memory model is used, the
> MSP430 backend currently places functions specified with the interrupt
> attribute in a section called ".lowtext". This section is placed at
> the beginning of .text in the MSP430 linker scripts.
>
> PR target/78838 (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78838)
> reports that a function with the interrupt attribute is placed in a
> non-existent section ".either.lowtext" when "-mlarge",
> "-mcode-region=either" and "-ffunction-sections" are passed. The
> backend has correctly decided to place the function in .lowtext, but
> has applied the .either prefix which is undesirable.
>
> No additional .lower/.upper/.either prefixes should be applied to the
> section name once it has been placed in .lowtext, the attached patch
> implements this, and adds a test.
>
> The patch passed regression testing with "-mcpu=msp430x/-mlarge" for
> msp430-elf on the gcc-6-branch (r247086). Trunk doesn't build with C++
> support for msp430-elf which is why gcc-6-branch was used.
>
> I don't have write access to the GCC SVN repository, so if this patch
> is satisfactory, I would appreciate if someone could commit it for me.
> Thanks.

I don't normally review back end patches so forgive me for picking
on two of yours the same day but it seems to me that the first
argument to has_section_name() needs to be const-qualified:

+static bool
+has_section_name (char * name, tree decl = current_function_decl)
...

if the following is to compile without error in C++ where string
literals are const char[]:

+  if (has_section_name (".lowtext", decl))

Martin