[RFA] sh-tdep.c (sh_use_struct_convention): Restructure and fix

Corinna Vinschen
2003-10-04T11:39:44Z

Hi,

the below patch straightens out sh_use_struct_convention() so that it
allows a far better readability than before, especially by allowing
a bunch of comments spread out through the code.

Additionally it fixes one bug: A struct of lenght 4 bytes, which
consists of only a bitfield, is returned in register r0, not on the
stack using the struct convention. So far, GDB got that wrong.

Corinna

* sh-tdep.c (sh_use_struct_convention): Clean up to have a
more readable code. Accomodate 4 byte structs with 4 byte sized
first field (e.g. bitfields).

Index: sh-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/sh-tdep.c,v
retrieving revision 1.145
diff -u -p -r1.145 sh-tdep.c
--- sh-tdep.c 3 Oct 2003 08:13:37 -0000 1.145
+++ sh-tdep.c 4 Oct 2003 11:32:00 -0000
@@ -565,8 +565,25 @@ sh_use_struct_convention (int gcc_p, str
{
int len = TYPE_LENGTH (type);
int nelem = TYPE_NFIELDS (type);
- return ((len != 1 && len != 2 && len != 4 && len != 8) || nelem != 1) &&
- (len != 8 || TYPE_LENGTH (TYPE_FIELD_TYPE (type, 0)) != 4);
+
+ /* Non-power of 2 length types and types bigger than 8 bytes (which don't
+ fit in two registers anyway) use struct convention. */
+ if (len != 1 && len != 2 && len != 4 && len != 8)
+ return 1;
+ /* Structs with more than 1 fields use struct convention, if... */
+ if (nelem != 1)
+ {
+ /* ... they are 1 or 2 bytes in size (e.g. struct of two chars)... */
+ if (len != 4 && len != 8)
+ return 1;
+ /* ... or, if the struct is 4 or 8 bytes and the first field is
+ not of size 4 bytes. Note that this also covers structs with
+ bitfields. */
+ if (TYPE_LENGTH (TYPE_FIELD_TYPE (type, 0)) != 4)
+ return 1;
+ }
+ /* Otherwise return in registers. */
+ return 0;
}

/* Extract from an array REGBUF containing the (raw) register state

--
Corinna Vinschen
Cygwin Developer
Red Hat, Inc.