https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99144
Bug ID: 99144
Summary: -mtune=68040 doesn't respect restrictions set by
-march=68060
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: miro.kropacek at gmail dot com
Target Milestone: ---
man gcc states:
-m68060
[...]
This option inhibits the use of 68020 and 68881/68882 instructions that have to
be emulated by software on the 68060.
-mtune=tune
Tune the code for a particular microarchitecture, within the constraints set by
-march and -mcpu.
... and yet when I compile this code with -march=68060 -mtune=68040:
extern float x(int i);
extern unsigned long long y(int h);
extern unsigned long long z;
int main() {
z = y(0)*y(1);
return 0;
}
I can see a "mulu.l %d1,%d1:%d2" generated in the final code. This shouldn't be
possible as the 64-bit mulu has to be emulated by software on the 68060.
The same can be observered in a reverse scenario when "fintrz" (emulated on
040) is generated even if I set -march=68040 -mtune=68060.
Looking into m68k.md and m68k.h the reason is obvious, there is no TARGET_68060
defined, i.e. 040 and 060 instruction sets are considered equal and only
TUNE_68040 and TUNE_68060 is taken into account.
