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sim/erc32: avoid dereferencing type-punned pointer warnings

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When building the erc32 simulator I get a few warnings like this:

  /tmp/build/sim/../../src/sim/erc32/exec.c:1377:21: warning: dereferencing type-punned pointer will break strict-aliasing rules [-Wstrict-aliasing]
   1377 |   sregs->fs[rd] = *((float32 *) & ddata[0]);
        |                    ~^~~~~~~~~~~~~~~~~~~~~~~

The type of '& ddata[0]' will be 'uint32_t *', which is what triggers
the warning.

This commit makes use of memcpy when performing the type-punning,
which resolves the above warnings.

With this change, I now see no warnings when compiling exec.c, which
means that the line in Makefile.in that disables -Werror can be
removed.

There should be no change in behaviour after this commit.
This commit is contained in:
Andrew Burgess 2022-10-12 11:45:53 +01:00
parent e5961d2be5
commit d0a7ca87ab
2 changed files with 4 additions and 6 deletions
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3
sim/erc32/Makefile.in
View file

@ -32,9 +32,6 @@ SIM_EXTRA_CLEAN = clean-sis
# behaviour of UART interrupt routines ...
SIM_EXTRA_CFLAGS += -DFAST_UART -I$(srcroot)
# Some modules don't build cleanly yet.
exec.o: SIM_WERROR_CFLAGS =
## COMMON_POST_CONFIG_FRAG
# `sis' doesn't need interf.o.

7
sim/erc32/exec.c
View file

@ -1345,7 +1345,7 @@ dispatch_instruction(struct pstate *sregs)
if (mexc) {
sregs->trap = TRAP_DEXC;
} else {
sregs->fs[rd] = *((float32 *) & data);
memcpy (&sregs->fs[rd], &data, sizeof (sregs->fs[rd]));
}
break;
case LDDF:
@ -1373,11 +1373,12 @@ dispatch_instruction(struct pstate *sregs)
} else {
rd &= 0x1E;
sregs->flrd = rd;
sregs->fs[rd] = *((float32 *) & ddata[0]);
memcpy (&sregs->fs[rd], &ddata[0], sizeof (sregs->fs[rd]));
#ifdef STAT
sregs->nload++; /* Double load counts twice */
#endif
sregs->fs[rd + 1] = *((float32 *) & ddata[1]);
memcpy (&sregs->fs[rd + 1], &ddata[1],
sizeof (sregs->fs[rd + 1]));
sregs->ltime = ebase.simtime + sregs->icnt + FLSTHOLD +
sregs->hold + sregs->fhold;
}