This is V10 patch #12. It adds a test to make sure we don't generate a prefixed instruction with PRE_INC, PRE_DEC, or PRE_MODIFY. https://gcc.gnu.org/ml/gcc-patches/2019-12/msg00846.html
This test passes when I run it. Can I check this into the trunk? 2019-12-20 Michael Meissner <meiss...@linux.ibm.com> * gcc.target/powerpc/prefix-no-premodify.c: Make sure we do not generate the non-existent PLWZU instruction if -mcpu=future. Index: gcc/testsuite/gcc.target/powerpc/prefix-no-premodify.c =================================================================== --- gcc/testsuite/gcc.target/powerpc/prefix-no-premodify.c (revision 279259) +++ gcc/testsuite/gcc.target/powerpc/prefix-no-premodify.c (working copy) @@ -0,0 +1,50 @@ +/* { dg-do compile } */ +/* { dg-require-effective-target powerpc_prefixed_addr } */ +/* { dg-options "-O2 -mdejagnu-cpu=future" } */ + +/* Make sure that we don't generate a prefixed form of the load and store with + update instructions (i.e. instead of generating LWZU we have to generate + PLWZ plus a PADDI). */ + +#ifndef SIZE +#define SIZE 50000 +#endif + +struct foo { + unsigned int field; + char pad[SIZE]; +}; + +struct foo *inc_load (struct foo *p, unsigned int *q) +{ + *q = (++p)->field; /* PLWZ, PADDI, STW. */ + return p; +} + +struct foo *dec_load (struct foo *p, unsigned int *q) +{ + *q = (--p)->field; /* PLWZ, PADDI, STW. */ + return p; +} + +struct foo *inc_store (struct foo *p, unsigned int *q) +{ + (++p)->field = *q; /* LWZ, PADDI, PSTW. */ + return p; +} + +struct foo *dec_store (struct foo *p, unsigned int *q) +{ + (--p)->field = *q; /* LWZ, PADDI, PSTW. */ + return p; +} + +/* { dg-final { scan-assembler-times {\mlwz\M} 2 } } */ +/* { dg-final { scan-assembler-times {\mstw\M} 2 } } */ +/* { dg-final { scan-assembler-times {\mpaddi\M} 4 } } */ +/* { dg-final { scan-assembler-times {\mplwz\M} 2 } } */ +/* { dg-final { scan-assembler-times {\mpstw\M} 2 } } */ +/* { dg-final { scan-assembler-not {\mplwzu\M} } } */ +/* { dg-final { scan-assembler-not {\mpstwu\M} } } */ +/* { dg-final { scan-assembler-not {\maddis\M} } } */ +/* { dg-final { scan-assembler-not {\maddi\M} } } */ -- Michael Meissner, IBM IBM, M/S 2506R, 550 King Street, Littleton, MA 01460-6245, USA email: meiss...@linux.ibm.com, phone: +1 (978) 899-4797