selftests/powerpc: Add test for 32 bits memcmp

This patch renames memcmp test to memcmp_64 and adds a memcmp_32 test
for testing the 32 bits version of memcmp()

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Fix 64-bit build by adding build_32bit test]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

tools/testing/selftests/powerpc/stringloops/Makefile

@@ -1,10 +1,24 @@
 # SPDX-License-Identifier: GPL-2.0
 # The loops are all 64-bit code
-CFLAGS += -m64 -maltivec
 CFLAGS += -I$(CURDIR)
 
-TEST_GEN_PROGS := memcmp
-EXTRA_SOURCES := memcmp_64.S ../harness.c
+EXTRA_SOURCES := ../harness.c
+
+build_32bit = $(shell if ($(CC) $(CFLAGS) -m32 -o /dev/null memcmp.c >/dev/null 2>&1) then echo "1"; fi)
+
+TEST_GEN_PROGS := memcmp_64
+
+$(OUTPUT)/memcmp_64: memcmp.c
+$(OUTPUT)/memcmp_64: CFLAGS += -m64 -maltivec
+
+ifeq ($(build_32bit),1)
+$(OUTPUT)/memcmp_32: memcmp.c
+$(OUTPUT)/memcmp_32: CFLAGS += -m32
+
+TEST_GEN_PROGS += memcmp_32
+endif
+
+ASFLAGS = $(CFLAGS)
 
 include ../../lib.mk
 

tools/testing/selftests/powerpc/stringloops/memcmp_32.S

@@ -0,0 +1 @@
+../../../../../arch/powerpc/lib/memcmp_32.S