benchtests: Support for cross-building benchmarks

This patch adds full support for cross-building benchmarks.  Some
benchmarks like those that need locales to be generated cannot be
built and are hence skipped for cross builds.

Tested by cross building for aarch64 on x86_64 and then running the
generated benchmark on aarch64.

	* benchtests/Makefile (wcsmbs-benchset): Include only for
	native builds and runs.
	(LOCALES): Likewise.
	(bench-build): Build timing-type here instead of the bench
	target.  Generate locale only for native builds.
	* benchtests/README: Add note for cross-building.

3 files changed, 29 insertions, 5 deletions

diff --git a/ChangeLog b/ChangeLog
index f26f8f8f1a..ded10937fa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,12 @@
 2016-04-20  Siddhesh Poyarekar  <sid@reserved-bit.com>
 
+	* benchtests/Makefile (wcsmbs-benchset): Include only for
+	native builds and runs.
+	(LOCALES): Likewise.
+	(bench-build): Build timing-type here instead of the bench
+	target.  Generate locale only for native builds.
+	* benchtests/README: Add note for cross-building.
+
 	* benchtests/Makefile (bench-clean): Clean up extra-objs.
 
 	* benchtests/README: Update README to include instructions on
diff --git a/benchtests/Makefile b/benchtests/Makefile
index 779eb395d5..144b32ea38 100644
--- a/benchtests/Makefile
+++ b/benchtests/Makefile
@@ -39,11 +39,19 @@ string-benchset := bcopy bzero memccpy memchr memcmp memcpy memmem memmove \
 		   strncasecmp strncat strncmp strncpy strnlen strpbrk strrchr \
 		   strspn strstr strcpy_chk stpcpy_chk memrchr strsep strtok \
 		   strcoll memcpy-large memmove-large memset-large
+
+# Build and run locale-dependent benchmarks only if we're building natively.
+ifeq (no,$(cross-compiling))
 wcsmbs-benchset := wcslen wcsnlen wcscpy wcpcpy wcsncpy wcpncpy wcscat wcsncat \
 		   wcscmp wcsncmp wcschr wcschrnul wcsrchr wcsspn wcspbrk wcscspn \
 		   wmemchr wmemset wmemcmp
+else
+wcsmbs-benchset :=
+endif
+
 string-benchset-all := $(string-benchset) ${wcsmbs-benchset}
 
+ifeq (no,$(cross-compiling))
 # We have to generate locales
 LOCALES := en_US.UTF-8 tr_TR.UTF-8 cs_CZ.UTF-8 fa_IR.UTF-8 fr_FR.UTF-8 \
 	   ja_JP.UTF-8 si_LK.UTF-8 en_GB.UTF-8 vi_VN.UTF-8 ar_SA.UTF-8 \
@@ -51,6 +59,7 @@ LOCALES := en_US.UTF-8 tr_TR.UTF-8 cs_CZ.UTF-8 fa_IR.UTF-8 fr_FR.UTF-8 \
 	   he_IL.UTF-8 is_IS.UTF-8 es_ES.UTF-8 hi_IN.UTF-8 sv_SE.UTF-8 \
 	   hu_HU.UTF-8 it_IT.UTF-8 sr_RS.UTF-8 zh_CN.UTF-8
 include ../gen-locales.mk
+endif
 
 stdlib-benchset := strtod
 
@@ -131,10 +140,16 @@ bench-clean:
 	rm -f $(timing-type) $(addsuffix .o,$(timing-type))
 	rm -f $(addprefix $(objpfx),$(bench-extra-objs))
 
-bench: $(timing-type) $(gen-locales) bench-build bench-set bench-func \
-	bench-malloc
-# Target to only build the benchmark without running it.
-bench-build: $(binaries-bench) $(binaries-benchset) $(binaries-bench-malloc)
+bench: bench-build bench-set bench-func bench-malloc
+# Target to only build the benchmark without running it.  We generate locales
+# only if we're building natively.
+ifeq (no,$(cross-compiling))
+bench-build: $(gen-locales) $(timing-type) $(binaries-bench) \
+	$(binaries-benchset) $(binaries-bench-malloc)
+else
+bench-build: $(timing-type) $(binaries-bench) $(binaries-benchset) \
+	$(binaries-bench-malloc)
+endif
 
 bench-set: $(binaries-benchset)
 	for run in $^; do \
diff --git a/benchtests/README b/benchtests/README
index 847df87c96..2c5f381135 100644
--- a/benchtests/README
+++ b/benchtests/README
@@ -49,7 +49,9 @@ benchmarks from the build directory as usual:
   $ make bench
 
 make sure the copy preserves timestamps by using either rsync or scp -p
-otherwise the above command may try to build the benchmark again.
+otherwise the above command may try to build the benchmark again.  Benchmarks
+that require generated code to be executed during the build are skipped when
+cross-building.
 
 Adding a function to benchtests:
 ===============================