libgcc CRIS: Define TARGET_HAS_NO_HW_DIVIDE

With this, execution time for e.g. __moddi3 go from 59 to 40 cycles in
the "fast" case or from 290 to 200 cycles in the "slow" case (when the
!TARGET_HAS_NO_HW_DIVIDE variant calls division and modulus functions
for 32-bit SImode), as exposed by gcc.c-torture/execute/arith-rand-ll.c
compiled for -march=v10.

Unfortunately, it just puts a performance improvement "dent" of 0.07%
in a arith-rand-ll.c-based performance test - where all loops are also
reduced to 1/10.

The size of every affected libgcc function is reduced to less than
half and they are all now leaf functions.

	* config/cris/t-cris (HOST_LIBGCC2_CFLAGS): Add
	-DTARGET_HAS_NO_HW_DIVIDE.

diff --git a/libgcc/config/cris/t-cris b/libgcc/config/cris/t-cris
index b582974a42eec18481d4b77908c950a8d56d5e74..e0020294be9698cfee1b050dc04d991f6380d674 100644 (file)
--- a/libgcc/config/cris/t-cris
+++ b/libgcc/config/cris/t-cris
@@ -8,3 +8,6 @@ $(LIB2ADD): $(srcdir)/config/cris/arit.c
        echo "#define L$$name" > tmp-$@ \
        && echo '#include "$<"' >> tmp-$@ \
        && mv -f tmp-$@ $@
+
+# Use an appropriate implementation when implementing DImode division.
+HOST_LIBGCC2_CFLAGS += -DTARGET_HAS_NO_HW_DIVIDE