Introduce a new ARM header file <machine/cpu-features.h>
Introduce a new header file containing ARM-specific feature
test macros (e.g. __ARM_HAVE_PAIR_LOAD_STORE corresponding
to ldrd/strd instructions). Also modify a few files in our
system to use the macros in order to build for ARMv4T.
diff --git a/libc/arch-arm/bionic/strlen.c b/libc/arch-arm/bionic/strlen.c
index 3d1fe45..01632e3 100644
--- a/libc/arch-arm/bionic/strlen.c
+++ b/libc/arch-arm/bionic/strlen.c
@@ -27,6 +27,7 @@
*/
#include <string.h>
#include <stdint.h>
+#include <machine/cpu-features.h>
size_t strlen(const char *s)
{
@@ -62,7 +63,9 @@
"ldr %[v], [ %[s] ], #4 \n"
"sub %[l], %[l], %[s] \n"
"0: \n"
+#if __ARM_HAVE_PLD
"pld [ %[s], #64 ] \n"
+#endif
"sub %[t], %[v], %[mask], lsr #7\n"
"and %[t], %[t], %[mask] \n"
"bics %[t], %[t], %[v] \n"