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authorRich Felker <dalias@aerifal.cx>2012-09-11 02:23:47 -0400
committerRich Felker <dalias@aerifal.cx>2012-09-11 02:23:47 -0400
commitcfc09b1ecf0c6981494fd73dffe234416f66af10 (patch)
tree6771fdf3c0f6efad93919597e327da9ba0495877
parentb94067eeae894b5a26170cebc378261f83ad00cb (diff)
downloadmusl-cfc09b1ecf0c6981494fd73dffe234416f66af10.tar.gz
improve mips syscall asm constraints to use immediates, if possible
by using the "ir" constraint (immediate or register) and the carefully constructed instruction addu $2,$0,%2 which can take either an immediate or a register for %2, the new inline asm admits maximal optimization with no register spillage to the stack when the compiler successfully performs constant propagration, but still works by allocating a register when the syscall number cannot be recognized as a constant. in the case of syscalls with 0-3 arguments it barely matters, but for 4-argument syscalls, using an immediate for the syscall number avoids creating a stack frame for the syscall wrapper function.
-rw-r--r--arch/mips/syscall_arch.h33
1 files changed, 21 insertions, 12 deletions
diff --git a/arch/mips/syscall_arch.h b/arch/mips/syscall_arch.h
index 58904765..b1e68ffb 100644
--- a/arch/mips/syscall_arch.h
+++ b/arch/mips/syscall_arch.h
@@ -10,8 +10,8 @@
#define __asm_syscall(...) do { \
register long r2 __asm__("$2"); \
__asm__ __volatile__ ( \
- "move $2,$7 ; syscall" \
- : "=&r"(r2), "=r"(r7) : __VA_ARGS__ \
+ "addu $2,$0,%2 ; syscall" \
+ : "=&r"(r2), "=r"(r7) : "ir"(n), __VA_ARGS__, "r"(r2) \
: "$1", "$3", "$8", "$9", "$10", "$11", "$12", "$13", \
"$14", "$15", "$24", "$25", "hi", "lo", "memory"); \
return r7 ? -r2 : r2; \
@@ -19,32 +19,41 @@
static inline long __syscall0(long n)
{
- register long r7 __asm__("$7") = n;
- __asm_syscall("r"(r7));
+ register long r7 __asm__("$7");
+ __asm_syscall("i"(0));
}
static inline long __syscall1(long n, long a)
{
- register long r7 __asm__("$7") = n;
register long r4 __asm__("$4") = a;
- __asm_syscall("r"(r7), "r"(r4));
+ register long r7 __asm__("$7");
+ __asm_syscall("r"(r4));
}
static inline long __syscall2(long n, long a, long b)
{
- register long r7 __asm__("$7") = n;
register long r4 __asm__("$4") = a;
register long r5 __asm__("$5") = b;
- __asm_syscall("r"(r7), "r"(r4), "r"(r5));
+ register long r7 __asm__("$7");
+ __asm_syscall("r"(r4), "r"(r5));
}
static inline long __syscall3(long n, long a, long b, long c)
{
- register long r7 __asm__("$7") = n;
register long r4 __asm__("$4") = a;
register long r5 __asm__("$5") = b;
register long r6 __asm__("$6") = c;
- __asm_syscall("r"(r7), "r"(r4), "r"(r5), "r"(r6));
+ register long r7 __asm__("$7");
+ __asm_syscall("r"(r4), "r"(r5), "r"(r6));
+}
+
+static inline long __syscall4(long n, long a, long b, long c, long d)
+{
+ register long r4 __asm__("$4") = a;
+ register long r5 __asm__("$5") = b;
+ register long r6 __asm__("$6") = c;
+ register long r7 __asm__("$7") = d;
+ __asm_syscall("r"(r4), "r"(r5), "r"(r6), "r"(r7));
}
#else
@@ -69,13 +78,13 @@ static inline long __syscall3(long n, long a, long b, long c)
return (__syscall)(n, a, b, c);
}
-#endif
-
static inline long __syscall4(long n, long a, long b, long c, long d)
{
return (__syscall)(n, a, b, c, d);
}
+#endif
+
static inline long __syscall5(long n, long a, long b, long c, long d, long e)
{
return (__syscall)(n, a, b, c, d, e);