[PATCH 8/8] softfloat: Use aarch64 assembly for {add,sub}{192,256}

[Richard Henderson <richard.henderson@linaro.org>]

The compiler cannot chain more than two additions together.
Use inline assembly for 3 or 4 additions.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 include/fpu/softfloat-macros.h | 14 ++++++++++++++
 fpu/softfloat.c                | 25 +++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/fpu/softfloat-macros.h b/include/fpu/softfloat-macros.h
index 99fa124e56..969a486fd2 100644
--- a/include/fpu/softfloat-macros.h
+++ b/include/fpu/softfloat-macros.h
@@ -442,6 +442,13 @@ static inline void
         "adc %3, %0"
         : "=&r"(*z0Ptr), "=&r"(*z1Ptr), "=&r"(*z2Ptr)
         : "rm"(b0), "rm"(b1), "rm"(b2), "0"(a0), "1"(a1), "2"(a2));
+#elif defined(__aarch64__)
+    asm("adds %2, %x5, %x8\n\t"
+        "adcs %1, %x4, %x7\n\t"
+        "adc  %0, %x3, %x6"
+        : "=&r"(*z0Ptr), "=&r"(*z1Ptr), "=&r"(*z2Ptr)
+        : "rZ"(a0), "rZ"(a1), "rZ"(a2), "rZ"(b0), "rZ"(b1), "rZ"(b2)
+        : "cc");
 #else
     uint64_t z0, z1, z2;
     int8_t carry0, carry1;
@@ -507,6 +514,13 @@ static inline void
         "sbb %3, %0"
         : "=&r"(*z0Ptr), "=&r"(*z1Ptr), "=&r"(*z2Ptr)
         : "rm"(b0), "rm"(b1), "rm"(b2), "0"(a0), "1"(a1), "2"(a2));
+#elif defined(__aarch64__)
+    asm("subs %2, %x5, %x8\n\t"
+        "sbcs %1, %x4, %x7\n\t"
+        "sbc  %0, %x3, %x6"
+        : "=&r"(*z0Ptr), "=&r"(*z1Ptr), "=&r"(*z2Ptr)
+        : "rZ"(a0), "rZ"(a1), "rZ"(a2), "rZ"(b0), "rZ"(b1), "rZ"(b2)
+        : "cc");
 #else
     uint64_t z0, z1, z2;
     int8_t borrow0, borrow1;
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index d8e5d90fd7..1601095d60 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -7305,6 +7305,16 @@ static void sub256(uint64_t r[4], uint64_t a[4], uint64_t b[4])
         : "=&r"(r[0]), "=&r"(r[1]), "=&r"(r[2]), "=&r"(r[3])
         : "rme"(b[0]), "rme"(b[1]), "rme"(b[2]), "rme"(b[3]),
             "0"(a[0]),   "1"(a[1]),   "2"(a[2]),   "3"(a[3]));
+#elif defined(__aarch64__)
+    asm("subs %[r3], %x[a3], %x[b3]\n\t"
+        "sbcs %[r2], %x[a2], %x[b2]\n\t"
+        "sbcs %[r1], %x[a1], %x[b1]\n\t"
+        "sbc  %[r0], %x[a0], %x[b0]"
+        : [r0] "=&r"(r[0]), [r1] "=&r"(r[1]),
+          [r2] "=&r"(r[2]), [r3] "=&r"(r[3])
+        : [a0] "rZ"(a[0]), [a1] "rZ"(a[1]), [a2] "rZ"(a[2]), [a3] "rZ"(a[3]),
+          [b0] "rZ"(b[0]), [b1] "rZ"(b[1]), [b2] "rZ"(b[2]), [b3] "rZ"(b[3])
+        : "cc");
 #else
     bool borrow = false;
 
@@ -7330,6 +7340,13 @@ static void neg256(uint64_t a[4])
         "sbb %4, %0"
         : "=&r"(a[0]), "=&r"(a[1]), "=&r"(a[2]), "+rm"(a[3])
         : "rme"(a[0]), "rme"(a[1]), "rme"(a[2]), "0"(0), "1"(0), "2"(0));
+#elif defined(__aarch64__)
+    asm("negs %3, %3\n\t"
+        "ngcs %2, %2\n\t"
+        "ngcs %1, %1\n\t"
+        "ngc  %0, %0"
+        : "+r"(a[0]), "+r"(a[1]), "+r"(a[2]), "+r"(a[3])
+        : : "cc");
 #else
     a[3] = -a[3];
     if (likely(a[3])) {
@@ -7364,6 +7381,14 @@ static void add256(uint64_t a[4], uint64_t b[4])
         "adc %4, %0"
         :  "+r"(a[0]),  "+r"(a[1]),  "+r"(a[2]),  "+r"(a[3])
         : "rme"(b[0]), "rme"(b[1]), "rme"(b[2]), "rme"(b[3]));
+#elif defined(__aarch64__)
+    asm("adds %3, %3, %x7\n\t"
+        "adcs %2, %2, %x6\n\t"
+        "adcs %1, %1, %x5\n\t"
+        "adc  %0, %0, %x4"
+        : "+r"(a[0]), "+r"(a[1]), "+r"(a[2]), "+r"(a[3])
+        : "rZ"(b[0]), "rZ"(b[1]), "rZ"(b[2]), "rZ"(b[3])
+        : "cc");
 #else
     bool carry = false;
 
-- 
2.25.1