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[v2,08/10] softfloat: Use x86_64 assembly for sh[rl]_double

Message ID 20200925152047.709901-9-richard.henderson@linaro.org
State New
Headers show
Series softfloat: Implement float128_muladd | expand

Commit Message

Richard Henderson Sept. 25, 2020, 3:20 p.m. UTC 
GCC isn't recognizing this pattern for x86, and it
probably couldn't recognize that the outer condition
is not required either.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 fpu/softfloat.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
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Patch

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 54d0b210ac..fdf5bde69e 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -7260,12 +7260,22 @@  typedef struct UInt256 {
 
 static inline uint64_t shl_double(uint64_t h, uint64_t l, unsigned lsh)
 {
+#ifdef __x86_64__
+    asm("shld %b2, %1, %0" : "+r"(h) : "r"(l), "ci"(lsh));
+    return h;
+#else
     return lsh ? (h << lsh) | (l >> (64 - lsh)) : h;
+#endif
 }
 
 static inline uint64_t shr_double(uint64_t h, uint64_t l, unsigned rsh)
 {
+#ifdef __x86_64__
+    asm("shrd %b2, %1, %0" : "+r"(l) : "r"(h), "ci"(rsh));
+    return l;
+#else
     return rsh ? (h << (64 - rsh)) | (l >> rsh) : l;
+#endif
 }
 
 static void shortShift256Left(UInt256 *p, unsigned lsh)