Merge pull request #18578 from JuliaLang/yyc/arm/denormal

Support set/get_zero_subnormals on AArch64
JuliaLang · Sep 20, 2016 · 1621d7e · 1621d7e · nanosoldier · Sep 20, 2016
2 parents a6a8946 + 9a8001d
commit 1621d7e
Showing 1 changed file with 32 additions and 2 deletions.
diff --git a/src/sys.c b/src/sys.c
@@ -505,7 +505,7 @@ static int32_t get_subnormal_flags(void)
 }
 
 // Returns non-zero if subnormals go to 0; zero otherwise.
-JL_DLLEXPORT int32_t jl_get_zero_subnormals(int8_t isZero)
+JL_DLLEXPORT int32_t jl_get_zero_subnormals(void)
 {
  uint32_t flags = get_subnormal_flags();
  return _mm_getcsr() & flags;
@@ -530,9 +530,39 @@ JL_DLLEXPORT int32_t jl_set_zero_subnormals(int8_t isZero)
  }
 }
 
+#elif defined(_CPU_AARCH64_)
+
+// FZ, bit [24]
+static const uint32_t fpcr_fz_mask = 1 << 24;
+
+static inline uint32_t get_fpcr_aarch64(void)
+{
+ uint32_t fpcr;
+ asm volatile("mrs %0, fpcr" : "=r"(fpcr));
+ return fpcr;
+}
+
+static inline void set_fpcr_aarch64(uint32_t fpcr)
+{
+ asm volatile("msr fpcr, %0" :: "r"(fpcr));
+}
+
+JL_DLLEXPORT int32_t jl_get_zero_subnormals(void)
+{
+ return (get_fpcr_aarch64() & fpcr_fz_mask) != 0;
+}
+
+JL_DLLEXPORT int32_t jl_set_zero_subnormals(int8_t isZero)
+{
+ uint32_t fpcr = get_fpcr_aarch64();
+ fpcr = isZero ? (fpcr | fpcr_fz_mask) : (fpcr & ~fpcr_fz_mask);
+ set_fpcr_aarch64(fpcr);
+ return 0;
+}
+
 #else
 
-JL_DLLEXPORT int32_t jl_get_zero_subnormals(int8_t isZero)
+JL_DLLEXPORT int32_t jl_get_zero_subnormals(void)
 {
  return 0;
 }