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62 lines
2.0 KiB

commit 656b84c2ef525e3b69802c9057c5897e327b0332
Author: Wilco Dijkstra <wdijkstr@arm.com>
Date: Thu Aug 7 16:29:55 2014 +0000
This patch adds new function libc_feholdsetround_noex_aarch64_ctx, enabling
further optimization. libc_feholdsetround_aarch64_ctx now only needs to
read the FPCR in the typical case, avoiding a redundant FPSR read.
Performance results show a good improvement (5-10% on sin()) on cores with
expensive FPCR/FPSR instructions.
diff --git a/ports/sysdeps/aarch64/fpu/math_private.h b/ports/sysdeps/aarch64/fpu/math_private.h
index 023c9d0..b13c030 100644
--- a/ports/sysdeps/aarch64/fpu/math_private.h
+++ b/ports/sysdeps/aarch64/fpu/math_private.h
@@ -228,12 +228,9 @@ static __always_inline void
libc_feholdsetround_aarch64_ctx (struct rm_ctx *ctx, int r)
{
fpu_control_t fpcr;
- fpu_fpsr_t fpsr;
int round;
_FPU_GETCW (fpcr);
- _FPU_GETFPSR (fpsr);
- ctx->env.__fpsr = fpsr;
/* Check whether rounding modes are different. */
round = (fpcr ^ r) & _FPU_FPCR_RM_MASK;
@@ -264,6 +261,33 @@ libc_feresetround_aarch64_ctx (struct rm_ctx *ctx)
#define libc_feresetroundl_ctx libc_feresetround_aarch64_ctx
static __always_inline void
+libc_feholdsetround_noex_aarch64_ctx (struct rm_ctx *ctx, int r)
+{
+ fpu_control_t fpcr;
+ fpu_fpsr_t fpsr;
+ int round;
+
+ _FPU_GETCW (fpcr);
+ _FPU_GETFPSR (fpsr);
+ ctx->env.__fpsr = fpsr;
+
+ /* Check whether rounding modes are different. */
+ round = (fpcr ^ r) & _FPU_FPCR_RM_MASK;
+ ctx->updated_status = round != 0;
+
+ /* Set the rounding mode if changed. */
+ if (__glibc_unlikely (round != 0))
+ {
+ ctx->env.__fpcr = fpcr;
+ _FPU_SETCW (fpcr ^ round);
+ }
+}
+
+#define libc_feholdsetround_noex_ctx libc_feholdsetround_noex_aarch64_ctx
+#define libc_feholdsetround_noexf_ctx libc_feholdsetround_noex_aarch64_ctx
+#define libc_feholdsetround_noexl_ctx libc_feholdsetround_noex_aarch64_ctx
+
+static __always_inline void
libc_feresetround_noex_aarch64_ctx (struct rm_ctx *ctx)
{
/* Restore the rounding mode if updated. */