target-arm: Add support for 'Standard FPSCR Value' as used by Neon
Add support to the ARM helper routines for a second fp_status value
which should be used for operations which the ARM ARM indicates use
"ARM standard floating-point arithmetic" rather than being controlled
by the rounding/flush/NaN settings in the FPSCR.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/target-arm/cpu.h b/target-arm/cpu.h
index 340933e..e501cf5 100644
--- a/target-arm/cpu.h
+++ b/target-arm/cpu.h
@@ -173,7 +173,20 @@
/* scratch space when Tn are not sufficient. */
uint32_t scratch[8];
+ /* fp_status is the "normal" fp status. standard_fp_status retains
+ * values corresponding to the ARM "Standard FPSCR Value", ie
+ * default-NaN, flush-to-zero, round-to-nearest and is used by
+ * any operations (generally Neon) which the architecture defines
+ * as controlled by the standard FPSCR value rather than the FPSCR.
+ *
+ * To avoid having to transfer exception bits around, we simply
+ * say that the FPSCR cumulative exception flags are the logical
+ * OR of the flags in the two fp statuses. This relies on the
+ * only thing which needs to read the exception flags being
+ * an explicit FPSCR read.
+ */
float_status fp_status;
+ float_status standard_fp_status;
} vfp;
uint32_t exclusive_addr;
uint32_t exclusive_val;
