RISC-V: NaN-box FP values smaller than an FP register.

The hardware requires that values in FP registers be NaN-boxed, so we must
extend them with 1's instead of 0's as we do for integer values.

	gdb/
	* riscv-tdep.c (riscv_push_dummy_call) <in_reg>: Check for value in
	FP reg smaller than FP reg size, and fill with -1 instead of 0.

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 9055a3a57f0814c139588a7fb449f928e6036923..a30d72b27ff728c968b9cadae7ba261c95b109f3 100644 (file)
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,8 @@
 2018-10-22  Jim Wilson  <jimw@sifive.com>
 
+       * riscv-tdep.c (riscv_push_dummy_call) <in_reg>: Check for value in
+       FP reg smaller than FP reg size, and fill with -1 instead of 0.
+
        * riscv-tdep.c (riscv_fpreg_d_type, riscv_fpreg_q_type): New.
        (riscv_register_type): Use them.
        (riscv_print_one_register_info): Handle union of floats same as float.

diff --git a/gdb/riscv-tdep.c b/gdb/riscv-tdep.c
index 1a75788489478fe61783f5a71ca97a03f6321423..dd80f95c983c0a75d240860db646804ebccf9e8f 100644 (file)
--- a/gdb/riscv-tdep.c
+++ b/gdb/riscv-tdep.c
@@ -2408,7 +2408,12 @@ riscv_push_dummy_call (struct gdbarch *gdbarch,
            gdb_byte tmp [sizeof (ULONGEST)];
 
            gdb_assert (info->argloc[0].c_length <= info->length);
-           memset (tmp, 0, sizeof (tmp));
+           /* FP values in FP registers must be NaN-boxed.  */
+           if (riscv_is_fp_regno_p (info->argloc[0].loc_data.regno)
+               && info->argloc[0].c_length < call_info.flen)
+             memset (tmp, -1, sizeof (tmp));
+           else
+             memset (tmp, 0, sizeof (tmp));
            memcpy (tmp, info->contents, info->argloc[0].c_length);
            regcache->cooked_write (info->argloc[0].loc_data.regno, tmp);
            second_arg_length =
@@ -2447,7 +2452,12 @@ riscv_push_dummy_call (struct gdbarch *gdbarch,
                gdb_assert ((riscv_is_fp_regno_p (info->argloc[1].loc_data.regno)
                             && second_arg_length <= call_info.flen)
                            || second_arg_length <= call_info.xlen);
-               memset (tmp, 0, sizeof (tmp));
+               /* FP values in FP registers must be NaN-boxed.  */
+               if (riscv_is_fp_regno_p (info->argloc[1].loc_data.regno)
+                   && second_arg_length < call_info.flen)
+                 memset (tmp, -1, sizeof (tmp));
+               else
+                 memset (tmp, 0, sizeof (tmp));
                memcpy (tmp, second_arg_data, second_arg_length);
                regcache->cooked_write (info->argloc[1].loc_data.regno, tmp);
              }