[PATCH 2/2] gdb/riscv: Fix assertion in inferior call code

[Andrew Burgess <andrew.burgess@embecosm.com>]

An assertion when setting up arguments for an inferior call checks the
size of the argument against xlen.  However, if xlen and flen are
different sizes, and the argument is being placed into a floating
pointer register then we should be comparing against flen not xlen.

This issue shows up as an assertion failure when running on an rv32g
target with a binary compiled using the rv32f abi and making an
inferior call involving large floating point arguments, for example
the test gdb.base/infcall-nested-structs.exp.

gdb/ChangeLog:

	* riscv-tdep.c (riscv_is_fp_regno_p): New function.
	(riscv_register_reggroup_p): Use new function, remove unneeded
	parenthesis.
	(riscv_push_dummy_call): Extend assert to compare against xlen or
	flen based on register type.
---
 gdb/ChangeLog    |  8 ++++++++
 gdb/riscv-tdep.c | 21 ++++++++++++++++-----
 2 files changed, 24 insertions(+), 5 deletions(-)

diff --git a/gdb/riscv-tdep.c b/gdb/riscv-tdep.c
index e2be993eaf0..25a8fda29c4 100644
--- a/gdb/riscv-tdep.c
+++ b/gdb/riscv-tdep.c
@@ -413,6 +413,15 @@ riscv_has_fp_abi (struct gdbarch *gdbarch)
   return (gdbarch_tdep (gdbarch)->abi.fields.float_abi != 0);
 }
 
+/* Return true if REGNO is a floating pointer register.  */
+
+static bool
+riscv_is_fp_regno_p (int regno)
+{
+  return (regno >= RISCV_FIRST_FP_REGNUM
+	  && regno <= RISCV_LAST_FP_REGNUM);
+}
+
 /* Implement the breakpoint_kind_from_pc gdbarch method.  */
 
 static int
@@ -787,10 +796,10 @@ riscv_register_reggroup_p (struct gdbarch  *gdbarch, int regnum,
       return 0;
     }
   else if (reggroup == float_reggroup)
-    return ((regnum >= RISCV_FIRST_FP_REGNUM && regnum <= RISCV_LAST_FP_REGNUM)
-	    || (regnum == RISCV_CSR_FCSR_REGNUM
-		|| regnum == RISCV_CSR_FFLAGS_REGNUM
-	        || regnum == RISCV_CSR_FRM_REGNUM));
+    return (riscv_is_fp_regno_p (regnum)
+	    || regnum == RISCV_CSR_FCSR_REGNUM
+	    || regnum == RISCV_CSR_FFLAGS_REGNUM
+	    || regnum == RISCV_CSR_FRM_REGNUM);
   else if (reggroup == general_reggroup)
     return regnum < RISCV_FIRST_FP_REGNUM;
   else if (reggroup == restore_reggroup || reggroup == save_reggroup)
@@ -2154,7 +2163,9 @@ riscv_push_dummy_call (struct gdbarch *gdbarch,
 	      {
 		gdb_byte tmp [sizeof (ULONGEST)];
 
-		gdb_assert (second_arg_length <= call_info.xlen);
+		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));
 		memcpy (tmp, second_arg_data, second_arg_length);
 		regcache->cooked_write (info->argloc[1].loc_data.regno, tmp);
-- 
2.14.4