From: John Darrington <john@darrington.wattle.id.au>
Date: Fri, 1 Feb 2019 16:42:54 +0000 (+0100)
Subject: S12Z: GAS: Issue warning if TFR/EXG have identical source and destination.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=1d4d86699fcc9641c1f4dfb3a44a1588353c2137;p=binutils-gdb.git

S12Z: GAS: Issue warning if TFR/EXG have identical source and destination.

It is permissible for the source and destination operands of TFR and EXG to be
the same register.  However it is a pointless instruction and anyone writing it
has probably made a mistake.  This change emits a warning if such an instruction
is encountered.

gas/
	* config/tc-s12z.c (tfr): Emit warning if operands are the same.
	* testsuite/gas/s12z/exg.d: New test case.
	* testsuite/gas/s12z/exg.l: New file.
---

diff --git a/gas/ChangeLog b/gas/ChangeLog
index 7905717272a..e168d7280ad 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,9 @@
+2019-01-31  John Darrington <john@darrington.wattle.id.au>
+
+	* config/tc-s12z.c (tfr): Emit warning if operands are the same.
+	* testsuite/gas/s12z/exg.d: New test case.
+	* testsuite/gas/s12z/exg.l: New file.
+
 2019-01-31  John Darrington <john@darrington.wattle.id.au>
 
 	* config/tc-s12z.c (lex_opr): Add a parameter to indicate whether
diff --git a/gas/config/tc-s12z.c b/gas/config/tc-s12z.c
index 2bd536aca3e..a0131490ba6 100644
--- a/gas/config/tc-s12z.c
+++ b/gas/config/tc-s12z.c
@@ -1328,6 +1328,8 @@ tfr (const struct instruction *insn)
        && (registers[reg2].bytes <= registers[reg1].bytes))
       as_warn (_("Source register for %s is no larger than the destination register"),
                insn->name);
+  else if (reg1 == reg2)
+    as_warn (_("The destination and source registers are identical"));
 
   char *f = s12z_new_insn (1 + insn->page);
   if (insn->page == 2)
diff --git a/gas/testsuite/gas/s12z/exg.d b/gas/testsuite/gas/s12z/exg.d
index 54cf2686205..e9af154e82d 100644
--- a/gas/testsuite/gas/s12z/exg.d
+++ b/gas/testsuite/gas/s12z/exg.d
@@ -1,6 +1,7 @@
 #objdump: -d
 #name:    
 #source:  exg.s
+#warning_output: exg.l
 
 
 .*:     file format elf32-s12z
diff --git a/gas/testsuite/gas/s12z/exg.l b/gas/testsuite/gas/s12z/exg.l
new file mode 100644
index 00000000000..018d8f90dfc
--- /dev/null
+++ b/gas/testsuite/gas/s12z/exg.l
@@ -0,0 +1,2 @@
+.*: Assembler messages:
+.*:2: Warning: The destination and source registers are identical