[xstormy16] Add extendhisi2 and zero_extendhisi2 patterns to stormy16.md

This patch adds a pair of define_insn patterns to the xstormy16 machine
description that provide extendhisi2 and zero_extendhisi2, i.e. 16-bit
to 32-bit sign- and zero-extension respectively.  This functionality is
already synthesized during RTL expansion, but providing patterns allow
the semantics to be exposed to the RTL optimizers.  To simplify things,
this patch introduces a new %h0 output format, for emitting the high_part
register name of a double-word (SImode) register pair.  The actual
code generated is identical to before.

Whilst there, I also fixed the instruction lengths and formatting of
the zero_extendqihi2 pattern.  Then, mostly for documentation purposes
as the 'T' constraint isn't yet implemented, I've added a "and Rx,#255"
alternative to zero_extendqihi2 that takes advantage of its efficient
instruction encoding.

2023-04-23  Roger Sayle  <roger@nextmovesoftware.com>

gcc/ChangeLog
	* config/stormy16/stormy16.cc (xstormy16_print_operand): Add %h
	format specifier to output high_part register name of SImode reg.
	* config/stormy16/stormy16.md (extendhisi2): New define_insn.
	(zero_extendqihi2): Fix lengths, consistent formatting and add
	"and Rx,#255" alternative, for documentation purposes.
	(zero_extendhisi2): New define_insn.

gcc/testsuite/ChangeLog
	* gcc.target/xstormy16/extendhisi2.c: New test case.
	* gcc.target/xstormy16/zextendhisi2.c: Likewise.

2 files changed, 32 insertions, 7 deletions

diff --git a/gcc/config/stormy16/stormy16.cc b/gcc/config/stormy16/stormy16.cc
index cf2f807..647b72c 100644
--- a/gcc/config/stormy16/stormy16.cc
+++ b/gcc/config/stormy16/stormy16.cc
@@ -1828,6 +1828,14 @@ xstormy16_print_operand (FILE *file, rtx x, int code)
 	return;
       }
 
+    case 'h':
+      /* Print the highpart register of an SI mode register pair.  */
+      if (REG_P (x) && GET_MODE (x) == SImode)
+        fputs (reg_names [REGNO (x) + 1], file);
+      else
+	output_operand_lossage ("'h' operand is not SImode register");
+      return;
+
     case 0:
       /* Handled below.  */
       break;
diff --git a/gcc/config/stormy16/stormy16.md b/gcc/config/stormy16/stormy16.md
index d27c9fb..fd52588 100644
--- a/gcc/config/stormy16/stormy16.md
+++ b/gcc/config/stormy16/stormy16.md
@@ -268,17 +268,34 @@
   ""
   "cbw %0")
 
+(define_insn "extendhisi2"
+  [(set (match_operand:SI 0 "register_operand" "=r")
+	(sign_extend:SI (match_operand:HI 1 "register_operand" "0")))]
+  ""
+  "mov %h0,%0 | asr %h0,#15"
+  [(set_attr "length" "4")
+   (set_attr "psw_operand" "clobber")])
+
 (define_insn "zero_extendqihi2"
-  [(set (match_operand:HI                 0 "register_operand" 	   "=e,r")
-	(zero_extend:HI (match_operand:QI 1 "nonimmediate_operand" "m,0")))]
+  [(set (match_operand:HI                 0 "register_operand" 	   "=e,T,r")
+	(zero_extend:HI (match_operand:QI 1 "nonimmediate_operand" "m,0,0")))]
   ""
   "@
-   mov.b %0, %1
-   shl %0,#8\n\tshr %0,#8"
-  [(set_attr "psw_operand" "nop,0")
+   mov.b %0,%1
+   and Rx,#255
+   shl %0,#8 | shr %0,#8"
+  [(set_attr "psw_operand" "nop,nop,0")
    (set_attr_alternative "length"
-	     [(const_int 4)
-	      (const_int 8)])])
+	     [(const_int 2)
+	      (const_int 2)
+	      (const_int 4)])])
+
+(define_insn "zero_extendhisi2"
+  [(set (match_operand:SI 0 "register_operand" "=r")
+	(zero_extend:SI (match_operand:HI 1 "register_operand" "0")))]
+  ""
+  "mov %h0,#0"
+  [(set_attr "psw_operand" "clobber")])
 
 ;; ::::::::::::::::::::
 ;; ::