[PATCH] Fix MIPS LHX in mips-dsp.md

[Fu, Chao-Ying]

Hi,

  I found a bug for the MIPS DSP LHX pattern in mips-dsp.md.
We should use sign_extend, because LHX loads a halfword as a signed value.
This patch is for GCC mainline and GCC 4.4.

  Ok to check in?  Thanks a lot!

Regards,
Chao-ying

gcc/ChangeLog
2009-11-10  Chao-ying Fu  <fu@mips.com>

        * config/mips/mips-dsp.md (mips_lhx_<mode>): Use sign_extend.

gcc/testsuite/ChangeLog
2009-11-10  Chao-ying Fu  <fu@mips.com>

        * gcc.target/mips/dsp-lhx.c: New test.
        * gcc.target/mips/dsp-no-lhx.c: New test.

Index: mips-dsp.md
===================================================================
--- mips-dsp.md	(revision 154055)
+++ mips-dsp.md	(working copy)
@@ -1066,7 +1066,7 @@
 
 (define_insn "mips_lhx_<mode>"
   [(set (match_operand:SI 0 "register_operand" "=d")
-	(zero_extend:SI
+	(sign_extend:SI
 	  (mem:HI (plus:P (match_operand:P 1 "register_operand" "d")
 			  (match_operand:P 2 "register_operand" "d")))))]
   "ISA_HAS_DSP"


Index: dsp-lhx.c
===================================================================
--- dsp-lhx.c	(revision 0)
+++ dsp-lhx.c	(revision 0)
@@ -0,0 +1,10 @@
+/* Test MIPS32 DSP LHX instruction */
+/* { dg-do compile } */
+/* { dg-options "-mgp32 -mdsp -O2" } */
+
+/* { dg-final { scan-assembler "\tlhx\t" } } */
+
+NOMIPS16 signed short test (signed short *a, int index)
+{
+  return a[index];
+}
Index: dsp-no-lhx.c
===================================================================
--- dsp-no-lhx.c	(revision 0)
+++ dsp-no-lhx.c	(revision 0)
@@ -0,0 +1,10 @@
+/* Test MIPS32 DSP LHX instruction */
+/* { dg-do compile } */
+/* { dg-options "-mgp32 -mdsp -O2" } */
+
+/* { dg-final { scan-assembler-not "\tlhx\t" } } */
+
+NOMIPS16 unsigned short test (unsigned short *a, int index)
+{
+  return a[index];
+}