[Qemu-devel] Sparc taddctv/tsubcctv patch

[Qemu-devel] Sparc taddctv/tsubcctv patch

[David Matthews]

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This patch fixes a couple of bugs in taddcctv and tsubcctv on the Sparc. 
  It saves the state so that if the instructions trap the correct 
address is delivered to the kernel and it fixes the detection of 
overflow in taddcctv.  This was patched against CVS version of 20070816 
but the fixes don't seem to be in the current CVS.

To provide a bit of context: I'm maintaining Poly/ML (www.polyml.org) on 
various platforms including the Sparc.  The Sparc code-generator is now 
nearly 20 years old and uses the taddcctv and tsubcctv instructions for 
arbitrary precision arithmetic.  I'm using an ageing Sparcstation 5 with 
16M and it is painfully slow so I tried out qemu.  I couldn't get 
Solaris to boot but the Debian installation runs fine.  I was using the 
Debian package of qemu which seems to have been prepared on 16th August. 
  I did try the latest CVS but that gave an exception on booting Sparc 
Debian.  Perhaps I need a newer version of openbios as well.

Thanks for all your work on qemu.
David.


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Index: target-sparc/op.c
===================================================================
RCS file: /sources/qemu/qemu/target-sparc/op.c,v
retrieving revision 1.35
diff -u -r1.35 op.c
--- target-sparc/op.c	11 Jul 2007 16:43:30 -0000	1.35
+++ target-sparc/op.c	10 Oct 2007 16:26:34 -0000
@@ -531,7 +531,7 @@
 	 ((src1 & 0xffffffff) ^ (T0 & 0xffffffff))) & (1 << 31))
         raise_exception(TT_TOVF);
 #else
-    if ((src1 & 0x03) || (T1 & 0x03))
+    if (((src1 ^ T1 ^ -1) & (src1 ^ T0)) & (1 << 31))
         raise_exception(TT_TOVF);
 #endif
 
Index: target-sparc/translate.c
===================================================================
RCS file: /sources/qemu/qemu/target-sparc/translate.c,v
retrieving revision 1.65
diff -u -r1.65 translate.c
--- target-sparc/translate.c	11 Jul 2007 16:43:30 -0000	1.65
+++ target-sparc/translate.c	10 Oct 2007 16:26:36 -0000
@@ -1928,10 +1928,12 @@
 		        gen_movl_T0_reg(rd);
 			break;
 		    case 0x22: /* taddcctv */
+                        save_state(dc);
 			gen_op_tadd_T1_T0_ccTV();
 		        gen_movl_T0_reg(rd);
 			break;
 		    case 0x23: /* tsubcctv */
+                        save_state(dc);
 			gen_op_tsub_T1_T0_ccTV();
 		        gen_movl_T0_reg(rd);
 			break;