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[Qemu-devel] [PATCH] Fix Alpha ret instruction


From: Vince Weaver
Subject: [Qemu-devel] [PATCH] Fix Alpha ret instruction
Date: Wed, 5 Nov 2008 17:07:41 -0500 (EST)


Hopefully pine doesn't corrupt this patch, I've had problems recently.

For an alpha "ret" instruction, of the type
    ret $26

The return was being ignored.  This is because in translate.c
register $26 (the return address) was being over-written with the current PC before it could be jumped to. Thus the ret was ignored.

This patch just re-orders things so the return address is processed before it is over-written with the current PC.



Index: target-alpha/translate.c
===================================================================
--- target-alpha/translate.c    (revision 5636)
+++ target-alpha/translate.c    (working copy)
@@ -1634,12 +1634,13 @@
         break;
 #endif
     case 0x1A:
-        if (ra != 31)
-            tcg_gen_movi_i64(cpu_ir[ra], ctx->pc);
         if (rb != 31)
             tcg_gen_andi_i64(cpu_pc, cpu_ir[rb], ~3);
         else
             tcg_gen_movi_i64(cpu_pc, 0);
+        if (ra != 31)
+            tcg_gen_movi_i64(cpu_ir[ra], ctx->pc);
+
         /* Those four jumps only differ by the branch prediction hint */
         switch (fn2) {
         case 0x0:




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