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[Qemu-devel] Shifts, ppc[64], xtensa


From: malc
Subject: [Qemu-devel] Shifts, ppc[64], xtensa
Date: Tue, 18 Sep 2012 23:52:21 +0400 (MSK)
User-agent: Alpine 2.00 (LNX 1167 2008-08-23)

Looks like PPC/PPC64 is also hit by shift issues, on top of that xtensa 
exposed another bug in power's tcg - gototb's target was expected to be
always filled via tb_set_jmp_target (even though it's clearly not what
tcg/README prescribes, sorry about that).

Thanks to Max Filippov for pointing to xtensa test suite that helped to
narrow the search to gototb.

Testing of the following with other targets on ppc flavours is welcome..

P.S. Xtensa does mighty weird things with shifts i must say...

diff --git a/tcg/ppc/tcg-target.c b/tcg/ppc/tcg-target.c
index 26c4b33..08f62fa 100644
--- a/tcg/ppc/tcg-target.c
+++ b/tcg/ppc/tcg-target.c
@@ -409,6 +409,7 @@ static int tcg_target_const_match(tcg_target_long val,
 
 #define TW     XO31(4)
 #define TRAP   (TW | TO (31))
+#define NOP    0x60000000
 
 #define RT(r) ((r)<<21)
 #define RS(r) ((r)<<21)
@@ -1306,10 +1307,10 @@ void ppc_tb_set_jmp_target (unsigned long jmp_addr, 
unsigned long addr)
             *ptr = 0x48000000 | (disp & 0x03fffffc); /* b disp */
             patch_size = 4;
         } else {
-            ptr[0] = 0x60000000; /* nop */
-            ptr[1] = 0x60000000;
-            ptr[2] = 0x60000000;
-            ptr[3] = 0x60000000;
+            ptr[0] = NOP;
+            ptr[1] = NOP;
+            ptr[2] = NOP;
+            ptr[3] = NOP;
             patch_size = 16;
         }
     }
@@ -1330,7 +1331,10 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, 
const TCGArg *args,
             /* direct jump method */
 
             s->tb_jmp_offset[args[0]] = s->code_ptr - s->code_buf;
-            s->code_ptr += 16;
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
         }
         else {
             tcg_abort ();
@@ -1565,12 +1569,16 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, 
const TCGArg *args,
 
     case INDEX_op_shl_i32:
         if (const_args[2]) {
+            if (args[2] > 31) {
+                tcg_out_movi (s, TCG_TYPE_I32, 0, args[2]);
+                tcg_out32 (s, SLW | SAB (args[1], args[0], 0));
+            }
             tcg_out32 (s, (RLWINM
                            | RA (args[0])
                            | RS (args[1])
-                           | SH (args[2])
+                           | SH (args[2] & 31)
                            | MB (0)
-                           | ME (31 - args[2])
+                           | ME (31 - (args[2] & 31))
                            )
                 );
         }
@@ -1579,21 +1587,35 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, 
const TCGArg *args,
         break;
     case INDEX_op_shr_i32:
         if (const_args[2]) {
-            tcg_out32 (s, (RLWINM
-                           | RA (args[0])
-                           | RS (args[1])
-                           | SH (32 - args[2])
-                           | MB (args[2])
-                           | ME (31)
-                           )
-                );
+            if (args[2] > 31) {
+                tcg_out_movi (s, TCG_TYPE_I32, 0, args[2]);
+                tcg_out32 (s, SRW | SAB (args[1], args[0], 0));
+            }
+            else {
+                tcg_out32 (s, (RLWINM
+                               | RA (args[0])
+                               | RS (args[1])
+                               | SH (32 - args[2])
+                               | MB (args[2])
+                               | ME (31)
+                               )
+                    );
+            }
         }
-        else
+        else {
             tcg_out32 (s, SRW | SAB (args[1], args[0], args[2]));
+        }
         break;
     case INDEX_op_sar_i32:
-        if (const_args[2])
-            tcg_out32 (s, SRAWI | RS (args[1]) | RA (args[0]) | SH (args[2]));
+        if (const_args[2]) {
+            if (args[2] > 31) {
+                tcg_out_movi (s, TCG_TYPE_I32, 0, args[2]);
+                tcg_out32 (s, SRAW | SAB (args[1], args[0], 0));
+            }
+            else {
+                tcg_out32 (s, SRAWI | RS (args[1]) | RA (args[0]) | SH 
(args[2]));
+            }
+        }
         else
             tcg_out32 (s, SRAW | SAB (args[1], args[0], args[2]));
         break;
@@ -1604,7 +1626,7 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, 
const TCGArg *args,
                 | RS (args[1])
                 | MB (0)
                 | ME (31)
-                | (const_args[2] ? RLWINM | SH (args[2])
+                | (const_args[2] ? RLWINM | SH (args[2] & 31)
                                  : RLWNM | RB (args[2]))
                 ;
             tcg_out32 (s, op);
@@ -1619,7 +1641,7 @@ static void tcg_out_op(TCGContext *s, TCGOpcode opc, 
const TCGArg *args,
                 tcg_out32 (s, RLWINM
                            | RA (args[0])
                            | RS (args[1])
-                           | SH (32 - args[2])
+                           | SH (32 - (args[2] & 31))
                            | MB (0)
                            | ME (31)
                     );
diff --git a/tcg/ppc64/tcg-target.c b/tcg/ppc64/tcg-target.c
index 337cd41..5da7dc4 100644
--- a/tcg/ppc64/tcg-target.c
+++ b/tcg/ppc64/tcg-target.c
@@ -390,6 +390,7 @@ static int tcg_target_const_match (tcg_target_long val,
 
 #define TW     XO31( 4)
 #define TRAP   (TW | TO (31))
+#define NOP    0x60000000
 
 #define RT(r) ((r)<<21)
 #define RS(r) ((r)<<21)
@@ -1225,7 +1226,13 @@ static void tcg_out_op (TCGContext *s, TCGOpcode opc, 
const TCGArg *args,
             /* direct jump method */
 
             s->tb_jmp_offset[args[0]] = s->code_ptr - s->code_buf;
-            s->code_ptr += 28;
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
+            tcg_out32 (s, NOP);
         }
         else {
             tcg_abort ();
@@ -1430,21 +1437,36 @@ static void tcg_out_op (TCGContext *s, TCGOpcode opc, 
const TCGArg *args,
         break;
     case INDEX_op_shr_i32:
         if (const_args[2]) {
-            tcg_out32 (s, (RLWINM
-                           | RA (args[0])
-                           | RS (args[1])
-                           | SH (32 - args[2])
-                           | MB (args[2])
-                           | ME (31)
-                           )
-                );
+            if (args[2] > 31) {
+                tcg_out_movi (s, TCG_TYPE_I32, 0, args[2]);
+                tcg_out32 (s, SRW | SAB (args[1], args[0], 0));
+            }
+            else {
+                tcg_out32 (s, (RLWINM
+                               | RA (args[0])
+                               | RS (args[1])
+                               | SH (32 - args[2])
+                               | MB (args[2])
+                               | ME (31)
+                               )
+                    );
+            }
         }
-        else
+        else {
             tcg_out32 (s, SRW | SAB (args[1], args[0], args[2]));
+        }
+        break;
         break;
     case INDEX_op_sar_i32:
-        if (const_args[2])
-            tcg_out32 (s, SRAWI | RS (args[1]) | RA (args[0]) | SH (args[2]));
+        if (const_args[2]) {
+            if (args[2] > 31) {
+                tcg_out_movi (s, TCG_TYPE_I32, 0, args[2]);
+                tcg_out32 (s, SRAW | SAB (args[1], args[0], 0));
+            }
+            else {
+                tcg_out32 (s, SRAWI | RS (args[1]) | RA (args[0]) | SH 
(args[2]));
+            }
+        }
         else
             tcg_out32 (s, SRAW | SAB (args[1], args[0], args[2]));
         break;

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