[Qemu-devel] [PATCH 11/22] tcg-i386: Tidy non-immediate arithmetic operations.

[Richard Henderson]

Add more OPC values, and tgen_arithr.  Use the later throughout.

Note that normal reg/reg arithmetic now uses the Gv,Ev opcode form
instead of the Ev,Gv opcode form used previously.  Both forms
disassemble properly, and so there's no visible change when diffing
log files before and after the change.  This change makes the operand
ordering within the output routines more natural, and avoids the need
to define an OPC_ARITH_EvGv since a read-modify-write with memory is
not needed within TCG.

Signed-off-by: Richard Henderson <address@hidden>
---
 tcg/i386/tcg-target.c |   78 ++++++++++++++++++++++++++++++-------------------
 1 files changed, 48 insertions(+), 30 deletions(-)

diff --git a/tcg/i386/tcg-target.c b/tcg/i386/tcg-target.c
index df1bdfc..b4e8e74 100644
--- a/tcg/i386/tcg-target.c
+++ b/tcg/i386/tcg-target.c
@@ -165,7 +165,12 @@ static inline int tcg_target_const_match(tcg_target_long 
val,
 
 #define OPC_ARITH_EvIz (0x81)
 #define OPC_ARITH_EvIb (0x83)
+#define OPC_ARITH_GvEv (0x03)          /* ... plus (ARITH_FOO << 3) */
+#define OPC_ADD_GvEv   (OPC_ARITH_GvEv | (ARITH_ADD << 3))
+#define OPC_CMP_GvEv   (OPC_ARITH_GvEv | (ARITH_CMP << 3))
+#define OPC_DEC_r32    (0x48)
 #define OPC_BSWAP      (0xc8 | P_EXT)
+#define OPC_INC_r32    (0x40)
 #define OPC_JCC_long   (0x80 | P_EXT)  /* ... plus condition code */
 #define OPC_JCC_short  (0x70)          /* ... plus condition code */
 #define OPC_JMP_long   (0xe9)
@@ -180,6 +185,7 @@ static inline int tcg_target_const_match(tcg_target_long 
val,
 #define OPC_SHIFT_1    (0xd1)
 #define OPC_SHIFT_Ib   (0xc1)
 #define OPC_SHIFT_cl   (0xd3)
+#define OPC_TESTL      (0x85)
 
 /* Group 1 opcode extensions for 0x80-0x83.  */
 #define ARITH_ADD 0
@@ -280,6 +286,12 @@ static inline void tcg_out_modrm_offset(TCGContext *s, int 
opc, int r, int rm,
     }
 }
 
+/* Generate dest op= src.  Uses the same ARITH_* codes as tgen_arithi.  */
+static inline void tgen_arithr(TCGContext *s, int subop, int dest, int src)
+{
+    tcg_out_modrm(s, OPC_ARITH_GvEv + (subop << 3), dest, src);
+}
+
 static inline void tcg_out_mov(TCGContext *s, int ret, int arg)
 {
     if (arg != ret) {
@@ -291,8 +303,7 @@ static inline void tcg_out_movi(TCGContext *s, TCGType type,
                                 int ret, int32_t arg)
 {
     if (arg == 0) {
-        /* xor r0,r0 */
-        tcg_out_modrm(s, 0x01 | (ARITH_XOR << 3), ret, ret);
+        tgen_arithr(s, ARITH_XOR, ret, ret);
     } else {
         tcg_out8(s, 0xb8 + ret);
         tcg_out32(s, arg);
@@ -374,14 +385,15 @@ static inline void tcg_out_rolw_8(TCGContext *s, int reg)
     tcg_out_shifti(s, SHIFT_ROL, reg, 8);
 }
 
-static inline void tgen_arithi(TCGContext *s, int c, int r0, int32_t val, int 
cf)
+static inline void tgen_arithi(TCGContext *s, int c, int r0,
+                               int32_t val, int cf)
 {
-    if (!cf && ((c == ARITH_ADD && val == 1) || (c == ARITH_SUB && val == 
-1))) {
-        /* inc */
-        tcg_out_opc(s, 0x40 + r0);
-    } else if (!cf && ((c == ARITH_ADD && val == -1) || (c == ARITH_SUB && val 
== 1))) {
-        /* dec */
-        tcg_out_opc(s, 0x48 + r0);
+    /* ??? While INC is 2 bytes shorter than ADDL $1, they also induce
+       partial flags update stalls on Pentium4 and are not recommended
+       by current Intel optimization manuals.  */
+    if (!cf && (c == ARITH_ADD || c == ARITH_SUB) && (val == 1 || val == -1)) {
+        int opc = ((c == ARITH_ADD) ^ (val < 0) ? OPC_INC_r32 : OPC_DEC_r32);
+        tcg_out_opc(s, opc + r0);
     } else if (val == (int8_t)val) {
         tcg_out_modrm(s, OPC_ARITH_EvIb, c, r0);
         tcg_out8(s, val);
@@ -454,12 +466,12 @@ static void tcg_out_cmp(TCGContext *s, TCGArg arg1, 
TCGArg arg2,
     if (const_arg2) {
         if (arg2 == 0) {
             /* test r, r */
-            tcg_out_modrm(s, 0x85, arg1, arg1);
+            tcg_out_modrm(s, OPC_TESTL, arg1, arg1);
         } else {
             tgen_arithi(s, ARITH_CMP, arg1, arg2, 0);
         }
     } else {
-        tcg_out_modrm(s, 0x01 | (ARITH_CMP << 3), arg2, arg1);
+        tgen_arithr(s, ARITH_CMP, arg1, arg2);
     }
 }
 
@@ -674,7 +686,7 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg 
*args,
     tcg_out32(s, offsetof(CPUState, tlb_table[mem_index][0].addr_read));
 
     /* cmp 0(r1), r0 */
-    tcg_out_modrm_offset(s, 0x3b, r0, r1, 0);
+    tcg_out_modrm_offset(s, OPC_CMP_GvEv, r0, r1, 0);
     
     tcg_out_mov(s, r0, addr_reg);
     
@@ -690,7 +702,7 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg 
*args,
     s->code_ptr++;
     
     /* cmp 4(r1), addr_reg2 */
-    tcg_out_modrm_offset(s, 0x3b, addr_reg2, r1, 4);
+    tcg_out_modrm_offset(s, OPC_CMP_GvEv, addr_reg2, r1, 4);
 
     /* je label1 */
     tcg_out8(s, OPC_JCC_short + JCC_JE);
@@ -749,7 +761,8 @@ static void tcg_out_qemu_ld(TCGContext *s, const TCGArg 
*args,
     *label1_ptr = s->code_ptr - label1_ptr - 1;
 
     /* add x(r1), r0 */
-    tcg_out_modrm_offset(s, 0x03, r0, r1, offsetof(CPUTLBEntry, addend) - 
+    tcg_out_modrm_offset(s, OPC_ADD_GvEv, r0, r1,
+                         offsetof(CPUTLBEntry, addend) - 
                          offsetof(CPUTLBEntry, addr_read));
 #else
     r0 = addr_reg;
@@ -864,7 +877,7 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg 
*args,
     tcg_out32(s, offsetof(CPUState, tlb_table[mem_index][0].addr_write));
 
     /* cmp 0(r1), r0 */
-    tcg_out_modrm_offset(s, 0x3b, r0, r1, 0);
+    tcg_out_modrm_offset(s, OPC_CMP_GvEv, r0, r1, 0);
     
     tcg_out_mov(s, r0, addr_reg);
     
@@ -880,7 +893,7 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg 
*args,
     s->code_ptr++;
     
     /* cmp 4(r1), addr_reg2 */
-    tcg_out_modrm_offset(s, 0x3b, addr_reg2, r1, 4);
+    tcg_out_modrm_offset(s, OPC_CMP_GvEv, addr_reg2, r1, 4);
 
     /* je label1 */
     tcg_out8(s, OPC_JCC_short + JCC_JE);
@@ -961,7 +974,8 @@ static void tcg_out_qemu_st(TCGContext *s, const TCGArg 
*args,
     *label1_ptr = s->code_ptr - label1_ptr - 1;
 
     /* add x(r1), r0 */
-    tcg_out_modrm_offset(s, 0x03, r0, r1, offsetof(CPUTLBEntry, addend) - 
+    tcg_out_modrm_offset(s, OPC_ADD_GvEv, r0, r1,
+                         offsetof(CPUTLBEntry, addend) - 
                          offsetof(CPUTLBEntry, addr_write));
 #else
     r0 = addr_reg;
@@ -1113,7 +1127,7 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode 
opc,
         if (const_args[2]) {
             tgen_arithi(s, c, args[0], args[2], 0);
         } else {
-            tcg_out_modrm(s, 0x01 | (c << 3), args[2], args[0]);
+            tgen_arithr(s, c, args[0], args[2]);
         }
         break;
     case INDEX_op_mul_i32:
@@ -1163,24 +1177,28 @@ static inline void tcg_out_op(TCGContext *s, TCGOpcode 
opc,
         goto gen_shift32;
 
     case INDEX_op_add2_i32:
-        if (const_args[4]) 
+        if (const_args[4]) {
             tgen_arithi(s, ARITH_ADD, args[0], args[4], 1);
-        else
-            tcg_out_modrm(s, 0x01 | (ARITH_ADD << 3), args[4], args[0]);
-        if (const_args[5]) 
+        } else {
+            tgen_arithr(s, ARITH_ADD, args[0], args[4]);
+        }
+        if (const_args[5]) {
             tgen_arithi(s, ARITH_ADC, args[1], args[5], 1);
-        else
-            tcg_out_modrm(s, 0x01 | (ARITH_ADC << 3), args[5], args[1]);
+        } else {
+            tgen_arithr(s, ARITH_ADC, args[0], args[5]);
+        }
         break;
     case INDEX_op_sub2_i32:
-        if (const_args[4]) 
+        if (const_args[4]) {
             tgen_arithi(s, ARITH_SUB, args[0], args[4], 1);
-        else
-            tcg_out_modrm(s, 0x01 | (ARITH_SUB << 3), args[4], args[0]);
-        if (const_args[5]) 
+        } else {
+            tgen_arithr(s, ARITH_SUB, args[0], args[4]);
+        }
+        if (const_args[5]) {
             tgen_arithi(s, ARITH_SBB, args[1], args[5], 1);
-        else
-            tcg_out_modrm(s, 0x01 | (ARITH_SBB << 3), args[5], args[1]);
+        } else {
+            tgen_arithr(s, ARITH_SBB, args[1], args[5]);
+        }
         break;
     case INDEX_op_brcond_i32:
         tcg_out_brcond(s, args[2], args[0], args[1], const_args[1],
-- 
1.6.6.1