[Qemu-devel] [PATCH] lm32: use lookup table for opcodes

[Michael Walle]

Instead of a for loop use a faster lookup table.

Signed-off-by: Michael Walle <address@hidden>
---
 target-lm32/lm32-decode.h |   78 -------------------------------------------
 target-lm32/translate.c   |   80 ++++++++++----------------------------------
 2 files changed, 18 insertions(+), 140 deletions(-)
 delete mode 100644 target-lm32/lm32-decode.h

diff --git a/target-lm32/lm32-decode.h b/target-lm32/lm32-decode.h
deleted file mode 100644
index 42205d9..0000000
--- a/target-lm32/lm32-decode.h
+++ /dev/null
@@ -1,78 +0,0 @@
-/*
- *  LatticeMico32 instruction decoding macros.
- *
- *  Copyright (c) 2010 Michael Walle <address@hidden>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2 of the License, or (at your option) any later version.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, see <http://www.gnu.org/licenses/>.
- */
-
-/* Convenient binary macros */
-#define HEX__(n) 0x##n##LU
-#define B8__(x) (((x&0x0000000FLU) ? 1 : 0) \
-                  + ((x&0x000000F0LU) ? 2 : 0) \
-                  + ((x&0x00000F00LU) ? 4 : 0) \
-                  + ((x&0x0000F000LU) ? 8 : 0) \
-                  + ((x&0x000F0000LU) ? 16 : 0) \
-                  + ((x&0x00F00000LU) ? 32 : 0) \
-                  + ((x&0x0F000000LU) ? 64 : 0) \
-                  + ((x&0xF0000000LU) ? 128 : 0))
-#define B8(d) ((unsigned char)B8__(HEX__(d)))
-
-/* Decode logic, value and mask.  */
-#define DEC_ADD     {B8(00001101), B8(00011111)}
-#define DEC_AND     {B8(00001000), B8(00011111)}
-#define DEC_ANDHI   {B8(00011000), B8(00111111)}
-#define DEC_B       {B8(00110000), B8(00111111)}
-#define DEC_BI      {B8(00111000), B8(00111111)}
-#define DEC_BE      {B8(00010001), B8(00111111)}
-#define DEC_BG      {B8(00010010), B8(00111111)}
-#define DEC_BGE     {B8(00010011), B8(00111111)}
-#define DEC_BGEU    {B8(00010100), B8(00111111)}
-#define DEC_BGU     {B8(00010101), B8(00111111)}
-#define DEC_BNE     {B8(00010111), B8(00111111)}
-#define DEC_CALL    {B8(00110110), B8(00111111)}
-#define DEC_CALLI   {B8(00111110), B8(00111111)}
-#define DEC_CMPE    {B8(00011001), B8(00011111)}
-#define DEC_CMPG    {B8(00011010), B8(00011111)}
-#define DEC_CMPGE   {B8(00011011), B8(00011111)}
-#define DEC_CMPGEU  {B8(00011100), B8(00011111)}
-#define DEC_CMPGU   {B8(00011101), B8(00011111)}
-#define DEC_CMPNE   {B8(00011111), B8(00011111)}
-#define DEC_DIVU    {B8(00100011), B8(00111111)}
-#define DEC_LB      {B8(00000100), B8(00111111)}
-#define DEC_LBU     {B8(00010000), B8(00111111)}
-#define DEC_LH      {B8(00000111), B8(00111111)}
-#define DEC_LHU     {B8(00001011), B8(00111111)}
-#define DEC_LW      {B8(00001010), B8(00111111)}
-#define DEC_MODU    {B8(00110001), B8(00111111)}
-#define DEC_MUL     {B8(00000010), B8(00011111)}
-#define DEC_NOR     {B8(00000001), B8(00011111)}
-#define DEC_OR      {B8(00001110), B8(00011111)}
-#define DEC_ORHI    {B8(00011110), B8(00111111)}
-#define DEC_SCALL   {B8(00101011), B8(00111111)}
-#define DEC_RCSR    {B8(00100100), B8(00111111)}
-#define DEC_SB      {B8(00001100), B8(00111111)}
-#define DEC_SEXTB   {B8(00101100), B8(00111111)}
-#define DEC_SEXTH   {B8(00110111), B8(00111111)}
-#define DEC_SH      {B8(00000011), B8(00111111)}
-#define DEC_SL      {B8(00001111), B8(00011111)}
-#define DEC_SR      {B8(00000101), B8(00011111)}
-#define DEC_SRU     {B8(00000000), B8(00011111)}
-#define DEC_SUB     {B8(00110010), B8(00111111)}
-#define DEC_SW      {B8(00010110), B8(00111111)}
-#define DEC_USER    {B8(00110011), B8(00111111)}
-#define DEC_WCSR    {B8(00110100), B8(00111111)}
-#define DEC_XNOR    {B8(00001001), B8(00011111)}
-#define DEC_XOR     {B8(00000110), B8(00011111)}
-
diff --git a/target-lm32/translate.c b/target-lm32/translate.c
index aa08a14..666d5f4 100644
--- a/target-lm32/translate.c
+++ b/target-lm32/translate.c
@@ -29,7 +29,6 @@
 #include "disas.h"
 #include "helper.h"
 #include "tcg-op.h"
-#include "lm32-decode.h"
 #include "qemu-common.h"
 
 #include "hw/lm32_pic.h"
@@ -963,66 +962,28 @@ static void dec_xor(DisasContext *dc)
     }
 }
 
-typedef struct {
-    struct {
-        uint32_t bits;
-        uint32_t mask;
-    };
-    void (*dec)(DisasContext *dc);
-} DecoderInfo;
+static void dec_ill(DisasContext *dc)
+{
+    cpu_abort(dc->env, "unknown opcode 0x%02x\n", dc->opcode);
+}
 
+typedef void (*DecoderInfo)(DisasContext *dc);
 static const DecoderInfo decinfo[] = {
-    {DEC_ADD, dec_add},
-    {DEC_AND, dec_and},
-    {DEC_ANDHI, dec_andhi},
-    {DEC_B, dec_b},
-    {DEC_BI, dec_bi},
-    {DEC_BE, dec_be},
-    {DEC_BG, dec_bg},
-    {DEC_BGE, dec_bge},
-    {DEC_BGEU, dec_bgeu},
-    {DEC_BGU, dec_bgu},
-    {DEC_BNE, dec_bne},
-    {DEC_CALL, dec_call},
-    {DEC_CALLI, dec_calli},
-    {DEC_CMPE, dec_cmpe},
-    {DEC_CMPG, dec_cmpg},
-    {DEC_CMPGE, dec_cmpge},
-    {DEC_CMPGEU, dec_cmpgeu},
-    {DEC_CMPGU, dec_cmpgu},
-    {DEC_CMPNE, dec_cmpne},
-    {DEC_DIVU, dec_divu},
-    {DEC_LB, dec_lb},
-    {DEC_LBU, dec_lbu},
-    {DEC_LH, dec_lh},
-    {DEC_LHU, dec_lhu},
-    {DEC_LW, dec_lw},
-    {DEC_MODU, dec_modu},
-    {DEC_MUL, dec_mul},
-    {DEC_NOR, dec_nor},
-    {DEC_OR, dec_or},
-    {DEC_ORHI, dec_orhi},
-    {DEC_SCALL, dec_scall},
-    {DEC_RCSR, dec_rcsr},
-    {DEC_SB, dec_sb},
-    {DEC_SEXTB, dec_sextb},
-    {DEC_SEXTH, dec_sexth},
-    {DEC_SH, dec_sh},
-    {DEC_SL, dec_sl},
-    {DEC_SR, dec_sr},
-    {DEC_SRU, dec_sru},
-    {DEC_SUB, dec_sub},
-    {DEC_SW, dec_sw},
-    {DEC_USER, dec_user},
-    {DEC_WCSR, dec_wcsr},
-    {DEC_XNOR, dec_xnor},
-    {DEC_XOR, dec_xor},
+    dec_sru, dec_nor, dec_mul, dec_sh, dec_lb, dec_sr, dec_xor, dec_lh,
+    dec_and, dec_xnor, dec_lw, dec_lhu, dec_sb, dec_add, dec_or, dec_sl,
+    dec_lbu, dec_be, dec_bg, dec_bge, dec_bgeu, dec_bgu, dec_sw, dec_bne,
+    dec_andhi, dec_cmpe, dec_cmpg, dec_cmpge, dec_cmpgeu, dec_cmpgu, dec_orhi,
+    dec_cmpne,
+    dec_sru, dec_nor, dec_mul, dec_divu, dec_rcsr, dec_sr, dec_xor, dec_ill,
+    dec_and, dec_xnor, dec_ill, dec_scall, dec_sextb, dec_add, dec_or, dec_sl,
+    dec_b, dec_modu, dec_sub, dec_user, dec_wcsr, dec_ill, dec_call, dec_sexth,
+    dec_bi, dec_cmpe, dec_cmpg, dec_cmpge, dec_cmpgeu, dec_cmpgu, dec_calli,
+    dec_cmpne
 };
 
 static inline void decode(DisasContext *dc)
 {
     uint32_t ir;
-    int i;
 
     if (unlikely(qemu_loglevel_mask(CPU_LOG_TB_OP))) {
         tcg_gen_debug_insn_start(dc->pc);
@@ -1061,15 +1022,10 @@ static inline void decode(DisasContext *dc)
         dc->format = OP_FMT_RI;
     }
 
-    /* Large switch for all insns.  */
-    for (i = 0; i < ARRAY_SIZE(decinfo); i++) {
-        if ((dc->opcode & decinfo[i].mask) == decinfo[i].bits) {
-            decinfo[i].dec(dc);
-            return;
-        }
-    }
+    assert(ARRAY_SIZE(decinfo) == 64);
+    assert(dc->opcode < 64);
 
-    cpu_abort(dc->env, "unknown opcode 0x%02x\n", dc->opcode);
+    decinfo[dc->opcode](dc);
 }
 
 static void check_breakpoint(CPUState *env, DisasContext *dc)
-- 
1.7.2.3