From 9d3f34bcc62ed5b4323cc4018f9b505c7a354c50 Mon Sep 17 00:00:00 2001
From: Alexis Engelke <alexis.engelke@googlemail.com>
Date: Sun, 13 Jan 2019 16:19:41 +0100
Subject: [PATCH] No longer store sizes as bitfields

On most (x86) processors, using bitfields is low than using slightly
more memory.
---
 decode.c | 42 ++++++++++--------------------------------
 decode.h | 10 +++++-----
 2 files changed, 15 insertions(+), 37 deletions(-)

diff --git a/decode.c b/decode.c
index d7b1734..d1f1f84 100644
--- a/decode.c
+++ b/decode.c
@@ -456,40 +456,19 @@ decode(const uint8_t* buffer, int len, DecodeMode mode, Instr* instr)
         instr->segment = RI_DS;
     }
 
-    uint8_t op_size_log = 0;
+    uint8_t op_size = 0;
     if (desc->gp_size_8)
-    {
-        op_size_log = 1;
-    }
+        op_size = 1;
     else if (mode == DECODE_64 && (prefixes & PREFIX_REXW))
-    {
-        op_size_log = 4;
-    }
+        op_size = 8;
     else if (prefixes & PREFIX_OPSZ)
-    {
-        op_size_log = 2;
-    }
-#if defined(ARCH_X86_64)
+        op_size = 2;
     else if (mode == DECODE_64 && desc->gp_size_def64)
-    {
-        op_size_log = 4;
-    }
-#endif
+        op_size = 8;
     else
-    {
-        op_size_log = 3;
-    }
+        op_size = 4;
 
-    uint8_t op_size = (1 << op_size_log) >> 1;
-
-    if (UNLIKELY(desc->gp_instr_width))
-    {
-        instr->width = op_size_log;
-    }
-    else
-    {
-        instr->width = 0;
-    }
+    instr->op_size = UNLIKELY(desc->gp_instr_width) ? op_size : 0;
 
     uint8_t vec_size = 16;
     if (prefixes & PREFIX_VEXL)
@@ -498,11 +477,10 @@ decode(const uint8_t* buffer, int len, DecodeMode mode, Instr* instr)
     }
 
     // Compute address size.
-    uint8_t addr_size_log = mode == DECODE_64 ? 4 : 3;
+    uint8_t addr_size = mode == DECODE_64 ? 8 : 4;
     if (prefixes & PREFIX_ADDRSZ)
-        addr_size_log -= 1;
-    instr->addr_size = addr_size_log;
-    uint8_t addr_size = (1 << addr_size_log) >> 1;
+        addr_size >>= 1;
+    instr->addr_size = addr_size;
 
     uint8_t operand_sizes[4] = {
         0, 1 << desc->gp_fixed_operand_size, op_size, vec_size
diff --git a/decode.h b/decode.h
index d24264d..c81323e 100644
--- a/decode.h
+++ b/decode.h
@@ -116,9 +116,9 @@ struct Instr
 {
     uint16_t type;
     struct Operand operands[4];
-    uint8_t segment : 3;
-    uint8_t width : 3;
-    uint8_t addr_size : 2;
+    uint8_t segment;
+    uint8_t op_size;
+    uint8_t addr_size;
 
     /**
      * Encoded as 1 << (scale - 1)  **or**  no scaled register at all if zero.
@@ -137,8 +137,8 @@ struct Instr
 typedef struct Instr Instr;
 
 #define INSTR_SEGMENT(instr) ((instr)->segment)
-#define INSTR_WIDTH(instr) ((1 << (instr)->width) >> 1)
-#define INSTR_ADDRSZ(instr) ((1 << (instr)->addr_size) >> 1)
+#define INSTR_WIDTH(instr) ((instr)->op_size)
+#define INSTR_ADDRSZ(instr) ((instr)->addr_size)
 #define INSTR_HAS_REP(instr) ((instr)->prefixes & PREFIX_REP)
 #define INSTR_HAS_REPNZ(instr) ((instr)->prefixes & PREFIX_REPNZ)
 #define INSTR_HAS_LOCK(instr) ((instr)->prefixes & PREFIX_LOCK)