Optimizations

bddisasm/bdx86_decoder.c

@@ -1298,7 +1298,7 @@ NdParseMemoryOperand16(
     // Store the displacement.
     Operand->Info.Memory.HasDisp = !!Instrux->HasDisp;
     Operand->Info.Memory.DispSize = Instrux->DispLength;
-    Operand->Info.Memory.Disp = ND_SIGN_EX(Instrux->DispLength, Instrux->Displacement);
+    Operand->Info.Memory.Disp = Instrux->HasDisp ? ND_SIGN_EX(Instrux->DispLength, Instrux->Displacement) : 0;
 
     return ND_STATUS_SUCCESS;
 }
@@ -1416,7 +1416,7 @@ NdParseMemoryOperand3264(
 
     Operand->Info.Memory.HasDisp = Instrux->HasDisp;
     Operand->Info.Memory.DispSize = Instrux->DispLength;
-    Operand->Info.Memory.Disp = ND_SIGN_EX(Instrux->DispLength, Instrux->Displacement);
+    Operand->Info.Memory.Disp = Instrux->HasDisp ? ND_SIGN_EX(Instrux->DispLength, Instrux->Displacement) : 0;
 
     return ND_STATUS_SUCCESS;
 }
@@ -1441,14 +1441,14 @@ NdParseOperand(
     ND_UINT8 opt, ops, opf, opa, opd, opb;
     ND_REG_SIZE vsibRegSize;
     ND_UINT8 vsibIndexSize, vsibIndexCount;
-    ND_OPERAND_SIZE size, bcstSize;
+    ND_OPERAND_SIZE size;
     ND_BOOL width;
 
     // pre-init
     status = ND_STATUS_SUCCESS;
     vsibRegSize = 0;
     vsibIndexSize = vsibIndexCount = 0;
-    size = bcstSize = 0;
+    size = 0;
 
     // Get actual width.
     width = Instrux->Exs.w && !(Instrux->Attributes & ND_FLAG_WIG);
@@ -1877,7 +1877,7 @@ NdParseOperand(
     }
 
     // Store operand info.
-    operand->Size = bcstSize = size;
+    operand->Size = size;
 
     //
     // Fill in the operand type.
@@ -2242,7 +2242,7 @@ NdParseOperand(
         break;
 
     case ND_OPT_LSTAR:
-        // The operand is implicit and is the IA32_STAR.
+        // The operand is implicit and is the IA32_LSTAR.
         operand->Type = ND_OP_REG;
         operand->Info.Register.Type = ND_REG_MSR;
         operand->Info.Register.Size = ND_SIZE_64BIT;
@@ -2778,6 +2778,7 @@ NdParseOperand(
         // bcstSize / rawSize.
         if (Instrux->HasBroadcast)
         {
+            ND_OPERAND_SIZE bcstSize = size;
             operand->Info.Memory.HasBroadcast = ND_TRUE;
 
             if (opd & ND_OPD_B32)

benchmark.sh

@@ -0,0 +1,60 @@
+#!/bin/sh
+set -e
+
+if [ "$#" -ne 4 ] ; then
+    echo "Compare the speed of two different disasmtool versions"
+    echo "Usage $0 <first disasmtool> <second disasmtool> <input file> <iterations>"
+    exit 0
+fi
+
+FIRST=$1
+SECOND=$2
+INPUT=$3
+COUNT=$4
+
+if [ ! -x "$FIRST" ] ; then
+    echo "First program $FIRST does not exist or is not executable"
+    exit 1
+fi
+
+if [ ! -x "$SECOND" ] ; then
+    echo "Second program $SECOND does not exist or is not executable"
+    exit 1
+fi
+
+if [ ! -f "$INPUT" ] ; then
+    echo "Input file $INPUT does not exist"
+    exit 1
+fi
+
+case $COUNT in
+    ''|*[!0-9]*) echo "Iteration count $COUNT is not a number" ; exit 1 ;;
+    *) ;;
+esac
+
+if [ "$COUNT" -lt 3 ] ; then
+    echo "ministat requires at least 3 samples"
+    exit 1
+fi
+
+FIRSTRESULT="$FIRST.result"
+SECONDRESULT="$SECOND.result"
+
+truncate -s 0 $FIRSTRESULT
+truncate -s 0 $SECONDRESULT
+
+# Make sure all necessary files are in cache
+$FIRST  -f $INPUT -nv > /dev/null
+$SECOND -f $INPUT -nv > /dev/null
+
+for n in `seq 1 $COUNT` ; do
+    echo "$n"
+    $FIRST  -f $INPUT -nv -iv | tee -a $FIRSTRESULT
+    $SECOND -f $INPUT -nv -iv | tee -a $SECONDRESULT
+done
+
+ministat -C 6 $FIRSTRESULT $SECONDRESULT
+echo 'Instructions/second, higher is better'
+if [ "$COUNT" -lt 30 ] ; then
+    echo "Sample count $COUNT was less than 30, results might be unreliable"
+fi

inc/bdx86_core.h

@@ -353,15 +353,14 @@ typedef ND_UINT32 ND_REG_SIZE;
 #define ND_SIGN_EX_16(x)            (((x) & 0x00008000) ? (0xFFFFFFFFFFFF0000 | (x)) : ((x) & 0xFFFF))
 // Sign extend 32 bit to 64 bit.
 #define ND_SIGN_EX_32(x)            (((x) & 0x80000000) ? (0xFFFFFFFF00000000 | (x)) : ((x) & 0xFFFFFFFF))
-// Wrapper for for ND_SIGN_EX_8/ND_SIGN_EX_16/ND_SIGN_EX_32. Sign extend sz bytes to 64 bits.
-#define ND_SIGN_EX(sz, x)           ((sz) == 1 ? ND_SIGN_EX_8(x) : (sz) == 2 ? ND_SIGN_EX_16(x) :                   \
-                                     (sz) == 4 ? ND_SIGN_EX_32(x) : (x))
+// Sign extend to 64 bit, with minimal branches
+#define ND_SIGN_EX(sz, x)           (((x) & ND_SIZE_TO_MASK(sz)) | (~ND_SIZE_TO_MASK(sz) * ND_GET_SIGN(sz, x)))
+
 // Trim 64 bits to sz bytes.
 #define ND_TRIM(sz, x)              ((sz) == 1 ? (x) & 0xFF : (sz) == 2 ? (x) & 0xFFFF :                            \
                                      (sz) == 4 ? (x) & 0xFFFFFFFF : (x))
 // Returns most significant bit, given size in bytes sz.
-#define ND_MSB(sz, x)               ((sz) == 1 ? ((x) >> 7) & 1 : (sz) == 2 ? ((x) >> 15) & 1 :                     \
-                                     (sz) == 4 ? ((x) >> 31) & 1 : ((x) >> 63) & 1)
+#define ND_MSB(sz, x)               (((x) >> ( (sz) * 8 - 1)) & 1)
 // Returns least significant bit.
 #define ND_LSB(sz, x)               ((x) & 1)
 // Convert a size in bytes to a bitmask.