Move validator_x86_XX.rl out of unreviewed.

src/trusted/validator_ragel/decoding.h

 /*
  * Copyright (c) 2012 The Native Client Authors. All rights reserved.
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 /*
- * This file contains common parts of x86-32 and x86-64 internals (inline
- * functions and defines).
+ * This file contains common parts of ia32 and x86-64 decoder and validator
+ * internals (inline functions which are used to pull useful information from
+ * "well-known" bytes of the instruction: REX and VEX prefixes, ModR/M byte and
+ * so on).
  *
- * We only include simple schematic diagrams here.  For full description see
- * AMD/Intel manuals.
+ * See full description in AMD/Intel manuals.
  */
 
 #ifndef NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_RAGEL_DECODING_H_
 #define NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_RAGEL_DECODING_H_
 
 #include "native_client/src/trusted/validator_ragel/decoder.h"
 
 #if NACL_WINDOWS
 # define FORCEINLINE __forceinline
 #else
 # define FORCEINLINE __inline __attribute__ ((always_inline))
 #endif
 
 
 /*
- * Opcode with register number embedded:
+ * Opcode-with-register byte format:
  *
- *     7       6       5       4       3       2       1       0
- * ┌───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┒
- * │                Opcode                 │    register number    ┃
- * ┕━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┛
+ * bits 0-2: register number
+ * bits 3-7: actual opcode
  */
 static FORCEINLINE uint8_t RegFromOpcode(uint8_t modrm) {
   return modrm & 0x07;
 }
 
 /*
  * ModRM byte format:
  *
- *     7       6       5       4       3       2       1       0
- * ┌───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┒
- * │      mod      │          reg          │          r/m          ┃
- * ┕━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┛
+ * bits 0-2: r/m
+ * bits 3-5: reg
+ * bits 6-7: mod
  */
 static FORCEINLINE uint8_t ModFromModRM(uint8_t modrm) {
   return modrm >> 6;
 }
 
 static FORCEINLINE uint8_t RegFromModRM(uint8_t modrm) {
-  return (modrm & 0x38) >> 3;
+  return (modrm >> 3) & 0x07;
 }
 
 static FORCEINLINE uint8_t RMFromModRM(uint8_t modrm) {
   return modrm & 0x07;
 }
 
 /*
  * SIB byte format:
  *
- *     7       6       5       4       3       2       1       0
- * ┌───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┒
- * │     scale     │         index         │          base         ┃
- * ┕━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┛
+ * bits 0-2: base
+ * bits 3-5: index
+ * bits 6-7: scale
  */
 static FORCEINLINE uint8_t ScaleFromSIB(uint8_t sib) {
   return sib >> 6;
 }
 
 static FORCEINLINE uint8_t IndexFromSIB(uint8_t sib) {
-  return (sib & 0x38) >> 3;
+  return (sib >> 3) & 0x07;
 }
 
 static FORCEINLINE uint8_t BaseFromSIB(uint8_t sib) {
   return sib & 0x07;
 }
 
 /*
  * REX byte format:
  *
- *     7       6       5       4       3       2       1       0
- * ┌───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┒
- * │   0   │   1   │   0   │   0   │   W   │   R   │   X   │   B   ┃
- * ┕━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┛
+ * bit 0: B (Base)
+ * bit 1: X (indeX)
+ * bit 2: R (Register)
+ * bit 3: W (Wide)
+ * 4-7 bits: 0x4 (REX signature)
  */
 
 enum {
   REX_B = 1,
   REX_X = 2,
   REX_R = 4,
   REX_W = 8
 };
 
+/* How much to add to "base register" number: 0 or 8  */
 static FORCEINLINE uint8_t BaseExtentionFromREX(uint8_t rex) {
   return (rex & REX_B) << 3;
 }
 
+/* How much to add to "index register" number: 0 or 8  */
 static FORCEINLINE uint8_t IndexExtentionFromREX(uint8_t rex) {
   return (rex & REX_X) << 2;
 }
 
+/* How much to add to "register operand" number: 0 or 8  */
 static FORCEINLINE uint8_t RegisterExtentionFromREX(uint8_t rex) {
   return (rex & REX_R) << 1;
 }
 
 /*
  * VEX 2nd byte format:
  *
- *     7       6       5       4       3       2       1       0
- * ┌───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┒
- * │  ¬R   │  ¬X   │  ¬B   │          opcode map selector          ┃
- * ┕━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┛
+ * 0-4 bits: opcode selector
+ * bit 5 bit: inverted B (Base)
+ * bit 6 bit: inverted X (indeX)
+ * bit 7 bit: inverted R (Register)
  */
 
 enum {
   VEX_MAP1 = 0x01,
   VEX_MAP2 = 0x02,
   VEX_MAP3 = 0x03,
   VEX_MAP8 = 0x08,
   VEX_MAP9 = 0x09,
   VEX_MAPA = 0x0a,
   VEX_B    = 0x20,
   VEX_X    = 0x40,
   VEX_R    = 0x80,
   VEX_W    = 0x80

[halyavin, 2013/03/25 09:43:41]

Add a comment explaining that VEX_W is in the third VEX byte.

[khim, 2013/03/25 11:33:48]

Added separate enum for 3rd byte instead.

 };
 
 static FORCEINLINE uint8_t BaseExtentionFromVEX(uint8_t vex2) {

[halyavin, 2013/03/25 09:43:41]

Add comments similar to comments for REX prefixes.

[khim, 2013/03/25 11:33:48]

Done.

   return ((~vex2) & VEX_B) >> 2;
 }
 
 static FORCEINLINE uint8_t IndexExtentionFromVEX(uint8_t vex2) {
   return ((~vex2) & VEX_X) >> 3;
 }
 
 static FORCEINLINE uint8_t RegisterExtentionFromVEX(uint8_t vex2) {
   return ((~vex2) & VEX_R) >> 4;
 }
 
 /*
  * VEX 3rd byte format:
  *
- *     7       6       5       4       3       2       1       0
- * ┌───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┒
- * │   W   │    ¬vvvv (register number)    │   L   │      pp       ┃
- * ┕━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┛
+ * bits 0-1: pp (Packed Prefix)
+ * bit 2: L (Long)
+ * bits 3-6: negated vvvv (register number)
+ * bit 7: W (Wide)
  */
 
 static FORCEINLINE uint8_t GetOperandFromVexIA32(uint8_t vex3) {
-  return ((~vex3) & 0x38) >> 3;
+  return ((~vex3) >> 3) & 0x07;
 }
 
 static FORCEINLINE uint8_t GetOperandFromVexAMD64(uint8_t vex3) {
-  return ((~vex3) & 0x78) >> 3;
+  return ((~vex3) >> 3) & 0x0f;
 }
 
 /*
- * is4 byte format:
+ * is4/is5 byte format:
  *
- *     7       6       5       4       3       2       1       0
- * ┌───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┒
- * │     vvvv (register number)    │   0   │   0   │  imm2 or zero ┃
- * ┕━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┷━━━━━━━┛
+ * bits 0-1: imm2 or zero
+ * bits 2-3: 0
+ * bits 4-7: register number
  */
 static FORCEINLINE uint8_t RegisterFromIS4(uint8_t is4) {
   return is4 >> 4;
 }
 
 /*
  * SignExtendXXBit is used to sign-extend XX-bit value to unsigned 64-bit value.
  *
  * To do that you need to pass unsigned value of smaller then 64-bit size
  * to this function: it will be converted to signed value and then
  * sign-extended to become 64-bit value.
  *
- * Smaller values can be obtained by restricting this value further (which is
- * safe according to the C language specification: see 6.2.1.2 in C90 and
+ * Return values can be restricted to smaller unsigned type when needed (which
+ * is safe according to the C language specification: see 6.2.1.2 in C90 and
  * 6.3.1.3.2 in C99 specification).
  *
  * Note that these operations are safe but slightly unusual: they come very
  * close to the edge of what "well-behaved C program is not supposed to do",
  * but they stay on the "safe" side of this boundary.  Specifically: this
- * behavior triggers "implementation-defined behavior" (see 6.2.1.2 in C90
- * specification and 6.3.1.3.3 in C99 specification) which sounds suspiciously
- * similar to the dreaded "undefined behavior", but in reality these two are
- * quite different: any program which triggers "undefined behavior" is not a
- * valid C program at all, but program which triggers "implementation-defined
- * behavior" is quite valid C program.  What this program actually *does*
- * depends on the specification of a given C compiler: each particular
- * implementation must decide for itself what it'll do in this particular case
- * and *stick* *to* *it*.  If the implementation uses two's-complement negative
- * numbers (and all the implementation which can compile this code *must*
- * support two's-complement arythmetic - see 7.18.1.1 in C99 specification) then
- * the easiest thing to do is to do what we need here - this is what all known
- * compilers for all known platforms are actually doing.
+ * (conversion to intXX_t) behavior triggers "implementation-defined behavior"
+ * (see 6.2.1.2 in C90 specification and 6.3.1.3.3 in C99 specification) which
+ * sounds suspiciously similar to the dreaded "undefined behavior", but in
+ * reality these two are quite different: any program which triggers "undefined
+ * behavior" is not a valid C program at all, but program which triggers
+ * "implementation-defined behavior" is quite valid C program.  What this
+ * program actually *does* depends on the specification of a given C compiler:
+ * each particular implementation must decide for itself what it'll do in this
+ * particular case and *stick* *to* *it*.  If the implementation actually uses
+ * two's-complement negative numbers (and all the implementation which can
+ * compile this code *must* support two's-complement arythmetic - see 7.18.1.1
+ * in C99 specification) then the easiest thing to do is to do what we need
+ * here - this is what all known compilers for all known platforms are actually
+ * doing.
+ *
+ * Conversion from intXX_t to uint64_t is always safe (same as before: see
+ * see 6.2.1.2 in C90 specification and 6.3.1.3.2 in C99 specification).
  */
 static FORCEINLINE uint64_t SignExtend8Bit(uint64_t value) {
   return (int8_t)value;
 }
 
 static FORCEINLINE uint64_t SignExtend16Bit(uint64_t value) {
   return (int16_t)value;
 }
 
 static FORCEINLINE uint64_t SignExtend32Bit(uint64_t value) {
@@ skipping 19 matching lines @@
 
 static const uint8_t index_registers[] = {
   /* Note how REG_RIZ falls out of the pattern. */
   REG_RAX, REG_RCX, REG_RDX, REG_RBX,
   REG_RIZ, REG_RBP, REG_RSI, REG_RDI,
   REG_R8,  REG_R9,  REG_R10, REG_R11,
   REG_R12, REG_R13, REG_R14, REG_R15
 };
 
 #endif  /* NATIVE_CLIENT_SRC_TRUSTED_VALIDATOR_RAGEL_DECODING_H_ */