Constify backend data (capstone-engine#1040)

* Constify string literals

Use -Wwrite-strings to force string literals to be of
type "const char[]", then fix up all warning fallout.

* Constify common infrastructure

Step one in allowing backend data to be readonly.
Minimal changes to backends for now; just set all pointers
in common structs that aren't modified to const.

* Constify AArch64 backend

Section size changes within libcapstone.so are

-.rodata               602587
-.data.rel.ro          228416
-.data                1003746
+.rodata               769051
+.data.rel.ro          241120
+.data                 824578

* Constify ARM backend

Section size changes within libcapstone.so are

-.rodata               769051
-.data.rel.ro          241120
-.data                 824578
+.rodata               959835
+.data.rel.ro          245120
+.data                 629506

* Constify Mips backend

Section size changes within libcapstone.so are

-.rodata               959835
-.data.rel.ro          245120
-.data                 629506
+.rodata              1069851
+.data.rel.ro          256416
+.data                 508194

* Constify PowerPC backend

Section size changes within libcapstone.so are

-.rodata              1069851
-.data.rel.ro          256416
-.data                 508194
+.rodata              1142715
+.data.rel.ro          272224
+.data                 419490

* Constify Sparc backend

Section size changes within libcapstone.so are

-.rodata              1142715
-.data.rel.ro          272224
-.data                 419490
+.rodata              1175227
+.data.rel.ro          277536
+.data                 381666

* Constify SystemZ backend

Section size changes within libcapstone.so are

-.rodata              1175227
-.data.rel.ro          277536
-.data                 381666
+.rodata              1221883
+.data.rel.ro          278016
+.data                 334498

* Constify X86 backend

Section size changes within libcapstone.so are

-.rodata              1221883
-.data.rel.ro          278016
-.data                 334498
+.rodata              1533531
+.data.rel.ro          281184
+.data                  19714

* Constify XCore backend

Section size changes within libcapstone.so are

-.rodata              1533531
-.data.rel.ro          281184
-.data                  19714
+.rodata              1553026
+.data.rel.ro          281280
+.data                     40

MCInstrDesc.c

@@ -5,14 +5,14 @@
 
 /// isPredicate - Set if this is one of the operands that made up of
 /// the predicate operand that controls an isPredicable() instruction.
-bool MCOperandInfo_isPredicate(MCOperandInfo *m)
+bool MCOperandInfo_isPredicate(const MCOperandInfo *m)
 {
 	return m->Flags & (1 << MCOI_Predicate);
 }
 
 /// isOptionalDef - Set if this operand is a optional def.
 ///
-bool MCOperandInfo_isOptionalDef(MCOperandInfo *m)
+bool MCOperandInfo_isOptionalDef(const MCOperandInfo *m)
 {
 	return m->Flags & (1 << MCOI_OptionalDef);
 }

MCInstrDesc.h

@@ -130,16 +130,16 @@ typedef struct MCInstrDesc {
 	uint64_t        TSFlags;       // Target Specific Flag values
 	char ImplicitUses;  // Registers implicitly read by this instr
 	char ImplicitDefs;  // Registers implicitly defined by this instr
-	MCOperandInfo *OpInfo;   // 'NumOperands' entries about operands
+	const MCOperandInfo *OpInfo;   // 'NumOperands' entries about operands
 	uint64_t DeprecatedFeatureMask;// Feature bits that this is deprecated on, if any     
 	// A complex method to determine is a certain is deprecated or not, and return        
 	// the reason for deprecation.
 	//bool (*ComplexDeprecationInfo)(MCInst &, MCSubtargetInfo &, std::string &);           
 	unsigned char ComplexDeprecationInfo;	// dummy field, just to satisfy initializer
 } MCInstrDesc;
 
-bool MCOperandInfo_isPredicate(MCOperandInfo *m);
+bool MCOperandInfo_isPredicate(const MCOperandInfo *m);
 
-bool MCOperandInfo_isOptionalDef(MCOperandInfo *m);
+bool MCOperandInfo_isOptionalDef(const MCOperandInfo *m);
 
 #endif

MCRegisterInfo.c

@@ -22,18 +22,18 @@
 /// defined below.
 typedef struct DiffListIterator {
 	uint16_t Val;
-	MCPhysReg *List;
+	const MCPhysReg *List;
 } DiffListIterator;
 
 void MCRegisterInfo_InitMCRegisterInfo(MCRegisterInfo *RI,
-		MCRegisterDesc *D, unsigned NR,
+		const MCRegisterDesc *D, unsigned NR,
 		unsigned RA, unsigned PC,
-		MCRegisterClass *C, unsigned NC,
+		const MCRegisterClass *C, unsigned NC,
 		uint16_t (*RURoots)[2], unsigned NRU,
-		MCPhysReg *DL,
-		char *Strings,
-		uint16_t *SubIndices, unsigned NumIndices,
-		uint16_t *RET)
+		const MCPhysReg *DL,
+		const char *Strings,
+		const uint16_t *SubIndices, unsigned NumIndices,
+		const uint16_t *RET)
 {
 	RI->Desc = D;
 	RI->NumRegs = NR;
@@ -50,7 +50,7 @@ void MCRegisterInfo_InitMCRegisterInfo(MCRegisterInfo *RI,
 	RI->RegEncodingTable = RET;
 }
 
-static void DiffListIterator_init(DiffListIterator *d, MCPhysReg InitVal, MCPhysReg *DiffList)
+static void DiffListIterator_init(DiffListIterator *d, MCPhysReg InitVal, const MCPhysReg *DiffList)
 {
 	d->Val = InitVal;
 	d->List = DiffList;
@@ -83,7 +83,7 @@ static bool DiffListIterator_isValid(DiffListIterator *d)
 	return (d->List != 0);
 }
 
-unsigned MCRegisterInfo_getMatchingSuperReg(MCRegisterInfo *RI, unsigned Reg, unsigned SubIdx, MCRegisterClass *RC)
+unsigned MCRegisterInfo_getMatchingSuperReg(const MCRegisterInfo *RI, unsigned Reg, unsigned SubIdx, const MCRegisterClass *RC)
 {
 	DiffListIterator iter;
 
@@ -105,10 +105,10 @@ unsigned MCRegisterInfo_getMatchingSuperReg(MCRegisterInfo *RI, unsigned Reg, un
 	return 0;
 }
 
-unsigned MCRegisterInfo_getSubReg(MCRegisterInfo *RI, unsigned Reg, unsigned Idx)
+unsigned MCRegisterInfo_getSubReg(const MCRegisterInfo *RI, unsigned Reg, unsigned Idx)
 {
 	DiffListIterator iter;
-	uint16_t *SRI = RI->SubRegIndices + RI->Desc[Reg].SubRegIndices;
+	const uint16_t *SRI = RI->SubRegIndices + RI->Desc[Reg].SubRegIndices;
 
 	DiffListIterator_init(&iter, (MCPhysReg)Reg, RI->DiffLists + RI->Desc[Reg].SubRegs);
 	DiffListIterator_next(&iter);
@@ -123,15 +123,15 @@ unsigned MCRegisterInfo_getSubReg(MCRegisterInfo *RI, unsigned Reg, unsigned Idx
 	return 0;
 }
 
-MCRegisterClass* MCRegisterInfo_getRegClass(MCRegisterInfo *RI, unsigned i)
+const MCRegisterClass* MCRegisterInfo_getRegClass(const MCRegisterInfo *RI, unsigned i)
 {
 	//assert(i < getNumRegClasses() && "Register Class ID out of range");
 	if (i >= RI->NumClasses)
 		return 0;
 	return &(RI->Classes[i]);
 }
 
-bool MCRegisterClass_contains(MCRegisterClass *c, unsigned Reg)
+bool MCRegisterClass_contains(const MCRegisterClass *c, unsigned Reg)
 {
 	unsigned InByte = Reg % 8;
 	unsigned Byte = Reg / 8;

MCRegisterInfo.h

@@ -27,12 +27,12 @@
 /// An unsigned integer type large enough to represent all physical registers,
 /// but not necessarily virtual registers.
 typedef uint16_t MCPhysReg;
-typedef MCPhysReg* iterator;
+typedef const MCPhysReg* iterator;
 
 typedef struct MCRegisterClass {
-	char *Name;
+	const char *Name;
 	iterator RegsBegin;
-	uint8_t *RegSet;
+	const uint8_t *RegSet;
 	uint16_t RegsSize;
 	uint16_t RegSetSize;
 	uint16_t ID;
@@ -75,42 +75,42 @@ typedef struct MCRegisterDesc {
 /// virtual methods.
 ///
 typedef struct MCRegisterInfo {
-	MCRegisterDesc *Desc;                 // Pointer to the descriptor array
+	const MCRegisterDesc *Desc;                 // Pointer to the descriptor array
 	unsigned NumRegs;                           // Number of entries in the array
 	unsigned RAReg;                             // Return address register
 	unsigned PCReg;                             // Program counter register
-	MCRegisterClass *Classes;             // Pointer to the regclass array
+	const MCRegisterClass *Classes;             // Pointer to the regclass array
 	unsigned NumClasses;                        // Number of entries in the array
 	unsigned NumRegUnits;                       // Number of regunits.
 	uint16_t (*RegUnitRoots)[2];          // Pointer to regunit root table.
-	MCPhysReg *DiffLists;                 // Pointer to the difflists array
-	char *RegStrings;                     // Pointer to the string table.
-	uint16_t *SubRegIndices;              // Pointer to the subreg lookup
+	const MCPhysReg *DiffLists;                 // Pointer to the difflists array
+	const char *RegStrings;                     // Pointer to the string table.
+	const uint16_t *SubRegIndices;              // Pointer to the subreg lookup
 	// array.
 	unsigned NumSubRegIndices;                  // Number of subreg indices.
-	uint16_t *RegEncodingTable;           // Pointer to array of register
+	const uint16_t *RegEncodingTable;           // Pointer to array of register
 	// encodings.
 } MCRegisterInfo;
 
 void MCRegisterInfo_InitMCRegisterInfo(MCRegisterInfo *RI,
-		MCRegisterDesc *D, unsigned NR, unsigned RA,
+		const MCRegisterDesc *D, unsigned NR, unsigned RA,
 		unsigned PC,
-		MCRegisterClass *C, unsigned NC,
+		const MCRegisterClass *C, unsigned NC,
 		uint16_t (*RURoots)[2],
 		unsigned NRU,
-		MCPhysReg *DL,
-		char *Strings,
-		uint16_t *SubIndices,
+		const MCPhysReg *DL,
+		const char *Strings,
+		const uint16_t *SubIndices,
 		unsigned NumIndices,
-		uint16_t *RET);
+		const uint16_t *RET);
 
 
-unsigned MCRegisterInfo_getMatchingSuperReg(MCRegisterInfo *RI, unsigned Reg, unsigned SubIdx, MCRegisterClass *RC);
+unsigned MCRegisterInfo_getMatchingSuperReg(const MCRegisterInfo *RI, unsigned Reg, unsigned SubIdx, const MCRegisterClass *RC);
 
-unsigned MCRegisterInfo_getSubReg(MCRegisterInfo *RI, unsigned Reg, unsigned Idx);
+unsigned MCRegisterInfo_getSubReg(const MCRegisterInfo *RI, unsigned Reg, unsigned Idx);
 
-MCRegisterClass* MCRegisterInfo_getRegClass(MCRegisterInfo *RI, unsigned i);
+const MCRegisterClass* MCRegisterInfo_getRegClass(const MCRegisterInfo *RI, unsigned i);
 
-bool MCRegisterClass_contains(MCRegisterClass *c, unsigned Reg);
+bool MCRegisterClass_contains(const MCRegisterClass *c, unsigned Reg);
 
 #endif

Makefile

@@ -37,7 +37,7 @@ ifneq (,$(findstring yes,$(CAPSTONE_X86_ATT_DISABLE)))
 CFLAGS += -DCAPSTONE_X86_ATT_DISABLE
 endif
 
-CFLAGS += -fPIC -Wall -Iinclude
+CFLAGS += -fPIC -Wall -Wwrite-strings -Iinclude
 
 ifeq ($(CAPSTONE_USE_SYS_DYN_MEM),yes)
 CFLAGS += -DCAPSTONE_USE_SYS_DYN_MEM

SStream.c

@@ -28,7 +28,7 @@ void SStream_Init(SStream *ss)
 	ss->buffer[0] = '\0';
 }
 
-void SStream_concat0(SStream *ss, char *s)
+void SStream_concat0(SStream *ss, const char *s)
 {
 #ifndef CAPSTONE_DIET
 	unsigned int len = (unsigned int) strlen(s);

SStream.h

@@ -13,7 +13,7 @@ void SStream_Init(SStream *ss);
 
 void SStream_concat(SStream *ss, const char *fmt, ...);
 
-void SStream_concat0(SStream *ss, char *s);
+void SStream_concat0(SStream *ss, const char *s);
 
 void printInt64Bang(SStream *O, int64_t val);