shithub: rgbds

--- a/Makefile

+++ b/Makefile

@@ -54,7 +54,6 @@

 rgbasm_obj := \

 	src/asm/asmy.o \

 	src/asm/charmap.o \

-	src/asm/constexpr.o \

 	src/asm/fstack.o \

 	src/asm/globlex.o \

 	src/asm/lexer.o \

--- a/include/asm/constexpr.h

+++ /dev/null

@@ -1,35 +1,0 @@

-/*

- * This file is part of RGBDS.

- *

- * Copyright (c) 1997-2018, Carsten Sorensen and RGBDS contributors.

- *

- * SPDX-License-Identifier: MIT

- */

-#ifndef RGBDS_ASM_CONSTEXPR_H

-#define RGBDS_ASM_CONSTEXPR_H

-#include <stdint.h>

-struct ConstExpression {

-	union {

-		int32_t nVal;

-		struct sSymbol *pSym;

-	} u;

-	uint32_t isSym;

-};

-void constexpr_Symbol(struct ConstExpression *expr, char *tzSym);

-void constexpr_BankSymbol(struct ConstExpression *expr, char *tzSym);

-void constexpr_BankSection(struct ConstExpression *expr, char *tzSym);

-void constexpr_Number(struct ConstExpression *expr, int32_t i);

-void constexpr_UnaryOp(struct ConstExpression *expr,

-		       int32_t op,

-		       const struct ConstExpression *src);

-void constexpr_BinaryOp(struct ConstExpression *expr,

-			int32_t op,

-			const struct ConstExpression *src1,

-			const struct ConstExpression *src2);

-int32_t constexpr_GetConstantValue(struct ConstExpression *expr);

-#endif /* RGBDS_ASM_CONSTEXPR_H */

--- a/include/asm/rpn.h

+++ b/include/asm/rpn.h

@@ -19,6 +19,7 @@

 struct Expression {

 	bool     isKnown;       // Whether the expression's value is known

 	int32_t  nVal;          // If the expression's value is known, it's here

+	char     *reason;       // Why the expression is not known, if it isn't

 	uint8_t  *tRPN;         // Array of bytes serializing the RPN expression

 	uint32_t nRPNCapacity;  // Size of the `tRPN` buffer

 	uint32_t nRPNLength;    // Used size of the `tRPN` buffer

--- a/src/asm/asmy.y

+++ b/src/asm/asmy.y

@@ -18,7 +18,6 @@

 #include "asm/asm.h"

 #include "asm/charmap.h"

-#include "asm/constexpr.h"

 #include "asm/fstack.h"

 #include "asm/lexer.h"

 #include "asm/main.h"

@@ -510,11 +509,10 @@

 	char tzString[MAXSTRLEN + 1];

 	struct Expression sVal;

 	int32_t nConstValue;

-	struct ConstExpression sConstExpr;

 %type	<sVal>		relocconst

-%type	<sConstExpr>	const

+%type	<nConstValue>	const

 %type	<nConstValue>	uconst

 %type	<nConstValue>	const_3bit

 %type	<sVal>		const_8bit

@@ -966,17 +964,17 @@

 equ		: T_LABEL T_POP_EQU const

-			sym_AddEqu($1, constexpr_GetConstantValue(&$3));

+			sym_AddEqu($1, $3);

 set		: T_LABEL T_POP_SET const

-			sym_AddSet($1, constexpr_GetConstantValue(&$3));

+			sym_AddSet($1, $3);

 		| T_LABEL T_POP_EQUAL const

-			sym_AddSet($1, constexpr_GetConstantValue(&$3));

+			sym_AddSet($1, $3);

@@ -1004,12 +1002,10 @@

 charmap		: T_POP_CHARMAP string comma const

-			int32_t value = constexpr_GetConstantValue(&$4);

-			if ((value & 0xFF) != value)

+			if (($4 & 0xFF) != $4)

 				warning(WARNING_TRUNCATION, "Expression must be 8-bit");

-			if (charmap_Add($2, value & 0xFF) == -1)

+			if (charmap_Add($2, $4 & 0xFF) == -1)

 				yyerror("Error parsing charmap. Either you've added too many (%i), or the input character length is too long (%i)' : %s\n", MAXCHARMAPS, CHARMAPLENGTH, strerror(errno));

@@ -1044,19 +1040,19 @@

 printv		: T_POP_PRINTV const

-			printf("$%X", constexpr_GetConstantValue(&$2));

+			printf("$%X", $2);

 printi		: T_POP_PRINTI const

-			printf("%d", constexpr_GetConstantValue(&$2));

+			printf("%d", $2);

 printf		: T_POP_PRINTF const

-			math_Print(constexpr_GetConstantValue(&$2));

+			math_Print($2);

@@ -1063,7 +1059,7 @@

 if		: T_POP_IF const

 			nIFDepth++;

-			if (!constexpr_GetConstantValue(&$2)) {

+			if (!$2) {

/*

 				 * Continue parsing after ELSE, or at ELIF or

 				 * ENDC keyword.

@@ -1095,7 +1091,7 @@

*/

 				skipElif = true;

-				if (!constexpr_GetConstantValue(&$2)) {

+				if (!$2) {

/*

 					 * Continue parsing after ELSE, or at

 					 * ELIF or ENDC keyword.

@@ -1127,7 +1123,7 @@

 const_3bit	: const

-			int32_t value = constexpr_GetConstantValue(&$1);

+			int32_t value = $1;

 			if ((value < 0) || (value > 7))

 				yyerror("Immediate value must be 3-bit");

 			else

@@ -1268,57 +1264,57 @@

 		| T_OP_ROUND '(' const ')'

-			rpn_Number(&$$, math_Round(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_Round($3));

 		| T_OP_CEIL '(' const ')'

-			rpn_Number(&$$, math_Ceil(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_Ceil($3));

 		| T_OP_FLOOR '(' const ')'

-			rpn_Number(&$$, math_Floor(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_Floor($3));

 		| T_OP_FDIV '(' const comma const ')'

 			rpn_Number(&$$,

-				   math_Div(constexpr_GetConstantValue(&$3),

-					    constexpr_GetConstantValue(&$5)));

+				   math_Div($3,

+					    $5));

 		| T_OP_FMUL '(' const comma const ')'

 			rpn_Number(&$$,

-				   math_Mul(constexpr_GetConstantValue(&$3),

-					    constexpr_GetConstantValue(&$5)));

+				   math_Mul($3,

+					    $5));

 		| T_OP_SIN '(' const ')'

-			rpn_Number(&$$, math_Sin(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_Sin($3));

 		| T_OP_COS '(' const ')'

-			rpn_Number(&$$, math_Cos(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_Cos($3));

 		| T_OP_TAN '(' const ')'

-			rpn_Number(&$$, math_Tan(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_Tan($3));

 		| T_OP_ASIN '(' const ')'

-			rpn_Number(&$$, math_ASin(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_ASin($3));

 		| T_OP_ACOS '(' const ')'

-			rpn_Number(&$$, math_ACos(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_ACos($3));

 		| T_OP_ATAN '(' const ')'

-			rpn_Number(&$$, math_ATan(constexpr_GetConstantValue(&$3)));

+			rpn_Number(&$$, math_ATan($3));

 		| T_OP_ATAN2 '(' const comma const ')'

 			rpn_Number(&$$,

-				   math_ATan2(constexpr_GetConstantValue(&$3),

-					      constexpr_GetConstantValue(&$5)));

+				   math_ATan2($3,

+					      $5));

 		| T_OP_STRCMP '(' string comma string ')'

@@ -1339,7 +1335,7 @@

 uconst		: const

-			int32_t value = constexpr_GetConstantValue(&$1);

+			int32_t value = $1;

 			if (value < 0)

 				fatalerror("Constant mustn't be negative: %d", value);

 			$$ = value;

@@ -1346,85 +1342,16 @@

-const		: T_ID					{ constexpr_Symbol(&$$, $1); }

-		| T_NUMBER				{ constexpr_Number(&$$, $1); }

-		| T_OP_HIGH '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_LOW '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_BANK '(' T_ID ')'

+const		: relocconst

-			constexpr_BankSymbol(&$$, $3);

+			if (!rpn_isKnown(&$1)) {

+				yyerror("Expected constant expression: %s",

+					$1.reason);

+				$$ = 0;

+			} else {

+				$$ = $1.nVal;

+			}

-		| T_OP_BANK '(' string ')'

-		{

-			constexpr_BankSection(&$$, $3);

-		}

-		| string

-		{

-			char *s = $1;

-			int32_t length = charmap_Convert(&s);

-			constexpr_Number(&$$, str2int2(s, length));

-			free(s);

-		}

-		| T_OP_LOGICNOT const %prec NEG		{ constexpr_UnaryOp(&$$, $1, &$2); }

-		| const T_OP_LOGICOR const		{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_LOGICAND const		{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_LOGICEQU const		{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_LOGICGT const		{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_LOGICLT const		{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_LOGICGE const		{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_LOGICLE const		{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_LOGICNE const		{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_ADD const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_SUB const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_XOR const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_OR const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_AND const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_SHL const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_SHR const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_MUL const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_DIV const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| const T_OP_MOD const			{ constexpr_BinaryOp(&$$, $2, &$1, &$3); }

-		| T_OP_ADD const %prec NEG		{ constexpr_UnaryOp(&$$, $1, &$2); }

-		| T_OP_SUB const %prec NEG		{ constexpr_UnaryOp(&$$, $1, &$2); }

-		| T_OP_NOT const %prec NEG		{ constexpr_UnaryOp(&$$, $1, &$2); }

-		| T_OP_ROUND '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_CEIL '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_FLOOR '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_FDIV '(' const comma const ')'	{ constexpr_BinaryOp(&$$, $1, &$3, &$5); }

-		| T_OP_FMUL '(' const comma const ')'	{ constexpr_BinaryOp(&$$, $1, &$3, &$5); }

-		| T_OP_SIN '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_COS '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_TAN '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_ASIN '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_ACOS '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_ATAN '(' const ')'		{ constexpr_UnaryOp(&$$, $1, &$3); }

-		| T_OP_ATAN2 '(' const comma const ')'	{ constexpr_BinaryOp(&$$, $1, &$3, &$5); }

-		| T_OP_DEF {

-				oDontExpandStrings = true;

-			} '(' T_ID ')'

-		{

-			struct sSymbol const *sym = sym_FindSymbol($4);

-			if (sym && !(sym_IsDefined(sym) && sym->type != SYM_LABEL))

-				yyerror("Label \"%s\" is not a valid argument to DEF",

-					$4);

-			constexpr_Number(&$$, !!sym);

-			oDontExpandStrings = false;

-		}

-		| T_OP_STRCMP '(' string comma string ')'

-		{

-			constexpr_Number(&$$, strcmp($3, $5));

-		}

-		| T_OP_STRIN '(' string comma string ')'

-		{

-			char *p = strstr($3, $5);

-			if (p != NULL)

-				constexpr_Number(&$$, p - $3 + 1);

-			else

-				constexpr_Number(&$$, 0);

-		}

-		| T_OP_STRLEN '(' string ')'		{ constexpr_Number(&$$, strlenUTF8($3)); }

-		| '(' const ')'				{ $$ = $2; }

 string		: T_STRING

--- a/src/asm/constexpr.c

+++ /dev/null

@@ -1,298 +1,0 @@

-/*

- * This file is part of RGBDS.

- *

- * Copyright (c) 1997-2018, Carsten Sorensen and RGBDS contributors.

- *

- * SPDX-License-Identifier: MIT

- */

-#include <stdint.h>

-#include <stdio.h>

-#include <string.h>

-#include "asm/asm.h"

-#include "asm/constexpr.h"

-#include "asm/lexer.h"

-#include "asm/main.h"

-#include "asm/mymath.h"

-#include "asm/output.h"

-#include "asm/rpn.h"

-#include "asm/symbol.h"

-#include "asm/warning.h"

-#include "asmy.h"

-void constexpr_Symbol(struct ConstExpression *expr, char *tzSym)

-{

-	struct sSymbol *sym = sym_FindSymbol(tzSym);

-	if (!sym) {

-		fatalerror("'%s' not defined", tzSym);

-	} else if (!sym_IsConstant(sym)) {

-		expr->u.pSym = sym;

-		expr->isSym = 1;

-	} else {

-		constexpr_Number(expr, sym_GetConstantValue(tzSym));

-	}

-}

-void constexpr_BankSymbol(struct ConstExpression *expr, char *tzSym)

-{

-	constexpr_Number(expr, 0);

-	struct sSymbol *sym = sym_FindSymbol(tzSym);

-	if (!sym) {

-		yyerror("BANK argument doesn't exist");

-	} else if (sym == pPCSymbol) {

-		if (pCurrentSection->nBank == -1)

-			yyerror("Current bank is not known yet");

-		else

-			constexpr_Number(expr, pCurrentSection->nBank);

-	} else if (sym->type != SYM_LABEL) {

-		yyerror("BANK argument must be a label");

-	} else if (sym->pSection->nBank == -1) {

-		yyerror("BANK argument's bank is not known yet'");

-	} else {

-		constexpr_Number(expr, sym->pSection->nBank);

-	}

-}

-void constexpr_BankSection(struct ConstExpression *expr, char *tzSectionName)

-{

-	constexpr_Number(expr, 0);

-	struct Section *pSection = out_FindSectionByName(tzSectionName);

-	if (!pSection)

-		yyerror("Section \"%s\" doesn't exist", tzSectionName);

-	else if (pSection->nBank == -1)

-		yyerror("Section \"%s\"'s bank is not known yet",

-			tzSectionName);

-	else

-		constexpr_Number(expr, pSection->nBank);

-}

-void constexpr_Number(struct ConstExpression *expr, int32_t i)

-{

-	expr->u.nVal = i;

-	expr->isSym = 0;

-}

-void constexpr_UnaryOp(struct ConstExpression *expr,

-		       int32_t op,

-		       const struct ConstExpression *src)

-{

-	if (src->isSym)

-		fatalerror("Non-constant operand in constant expression");

-	int32_t value = src->u.nVal;

-	int32_t result = 0;

-	switch (op) {

-	case T_OP_HIGH:

-		result = (value >> 8) & 0xFF;

-		break;

-	case T_OP_LOW:

-		result = value & 0xFF;

-		break;

-	case T_OP_LOGICNOT:

-		result = !value;

-		break;

-	case T_OP_ADD:

-		result = value;

-		break;

-	case T_OP_SUB:

-		result = -(uint32_t)value;

-		break;

-	case T_OP_NOT:

-		result = ~value;

-		break;

-	case T_OP_ROUND:

-		result = math_Round(value);

-		break;

-	case T_OP_CEIL:

-		result = math_Ceil(value);

-		break;

-	case T_OP_FLOOR:

-		result = math_Floor(value);

-		break;

-	case T_OP_SIN:

-		result = math_Sin(value);

-		break;

-	case T_OP_COS:

-		result = math_Cos(value);

-		break;

-	case T_OP_TAN:

-		result = math_Tan(value);

-		break;

-	case T_OP_ASIN:

-		result = math_ASin(value);

-		break;

-	case T_OP_ACOS:

-		result = math_ACos(value);

-		break;

-	case T_OP_ATAN:

-		result = math_ATan(value);

-		break;

-	default:

-		fatalerror("Unknown unary op");

-	}

-	constexpr_Number(expr, result);

-}

-void constexpr_BinaryOp(struct ConstExpression *expr,

-			int32_t op,

-			const struct ConstExpression *src1,

-			const struct ConstExpression *src2)

-{

-	int32_t value1;

-	int32_t value2;

-	int32_t result = 0;

-	if (op == T_OP_SUB && src1->isSym && src2->isSym) {

-		char *symName1 = src1->u.pSym->tzName;

-		char *symName2 = src2->u.pSym->tzName;

-		if (!sym_IsRelocDiffDefined(symName1, symName2))

-			fatalerror("'%s - %s' not defined", symName1, symName2);

-		value1 = sym_GetDefinedValue(symName1);

-		value2 = sym_GetDefinedValue(symName2);

-		result = value1 - value2;

-	} else if (src1->isSym || src2->isSym) {

-		fatalerror("Non-constant operand in constant expression");

-	} else {

-		value1 = src1->u.nVal;

-		value2 = src2->u.nVal;

-		switch (op) {

-		case T_OP_LOGICOR:

-			result = value1 || value2;

-			break;

-		case T_OP_LOGICAND:

-			result = value1 && value2;

-			break;

-		case T_OP_LOGICEQU:

-			result = value1 == value2;

-			break;

-		case T_OP_LOGICGT:

-			result = value1 > value2;

-			break;

-		case T_OP_LOGICLT:

-			result = value1 < value2;

-			break;

-		case T_OP_LOGICGE:

-			result = value1 >= value2;

-			break;

-		case T_OP_LOGICLE:

-			result = value1 <= value2;

-			break;

-		case T_OP_LOGICNE:

-			result = value1 != value2;

-			break;

-		case T_OP_ADD:

-			result = (uint32_t)value1 + (uint32_t)value2;

-			break;

-		case T_OP_SUB:

-			result = (uint32_t)value1 - (uint32_t)value2;

-			break;

-		case T_OP_XOR:

-			result = value1 ^ value2;

-			break;

-		case T_OP_OR:

-			result = value1 | value2;

-			break;

-		case T_OP_AND:

-			result = value1 & value2;

-			break;

-		case T_OP_SHL:

-		case T_OP_SHR:

-			if (value2 < 0)

-				warning(WARNING_SHIFT_AMOUNT, "Shifting %s by negative amount %d",

-					op == T_OP_SHL ? "left" : "right",

-					value2);

-			if (op == T_OP_SHR) {

-				value2 = -value2; /* Right shift == neg left */

-				if (value1 < 0)

-					warning(WARNING_SHIFT, "Shifting negative value %d",

-						value1);

-			}

-			if (value2 >= 0) {

-				// Shift left

-				if (value2 >= 32) {

-					warning(WARNING_SHIFT_AMOUNT, "Shifting left by large amount %d",

-						value2);

-					result = 0;

-				} else {

-					/*

-					 * Use unsigned to force a bitwise shift

-					 * Casting back is OK because the types

-					 * implement two's complement behavior

-					 */

-					result = (uint32_t)value1 << value2;

-				}

-			} else {

-				// Shift right

-				value2 = -value2;

-				if (value2 >= 32) {

-					warning(WARNING_SHIFT_AMOUNT, "Shifting right by large amount %d",

-						value2);

-					result = value1 < 0 ? -1 : 0;

-				} else if (value1 >= 0) {

-					result = value1 >> value2;

-				} else {

-					/*

-					 * The C standard leaves shifting right

-					 * negative values undefined, so use a

-					 * left shift manually sign-extended

-					 */

-					result = (uint32_t)value1 >> value2 |

-						-((uint32_t)1 << (32 - value2));

-				}

-			}

-			break;

-		case T_OP_MUL:

-			result = (uint32_t)value1 * (uint32_t)value2;

-			break;

-		case T_OP_DIV:

-			if (value2 == 0)

-				fatalerror("Division by zero");

-			if (value1 == INT32_MIN && value2 == -1) {

-				warning(WARNING_DIV, "Division of min value by -1");

-				result = INT32_MIN;

-			} else {

-				result = value1 / value2;

-			}

-			break;

-		case T_OP_MOD:

-			if (value2 == 0)

-				fatalerror("Division by zero");

-			if (value1 == INT32_MIN && value2 == -1)

-				result = 0;

-			else

-				result = value1 % value2;

-			break;

-		case T_OP_FDIV:

-			result = math_Div(value1, value2);

-			break;

-		case T_OP_FMUL:

-			result = math_Mul(value1, value2);

-			break;

-		case T_OP_ATAN2:

-			result = math_ATan2(value1, value2);

-			break;

-		default:

-			fatalerror("Unknown binary op");

-		}

-	}

-	constexpr_Number(expr, result);

-}

-int32_t constexpr_GetConstantValue(struct ConstExpression *expr)

-{

-	if (expr->isSym)

-		fatalerror("Non-constant expression");

-	return expr->u.nVal;

-}

--- a/src/asm/globlex.c

+++ b/src/asm/globlex.c

@@ -14,7 +14,6 @@

 #include <string.h>

 #include "asm/asm.h"

-#include "asm/constexpr.h"

 #include "asm/lexer.h"

 #include "asm/main.h"

 #include "asm/rpn.h"

--- a/src/asm/lexer.c

+++ b/src/asm/lexer.c

@@ -15,7 +15,6 @@

 #include <ctype.h>

 #include "asm/asm.h"

-#include "asm/constexpr.h"

 #include "asm/fstack.h"

 #include "asm/lexer.h"

 #include "asm/main.h"

--- a/src/asm/rpn.c

+++ b/src/asm/rpn.c

@@ -23,6 +23,21 @@

 #include "asm/output.h"

 #include "asm/warning.h"

+/* Makes an expression "not known", also setting its error message */

+#define makeUnknown(expr_, ...) do { \

+	struct Expression *_expr = expr_; \

+	_expr->isKnown = false; \

+	/* If we had `asprintf` this would be great, but alas. */ \

+	_expr->reason = malloc(128); /* Use an initial reasonable size */ \

+	if (!_expr->reason) \

+		fatalerror("Can't allocate err string: %s", strerror(errno)); \

+	int size = snprintf(_expr->reason, 128, __VA_ARGS__); \

+	if (size >= 128) { /* If this wasn't enough, try again */ \

+		_expr->reason = realloc(_expr->reason, size + 1); \

+		sprintf(_expr->reason, __VA_ARGS__); \

+	} \

+} while (0)

 static uint8_t *reserveSpace(struct Expression *expr, uint32_t size)

 	/* This assumes the RPN length is always less than the capacity */

@@ -65,6 +80,7 @@

 	expr->nRPNPatchSize = 0;

 	expr->nRPNOut = 0;

 	expr->isKnown = true;

+	expr->reason = NULL;

/*

@@ -73,6 +89,7 @@

 void rpn_Free(struct Expression *expr)

 	free(expr->tRPN);

+	free(expr->reason);

 	rpn_Init(expr);

@@ -111,7 +128,7 @@

 	if (!sym || !sym_IsConstant(sym)) {

 		rpn_Init(expr);

 		sym_Ref(tzSym);

-		expr->isKnown = false;

+		makeUnknown(expr, "'%s' is not defined", tzSym);

 		expr->nRPNPatchSize += 5; /* 1-byte opcode + 4-byte symbol ID */

 		size_t nameLen = strlen(tzSym) + 1; /* Don't forget NUL! */

@@ -136,7 +153,7 @@

 	rpn_Init(expr);

 	if (pCurrentSection->nBank == -1)

-		expr->isKnown = false;

+		makeUnknown(expr, "Current section's bank is not known");

 	else

 		expr->nVal = pCurrentSection->nBank;

@@ -173,7 +190,7 @@

 			/* Symbol's section is known and bank is fixed */

 			expr->nVal = pSymbol->pSection->nBank;

 		else

-			expr->isKnown = false;

+			makeUnknown(expr, "\"%s\"'s bank is not known", tzSym);

@@ -186,7 +203,8 @@

 	if (pSection && pSection->nBank != -1)

 		expr->nVal = pSection->nBank;

 	else

-		expr->isKnown = false;

+		makeUnknown(expr, "Section \"%s\"'s bank is not known",

+			    tzSectionName);

 	size_t nameLen = strlen(tzSectionName) + 1; /* Don't forget NUL! */

 	uint8_t *ptr = reserveSpace(expr, nameLen + 1);

@@ -234,9 +252,6 @@

 static int32_t shift(int32_t shiftee, int32_t amount)

-	if (shiftee < 0)

-		warning(WARNING_SHIFT, "Shifting negative value %d", shiftee);

 	if (amount >= 0) {

 		// Left shift

 		if (amount >= 32) {

@@ -346,50 +361,46 @@

 			expr->nVal = src1->nVal & src2->nVal;

 			break;

 		case RPN_SHL:

-			if (expr->isKnown) {

-				if (src2->nVal < 0)

-					warning(WARNING_SHIFT_AMOUNT, "Shifting left by negative value: %d",

-						src2->nVal);

+			if (src2->nVal < 0)

+				warning(WARNING_SHIFT_AMOUNT, "Shifting left by negative amount %d",

+					src2->nVal);

-				expr->nVal = shift(src1->nVal, src2->nVal);

-			}

+			expr->nVal = shift(src1->nVal, src2->nVal);

 			break;

 		case RPN_SHR:

-			if (expr->isKnown) {

-				if (src2->nVal < 0)

-					warning(WARNING_SHIFT_AMOUNT, "Shifting right by negative value: %d",

-						src2->nVal);

+			if (src1->nVal < 0)

+				warning(WARNING_SHIFT, "Shifting negative value %d",

+					src1->nVal);

-				expr->nVal = shift(src1->nVal, -src2->nVal);

-			}

+			if (src2->nVal < 0)

+				warning(WARNING_SHIFT_AMOUNT, "Shifting right by negative amount %d",

+					src2->nVal);

+			expr->nVal = shift(src1->nVal, -src2->nVal);

 			break;

 		case RPN_MUL:

 			expr->nVal = uleft * uright;

 			break;

 		case RPN_DIV:

-			if (expr->isKnown) {

-				if (src2->nVal == 0)

-					fatalerror("Division by zero");

+			if (src2->nVal == 0)

+				fatalerror("Division by zero");

-				if (src1->nVal == INT32_MIN

-				 && src2->nVal == -1) {

-					warning(WARNING_DIV, "Division of min value by -1");

-					expr->nVal = INT32_MIN;

-				} else {

-					expr->nVal = src1->nVal / src2->nVal;

-				}

+			if (src1->nVal == INT32_MIN

+			 && src2->nVal == -1) {

+				warning(WARNING_DIV, "Division of min value by -1");

+				expr->nVal = INT32_MIN;

+			} else {

+				expr->nVal = src1->nVal / src2->nVal;

 			break;

 		case RPN_MOD:

-			if (expr->isKnown) {

-				if (src2->nVal == 0)

-					fatalerror("Division by zero");

+			if (src2->nVal == 0)

+				fatalerror("Division by zero");

-				if (src1->nVal == INT32_MIN && src2->nVal == -1)

-					expr->nVal = 0;

-				else

-					expr->nVal = src1->nVal % src2->nVal;

-			}

+			if (src1->nVal == INT32_MIN && src2->nVal == -1)

+				expr->nVal = 0;

+			else

+				expr->nVal = src1->nVal % src2->nVal;

 			break;

 		case RPN_UNSUB:

@@ -425,6 +436,10 @@

 			expr->nRPNLength = 0;

 			memcpy(reserveSpace(expr, sizeof(bytes)), bytes,

 			       sizeof(bytes));

+			/* Use the other expression's un-const reason */

+			expr->reason = src2->reason;

+			free(src1->reason);

 		} else {

 			/* Otherwise just reuse its RPN buffer */

 			expr->nRPNPatchSize = src1->nRPNPatchSize;

@@ -431,6 +446,8 @@

 			expr->tRPN = src1->tRPN;

 			expr->nRPNCapacity = src1->nRPNCapacity;

 			expr->nRPNLength = src1->nRPNLength;

+			expr->reason = src1->reason;

+			free(src2->reason);

 		/* Now, merge the right expression into the left one */

--- a/test/asm/bank.err

+++ b/test/asm/bank.err

@@ -1,9 +1,9 @@

 ERROR: bank.asm(14) -> bank.asm::def_sect(8):

-    Section "ROMX_bad"'s bank is not known yet

+    Expected constant expression: Section "ROMX_bad"'s bank is not known

 ERROR: bank.asm(16) -> bank.asm::def_sect(8):

-    Section "VRAM_bad"'s bank is not known yet

+    Expected constant expression: Section "VRAM_bad"'s bank is not known

 ERROR: bank.asm(18) -> bank.asm::def_sect(8):

-    Section "SRAM_bad"'s bank is not known yet

+    Expected constant expression: Section "SRAM_bad"'s bank is not known

 ERROR: bank.asm(21) -> bank.asm::def_sect(8):

-    Section "WRAMX_bad"'s bank is not known yet

+    Expected constant expression: Section "WRAMX_bad"'s bank is not known

 error: Assembly aborted (4 errors)!

--- a/test/asm/overflow.err

+++ b/test/asm/overflow.err

@@ -2,8 +2,6 @@

     Division of min value by -1

 warning: overflow.asm(25): [-Wdiv]

     Division of min value by -1

-warning: overflow.asm(35): [-Wshift]

-    Shifting negative value -1

 warning: overflow.asm(39): [-Wlarge-constant]

     Integer constant '4294967296' is too large

 warning: overflow.asm(42): [-Wlarge-constant]

--- a/test/asm/pc-bank.err

+++ b/test/asm/pc-bank.err

@@ -1,5 +1,5 @@

 ERROR: pc-bank.asm(2):

     Source address $2a00 not in $FF00 to $FFFF

 ERROR: pc-bank.asm(11):

-    Current bank is not known yet

+    Expected constant expression: Current section's bank is not known

 error: Assembly aborted (2 errors)!

--- a/test/asm/shift.err

+++ b/test/asm/shift.err

@@ -6,18 +6,12 @@

     Shifting left by large amount 9001

 warning: shift.asm(14) -> shift.asm::test(6): [-Wshift-amount]

     Shifting left by large amount 9001

-warning: shift.asm(15) -> shift.asm::test(3): [-Wshift]

-    Shifting negative value -1

-warning: shift.asm(16) -> shift.asm::test(3): [-Wshift]

-    Shifting negative value -1

 warning: shift.asm(16) -> shift.asm::test(3): [-Wshift-amount]

     Shifting left by large amount 32

 warning: shift.asm(16) -> shift.asm::test(6): [-Wshift-amount]

     Shifting left by large amount 32

 warning: shift.asm(17) -> shift.asm::test(3): [-Wshift-amount]

-    Shifting left by negative value: -9001

-warning: shift.asm(17) -> shift.asm::test(3): [-Wshift]

-    Shifting negative value -1

+    Shifting left by negative amount -9001

 warning: shift.asm(17) -> shift.asm::test(3): [-Wshift-amount]

     Shifting right by large amount 9001

 warning: shift.asm(17) -> shift.asm::test(6): [-Wshift-amount]

@@ -52,15 +46,15 @@

     Shifting negative value -4

 warning: shift.asm(23) -> shift.asm::test(6): [-Wshift]

     Shifting negative value -4

-warning: shift.asm(24) -> shift.asm::test(3): [-Wshift-amount]

-    Shifting right by negative value: -9001

 warning: shift.asm(24) -> shift.asm::test(3): [-Wshift]

     Shifting negative value -1

 warning: shift.asm(24) -> shift.asm::test(3): [-Wshift-amount]

-    Shifting left by large amount 9001

-warning: shift.asm(24) -> shift.asm::test(6): [-Wshift-amount]

     Shifting right by negative amount -9001

+warning: shift.asm(24) -> shift.asm::test(3): [-Wshift-amount]

+    Shifting left by large amount 9001

 warning: shift.asm(24) -> shift.asm::test(6): [-Wshift]

     Shifting negative value -1

+warning: shift.asm(24) -> shift.asm::test(6): [-Wshift-amount]

+    Shifting right by negative amount -9001

 warning: shift.asm(24) -> shift.asm::test(6): [-Wshift-amount]

     Shifting left by large amount 9001