Add `-integer-division-by-zero:self`

5 files changed, 48 insertions, 14 deletions

diff --git a/src/build_settings.cpp b/src/build_settings.cpp
index e21e7da12..a6dce5233 100644
--- a/src/build_settings.cpp
+++ b/src/build_settings.cpp
@@ -355,8 +355,9 @@ enum OptInFeatureFlags : u64 {
 
 	OptInFeatureFlag_IntegerDivisionByZero_Trap = 1u<<1,
 	OptInFeatureFlag_IntegerDivisionByZero_Zero = 1u<<2,
+	OptInFeatureFlag_IntegerDivisionByZero_Self = 1u<<3,
 
-	OptInFeatureFlag_IntegerDivisionByZero_ALL = OptInFeatureFlag_IntegerDivisionByZero_Trap|OptInFeatureFlag_IntegerDivisionByZero_Zero,
+	OptInFeatureFlag_IntegerDivisionByZero_ALL = OptInFeatureFlag_IntegerDivisionByZero_Trap|OptInFeatureFlag_IntegerDivisionByZero_Zero|OptInFeatureFlag_IntegerDivisionByZero_Self,
 
 };
 
@@ -370,6 +371,9 @@ u64 get_feature_flag_from_name(String const &name) {
 	if (name == "integer-division-by-zero:zero") {
 		return OptInFeatureFlag_IntegerDivisionByZero_Zero;
 	}
+	if (name == "integer-division-by-zero:self") {
+		return OptInFeatureFlag_IntegerDivisionByZero_Self;
+	}
 	return OptInFeatureFlag_NONE;
 }
 
@@ -419,6 +423,7 @@ String linker_choices[Linker_COUNT] = {
 enum IntegerDivisionByZeroKind : u8 {
 	IntegerDivisionByZero_Trap,
 	IntegerDivisionByZero_Zero,
+	IntegerDivisionByZero_Self,
 };
 
 // This stores the information for the specify architecture of this build
diff --git a/src/check_expr.cpp b/src/check_expr.cpp
index b68fe0ed0..782080c93 100644
--- a/src/check_expr.cpp
+++ b/src/check_expr.cpp
@@ -4311,7 +4311,7 @@ gb_internal void check_binary_expr(CheckerContext *c, Operand *x, Ast *node, Typ
 
 			if (fail) {
 				if (is_type_integer(x->type) || (x->mode == Addressing_Constant && x->value.kind == ExactValue_Integer)) {
-					if (check_for_integer_division_by_zero(c, node) == IntegerDivisionByZero_Zero) {
+					if (check_for_integer_division_by_zero(c, node) != IntegerDivisionByZero_Trap) {
 						// Okay
 						break;
 					}
@@ -4371,14 +4371,19 @@ gb_internal void check_binary_expr(CheckerContext *c, Operand *x, Ast *node, Typ
 		match_exact_values(&a, &b);
 
 
-		if (check_for_integer_division_by_zero(c, node) == IntegerDivisionByZero_Zero &&
+		IntegerDivisionByZeroKind zero_behaviour = check_for_integer_division_by_zero(c, node);
+		if (zero_behaviour != IntegerDivisionByZero_Trap &&
 		    b.kind == ExactValue_Integer && big_int_is_zero(&b.value_integer) &&
 		    (op.kind == Token_QuoEq || op.kind == Token_Mod || op.kind == Token_ModMod)) {
 		    	if (op.kind == Token_QuoEq) {
-		    		// x/0 == 0
-				x->value = b;
+		    		if (zero_behaviour == IntegerDivisionByZero_Zero) {
+			    		// x/0 == 0
+					x->value = b;
+				} else {
+			    		// x/0 == x
+					x->value = a;
+				}
 			} else {
-		    		// x%0 == x
 		    		/*
 					NOTE(bill): @integer division by zero rules
 
@@ -4386,8 +4391,16 @@ gb_internal void check_binary_expr(CheckerContext *c, Operand *x, Ast *node, Typ
 		    			floored:   r = a - b*floor(a/b)
 
 		    			IFF a/0 == 0, then (a%0 == a) or (a%%0 == a)
+		    			IFF a/0 == a, then (a%0 == 0) or (a%%0 == 0)
 		    		*/
-				x->value = a;
+
+		    		if (zero_behaviour == IntegerDivisionByZero_Zero) {
+			    		// x%0 == x
+					x->value = a;
+				} else {
+			    		// x%0 == 0
+					x->value = b;
+				}
 			}
 		} else {
 			x->value = exact_binary_operator_value(op.kind, a, b);
@@ -9647,6 +9660,9 @@ gb_internal IntegerDivisionByZeroKind check_for_integer_division_by_zero(Checker
 	if ((flags & OptInFeatureFlag_IntegerDivisionByZero_Zero) != 0) {
 		return IntegerDivisionByZero_Zero;
 	}
+	if ((flags & OptInFeatureFlag_IntegerDivisionByZero_Self) != 0) {
+		return IntegerDivisionByZero_Self;
+	}
 	return build_context.integer_division_by_zero_behaviour;
 }
 
diff --git a/src/llvm_backend_expr.cpp b/src/llvm_backend_expr.cpp
index b20aef742..b44d2215e 100644
--- a/src/llvm_backend_expr.cpp
+++ b/src/llvm_backend_expr.cpp
@@ -302,6 +302,9 @@ gb_internal IntegerDivisionByZeroKind lb_check_for_integer_division_by_zero_beha
 		if (flags & OptInFeatureFlag_IntegerDivisionByZero_Zero) {
 			return IntegerDivisionByZero_Zero;
 		}
+		if (flags & OptInFeatureFlag_IntegerDivisionByZero_Self) {
+			return IntegerDivisionByZero_Self;
+		}
 	}
 	return build_context.integer_division_by_zero_behaviour;
 }
@@ -1159,7 +1162,6 @@ gb_internal LLVMValueRef lb_integer_division(lbProcedure *p, LLVMValueRef lhs, L
 
 	lb_start_block(p, edge_case_block);
 
-	incoming_values[1] = zero;
 
 	switch (lb_check_for_integer_division_by_zero_behaviour(p))  {
 	case IntegerDivisionByZero_Trap:
@@ -1167,7 +1169,10 @@ gb_internal LLVMValueRef lb_integer_division(lbProcedure *p, LLVMValueRef lhs, L
 		LLVMBuildUnreachable(p->builder);
 		break;
 	case IntegerDivisionByZero_Zero:
-		// Already fine
+		incoming_values[1] = zero;
+		break;
+	case IntegerDivisionByZero_Self:
+		incoming_values[1] = lhs;
 		break;
 	}
 
@@ -1178,6 +1183,7 @@ gb_internal LLVMValueRef lb_integer_division(lbProcedure *p, LLVMValueRef lhs, L
 
 	switch (lb_check_for_integer_division_by_zero_behaviour(p))  {
 	case IntegerDivisionByZero_Trap:
+	case IntegerDivisionByZero_Self:
 		res = incoming_values[0];
 		break;
 	case IntegerDivisionByZero_Zero:
@@ -1242,7 +1248,6 @@ gb_internal LLVMValueRef lb_integer_modulo(lbProcedure *p, LLVMValueRef lhs, LLV
 
 		IFF a/0 == 0, then (a%0 == a) or (a%%0 == a)
 	*/
-	incoming_values[1] = lhs;
 
 	switch (lb_check_for_integer_division_by_zero_behaviour(p))  {
 	case IntegerDivisionByZero_Trap:
@@ -1250,7 +1255,10 @@ gb_internal LLVMValueRef lb_integer_modulo(lbProcedure *p, LLVMValueRef lhs, LLV
 		LLVMBuildUnreachable(p->builder);
 		break;
 	case IntegerDivisionByZero_Zero:
-		// Already fine
+		incoming_values[1] = lhs;
+		break;
+	case IntegerDivisionByZero_Self:
+		incoming_values[1] = zero;
 		break;
 	}
 
@@ -1261,6 +1269,7 @@ gb_internal LLVMValueRef lb_integer_modulo(lbProcedure *p, LLVMValueRef lhs, LLV
 
 	switch (lb_check_for_integer_division_by_zero_behaviour(p))  {
 	case IntegerDivisionByZero_Trap:
+	case IntegerDivisionByZero_Self:
 		res = incoming_values[0];
 		break;
 	case IntegerDivisionByZero_Zero:
diff --git a/src/main.cpp b/src/main.cpp
index 0bfab0344..2f0b1c19b 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1550,8 +1550,10 @@ gb_internal bool parse_build_flags(Array<String> args) {
 								build_context.integer_division_by_zero_behaviour = IntegerDivisionByZero_Trap;
 							} else if (str_eq_ignore_case(value.value_string, "zero")) {
 								build_context.integer_division_by_zero_behaviour = IntegerDivisionByZero_Zero;
-							} else {
-								gb_printf_err("-integer-division-by-zero options are 'trap' and 'zero'.\n");
+							} else if (str_eq_ignore_case(value.value_string, "self")) {
+								build_context.integer_division_by_zero_behaviour = IntegerDivisionByZero_Self;
+							}else {
+								gb_printf_err("-integer-division-by-zero options are 'trap', 'zero', and 'self'.\n");
 								bad_flags = true;
 							}
 							break;
@@ -2585,7 +2587,8 @@ gb_internal int print_show_help(String const arg0, String command, String option
 			print_usage_line(2, "Specifies the default behaviour for integer division by zero.");
 			print_usage_line(2, "Available Options:");
 			print_usage_line(3, "-integer-division-by-zero:trap        Trap on division/modulo/remainder by zero");
-			print_usage_line(3, "-integer-division-by-zero:zero        x/0 == 0 and x%%0 == x and x%%%%0 == 0");
+			print_usage_line(3, "-integer-division-by-zero:zero        x/0 == 0 and x%%0 == x and x%%%%0 == x");
+			print_usage_line(3, "-integer-division-by-zero:self        x/0 == x and x%%0 == 0 and x%%%%0 == 0");
 		}
 	}
 
diff --git a/src/parser.cpp b/src/parser.cpp
index 58d7acfa5..c63ffe747 100644
--- a/src/parser.cpp
+++ b/src/parser.cpp
@@ -6428,6 +6428,7 @@ gb_internal u64 parse_feature_tag(Token token_for_pos, String s) {
 			error_line("\tdynamic-literals\n");
 			error_line("\tinteger-division-by-zero:trap\n");
 			error_line("\tinteger-division-by-zero:zero\n");
+			error_line("\tinteger-division-by-zero:self\n");
 			return OptInFeatureFlag_NONE;
 		}
 	}