Fix `-integer-division-by-zero` modes and document `all-bits`

3 files changed, 15 insertions, 12 deletions

diff --git a/src/llvm_backend_expr.cpp b/src/llvm_backend_expr.cpp
index d5658b9d5..9b8df5a37 100644
--- a/src/llvm_backend_expr.cpp
+++ b/src/llvm_backend_expr.cpp
@@ -1161,8 +1161,7 @@ gb_internal LLVMValueRef lb_integer_division(lbProcedure *p, LLVMValueRef lhs, L
 			case IntegerDivisionByZero_Zero:
 				return zero;
 			case IntegerDivisionByZero_AllBits:
-				// return all_bits;
-				break;
+				return all_bits;
 			}
 		} else {
 			if (!is_signed && lb_sizeof(type) <= 8) {
@@ -1198,7 +1197,6 @@ gb_internal LLVMValueRef lb_integer_division(lbProcedure *p, LLVMValueRef lhs, L
 
 	lb_start_block(p, edge_case_block);
 
-
 	switch (behaviour)  {
 	case IntegerDivisionByZero_Trap:
 		lb_call_intrinsic(p, "llvm.trap", nullptr, 0, nullptr, 0);
@@ -1214,17 +1212,17 @@ gb_internal LLVMValueRef lb_integer_division(lbProcedure *p, LLVMValueRef lhs, L
 		incoming_values[1] = all_bits;
 		break;
 	}
+	LLVMValueRef res = nullptr;
 
 	lb_emit_jump(p, done_block);
 	lb_start_block(p, done_block);
 
-	LLVMValueRef res = incoming_values[0];
 
 	switch (behaviour)  {
 	case IntegerDivisionByZero_Trap:
-	case IntegerDivisionByZero_Self:
 		res = incoming_values[0];
 		break;
+	case IntegerDivisionByZero_Self:
 	case IntegerDivisionByZero_Zero:
 	case IntegerDivisionByZero_AllBits:
 		res = LLVMBuildPhi(p->builder, type, "");
@@ -1233,6 +1231,9 @@ gb_internal LLVMValueRef lb_integer_division(lbProcedure *p, LLVMValueRef lhs, L
 		incoming_blocks[0] = p->curr_block->preds[0]->block;
 		incoming_blocks[1] = p->curr_block->preds[1]->block;
 
+		GB_ASSERT(incoming_blocks[0] == safe_block->block);
+		GB_ASSERT(incoming_blocks[1] == edge_case_block->block);
+
 		LLVMAddIncoming(res, incoming_values, incoming_blocks, 2);
 		break;
 	}
@@ -1240,7 +1241,7 @@ gb_internal LLVMValueRef lb_integer_division(lbProcedure *p, LLVMValueRef lhs, L
 	return res;
 }
 
-gb_internal LLVMValueRef lb_integer_division_intrinsics(lbProcedure *p, LLVMValueRef lhs, LLVMValueRef rhs, LLVMValueRef scale, Type *platform_type, char const *name) {
+gb_internal LLVMValueRef lb_integer_division_fixed_point_intrinsics(lbProcedure *p, LLVMValueRef lhs, LLVMValueRef rhs, LLVMValueRef scale, Type *platform_type, char const *name) {
 	LLVMTypeRef type = LLVMTypeOf(rhs);
 	GB_ASSERT(LLVMTypeOf(lhs) == type);
 
@@ -1310,13 +1311,13 @@ gb_internal LLVMValueRef lb_integer_division_intrinsics(lbProcedure *p, LLVMValu
 	lb_emit_jump(p, done_block);
 	lb_start_block(p, done_block);
 
-	LLVMValueRef res = incoming_values[0];
+	LLVMValueRef res = nullptr;
 
 	switch (behaviour)  {
 	case IntegerDivisionByZero_Trap:
-	case IntegerDivisionByZero_Self:
 		res = incoming_values[0];
 		break;
+	case IntegerDivisionByZero_Self:
 	case IntegerDivisionByZero_Zero:
 	case IntegerDivisionByZero_AllBits:
 		res = LLVMBuildPhi(p->builder, type, "");
@@ -1423,9 +1424,9 @@ gb_internal LLVMValueRef lb_integer_modulo(lbProcedure *p, LLVMValueRef lhs, LLV
 
 	switch (behaviour)  {
 	case IntegerDivisionByZero_Trap:
-	case IntegerDivisionByZero_Self:
 		res = incoming_values[0];
 		break;
+	case IntegerDivisionByZero_Self:
 	case IntegerDivisionByZero_Zero:
 	case IntegerDivisionByZero_AllBits:
 		res = LLVMBuildPhi(p->builder, type, "");
diff --git a/src/llvm_backend_proc.cpp b/src/llvm_backend_proc.cpp
index 10e10564e..27167aefd 100644
--- a/src/llvm_backend_proc.cpp
+++ b/src/llvm_backend_proc.cpp
@@ -3305,7 +3305,7 @@ gb_internal lbValue lb_build_builtin_proc(lbProcedure *p, Ast *expr, TypeAndValu
 
 			if (id == BuiltinProc_fixed_point_div ||
 			    id == BuiltinProc_fixed_point_div_sat) {
-				res.value = lb_integer_division_intrinsics(p, x.value, y.value, scale.value, platform_type, name);
+				res.value = lb_integer_division_fixed_point_intrinsics(p, x.value, y.value, scale.value, platform_type, name);
 			} else {
 				LLVMTypeRef types[1] = {lb_type(p->module, platform_type)};
 
diff --git a/src/main.cpp b/src/main.cpp
index 544cd54bb..ca05bb177 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -1570,8 +1570,10 @@ gb_internal bool parse_build_flags(Array<String> args) {
 								build_context.integer_division_by_zero_behaviour = IntegerDivisionByZero_Zero;
 							} 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");
+							} else if (str_eq_ignore_case(value.value_string, "all-bits")) {
+								build_context.integer_division_by_zero_behaviour = IntegerDivisionByZero_AllBits;
+							} else {
+								gb_printf_err("-integer-division-by-zero options are 'trap', 'zero', 'self', and 'all-bits'.\n");
 								bad_flags = true;
 							}
 							break;