fix iterating over a void slice

andrewrk · andrewrk · commit 4ad4cd265412 · 2018-07-06T17:27:44.000-04:00
closes #1203
diff --git a/src/codegen.cpp b/src/codegen.cpp
@@ -2992,18 +2992,26 @@ static LLVMValueRef ir_render_elem_ptr(CodeGen *g, IrExecutable *executable, IrI
         return LLVMBuildInBoundsGEP(g->builder, array_ptr, indices, 1, "");
     } else if (array_type->id == TypeTableEntryIdStruct) {
         assert(array_type->data.structure.is_slice);
+        if (!type_has_bits(instruction->base.value.type)) {
+            if (safety_check_on) {
+                assert(LLVMGetTypeKind(LLVMTypeOf(array_ptr)) == LLVMIntegerTypeKind);
+                add_bounds_check(g, subscript_value, LLVMIntEQ, nullptr, LLVMIntULT, array_ptr);
+            }
+            return nullptr;
+        }
+
         assert(LLVMGetTypeKind(LLVMTypeOf(array_ptr)) == LLVMPointerTypeKind);
         assert(LLVMGetTypeKind(LLVMGetElementType(LLVMTypeOf(array_ptr))) == LLVMStructTypeKind);
 
         if (safety_check_on) {
-            size_t len_index = array_type->data.structure.fields[1].gen_index;
+            size_t len_index = array_type->data.structure.fields[slice_len_index].gen_index;
             assert(len_index != SIZE_MAX);
             LLVMValueRef len_ptr = LLVMBuildStructGEP(g->builder, array_ptr, (unsigned)len_index, "");
             LLVMValueRef len = gen_load_untyped(g, len_ptr, 0, false, "");
             add_bounds_check(g, subscript_value, LLVMIntEQ, nullptr, LLVMIntULT, len);
         }
 
-        size_t ptr_index = array_type->data.structure.fields[0].gen_index;
+        size_t ptr_index = array_type->data.structure.fields[slice_ptr_index].gen_index;
         assert(ptr_index != SIZE_MAX);
         LLVMValueRef ptr_ptr = LLVMBuildStructGEP(g->builder, array_ptr, (unsigned)ptr_index, "");
         LLVMValueRef ptr = gen_load_untyped(g, ptr_ptr, 0, false, "");
@@ -3983,11 +3991,15 @@ static LLVMValueRef ir_render_slice(CodeGen *g, IrExecutable *executable, IrInst
             add_bounds_check(g, start_val, LLVMIntEQ, nullptr, LLVMIntULE, end_val);
         }
 
-        LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, slice_ptr_index, "");
-        LLVMValueRef slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, &start_val, 1, "");
-        gen_store_untyped(g, slice_start_ptr, ptr_field_ptr, 0, false);
+        if (type_has_bits(array_type)) {
+            size_t gen_ptr_index = instruction->base.value.type->data.structure.fields[slice_ptr_index].gen_index;
+            LLVMValueRef ptr_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, gen_ptr_index, "");
+            LLVMValueRef slice_start_ptr = LLVMBuildInBoundsGEP(g->builder, array_ptr, &start_val, 1, "");
+            gen_store_untyped(g, slice_start_ptr, ptr_field_ptr, 0, false);
+        }
 
-        LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, slice_len_index, "");
+        size_t gen_len_index = instruction->base.value.type->data.structure.fields[slice_len_index].gen_index;
+        LLVMValueRef len_field_ptr = LLVMBuildStructGEP(g->builder, tmp_struct_ptr, gen_len_index, "");
         LLVMValueRef len_value = LLVMBuildNSWSub(g->builder, end_val, start_val, "");
         gen_store_untyped(g, len_value, len_field_ptr, 0, false);
 
diff --git a/test/cases/void.zig b/test/cases/void.zig
@@ -16,3 +16,15 @@ test "compare void with void compile time known" {
         assert(foo.a == {});
     }
 }
+
+test "iterate over a void slice" {
+    var j: usize = 0;
+    for (times(10)) |_, i| {
+        assert(i == j);
+        j += 1;
+    }
+}
+
+fn times(n: usize) []const void {
+    return ([*]void)(undefined)[0..n];
+}
