From 1ae2002b415614935746946c511e8093a1de2902 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Mon, 29 May 2017 14:25:00 -0400
Subject: [PATCH] fix crash when writing to const hardcoded ptr

closes #381
---
 src/ir.cpp          | 13 +++++++++++--
 test/cases/misc.zig |  8 ++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)

diff --git a/src/ir.cpp b/src/ir.cpp
index 669de6e281..7658db47fe 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -9913,8 +9913,8 @@ static TypeTableEntry *ir_analyze_instruction_elem_ptr(IrAnalyze *ira, IrInstruc
             (array_type->id != TypeTableEntryIdPointer ||
                 array_ptr_val->data.x_ptr.special != ConstPtrSpecialHardCodedAddr))
         {
-            ConstExprValue *out_val = ir_build_const_from(ira, &elem_ptr_instruction->base);
             if (array_type->id == TypeTableEntryIdPointer) {
+                ConstExprValue *out_val = ir_build_const_from(ira, &elem_ptr_instruction->base);
                 out_val->data.x_ptr.mut = array_ptr_val->data.x_ptr.mut;
                 size_t new_index;
                 size_t mem_size;
@@ -9959,9 +9959,16 @@ static TypeTableEntry *ir_analyze_instruction_elem_ptr(IrAnalyze *ira, IrInstruc
                         buf_sprintf("index %" ZIG_PRI_u64 " outside pointer of size %" ZIG_PRI_usize "", index, old_size));
                     return ira->codegen->builtin_types.entry_invalid;
                 }
+                return return_type;
             } else if (is_slice(array_type)) {
                 ConstExprValue *ptr_field = &array_ptr_val->data.x_struct.fields[slice_ptr_index];
+                if (ptr_field->data.x_ptr.special == ConstPtrSpecialHardCodedAddr) {
+                    ir_build_elem_ptr_from(&ira->new_irb, &elem_ptr_instruction->base, array_ptr,
+                            casted_elem_index, false);
+                    return return_type;
+                }
                 ConstExprValue *len_field = &array_ptr_val->data.x_struct.fields[slice_len_index];
+                ConstExprValue *out_val = ir_build_const_from(ira, &elem_ptr_instruction->base);
                 uint64_t slice_len = len_field->data.x_bignum.data.x_uint;
                 if (index >= slice_len) {
                     ir_add_error_node(ira, elem_ptr_instruction->base.source_node,
@@ -9996,15 +10003,17 @@ static TypeTableEntry *ir_analyze_instruction_elem_ptr(IrAnalyze *ira, IrInstruc
                     case ConstPtrSpecialHardCodedAddr:
                         zig_unreachable();
                 }
+                return return_type;
             } else if (array_type->id == TypeTableEntryIdArray) {
+                ConstExprValue *out_val = ir_build_const_from(ira, &elem_ptr_instruction->base);
                 out_val->data.x_ptr.special = ConstPtrSpecialBaseArray;
                 out_val->data.x_ptr.mut = array_ptr->value.data.x_ptr.mut;
                 out_val->data.x_ptr.data.base_array.array_val = array_ptr_val;
                 out_val->data.x_ptr.data.base_array.elem_index = index;
+                return return_type;
             } else {
                 zig_unreachable();
             }
-            return return_type;
         }
 
     }
diff --git a/test/cases/misc.zig b/test/cases/misc.zig
index c310fc8896..46f86c4bd1 100644
--- a/test/cases/misc.zig
+++ b/test/cases/misc.zig
@@ -526,3 +526,11 @@ var gdt = []GDTEntry {
     GDTEntry {.field = 2},
 };
 var global_ptr = &gdt[0];
+
+
+// can't really run this test but we can make sure it has no compile error
+// and generates code
+const vram = @intToPtr(&volatile u8, 0x20000000)[0..0x8000];
+export fn writeToVRam() {
+    vram[0] = 'X';
+}