From 643ab90ace52d6d752a12ece9d6a8655ca2ca596 Mon Sep 17 00:00:00 2001
From: Andrew Kelley <superjoe30@gmail.com>
Date: Mon, 23 Oct 2017 22:33:00 -0400
Subject: [PATCH] add maximum value for @setAlignStack

---
 src/ir.cpp              | 5 +++++
 test/cases/align.zig    | 2 +-
 test/compile_errors.zig | 7 +++++++
 3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/ir.cpp b/src/ir.cpp
index 0879942b3e..787d58442e 100644
--- a/src/ir.cpp
+++ b/src/ir.cpp
@@ -15312,6 +15312,11 @@ static TypeTableEntry *ir_analyze_instruction_set_align_stack(IrAnalyze *ira, Ir
     if (!ir_resolve_align(ira, align_bytes_inst, &align_bytes))
         return ira->codegen->builtin_types.entry_invalid;
 
+    if (align_bytes > 256) {
+        ir_add_error(ira, &instruction->base, buf_sprintf("attempt to @setAlignStack(%" PRIu32 "); maximum is 256", align_bytes));
+        return ira->codegen->builtin_types.entry_invalid;
+    }
+
     FnTableEntry *fn_entry = exec_fn_entry(ira->new_irb.exec);
     if (fn_entry == nullptr) {
         ir_add_error(ira, &instruction->base, buf_sprintf("@setAlignStack outside function"));
diff --git a/test/cases/align.zig b/test/cases/align.zig
index cd806a5dc6..3bf0d9c9af 100644
--- a/test/cases/align.zig
+++ b/test/cases/align.zig
@@ -188,6 +188,6 @@ test "alignstack" {
 }
 
 fn fnWithAlignedStack() -> i32 {
-    @setAlignStack(1024);
+    @setAlignStack(256);
     return 1234;
 }
diff --git a/test/compile_errors.zig b/test/compile_errors.zig
index dd25886d2b..efab136d7e 100644
--- a/test/compile_errors.zig
+++ b/test/compile_errors.zig
@@ -2187,6 +2187,13 @@ pub fn addCases(cases: &tests.CompileErrorContext) {
         ".tmp_source.zig:3:5: error: alignstack set twice",
         ".tmp_source.zig:2:5: note: first set here");
 
+    cases.add("@setAlignStack too big",
+        \\export fn entry() {
+        \\    @setAlignStack(511 + 1);
+        \\}
+    ,
+        ".tmp_source.zig:2:5: error: attempt to @setAlignStack(512); maximum is 256");
+
     cases.add("storing runtime value in compile time variable then using it",
         \\const Mode = @import("builtin").Mode;
         \\