From af49ac60cdddfda8c8a2afcc7aed4f5548e90c88 Mon Sep 17 00:00:00 2001
From: water111 <48171810+water111@users.noreply.github.com>
Date: Wed, 16 Jun 2021 22:15:22 -0400
Subject: [PATCH] fix shl by 16 constant being mistaken for a dynamic bitfield
 construction (#600)

---
 decompiler/IR2/bitfields.cpp | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/decompiler/IR2/bitfields.cpp b/decompiler/IR2/bitfields.cpp
index 514d40a4a5..6459f81c1b 100644
--- a/decompiler/IR2/bitfields.cpp
+++ b/decompiler/IR2/bitfields.cpp
@@ -581,6 +581,19 @@ std::optional<u64> get_goal_integer_constant(Form* in, const Env&) {
       return result;
     }
   }
+
+  // also (shl <something> 16)
+  matcher = Matcher::op(GenericOpMatcher::fixed(FixedOperatorKind::SHL),
+                        {Matcher::any(1), Matcher::integer(16)});
+  mr = match(matcher, in);
+  if (mr.matched) {
+    auto arg_as_atom = form_as_atom(mr.maps.forms.at(1));
+    if (arg_as_atom && arg_as_atom->is_int()) {
+      u64 result = arg_as_atom->get_int();
+      result <<= 16ull;
+      return result;
+    }
+  }
   return {};
 }