From 6a1ba090901cd15378acec12c4f172fb7d4c9e6b Mon Sep 17 00:00:00 2001
From: "William S. Moses" <gh@wsmoses.com>
Date: Mon, 26 Sep 2022 14:57:34 -0400
Subject: [PATCH] Don't crash on variable sized gc allocations

---
 src/llvm-alloc-opt.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/llvm-alloc-opt.cpp b/src/llvm-alloc-opt.cpp
index 5e44249e7b9c0..9cc125820d2f3 100644
--- a/src/llvm-alloc-opt.cpp
+++ b/src/llvm-alloc-opt.cpp
@@ -312,7 +312,10 @@ ssize_t Optimizer::getGCAllocSize(Instruction *I)
     if (call->getCalledOperand() != pass.alloc_obj_func)
         return -1;
     assert(call->arg_size() == 3);
-    size_t sz = (size_t)cast<ConstantInt>(call->getArgOperand(1))->getZExtValue();
+    auto CI = dyn_cast<ConstantInt>(call->getArgOperand(1));
+    if (!CI)
+        return -1;
+    size_t sz = (size_t)CI->getZExtValue();
     if (sz < IntegerType::MAX_INT_BITS / 8 && sz < INT32_MAX)
         return sz;
     return -1;