From 89a5decc33e532eca4ae3739ae89db508a700a8d Mon Sep 17 00:00:00 2001
From: gingerBill <bill@gingerbill.org>
Date: Wed, 13 Nov 2024 18:32:50 +0000
Subject: [PATCH] Keep ASAN happy on type assertions

---
 src/llvm_backend_utility.cpp | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/llvm_backend_utility.cpp b/src/llvm_backend_utility.cpp
index 6367d0118..e6049da84 100644
--- a/src/llvm_backend_utility.cpp
+++ b/src/llvm_backend_utility.cpp
@@ -124,8 +124,16 @@ gb_internal void lb_mem_zero_ptr(lbProcedure *p, LLVMValueRef ptr, Type *type, u
 	switch (kind) {
 	case LLVMStructTypeKind:
 	case LLVMArrayTypeKind:
-		// NOTE(bill): Enforce zeroing through memset to make sure padding is zeroed too
-		lb_mem_zero_ptr_internal(p, ptr, lb_const_int(p->module, t_int, sz).value, alignment, false);
+		if (is_type_tuple(type)) {
+			// NOTE(bill): even though this should be safe, to keep ASAN happy, do not zero the implicit padding at the end
+			GB_ASSERT(type->kind == Type_Tuple);
+			i64 n = type->Tuple.variables.count-1;
+			i64 end_offset = type->Tuple.offsets[n] + type_size_of(type->Tuple.variables[n]->type);
+			lb_mem_zero_ptr_internal(p, ptr, lb_const_int(p->module, t_int, end_offset).value, alignment, false);
+		} else {
+			// NOTE(bill): Enforce zeroing through memset to make sure padding is zeroed too
+			lb_mem_zero_ptr_internal(p, ptr, lb_const_int(p->module, t_int, sz).value, alignment, false);
+		}
 		break;
 	default:
 		LLVMBuildStore(p->builder, LLVMConstNull(lb_type(p->module, type)), ptr);