https://github.com/skvadrik/re2c/pull/555

From 44125b74628d17f0a0a6cf9b51dd1f24169cd2d5 Mon Sep 17 00:00:00 2001
From: Alexey Abramov <levenson@mmer.org>
Date: Fri, 22 Aug 2025 08:10:08 +0200
Subject: [PATCH] Use maximum alignment to ensure compatibility across all
 architectures.

---
 src/util/allocator.h | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/util/allocator.h b/src/util/allocator.h
index e6c85585b..56daf056f 100644
--- a/src/util/allocator.h
+++ b/src/util/allocator.h
@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <stddef.h>
 #include <algorithm>
 #include <vector>
 
@@ -78,11 +79,16 @@ class slab_allocator_t {
 };
 
 // Use maximum alignment.
+// Use alignment based on pointer size: 32-bit platforms need stronger alignment
+// for 64-bit types (double, long long), while 64-bit platforms are already
+// sufficiently aligned with pointer-sized alignment.
+constexpr size_t ALLOCATOR_ALIGNMENT = (sizeof(void*) == 4) ? alignof(max_align_t) : sizeof(void*);
+
 // Use different types to prevent accidentally mixing allocators for data with different life spans.
-using AstAllocator = slab_allocator_t<AllocatorKind::AST, 16 * 4096, sizeof(void*)>;
-using IrAllocator = slab_allocator_t<AllocatorKind::IR, 16 * 4096, sizeof(void*)>;
-using DfaAllocator = slab_allocator_t<AllocatorKind::DFA, 16 * 4096, sizeof(void*)>;
-using OutAllocator = slab_allocator_t<AllocatorKind::OUT, 16 * 4096, sizeof(void*)>;
+using AstAllocator = slab_allocator_t<AllocatorKind::AST, 16 * 4096, ALLOCATOR_ALIGNMENT>;
+using IrAllocator = slab_allocator_t<AllocatorKind::IR, 16 * 4096, ALLOCATOR_ALIGNMENT>;
+using DfaAllocator = slab_allocator_t<AllocatorKind::DFA, 16 * 4096, ALLOCATOR_ALIGNMENT>;
+using OutAllocator = slab_allocator_t<AllocatorKind::OUT, 16 * 4096, ALLOCATOR_ALIGNMENT>;
 
 } // namespace re2c
 
-- 
2.50.1