Description: Adjust int128 alignment
Author: Walter Bright <WalterBright@users.noreply.github.com>
Origin: backport, https://github.com/ldc-developers/ldc/commit/f634e2a6542a8b563d9ba1b680afd5337b4c09ea
Bug: https://github.com/ldc-developers/ldc/issues/1356
Last-Update: 2024-12-30
---
This patch header follows DEP-3: http://dep.debian.net/deps/dep3/
--- a/dmd/common/int128.d
+++ b/dmd/common/int128.d
@@ -20,7 +20,29 @@
 alias U = ulong;
 enum Ubits = uint(U.sizeof * 8);
 
-align(16) struct Cent
+version (DigitalMars)
+{
+    /* The alignment should follow target.stackAlign(),
+     * which is `isXmmSupported() ? 16 : (is64bit ? 8 : 4)
+     */
+    version (D_SIMD)
+        private enum Cent_alignment = 16;
+    else version (X86_64)
+        private enum Cent_alignment = 8;
+    else
+        private enum Cent_alignment = 4;
+}
+else
+{
+    version (LDC) version (X86) version = LDC_X86;
+
+    version (X86_64)       private enum Cent_alignment = 16;
+    // 32-bit x86: need default alignment due to https://github.com/ldc-developers/ldc/issues/1356
+    else version (LDC_X86) private enum Cent_alignment = U.alignof;
+    else                   private enum Cent_alignment = (size_t.sizeof * 2);
+}
+
+align(Cent_alignment) struct Cent
 {
     U lo;      // low 64 bits
     U hi;      // high 64 bits