From 5944e9cc5188955b60fa7701c1fb8081ccb8280e Mon Sep 17 00:00:00 2001
From: David Nadlinger <code@klickverbot.at>
Date: Sat, 10 Nov 2012 20:11:10 +0100
Subject: [PATCH] Correctly zero out real padding in struct literals.

Fixes the std.variant unit tests on x86_64.
---
 gen/toir.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/gen/toir.cpp b/gen/toir.cpp
index 0da3fbfa..edd7f2d4 100644
--- a/gen/toir.cpp
+++ b/gen/toir.cpp
@@ -2991,6 +2991,17 @@ DValue* StructLiteralExp::toElem(IRState* p)
         // store the initializer there
         DtoAssign(loc, &field, val, TOKconstruct);
 
+        // Also zero out padding bytes counted as being part of the type in DMD
+        // but not in LLVM; e.g. real/x86_fp80.
+        int implicitPadding =
+            vd->type->size() - gDataLayout->getTypeStoreSize(DtoType(vd->type));
+        assert(implicitPadding >= 0);
+        if (implicitPadding > 0)
+        {
+            Logger::println("zeroing %d padding bytes", implicitPadding);
+            voidptr = write_zeroes(voidptr, offset - implicitPadding, offset);
+        }
+
 #if DMDV2
         Type *tb = vd->type->toBasetype();
         if (tb->ty == Tstruct)