From: Erich Keane <erich.keane@intel.com>
Date: Tue, 8 Jan 2019 18:44:22 +0000 (+0000)
Subject: Limit COFF 'common' emission to <=32 alignment types.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=92f4b5cbeee88f31a8df876f73b823db284f68de;p=clang

Limit COFF 'common' emission to <=32 alignment types.

As reported in PR33035, LLVM crashes if given a common object with an
alignment of greater than 32 bits. This is because the COFF file format
does not support these alignments, so emitting them is broken anyway.

This patch changes any global definitions greater than 32 bit alignment
to no longer be in 'common'.

https://bugs.llvm.org/show_bug.cgi?id=33035

Differential Revision: https://reviews.llvm.org/D56391

Change-Id: I48609289753b7f3b58c5e2bc1712756750fbd45a

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@350643 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/CodeGen/CodeGenModule.cpp b/lib/CodeGen/CodeGenModule.cpp
index 54190493f0..ab0ac67d8e 100644
--- a/lib/CodeGen/CodeGenModule.cpp
+++ b/lib/CodeGen/CodeGenModule.cpp
@@ -3761,6 +3761,11 @@ static bool isVarDeclStrongDefinition(const ASTContext &Context,
       }
     }
   }
+  // COFF doesn't support alignments greater than 32, so these cannot be
+  // in common.
+  if (Context.getTargetInfo().getTriple().isKnownWindowsMSVCEnvironment() &&
+      Context.getTypeAlignIfKnown(D->getType()) > 32)
+    return true;
 
   return false;
 }
diff --git a/test/CodeGen/microsoft-no-common-align.c b/test/CodeGen/microsoft-no-common-align.c
new file mode 100644
index 0000000000..fc46946c00
--- /dev/null
+++ b/test/CodeGen/microsoft-no-common-align.c
@@ -0,0 +1,8 @@
+// RUN: %clang_cc1 -triple x86_64-windows-msvc -emit-llvm -o - %s | FileCheck %s
+typedef float TooLargeAlignment __attribute__((__vector_size__(64)));
+typedef float NormalAlignment __attribute__((__vector_size__(4)));
+
+TooLargeAlignment TooBig;
+// CHECK: @TooBig = dso_local global <16 x float>  zeroinitializer, align 64
+NormalAlignment JustRight;
+// CHECK: @JustRight = common dso_local global <1 x float>  zeroinitializer, align 4