From aa99b31ab47bc8a56a4868ecd3ce420d4bee212a Mon Sep 17 00:00:00 2001
From: Simi Pallipurath <simi.pallipurath@arm.com>
Date: Fri, 26 Jul 2019 15:05:19 +0000
Subject: [PATCH] [ARM] Set default alignment to 64bits

The maximum alignment used by ARM arch
is 64bits, not 128.

This could cause overaligned memory
access for 128 bit neon vector that
have unpredictable behaviour.

This fixes: https://bugs.llvm.org/show_bug.cgi?id=42668

Patch by: Diogo Sampaio(diogo.sampaio@arm.com)

Differential Revision: https://reviews.llvm.org/D65000

Change-Id: I5a62b766491f15dd51e4cfe6625929db897f67e3

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@367119 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Basic/Targets/ARM.cpp                     |  3 ++-
 test/CodeGen/ARM/exception-alignment.cpp      | 19 +++++++++++++++++++
 test/SemaCXX/warn-overaligned-type-thrown.cpp |  3 ++-
 3 files changed, 23 insertions(+), 2 deletions(-)
 create mode 100644 test/CodeGen/ARM/exception-alignment.cpp

diff --git a/lib/Basic/Targets/ARM.cpp b/lib/Basic/Targets/ARM.cpp
index c6834b9fac..3ae2091f4a 100644
--- a/lib/Basic/Targets/ARM.cpp
+++ b/lib/Basic/Targets/ARM.cpp
@@ -309,8 +309,9 @@ ARMTargetInfo::ARMTargetInfo(const llvm::Triple &Triple,
   setAtomic();
 
   // Maximum alignment for ARM NEON data types should be 64-bits (AAPCS)
+  // as well the default alignment
   if (IsAAPCS && (Triple.getEnvironment() != llvm::Triple::Android))
-    MaxVectorAlign = 64;
+    DefaultAlignForAttributeAligned = MaxVectorAlign = 64;
 
   // Do force alignment of members that follow zero length bitfields.  If
   // the alignment of the zero-length bitfield is greater than the member
diff --git a/test/CodeGen/ARM/exception-alignment.cpp b/test/CodeGen/ARM/exception-alignment.cpp
new file mode 100644
index 0000000000..24efbd8997
--- /dev/null
+++ b/test/CodeGen/ARM/exception-alignment.cpp
@@ -0,0 +1,19 @@
+// Bug: https://bugs.llvm.org/show_bug.cgi?id=42668
+// REQUIRES: arm-registered-target
+// RUN: %clang --target=arm-arm-none-eabi -march=armv8-a -S -emit-llvm -Os -o - %s | FileCheck --check-prefixes=CHECK,A8 %s
+// RUN: %clang --target=arm-linux-androideabi -march=armv8-a -S -emit-llvm -Os -o - %s | FileCheck --check-prefixes=CHECK,A16 %s
+// CHECK: [[E:%[A-z0-9]+]] = tail call i8* @__cxa_allocate_exception
+// CHECK-NEXT: [[BC:%[A-z0-9]+]] = bitcast i8* [[E]] to <2 x i64>*
+// A8-NEXT: store <2 x i64> <i64 1, i64 2>, <2 x i64>* [[BC]], align 8
+// A16-NEXT: store <2 x i64> <i64 1, i64 2>, <2 x i64>* [[BC]], align 16
+#include <arm_neon.h>
+
+int main(void) {
+  try {
+    throw vld1q_u64(((const uint64_t[2]){1, 2}));
+  } catch (uint64x2_t exc) {
+    return 0;
+  }
+  return 1;
+}
+
diff --git a/test/SemaCXX/warn-overaligned-type-thrown.cpp b/test/SemaCXX/warn-overaligned-type-thrown.cpp
index 0801017783..d7468445f8 100644
--- a/test/SemaCXX/warn-overaligned-type-thrown.cpp
+++ b/test/SemaCXX/warn-overaligned-type-thrown.cpp
@@ -2,11 +2,12 @@
 // RUN: %clang_cc1 -triple arm64-apple-ios10 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions -DUNDERALIGNED %s
 // RUN: %clang_cc1 -triple arm64-apple-tvos10 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions -DUNDERALIGNED %s
 // RUN: %clang_cc1 -triple arm64-apple-watchos4 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions -DUNDERALIGNED %s
+// RUN: %clang_cc1 -triple arm-linux-gnueabi -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions  -DUNDERALIGNED %s
 // RUN: %clang_cc1 -triple x86_64-apple-macosx10.14 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
 // RUN: %clang_cc1 -triple arm64-apple-ios12 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
 // RUN: %clang_cc1 -triple arm64-apple-tvos12 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
 // RUN: %clang_cc1 -triple arm64-apple-watchos5 -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
-// RUN: %clang_cc1 -triple arm-linux-gnueabi -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
+// RUN: %clang_cc1 -triple arm-linux-androideabi -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
 // RUN: %clang_cc1 -triple aarch64-linux-gnueabi -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
 // RUN: %clang_cc1 -triple mipsel-linux-gnu -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
 // RUN: %clang_cc1 -triple mips64el-linux-gnu -verify -fsyntax-only -std=c++11 -fcxx-exceptions -fexceptions %s
-- 
2.40.0