[Clang] Fix the guaranteed alignment of memory returned by malloc/new on OpenBSD

The guaranteed alignment is 16 bytes on OpenBSD.

(cherry picked from commit c7ee0b8)

Author: kettenis

clang/lib/Basic/TargetInfo.cpp

@@ -69,11 +69,11 @@ TargetInfo::TargetInfo(const llvm::Triple &T) : Triple(T) {
   // From the glibc documentation, on GNU systems, malloc guarantees 16-byte
   // alignment on 64-bit systems and 8-byte alignment on 32-bit systems. See
   // https://www.gnu.org/software/libc/manual/html_node/Malloc-Examples.html.
-  // This alignment guarantee also applies to Windows and Android. On Darwin,
-  // the alignment is 16 bytes on both 64-bit and 32-bit systems.
+  // This alignment guarantee also applies to Windows and Android. On Darwin
+  // and OpenBSD, the alignment is 16 bytes on both 64-bit and 32-bit systems.
   if (T.isGNUEnvironment() || T.isWindowsMSVCEnvironment() || T.isAndroid())
     NewAlign = Triple.isArch64Bit() ? 128 : Triple.isArch32Bit() ? 64 : 0;
-  else if (T.isOSDarwin())
+  else if (T.isOSDarwin() || T.isOSOpenBSD())
     NewAlign = 128;
   else
     NewAlign = 0; // Infer from basic type alignment.

clang/test/Preprocessor/init-arm.c

@@ -199,6 +199,9 @@
 // RUN: %clang_cc1 -E -dM -triple=armv7-apple-ios7.0 -x c++ < /dev/null | FileCheck -match-full-lines -check-prefix ARM-DARWIN-CXX %s
 // ARM-DARWIN-CXX: #define __STDCPP_DEFAULT_NEW_ALIGNMENT__ 16UL
 
+// RUN: %clang_cc1 -E -dM -triple=arm-unknown-openbsd -x c++ < /dev/null | FileCheck -match-full-lines -check-prefix ARM-OPENBSD-CXX %s
+// ARM-OPENBSD-CXX: #define __STDCPP_DEFAULT_NEW_ALIGNMENT__ 16UL
+
 // RUN: %clang_cc1 -dM -ffreestanding -triple arm-none-none -target-abi apcs-gnu -E /dev/null -o - | FileCheck -match-full-lines -check-prefix ARM-APCS-GNU %s
 // ARM-APCS-GNU: #define __INTPTR_TYPE__ int
 // ARM-APCS-GNU: #define __PTRDIFF_TYPE__ int

clang/test/Preprocessor/init-ppc.c

@@ -1176,3 +1176,6 @@
 // PPC-DARWIN:#define __WINT_WIDTH__ 32
 // PPC-DARWIN:#define __powerpc__ 1
 // PPC-DARWIN:#define __ppc__ 1
+
+// RUN: %clang_cc1 -E -dM -triple=powerpc-unknown-openbsd -x c++ < /dev/null | FileCheck -match-full-lines -check-prefix PPC-OPENBSD-CXX %s
+// PPC-OPENBSD-CXX: #define __STDCPP_DEFAULT_NEW_ALIGNMENT__ 16UL

clang/test/Preprocessor/init-x86.c

@@ -1732,3 +1732,6 @@
 // X86_64-NETBSD:#define __amd64__ 1
 // X86_64-NETBSD:#define __x86_64 1
 // X86_64-NETBSD:#define __x86_64__ 1
+
+// RUN: %clang_cc1 -E -dM -triple=i386-unknown-openbsd -x c++ < /dev/null | FileCheck -match-full-lines -check-prefix I386-OPENBSD-CXX %s
+// I386-OPENBSD-CXX: #define __STDCPP_DEFAULT_NEW_ALIGNMENT__ 16UL