Introduce f[no-]max-unknown-pointer-align=[number] option

to instruct the code generator to not enforce a higher alignment 
than the given number (of bytes) when accessing memory via an opaque 
pointer or reference. Patch reviewed by John McCall (with post-commit
review pending). rdar://16254558

llvm-svn: 214911

1 files changed, 15 insertions, 0 deletions

diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 9a205b3..93a1d91 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -4134,6 +4134,21 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
     CmdArgs.push_back("-fpack-struct=1");
   }
 
+  // Handle -fmax-type-align=N and -fno-type-align
+  bool SkipMaxTypeAlign = Args.hasArg(options::OPT_fno_max_type_align);
+  if (Arg *A = Args.getLastArg(options::OPT_fmax_type_align_EQ)) {
+    if (!SkipMaxTypeAlign) {
+      std::string MaxTypeAlignStr = "-fmax-type-align=";
+      MaxTypeAlignStr += A->getValue();
+      CmdArgs.push_back(Args.MakeArgString(MaxTypeAlignStr));
+    }
+  } else if (getToolChain().getTriple().isOSDarwin()) {
+    if (!SkipMaxTypeAlign) {
+      std::string MaxTypeAlignStr = "-fmax-type-align=16";
+      CmdArgs.push_back(Args.MakeArgString(MaxTypeAlignStr));
+    }
+  }
+
   if (KernelOrKext || isNoCommonDefault(getToolChain().getTriple())) {
     if (!Args.hasArg(options::OPT_fcommon))
       CmdArgs.push_back("-fno-common");