[PATCH] D72869: Add __warn_memset_zero_len builtin as a workaround for glibc issue

[serge via Phabricator via cfe-commits]

serge-sans-paille created this revision.
serge-sans-paille added reviewers: rnk, george.burgess.iv, akhuang.
Herald added a project: clang.
Herald added a subscriber: cfe-commits.
serge-sans-paille added a comment.

@akhuang can you confirm this fixes your issue? I've tested locally and it works fine on my side.


Glibc issue: https://sourceware.org/bugzilla/show_bug.cgi?id=25399

The fix consist in considering the missing function as a builtin lowered to a nop.

See https://reviews.llvm.org/D71082 for the original discussion that led to that patch.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D72869

Files:
  clang/include/clang/Basic/Builtins.def
  clang/lib/CodeGen/CGBuiltin.cpp


Index: clang/lib/CodeGen/CGBuiltin.cpp
===================================================================
--- clang/lib/CodeGen/CGBuiltin.cpp
+++ clang/lib/CodeGen/CGBuiltin.cpp
@@ -3222,6 +3222,8 @@
         Builder.CreateZExt(EmitSignBit(*this, EmitScalarExpr(E->getArg(0))),
                            ConvertType(E->getType())));
   }
+  case Builtin::BI__warn_memset_zero_len:
+    return RValue::getIgnored();
   case Builtin::BI__annotation: {
     // Re-encode each wide string to UTF8 and make an MDString.
     SmallVector<Metadata *, 1> Strings;
Index: clang/include/clang/Basic/Builtins.def
===================================================================
--- clang/include/clang/Basic/Builtins.def
+++ clang/include/clang/Basic/Builtins.def
@@ -788,6 +788,9 @@
 BUILTIN(__builtin_index, "c*cC*i", "Fn")
 BUILTIN(__builtin_rindex, "c*cC*i", "Fn")
 
+// ignored glibc builtin, see https://sourceware.org/bugzilla/show_bug.cgi?id=25399
+BUILTIN(__warn_memset_zero_len, "v", "nU")
+
 // Microsoft builtins.  These are only active with -fms-extensions.
 LANGBUILTIN(_alloca,          "v*z", "n", ALL_MS_LANGUAGES)
 LANGBUILTIN(__annotation,     "wC*.","n", ALL_MS_LANGUAGES)


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