禁用汇编程序警告".section __TEXT,__ textcoal_nt,coalesced,pure_instructions"

Question

在OS X上使用MacPorts GCC并通过通过Clang Integrated Assembler时-Wa,-q,汇编程序会为每个文件生成一个警告流.警告的示例如下所示(其中很多,Stack Overflow编辑器不允许我粘贴整个流).

我发现LLVM Commit r250349,停止生成煤炭部分.这是负责的代码,但我不清楚如何禁用警告.

+  // Issue a warning if the target is not powerpc and Section is a *coal* section.
+  Triple TT = getParser().getContext().getObjectFileInfo()->getTargetTriple();
+  Triple::ArchType ArchTy = TT.getArch();
+
+  if (ArchTy != Triple::ppc && ArchTy != Triple::ppc64) {
+    StringRef NonCoalSection = StringSwitch<StringRef>(Section)
+                                   .Case("__textcoal_nt", "__text")
+                                   .Case("__const_coal", "__const")
+                                   .Case("__datacoal_nt", "__data")
+                                   .Default(Section);
+
+    if (!Section.equals(NonCoalSection)) {
+      StringRef SectionVal(Loc.getPointer());
+      size_t B = SectionVal.find(',') + 1, E = SectionVal.find(',', B);
+      SMLoc BLoc = SMLoc::getFromPointer(SectionVal.data() + B);
+      SMLoc ELoc = SMLoc::getFromPointer(SectionVal.data() + E);
+      getParser().Warning(Loc, "section \"" + Section + "\" is deprecated",
+                          SMRange(BLoc, ELoc));
+      getParser().Note(Loc, "change section name to \"" + NonCoalSection +
+                       "\"", SMRange(BLoc, ELoc));
+    }
+  }
+

我无法重定向,2 > /dev/null因为此刻配置有点脆弱,它会丢弃其他警告和错误.

如何在煤炭部分禁用Clang汇编程序警告？

---

当GCC编译器遇到时-Wa,-q,它/opt/local/bin/clang用作汇编程序而不是/opt/local/bin/as.以下是相关版本.

$ /opt/local/bin/g++-mp-6 --version
g++-mp-6 (MacPorts gcc6 6.1.0_0) 6.1.0
Copyright (C) 2016 Free Software Foundation, Inc.

$ /opt/local/bin/clang --version
clang version 3.8.0 (branches/release_38 262722)
Target: x86_64-apple-darwin12.6.0

$ /opt/local/bin/as -version
Apple Inc version cctools-877.8, GNU assembler version 1.38

---

添加-Wno-deprecated到CXXFLAGS不抑制警告.我也-fno-tree-coalesce-vars没有尝试过(这可能会影响性能).

以下内容sed在OS X上使用sed或不匹配gsed:

$ CXXFLAGS="-DNDEBUG -g2 -O2" make CXX=/opt/local/bin/g++-mp-6 2>&1 | \
  gsed -e '/(__TEXT|__DATA)/,+2d'
/opt/local/bin/g++-mp-6 -DNDEBUG -g2 -O2 -fPIC -march=native -Wa,-q -pipe -c rijndael.cpp
<stdin>:3:11: warning: section "__textcoal_nt" is deprecated
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
<stdin>:3:11: note: change section name to "__text"
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
...

---

/opt/local/bin/g++-mp-6 -DNDEBUG -g2 -O2 -fPIC -march=native -Wa,-q -DMACPORTS_GCC_COMPILER=1 -c cryptlib.cpp
<stdin>:3:11: warning: section "__textcoal_nt" is deprecated
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
<stdin>:3:11: note: change section name to "__text"
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
<stdin>:2665:11: warning: section "__textcoal_nt" is deprecated
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
<stdin>:2665:11: note: change section name to "__text"
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
<stdin>:3925:11: warning: section "__textcoal_nt" is deprecated
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
<stdin>:3925:11: note: change section name to "__text"
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
<stdin>:3963:11: warning: section "__textcoal_nt" is deprecated
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~
<stdin>:3963:11: note: change section name to "__text"
        .section __TEXT,__textcoal_nt,coalesced,pure_instructions
                 ^      ~~~~~~~~~~~~~

[Hundred of these ommitted for each source file]

---

以下是相关的GCC和LLVM错误报告:

• GCC Issue 71767 - 将GCC与-Wa,-q和Clang集成汇编程序一起使用时无休止的警告流
• LLVM问题28427 - 将GCC与-Wa,-q和Clang集成汇编程序一起使用时无休止的警告流

Answer 1

目前,您无法禁用这些警告.您应该提交针对FSF GCC的错误报告,让他们更新他们的codegen以更加合规.

您可能还希望向llvm.org提交错误报告,请求有一种方法可以使这些警告静音或限制发出的数量,以免影响用户.