[PATCH] D109694: Driver: Add preferred gcc triples for Red Hat operating systems

[Tom Stellard via Phabricator via cfe-commits]

tstellar created this revision.
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The GCCInstallationDetector has a list of gcc triples to search
for when trying to find a valid gcc install on the system.  When
all else is equal, clang selects the first triple that appears in
the list.

This causes a problem on Red Hat operating systems, since there
is a cross-compiler gcc package that uses the triple x86_64-linux-gnu
and since this is listed in the triple list before the system gcc
install (x86_64-redhat-linux), the cross-compiler is always selected
by clang.

To solve this, we make it possible for a distro to provide a list of
preferred triples that will be selected before any triples in the
generic triple list.

Another solution to this problem would be to reorder the generic triple
lists so that distro supplied triples come first.  However, I don't
have confidence that I would be able to order the list so that it
is correct for every distro.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D109694

Files:
  clang/include/clang/Driver/Distro.h
  clang/lib/Driver/Distro.cpp
  clang/lib/Driver/ToolChains/Linux.cpp


Index: clang/lib/Driver/ToolChains/Linux.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Linux.cpp
+++ clang/lib/Driver/ToolChains/Linux.cpp
@@ -177,7 +177,9 @@
 
 Linux::Linux(const Driver &D, const llvm::Triple &Triple, const ArgList &Args)
     : Generic_ELF(D, Triple, Args) {
-  GCCInstallation.init(Triple, Args);
+
+  Distro Distro(D.getVFS(), Triple);
+  GCCInstallation.init(Triple, Args, Distro.getDefaultGCCTriples(Triple.getArch()));
   Multilibs = GCCInstallation.getMultilibs();
   SelectedMultilib = GCCInstallation.getMultilib();
   llvm::Triple::ArchType Arch = Triple.getArch();
@@ -186,7 +188,6 @@
 
   Generic_GCC::PushPPaths(PPaths);
 
-  Distro Distro(D.getVFS(), Triple);
 
   if (Distro.IsAlpineLinux() || Triple.isAndroid()) {
     ExtraOpts.push_back("-z");
Index: clang/lib/Driver/Distro.cpp
===================================================================
--- clang/lib/Driver/Distro.cpp
+++ clang/lib/Driver/Distro.cpp
@@ -225,3 +225,53 @@
 
 Distro::Distro(llvm::vfs::FileSystem &VFS, const llvm::Triple &TargetOrHost)
     : DistroVal(GetDistro(VFS, TargetOrHost)) {}
+
+/// @return An array of triples that should be used first when searching for
+/// a candidate gcc install on the system.
+llvm::ArrayRef<std::string> Distro::getDefaultGCCTriples(llvm::Triple::ArchType Arch) {
+  if (!IsRedhat())
+    return None;
+
+  static const std::array<std::string, 1> RedHatAArch64Triples = {{
+    "aarch64-redhat-linux"
+  }};
+
+  static const std::array<std::string, 1> RedHatArmTriples = {{
+    "armv7hl-redhat-linux-gnueabi"
+  }};
+
+  static const std::array<std::string, 1> RedHatPPC64LETriples = {{
+    "ppc64le-redhat-linux"
+  }};
+
+  static const std::array<std::string, 1> RedHatSystemZTriples = {{
+    "s390x-redhat-linux"
+  }};
+
+  static const std::array<std::string, 1> RedHatX86Triples = {{
+    "i686-redhat-linux"
+  }};
+
+  static const std::array<std::string, 1> RedHatX86_64Triples = {{
+    "x86_64-redhat-linux"
+  }};
+
+  switch (Arch) {
+  default:
+    break;
+  case llvm::Triple::aarch64:
+    return RedHatAArch64Triples;
+  case llvm::Triple::arm:
+    return RedHatArmTriples;
+  case llvm::Triple::ppc64le:
+    return  RedHatPPC64LETriples;
+  case llvm::Triple::systemz:
+    return RedHatSystemZTriples;
+  case llvm::Triple::x86:
+    return RedHatX86Triples;
+  case llvm::Triple::x86_64:
+    return RedHatX86_64Triples;
+  }
+
+  return None;
+}
Index: clang/include/clang/Driver/Distro.h
===================================================================
--- clang/include/clang/Driver/Distro.h
+++ clang/include/clang/Driver/Distro.h
@@ -91,6 +91,8 @@
   /// Detects the distribution using specified VFS.
   explicit Distro(llvm::vfs::FileSystem &VFS, const llvm::Triple &TargetOrHost);
 
+  llvm::ArrayRef<std::string> getDefaultGCCTriples(llvm::Triple::ArchType Arch);
+
   bool operator==(const Distro &Other) const {
     return DistroVal == Other.DistroVal;
   }


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