[clang] [MinGW] Guess the right ix86 arch name spelling as sysroot

For x86, most contempory mingw toolchains use i686 as 32 bit
x86 arch target.

As long as the target triple is set to the right form, this works
fine, either as the compiler's default target, or via e.g.
a triple prefix like i686-w64-mingw32-clang.

However, if the unprefixed toolchain targets x86_64, but the user
tries to switch it to target 32 bit by adding the -m32 option, the
computeTargetTriple function in Clang, together with
Triple::get32BitArchVariant, sets the arch to i386. This causes
the right sysroot to not be found.

When targeting an arch where there are potential spelling ambiguities
with respect to the sysroots (i386 and arm), check if the driver can
find a sysroot with the arch name - if not, try a couple other
candidates.

Differential Revision: https://reviews.llvm.org/D111952

diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index 2e69e6c..cd13a6d 100644 (file)
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -525,8 +525,11 @@ static llvm::Triple computeTargetTriple(const Driver &D,
       Target.setEnvironment(llvm::Triple::CODE16);
     }
 
-    if (AT != llvm::Triple::UnknownArch && AT != Target.getArch())
+    if (AT != llvm::Triple::UnknownArch && AT != Target.getArch()) {
       Target.setArch(AT);
+      if (Target.isWindowsGNUEnvironment())
+        toolchains::MinGW::fixTripleArch(D, Target, Args);
+    }
   }
 
   // Handle -miamcu flag.

diff --git a/clang/lib/Driver/ToolChains/MinGW.cpp b/clang/lib/Driver/ToolChains/MinGW.cpp
index 0bdeff3..b2a5b37 100644 (file)
--- a/clang/lib/Driver/ToolChains/MinGW.cpp
+++ b/clang/lib/Driver/ToolChains/MinGW.cpp
@@ -369,9 +369,9 @@ void toolchains::MinGW::findGccLibDir() {
   }
 }
 
-llvm::ErrorOr<std::string> toolchains::MinGW::findGcc() {
+static llvm::ErrorOr<std::string> findGcc(const llvm::Triple &T) {
   llvm::SmallVector<llvm::SmallString<32>, 2> Gccs;
-  Gccs.emplace_back(getTriple().getArchName());
+  Gccs.emplace_back(T.getArchName());
   Gccs[0] += "-w64-mingw32-gcc";
   Gccs.emplace_back("mingw32-gcc");
   // Please do not add "gcc" here
@@ -381,13 +381,14 @@ llvm::ErrorOr<std::string> toolchains::MinGW::findGcc() {
   return make_error_code(std::errc::no_such_file_or_directory);
 }
 
-llvm::ErrorOr<std::string> toolchains::MinGW::findClangRelativeSysroot() {
+static llvm::ErrorOr<std::string>
+findClangRelativeSysroot(const Driver &D, const llvm::Triple &T,
+                         std::string &SubdirName) {
   llvm::SmallVector<llvm::SmallString<32>, 2> Subdirs;
-  Subdirs.emplace_back(getTriple().str());
-  Subdirs.emplace_back(getTriple().getArchName());
+  Subdirs.emplace_back(T.str());
+  Subdirs.emplace_back(T.getArchName());
   Subdirs[1] += "-w64-mingw32";
-  StringRef ClangRoot =
-      llvm::sys::path::parent_path(getDriver().getInstalledDir());
+  StringRef ClangRoot = llvm::sys::path::parent_path(D.getInstalledDir());
   StringRef Sep = llvm::sys::path::get_separator();
   for (StringRef CandidateSubdir : Subdirs) {
     if (llvm::sys::fs::is_directory(ClangRoot + Sep + CandidateSubdir)) {
@@ -404,13 +405,16 @@ toolchains::MinGW::MinGW(const Driver &D, const llvm::Triple &Triple,
       RocmInstallation(D, Triple, Args) {
   getProgramPaths().push_back(getDriver().getInstalledDir());
 
+  // The sequence for detecting a sysroot here should be kept in sync with
+  // the testTriple function below.
   if (getDriver().SysRoot.size())
     Base = getDriver().SysRoot;
   // Look for <clang-bin>/../<triplet>; if found, use <clang-bin>/.. as the
   // base as it could still be a base for a gcc setup with libgcc.
-  else if (llvm::ErrorOr<std::string> TargetSubdir = findClangRelativeSysroot())
+  else if (llvm::ErrorOr<std::string> TargetSubdir =
+               findClangRelativeSysroot(getDriver(), getTriple(), SubdirName))
     Base = std::string(llvm::sys::path::parent_path(TargetSubdir.get()));
-  else if (llvm::ErrorOr<std::string> GPPName = findGcc())
+  else if (llvm::ErrorOr<std::string> GPPName = findGcc(getTriple()))
     Base = std::string(llvm::sys::path::parent_path(
         llvm::sys::path::parent_path(GPPName.get())));
   else
@@ -625,3 +629,55 @@ void toolchains::MinGW::AddClangCXXStdlibIncludeArgs(
     break;
   }
 }
+
+static bool testTriple(const Driver &D, const llvm::Triple &Triple,
+                       const ArgList &Args) {
+  // If an explicit sysroot is set, that will be used and we shouldn't try to
+  // detect anything else.
+  std::string SubdirName;
+  if (D.SysRoot.size())
+    return true;
+  if (llvm::ErrorOr<std::string> TargetSubdir =
+          findClangRelativeSysroot(D, Triple, SubdirName))
+    return true;
+  if (llvm::ErrorOr<std::string> GPPName = findGcc(Triple))
+    return true;
+  // If we neither found a colocated sysroot or a matching gcc executable,
+  // conclude that we can't know if this is the correct spelling of the triple.
+  return false;
+}
+
+static llvm::Triple adjustTriple(const Driver &D, const llvm::Triple &Triple,
+                                 const ArgList &Args) {
+  // First test if the original triple can find a sysroot with the triple
+  // name.
+  if (testTriple(D, Triple, Args))
+    return Triple;
+  llvm::SmallVector<llvm::StringRef, 3> Archs;
+  // If not, test a couple other possible arch names that might be what was
+  // intended.
+  if (Triple.getArch() == llvm::Triple::x86) {
+    Archs.emplace_back("i386");
+    Archs.emplace_back("i586");
+    Archs.emplace_back("i686");
+  } else if (Triple.getArch() == llvm::Triple::arm ||
+             Triple.getArch() == llvm::Triple::thumb) {
+    Archs.emplace_back("armv7");
+  }
+  for (auto A : Archs) {
+    llvm::Triple TestTriple(Triple);
+    TestTriple.setArchName(A);
+    if (testTriple(D, TestTriple, Args))
+      return TestTriple;
+  }
+  // If none was found, just proceed with the original value.
+  return Triple;
+}
+
+void toolchains::MinGW::fixTripleArch(const Driver &D, llvm::Triple &Triple,
+                                      const ArgList &Args) {
+  if (Triple.getArch() == llvm::Triple::x86 ||
+      Triple.getArch() == llvm::Triple::arm ||
+      Triple.getArch() == llvm::Triple::thumb)
+    Triple = adjustTriple(D, Triple, Args);
+}

diff --git a/clang/lib/Driver/ToolChains/MinGW.h b/clang/lib/Driver/ToolChains/MinGW.h
index efc50b4..f9659f0 100644 (file)
--- a/clang/lib/Driver/ToolChains/MinGW.h
+++ b/clang/lib/Driver/ToolChains/MinGW.h
@@ -60,6 +60,9 @@ public:
   MinGW(const Driver &D, const llvm::Triple &Triple,
         const llvm::opt::ArgList &Args);
 
+  static void fixTripleArch(const Driver &D, llvm::Triple &Triple,
+                            const llvm::opt::ArgList &Args);
+
   bool HasNativeLLVMSupport() const override;
 
   bool IsIntegratedAssemblerDefault() const override;
@@ -103,8 +106,6 @@ private:
   mutable std::unique_ptr<tools::gcc::Preprocessor> Preprocessor;
   mutable std::unique_ptr<tools::gcc::Compiler> Compiler;
   void findGccLibDir();
-  llvm::ErrorOr<std::string> findGcc();
-  llvm::ErrorOr<std::string> findClangRelativeSysroot();
 
   bool NativeLLVMSupport;
 };

diff --git a/clang/test/Driver/mingw-sysroot.cpp b/clang/test/Driver/mingw-sysroot.cpp
index 8a2fb7d..843bf46 100644 (file)
--- a/clang/test/Driver/mingw-sysroot.cpp
+++ b/clang/test/Driver/mingw-sysroot.cpp
@@ -12,6 +12,7 @@
 // RUN: mkdir -p %T/testroot-clang/bin
 // RUN: ln -s %clang %T/testroot-clang/bin/x86_64-w64-mingw32-clang
 // RUN: ln -s %S/Inputs/mingw_ubuntu_posix_tree/usr/x86_64-w64-mingw32 %T/testroot-clang/x86_64-w64-mingw32
+// RUN: ln -s %S/Inputs/mingw_arch_tree/usr/i686-w64-mingw32 %T/testroot-clang/i686-w64-mingw32
 
 
 // If we find a gcc in the path with the right triplet prefix, pick that as
@@ -36,3 +37,14 @@
 // the libgcc directory:
 
 // RUN: env "PATH=%T/testroot-gcc/bin:%PATH%" %T/testroot-gcc/bin/x86_64-w64-mingw32-clang -target x86_64-w64-mingw32 -rtlib=platform -stdlib=libstdc++ --sysroot="" -c -### %s 2>&1 | FileCheck -check-prefix=CHECK_TESTROOT_GCC %s
+
+
+// If the user requests a different arch via the -m32 option, which changes
+// x86_64 into i386, check that the driver notices that it can't find a
+// sysroot for i386 but there is one for i686, and uses that one.
+// (In practice, the real usecase is when using an unprefixed native clang
+// that defaults to x86_64 mingw, but it's easier to test this in cross setups
+// with symlinks, like the other tests here.)
+
+// RUN: env "PATH=%T/testroot-gcc/bin:%PATH%" %T/testroot-clang/bin/x86_64-w64-mingw32-clang --target=x86_64-w64-mingw32 -m32 -rtlib=compiler-rt -stdlib=libstdc++ --sysroot="" -c -### %s 2>&1 | FileCheck -check-prefix=CHECK_TESTROOT_CLANG_I686 %s
+// CHECK_TESTROOT_CLANG_I686: "{{[^"]+}}/testroot-clang{{/|\\\\}}i686-w64-mingw32{{/|\\\\}}include"