[Driver] Update GCC libraries detection logic for Gentoo.

Summary:
1. Find GCC's LDPATH from the actual GCC config file.
2. Avoid picking libraries from a similar named tuple if the exact
   tuple is installed.

Reviewers: mgorny, chandlerc, thakis, rnk

Reviewed By: mgorny, rnk

Subscribers: cfe-commits, mgorny

Differential Revision: https://reviews.llvm.org/D45233

llvm-svn: 329512

2 files changed, 80 insertions, 23 deletions

diff --git a/clang/lib/Driver/ToolChains/Gnu.cpp b/clang/lib/Driver/ToolChains/Gnu.cpp
index f961dc1dd7f..e10e14fb23b 100644
--- a/clang/lib/Driver/ToolChains/Gnu.cpp
+++ b/clang/lib/Driver/ToolChains/Gnu.cpp
@@ -1676,18 +1676,21 @@ void Generic_GCC::GCCInstallationDetector::init(
   // in /usr. This avoids accidentally enforcing the system GCC version
   // when using a custom toolchain.
   if (GCCToolchainDir == "" || GCCToolchainDir == D.SysRoot + "/usr") {
-    for (StringRef CandidateTriple : ExtraTripleAliases) {
-      if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple))
-        return;
-    }
-    for (StringRef CandidateTriple : CandidateTripleAliases) {
-      if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple))
-        return;
-    }
-    for (StringRef CandidateTriple : CandidateBiarchTripleAliases) {
-      if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple, true))
-        return;
-    }
+    SmallVector<StringRef, 16> GentooTestTriples;
+    // Try to match an exact triple as target triple first.
+    // e.g. crossdev -S x86_64-gentoo-linux-gnu will install gcc libs for
+    // x86_64-gentoo-linux-gnu. But "clang -target x86_64-gentoo-linux-gnu"
+    // may pick the libraries for x86_64-pc-linux-gnu even when exact matching
+    // triple x86_64-gentoo-linux-gnu is present.
+    GentooTestTriples.push_back(TargetTriple.str());
+    // Check rest of triples.
+    GentooTestTriples.append(ExtraTripleAliases.begin(),
+                             ExtraTripleAliases.end());
+    GentooTestTriples.append(CandidateTripleAliases.begin(),
+                             CandidateTripleAliases.end());
+    if (ScanGentooConfigs(TargetTriple, Args, GentooTestTriples,
+                          CandidateBiarchTripleAliases))
+      return;
   }
 
   // Loop over the various components which exist and select the best GCC
@@ -1700,6 +1703,9 @@ void Generic_GCC::GCCInstallationDetector::init(
       const std::string LibDir = Prefix + Suffix.str();
       if (!D.getVFS().exists(LibDir))
         continue;
+      // Try to match the exact target triple first.
+      ScanLibDirForGCCTriple(TargetTriple, Args, LibDir, TargetTriple.str());
+      // Try rest of possible triples.
       for (StringRef Candidate : ExtraTripleAliases) // Try these first.
         ScanLibDirForGCCTriple(TargetTriple, Args, LibDir, Candidate);
       for (StringRef Candidate : CandidateTripleAliases)
@@ -2193,6 +2199,22 @@ void Generic_GCC::GCCInstallationDetector::ScanLibDirForGCCTriple(
   }
 }
 
+bool Generic_GCC::GCCInstallationDetector::ScanGentooConfigs(
+    const llvm::Triple &TargetTriple, const ArgList &Args,
+    const SmallVectorImpl<StringRef> &CandidateTriples,
+    const SmallVectorImpl<StringRef> &CandidateBiarchTriples) {
+  for (StringRef CandidateTriple : CandidateTriples) {
+    if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple))
+      return true;
+  }
+
+  for (StringRef CandidateTriple : CandidateBiarchTriples) {
+    if (ScanGentooGccConfig(TargetTriple, Args, CandidateTriple, true))
+      return true;
+  }
+  return false;
+}
+
 bool Generic_GCC::GCCInstallationDetector::ScanGentooGccConfig(
     const llvm::Triple &TargetTriple, const ArgList &Args,
     StringRef CandidateTriple, bool NeedsBiarchSuffix) {
@@ -2205,23 +2227,53 @@ bool Generic_GCC::GCCInstallationDetector::ScanGentooGccConfig(
     for (StringRef Line : Lines) {
       Line = Line.trim();
       // CURRENT=triple-version
-      if (Line.consume_front("CURRENT=")) {
-        const std::pair<StringRef, StringRef> ActiveVersion =
-          Line.rsplit('-');
-        // Note: Strictly speaking, we should be reading
-        // /etc/env.d/gcc/${CURRENT} now. However, the file doesn't
-        // contain anything new or especially useful to us.
-        const std::string GentooPath = D.SysRoot + "/usr/lib/gcc/" +
-                                       ActiveVersion.first.str() + "/" +
-                                       ActiveVersion.second.str();
+      if (!Line.consume_front("CURRENT="))
+        continue;
+      // Process the config file pointed to by CURRENT.
+      llvm::ErrorOr<std::unique_ptr<llvm::MemoryBuffer>> ConfigFile =
+          D.getVFS().getBufferForFile(D.SysRoot + "/etc/env.d/gcc/" +
+                                      Line.str());
+      std::pair<StringRef, StringRef> ActiveVersion = Line.rsplit('-');
+      // List of paths to scan for libraries.
+      SmallVector<StringRef, 4> GentooScanPaths;
+      // Scan the Config file to find installed GCC libraries path.
+      // Typical content of the GCC config file:
+      // LDPATH="/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.x:/usr/lib/gcc/
+      // (continued from previous line) x86_64-pc-linux-gnu/4.9.x/32"
+      // MANPATH="/usr/share/gcc-data/x86_64-pc-linux-gnu/4.9.x/man"
+      // INFOPATH="/usr/share/gcc-data/x86_64-pc-linux-gnu/4.9.x/info"
+      // STDCXX_INCDIR="/usr/lib/gcc/x86_64-pc-linux-gnu/4.9.x/include/g++-v4"
+      // We are looking for the paths listed in LDPATH=... .
+      if (ConfigFile) {
+        SmallVector<StringRef, 2> ConfigLines;
+        ConfigFile.get()->getBuffer().split(ConfigLines, "\n");
+        for (StringRef ConfLine : ConfigLines) {
+          ConfLine = ConfLine.trim();
+          if (ConfLine.consume_front("LDPATH=")) {
+            // Drop '"' from front and back if present.
+            ConfLine.consume_back("\"");
+            ConfLine.consume_front("\"");
+            // Get all paths sperated by ':'
+            ConfLine.split(GentooScanPaths, ':', -1, /*AllowEmpty*/ false);
+          }
+        }
+      }
+      // Test the path based on the version in /etc/env.d/gcc/config-{tuple}.
+      std::string basePath = "/usr/lib/gcc/" + ActiveVersion.first.str() + "/"
+          + ActiveVersion.second.str();
+      GentooScanPaths.push_back(StringRef(basePath));
+
+      // Scan all paths for GCC libraries.
+      for (const auto &GentooScanPath : GentooScanPaths) {
+        std::string GentooPath = D.SysRoot + std::string(GentooScanPath);
         if (D.getVFS().exists(GentooPath + "/crtbegin.o")) {
           if (!ScanGCCForMultilibs(TargetTriple, Args, GentooPath,
                                    NeedsBiarchSuffix))
-            return false;
+            continue;
 
           Version = GCCVersion::Parse(ActiveVersion.second);
           GCCInstallPath = GentooPath;
-          GCCParentLibPath = GentooPath + "/../../..";
+          GCCParentLibPath = GentooPath + std::string("/../../..");
           GCCTriple.setTriple(ActiveVersion.first);
           IsValid = true;
           return true;
diff --git a/clang/lib/Driver/ToolChains/Gnu.h b/clang/lib/Driver/ToolChains/Gnu.h
index 9bad560c4d0..cc9b4a33455 100644
--- a/clang/lib/Driver/ToolChains/Gnu.h
+++ b/clang/lib/Driver/ToolChains/Gnu.h
@@ -265,6 +265,11 @@ public:
                                 StringRef CandidateTriple,
                                 bool NeedsBiarchSuffix = false);
 
+    bool ScanGentooConfigs(const llvm::Triple &TargetTriple,
+                           const llvm::opt::ArgList &Args,
+                           const SmallVectorImpl<StringRef> &CandidateTriples,
+                           const SmallVectorImpl<StringRef> &BiarchTriples);
+
     bool ScanGentooGccConfig(const llvm::Triple &TargetTriple,
                              const llvm::opt::ArgList &Args,
                              StringRef CandidateTriple,