[clang][driver] Special care for -l and -Wl, flags in config files

Currently, if a -l (or -Wl,) flag is added into a config file
(e.g. clang.cfg), it is situated before any object file in the
effective command line. If the library requested by given -l flag is
static, its symbols will not be made visible to any of the object
files provided by the user. Also, the presence of any of the linker
flags in a config file confuses the driver whenever the user invokes
clang without any parameters.

This patch solves both of those problems, by moving the -l and -Wl,
flags specified in a config file to the end of the input list, and by
discarding them when there are no other inputs provided by the user,
or the last phase is not the linking phase.

Author: pawosm-arm

clang/include/clang/Driver/Driver.h

@@ -297,6 +297,9 @@ class Driver {
   /// Object that stores strings read from configuration file.
   llvm::StringSaver Saver;
 
+  /// Linker inputs originated from configuration file.
+  std::unique_ptr<llvm::opt::InputArgList> CfgLinkerInputs;
+
   /// Arguments originated from configuration file.
   std::unique_ptr<llvm::opt::InputArgList> CfgOptions;
 

clang/lib/Driver/Driver.cpp

@@ -1062,6 +1062,16 @@ bool Driver::readConfigFile(StringRef FileName,
   for (Arg *A : *NewOptions)
     A->claim();
 
+  std::unique_ptr<InputArgList> NewLinkerIns = std::make_unique<InputArgList>();
+  for (Arg *A : NewOptions->filtered(options::OPT_Wl_COMMA, options::OPT_l)) {
+    const Arg *BaseArg = &A->getBaseArg();
+    if (BaseArg == A)
+      BaseArg = nullptr;
+    appendOneArg(*NewLinkerIns, A, BaseArg);
+  }
+  NewOptions->eraseArg(options::OPT_Wl_COMMA);
+  NewOptions->eraseArg(options::OPT_l);
+
   if (!CfgOptions)
     CfgOptions = std::move(NewOptions);
   else {
@@ -1073,6 +1083,19 @@ bool Driver::readConfigFile(StringRef FileName,
       appendOneArg(*CfgOptions, Opt, BaseArg);
     }
   }
+
+  if (!CfgLinkerInputs)
+    CfgLinkerInputs = std::move(NewLinkerIns);
+  else {
+    // If this is a subsequent config file, append options to the previous one.
+    for (auto *Opt : *NewLinkerIns) {
+      const Arg *BaseArg = &Opt->getBaseArg();
+      if (BaseArg == Opt)
+        BaseArg = nullptr;
+      appendOneArg(*CfgLinkerInputs, Opt, BaseArg);
+    }
+  }
+
   ConfigFiles.push_back(std::string(CfgFileName));
   return false;
 }
@@ -1250,6 +1273,7 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   if (!ContainsError)
     ContainsError = loadConfigFiles();
   bool HasConfigFile = !ContainsError && (CfgOptions.get() != nullptr);
+  bool HasConfigLinkerIn = !ContainsError && (CfgLinkerInputs.get() != nullptr);
 
   // All arguments, from both config file and command line.
   InputArgList Args = std::move(HasConfigFile ? std::move(*CfgOptions)
@@ -1552,6 +1576,15 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   // Construct the list of inputs.
   InputList Inputs;
   BuildInputs(C->getDefaultToolChain(), *TranslatedArgs, Inputs);
+  if (HasConfigLinkerIn && Inputs.size()) {
+    Arg *FinalPhaseArg;
+    if (getFinalPhase(*TranslatedArgs, &FinalPhaseArg) == phases::Link) {
+      DerivedArgList TranslatedLinkerIns(*CfgLinkerInputs);
+      for (Arg *A : *CfgLinkerInputs)
+        TranslatedLinkerIns.append(A);
+      BuildInputs(C->getDefaultToolChain(), TranslatedLinkerIns, Inputs);
+    }
+  }
 
   // Populate the tool chains for the offloading devices, if any.
   CreateOffloadingDeviceToolChains(*C, Inputs);

clang/test/Driver/Inputs/config-l.cfg

@@ -0,0 +1 @@
+-Wall -lm -Wl,-Bstatic -lhappy -Wl,-Bdynamic

clang/test/Driver/config-file.c

@@ -82,3 +82,24 @@
 // CHECK-TWO-CONFIGS: -isysroot
 // CHECK-TWO-CONFIGS-SAME: /opt/data
 // CHECK-TWO-CONFIGS-SAME: -Wall
+
+//--- The -l flags should be moved to the end of input list and appear only when linking.
+// RUN: %clang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -o %s.out %s -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING
+// RUN: %clang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -fopenmp -o %s.out %s -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING-LIBOMP-GOES-LAST
+// RUN: %clang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NOLINKING
+// RUN: %clang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -fopenmp -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NOLINKING
+// CHECK-LINKING: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-LINKING: "-Wall"
+// CHECK-LINKING: "{{.*}}-{{.*}}.o" "-lm" "-Bstatic" "-lhappy" "-Bdynamic"
+// CHECK-LINKING-LIBOMP-GOES-LAST: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-LINKING-LIBOMP-GOES-LAST: "-Wall"
+// CHECK-LINKING-LIBOMP-GOES-LAST-SAME: "-fopenmp"
+// CHECK-LINKING-LIBOMP-GOES-LAST: "{{.*}}-{{.*}}.o" "-lm" "-Bstatic" "-lhappy" "-Bdynamic"
+// CHECK-LINKING-LIBOMP-GOES-LAST-SAME: "-lomp"
+// CHECK-NOLINKING: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-NOLINKING: "-Wall"
+// CHECK-NOLINKING-NO: "-lm"
+// CHECK-NOLINKING-NO: "-Bstatic"
+// CHECK-NOLINKING-NO: "-lhappy"
+// CHECK-NOLINKING-NO: "-Bdynamic"
+// CHECK-NOLINKING-NO: "-lomp"

flang/test/Driver/Inputs/config-l.cfg

@@ -0,0 +1 @@
+-ffast-math -lm -Wl,-Bstatic -lhappy -Wl,-Bdynamic

flang/test/Driver/config-file.f90

@@ -61,3 +61,24 @@
 ! CHECK-TWO-CONFIGS-NEXT: Configuration file: {{.*}}Inputs{{.}}config2{{.}}config-4.cfg
 ! CHECK-TWO-CONFIGS: -ffp-contract=fast
 ! CHECK-TWO-CONFIGS: -O3
+
+!--- The -l flags should be moved to the end of input list and appear only when linking.
+! RUN: %flang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -o %s.out %s -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING
+! RUN: %flang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -fopenmp -o %s.out %s -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING-LIBOMP-GOES-LAST
+! RUN: %flang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NOLINKING
+! RUN: %flang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -fopenmp -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NOLINKING
+! CHECK-LINKING: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-LINKING: "-ffast-math"
+! CHECK-LINKING: "{{.*}}-{{.*}}.o" "-lm" "-Bstatic" "-lhappy" "-Bdynamic"
+! CHECK-LINKING-LIBOMP-GOES-LAST: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-LINKING-LIBOMP-GOES-LAST: "-ffast-math"
+! CHECK-LINKING-LIBOMP-GOES-LAST-SAME: "-fopenmp"
+! CHECK-LINKING-LIBOMP-GOES-LAST: "{{.*}}-{{.*}}.o" "-lm" "-Bstatic" "-lhappy" "-Bdynamic"
+! CHECK-LINKING-LIBOMP-GOES-LAST-SAME: "-lomp"
+! CHECK-NOLINKING: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-NOLINKING: "-ffast-math"
+! CHECK-NOLINKING-NO: "-lm"
+! CHECK-NOLINKING-NO: "-Bstatic"
+! CHECK-NOLINKING-NO: "-lhappy"
+! CHECK-NOLINKING-NO: "-Bdynamic"
+! CHECK-NOLINKING-NO: "-lomp"