[clang][driver] Use $ prefix with config file options to have them added after all of the command line options

clang/docs/UsersManual.rst

@@ -1059,6 +1059,16 @@ In this way, the user may only need to specify a root configuration file with
     -L <CFGDIR>/lib
     -T <CFGDIR>/ldscripts/link.ld
 
+Usually, config file options are placed before command-line options, regardless
+of the actual operation to be performed. The exception is being made for the
+options prefixed with the ``$`` character. These will be used only when linker
+is being invoked, and added after all of the command-line specified linker
+inputs. Here is some example of ``$``-prefixed options:
+
+::
+    $-Wl,-Bstatic $-lm
+    $-Wl,-Bshared
+
 Language and Target-Independent Features
 ========================================
 

clang/include/clang/Driver/Driver.h

@@ -297,8 +297,11 @@ class Driver {
   /// Object that stores strings read from configuration file.
   llvm::StringSaver Saver;
 
-  /// Arguments originated from configuration file.
-  std::unique_ptr<llvm::opt::InputArgList> CfgOptions;
+  /// Arguments originated from configuration file (head part).
+  std::unique_ptr<llvm::opt::InputArgList> CfgOptionsHead;
+
+  /// Arguments originated from configuration file (tail part).
+  std::unique_ptr<llvm::opt::InputArgList> CfgOptionsTail;
 
   /// Arguments originated from command line.
   std::unique_ptr<llvm::opt::InputArgList> CLOptions;

clang/lib/Driver/Driver.cpp

@@ -1039,34 +1039,59 @@ bool Driver::readConfigFile(StringRef FileName,
   }
 
   // Try reading the given file.
-  SmallVector<const char *, 32> NewCfgArgs;
-  if (llvm::Error Err = ExpCtx.readConfigFile(FileName, NewCfgArgs)) {
+  SmallVector<const char *, 32> NewCfgFileArgs;
+  if (llvm::Error Err = ExpCtx.readConfigFile(FileName, NewCfgFileArgs)) {
     Diag(diag::err_drv_cannot_read_config_file)
         << FileName << toString(std::move(Err));
     return true;
   }
 
+  // Populate head and tail lists. The tail list is used only when linking.
+  SmallVector<const char *, 32> NewCfgHeadArgs, NewCfgTailArgs;
+  for (const char *Opt : NewCfgFileArgs) {
+    // An $-prefixed option should go to the tail list.
+    if (Opt[0] == '$' && Opt[1])
+      NewCfgTailArgs.push_back(Opt + 1);
+    else
+      NewCfgHeadArgs.push_back(Opt);
+  }
+
   // Read options from config file.
   llvm::SmallString<128> CfgFileName(FileName);
   llvm::sys::path::native(CfgFileName);
-  bool ContainErrors;
-  auto NewOptions = std::make_unique<InputArgList>(
-      ParseArgStrings(NewCfgArgs, /*UseDriverMode=*/true, ContainErrors));
+  bool ContainErrors = false;
+  auto NewHeadOptions = std::make_unique<InputArgList>(
+      ParseArgStrings(NewCfgHeadArgs, /*UseDriverMode=*/true, ContainErrors));
+  if (ContainErrors)
+    return true;
+  auto NewTailOptions = std::make_unique<InputArgList>(
+      ParseArgStrings(NewCfgTailArgs, /*UseDriverMode=*/true, ContainErrors));
   if (ContainErrors)
     return true;
 
   // Claim all arguments that come from a configuration file so that the driver
   // does not warn on any that is unused.
-  for (Arg *A : *NewOptions)
+  for (Arg *A : *NewHeadOptions)
+    A->claim();
+  for (Arg *A : *NewTailOptions)
     A->claim();
 
-  if (!CfgOptions)
-    CfgOptions = std::move(NewOptions);
+  if (!CfgOptionsHead)
+    CfgOptionsHead = std::move(NewHeadOptions);
+  else {
+    // If this is a subsequent config file, append options to the previous one.
+    for (auto *Opt : *NewHeadOptions)
+      appendOneArg(*CfgOptionsHead, Opt);
+  }
+
+  if (!CfgOptionsTail)
+    CfgOptionsTail = std::move(NewTailOptions);
   else {
     // If this is a subsequent config file, append options to the previous one.
-    for (auto *Opt : *NewOptions)
-      appendOneArg(*CfgOptions, Opt);
+    for (auto *Opt : *NewTailOptions)
+      appendOneArg(*CfgOptionsTail, Opt);
   }
+
   ConfigFiles.push_back(std::string(CfgFileName));
   return false;
 }
@@ -1243,13 +1268,14 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   // Try parsing configuration file.
   if (!ContainsError)
     ContainsError = loadConfigFiles();
-  bool HasConfigFile = !ContainsError && (CfgOptions.get() != nullptr);
+  bool HasConfigFileHead = !ContainsError && CfgOptionsHead;
+  bool HasConfigFileTail = !ContainsError && CfgOptionsTail;
 
   // All arguments, from both config file and command line.
-  InputArgList Args = std::move(HasConfigFile ? std::move(*CfgOptions)
-                                              : std::move(*CLOptions));
+  InputArgList Args =
+      HasConfigFileHead ? std::move(*CfgOptionsHead) : std::move(*CLOptions);
 
-  if (HasConfigFile)
+  if (HasConfigFileHead)
     for (auto *Opt : *CLOptions)
       if (!Opt->getOption().matches(options::OPT_config))
         appendOneArg(Args, Opt);
@@ -1540,6 +1566,15 @@ Compilation *Driver::BuildCompilation(ArrayRef<const char *> ArgList) {
   // Construct the list of inputs.
   InputList Inputs;
   BuildInputs(C->getDefaultToolChain(), *TranslatedArgs, Inputs);
+  if (HasConfigFileTail && Inputs.size()) {
+    Arg *FinalPhaseArg;
+    if (getFinalPhase(*TranslatedArgs, &FinalPhaseArg) == phases::Link) {
+      DerivedArgList TranslatedLinkerIns(*CfgOptionsTail);
+      for (Arg *A : *CfgOptionsTail)
+        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 +1,3 @@
+-Wall $-lm
+-Wl,--as-needed $-Wl,-Bstatic
+$-lhappy $-Wl,-Bdynamic

clang/test/Driver/config-file.c

@@ -82,3 +82,29 @@
 // CHECK-TWO-CONFIGS: -isysroot
 // CHECK-TWO-CONFIGS-SAME: /opt/data
 // CHECK-TWO-CONFIGS-SAME: -Wall
+
+//--- The linker input 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 %s -lmylib -Wl,foo.a -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING
+// RUN: %clang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -fopenmp %s -lmylib -Wl,foo.a -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING-LIBOMP-GOES-AFTER
+// 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-OPENMP
+// RUN: %clang --target=x86_64-pc-windows-msvc    --config %S/Inputs/config-l.cfg %s -lmylib -Wl,foo.lib -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING-MSVC
+// RUN: %clang --target=x86_64-pc-windows-msvc    --config %S/Inputs/config-l.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NOLINKING-MSVC
+// CHECK-LINKING: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-LINKING: "-Wall"
+// CHECK-LINKING: "--as-needed" "{{.*}}-{{.*}}.o" "-lmylib" "foo.a" "-lm" "-Bstatic" "-lhappy" "-Bdynamic"
+// CHECK-LINKING-LIBOMP-GOES-AFTER: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-LINKING-LIBOMP-GOES-AFTER: "-Wall" {{.*}}"-fopenmp"
+// CHECK-LINKING-LIBOMP-GOES-AFTER: "--as-needed" "{{.*}}-{{.*}}.o" "-lmylib" "foo.a" "-lm" "-Bstatic" "-lhappy" "-Bdynamic" {{.*}}"-lomp"
+// CHECK-NOLINKING: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-NOLINKING: "-Wall"
+// CHECK-NOLINKING-NO: "-lm" "-Bstatic" "-lhappy" "-Bdynamic"
+// CHECK-NOLINKING-OPENMP: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-NOLINKING-OPENMP: "-Wall" {{.*}}"-fopenmp"
+// CHECK-NOLINKING-OPENMP-NO: "-lm" "-Bstatic" "-lhappy" "-Bdynamic" {{.*}}"-lomp"
+// CHECK-LINKING-MSVC: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-LINKING-MSVC: "-Wall"
+// CHECK-LINKING-MSVC: "--as-needed" "{{.*}}-{{.*}}.o" "mylib.lib" "foo.lib" "m.lib" "-Bstatic" "happy.lib" "-Bdynamic"
+// CHECK-NOLINKING-MSVC: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+// CHECK-NOLINKING-MSVC: "-Wall"
+// CHECK-NOLINKING-MSVC-NO: "m.lib" "-Bstatic" "happy.lib" "-Bdynamic"

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

@@ -0,0 +1,3 @@
+-ffast-math $-lm
+-Wl,--as-needed $-Wl,-Bstatic
+$-lhappy $-Wl,-Bdynamic

flang/test/Driver/config-file.f90

@@ -61,3 +61,29 @@
 ! CHECK-TWO-CONFIGS-NEXT: Configuration file: {{.*}}Inputs{{.}}config2{{.}}config-4.cfg
 ! CHECK-TWO-CONFIGS: -ffp-contract=fast
 ! CHECK-TWO-CONFIGS: -O3
+
+!--- The linker input 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 %s -lmylib -Wl,foo.a -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING
+! RUN: %flang --target=aarch64-unknown-linux-gnu --config %S/Inputs/config-l.cfg -fopenmp %s -lmylib -Wl,foo.a -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING-LIBOMP-GOES-AFTER
+! 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-OPENMP
+! RUN: %flang --target=x86_64-pc-windows-msvc    --config %S/Inputs/config-l.cfg %s -lmylib -Wl,foo.lib -### 2>&1 | FileCheck %s -check-prefix CHECK-LINKING-MSVC
+! RUN: %flang --target=x86_64-pc-windows-msvc    --config %S/Inputs/config-l.cfg -S %s -### 2>&1 | FileCheck %s -check-prefix CHECK-NOLINKING-MSVC
+! CHECK-LINKING: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-LINKING: "-ffast-math"
+! CHECK-LINKING: "--as-needed" "{{.*}}-{{.*}}.o" "-lmylib" "foo.a" "-lm" "-Bstatic" "-lhappy" "-Bdynamic"
+! CHECK-LINKING-LIBOMP-GOES-AFTER: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-LINKING-LIBOMP-GOES-AFTER: "-ffast-math" {{.*}}"-fopenmp"
+! CHECK-LINKING-LIBOMP-GOES-AFTER: "--as-needed" "{{.*}}-{{.*}}.o" "-lmylib" "foo.a" "-lm" "-Bstatic" "-lhappy" "-Bdynamic" {{.*}}"-lomp"
+! CHECK-NOLINKING: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-NOLINKING: "-ffast-math"
+! CHECK-NOLINKING-NO: "-lm" "-Bstatic" "-lhappy" "-Bdynamic"
+! CHECK-NOLINKING-OPENMP: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-NOLINKING-OPENMP: "-ffast-math" {{.*}}"-fopenmp"
+! CHECK-NOLINKING-OPENMP-NO: "-lm" "-Bstatic" "-lhappy" "-Bdynamic" {{.}}"-lomp"
+! CHECK-LINKING-MSVC: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-LINKING-MSVC: "-ffast-math"
+! CHECK-LINKING-MSVC: "--as-needed" "{{.*}}-{{.*}}.o" "mylib.lib" "foo.lib" "m.lib" "-Bstatic" "happy.lib" "-Bdynamic"
+! CHECK-NOLINKING-MSVC: Configuration file: {{.*}}Inputs{{.}}config-l.cfg
+! CHECK-NOLINKING-MSVC: "-ffast-math"
+! CHECK-NOLINKING-MSVC-NO: "m.lib" "-Bstatic" "happy.lib" "-Bdynamic"