Promote -fdebug-compilation-dir from a cc1 flag to clang and clang-cl driver flags

The flag is useful when wanting to create .o files that are independent
from the absolute path to the build directory. -fdebug-prefix-map= can
be used to the same effect, but it requires putting the absolute path
to the build directory on the build command line, so it still requires
the build command line to be dependent on the absolute path of the build
directory. With this flag, "-fdebug-compilation-dir ." makes it so that
both debug info and the compile command itself are independent of the
absolute path of the build directory, which is good for build
determinism (in the sense that the build is independent of which
directory it happens in) and for caching compile results.
(The tradeoff is that the debugger needs explicit configuration to know
the build directory. See also http://dwarfstd.org/ShowIssue.php?issue=171130.2)

Differential Revision: https://reviews.llvm.org/D63387

llvm-svn: 363548

clang/include/clang/Driver/CC1Options.td

@@ -190,8 +190,6 @@ def default_function_attr : Separate<["-"], "default-function-attr">,
   HelpText<"Apply given attribute to all functions">;
 def dwarf_version_EQ : Joined<["-"], "dwarf-version=">;
 def debugger_tuning_EQ : Joined<["-"], "debugger-tuning=">;
-def fdebug_compilation_dir : Separate<["-"], "fdebug-compilation-dir">,
-  HelpText<"The compilation directory to embed in the debug info.">;
 def dwarf_debug_flags : Separate<["-"], "dwarf-debug-flags">,
   HelpText<"The string to embed in the Dwarf debug flags record.">;
 def record_command_line : Separate<["-"], "record-command-line">,

clang/include/clang/Driver/Options.td

@@ -713,11 +713,14 @@ def fauto_profile_accurate : Flag<["-"], "fauto-profile-accurate">,
     Group<f_Group>, Alias<fprofile_sample_accurate>;
 def fno_auto_profile_accurate : Flag<["-"], "fno-auto-profile-accurate">,
     Group<f_Group>, Alias<fno_profile_sample_accurate>;
-def fdebug_info_for_profiling : Flag<["-"], "fdebug-info-for-profiling">, Group<f_Group>,
+def fdebug_compilation_dir : Separate<["-"], "fdebug-compilation-dir">,
-    Flags<[CC1Option]>,
+    Group<f_Group>, Flags<[CC1Option, CC1AsOption, CoreOption]>,
+    HelpText<"The compilation directory to embed in the debug info.">;
+def fdebug_info_for_profiling : Flag<["-"], "fdebug-info-for-profiling">,
+    Group<f_Group>, Flags<[CC1Option]>,
     HelpText<"Emit extra debug info to make sample profile more accurate.">;
-def fno_debug_info_for_profiling : Flag<["-"], "fno-debug-info-for-profiling">, Group<f_Group>,
+def fno_debug_info_for_profiling : Flag<["-"], "fno-debug-info-for-profiling">,
-    Flags<[DriverOption]>,
+    Group<f_Group>, Flags<[DriverOption]>,
     HelpText<"Do not emit extra debug info for sample profiler.">;
 def fprofile_instr_generate : Flag<["-"], "fprofile-instr-generate">,
     Group<f_Group>, Flags<[CoreOption]>,

clang/lib/Driver/ToolChains/Clang.cpp

@@ -618,7 +618,11 @@ static bool shouldUseLeafFramePointer(const ArgList &Args,
 /// Add a CC1 option to specify the debug compilation directory.
 static void addDebugCompDirArg(const ArgList &Args, ArgStringList &CmdArgs,
                                const llvm::vfs::FileSystem &VFS) {
-  if (llvm::ErrorOr<std::string> CWD = VFS.getCurrentWorkingDirectory()) {
+  if (Arg *A = Args.getLastArg(options::OPT_fdebug_compilation_dir)) {
+    CmdArgs.push_back("-fdebug-compilation-dir");
+    CmdArgs.push_back(A->getValue());
+  } else if (llvm::ErrorOr<std::string> CWD =
+                 VFS.getCurrentWorkingDirectory()) {
     CmdArgs.push_back("-fdebug-compilation-dir");
     CmdArgs.push_back(Args.MakeArgString(*CWD));
   }
@@ -637,7 +641,8 @@ static void addDebugPrefixMapArg(const Driver &D, const ArgList &Args, ArgString
 }
 
 /// Vectorize at all optimization levels greater than 1 except for -Oz.
-/// For -Oz the loop vectorizer is disable, while the slp vectorizer is enabled.
+/// For -Oz the loop vectorizer is disabled, while the slp vectorizer is
+/// enabled.
 static bool shouldEnableVectorizerAtOLevel(const ArgList &Args, bool isSlpVec) {
   if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
     if (A->getOption().matches(options::OPT_O4) ||

clang/test/Driver/cl-options.c

@@ -619,6 +619,7 @@
 // RUN:     -fno-coverage-mapping \
 // RUN:     -fdiagnostics-color \
 // RUN:     -fno-diagnostics-color \
+// RUN:     -fdebug-compilation-dir . \
 // RUN:     -fdiagnostics-parseable-fixits \
 // RUN:     -fdiagnostics-absolute-paths \
 // RUN:     -ferror-limit=10 \

clang/test/Driver/clang_f_opts.c

@@ -525,11 +525,15 @@
 // CHECK-CF-PROTECTION-BRANCH: -fcf-protection=branch
 // CHECK-NO-CF-PROTECTION-BRANCH-NOT: -fcf-protection=branch
 
+// RUN: %clang -### -S -fdebug-compilation-dir . %s 2>&1 | FileCheck -check-prefix=CHECK-DEBUG-COMPILATION-DIR %s
+// RUN: %clang -### -fdebug-compilation-dir . -x assembler %s 2>&1 | FileCheck -check-prefix=CHECK-DEBUG-COMPILATION-DIR %s
+// CHECK-DEBUG-COMPILATION-DIR: "-fdebug-compilation-dir" "."
+
 // RUN: %clang -### -S -fdiscard-value-names %s 2>&1 | FileCheck -check-prefix=CHECK-DISCARD-NAMES %s
 // RUN: %clang -### -S -fno-discard-value-names %s 2>&1 | FileCheck -check-prefix=CHECK-NO-DISCARD-NAMES %s
 // CHECK-DISCARD-NAMES: "-discard-value-names"
 // CHECK-NO-DISCARD-NAMES-NOT: "-discard-value-names"
-//
+
 // RUN: %clang -### -S -fmerge-all-constants %s 2>&1 | FileCheck -check-prefix=CHECK-MERGE-ALL-CONSTANTS %s
 // RUN: %clang -### -S -fno-merge-all-constants %s 2>&1 | FileCheck -check-prefix=CHECK-NO-MERGE-ALL-CONSTANTS %s
 // RUN: %clang -### -S -fmerge-all-constants -fno-merge-all-constants %s 2>&1 | FileCheck -check-prefix=CHECK-NO-MERGE-ALL-CONSTANTS %s