[flang][driver] Add support for -save-temps

[awarzynski]

Summary

This patch adds support for -save-temps in flang-new, Flang's
compiler driver. The semantics of this option are inherited from Clang.

The file extension for temporary Fortran preprocessed files is set to
i. This is identical to what Clang uses for C (or C++) preprocessed
files. I have tried researching what other compilers do here, but I
couldn't find any definitive answers. One GFortran thread [1] suggests
that indeed it is not clear what the right approach should be.

Normally, various phases in Clang/Flang are combined. The -save-temps
option works by forcing the compiler to run every phase separately. As
there is no integrated assembler driver in Flang, user will have to use
-save-temps together with -fno-integrated-as. Otherwise, an
invocation to the integrated assembler would be generated generated,
which is going to fail (i.e. something equivalent to clang -cc1as from
Clang).

There are no specific plans for implementing an integrated assembler for
Flang for now. One possible solution would be to share it entirely with
Clang.

[1] https://gcc.gnu.org/bugzilla//show_bug.cgi?id=81615

Depends on D124664
Depends on D124665
Depends on D124667

[schweitz]

clang/include/clang/Driver/Options.td

3998

nit: I noticed that this is getting rid of spaces after commas on a few lines. Is there any sense of a prior style being used in that regard?

[unterumarmung]

clang/include/clang/Driver/Options.td

4140

Why not to add FC1Option here and elsewhere like it's done for CC1Option?

[awarzynski]

clang/include/clang/Driver/Options.td

3998

I swear that somebody recently requested that I remove a space in one of my patches. I've tried finding it and failed ... I must have dreamed it!

Thanks Eric, I'll revert this change :)

4140

I'm not 100% sure what -fno-integrated-as controls in Clang's frontend driver, clang -cc1. I'm guessing that it might related to using/not-using LLVM's MCAsmParser. Perhaps for inline assembly?

In Flang, I'm only focusing on -save-temps for which I need to make sure that we don't try to call flang-new -fc1as or something similar (it does not exist). Instead, -save-temps will have to rely on an external assembler.

So, we basically don't require -fno-integrated-as in flang-new -fc1 just yet (that's what FC1Option is for - marking an option as available in the frontend driver).

[rovka]

clang/include/clang/Driver/Options.td

4140

I'm not 100% sure either (haven't looked at the code), but my understanding of -fno-integrated-as is that it forces clang to call the system assembler as opposed to using the LLVM libraries to generate machine code directly. Since flang never uses the system assembler, I would say the integrated assembler is always on in flang. So I'm not convinced it makes sense to add this flag to the driver, unless we're actually adding a
-fc1as.

[unterumarmung]

clang/include/clang/Driver/Options.td

4140

@awarzynski @rovka, thank you for the detailed explanation!

[rovka]

I think I confused myself yesterday, it does make sense to add -fno-integrated-as for this. Could we add a test for it independent of save-temps?

[awarzynski]

Add a test, restore white-space in Options.td

[awarzynski]

Fix failing test

[rovka]

flang/test/Driver/fno-integrated-as.f90

7

11

19

Nit (here and above): Is it a rule that -o blah comes right before the input file, or should we also add a {{.*}} in between in case other flags sneak in?

flang/test/Driver/save-temps.f90

2

[awarzynski]

Fix typos as per comments from @rovka, thanks!

[awarzynski]

flang/test/Driver/fno-integrated-as.f90

19

Nit (here and above): Is it a rule that -o blah comes right before the input file, or should we also add a {{.*}} in between in case other flags sneak in?

TBH, it's not something that I checked, but it's been the case so far :) We may need to insert {{.*}} there at some point, but perhaps lets delay until it's really needed? This way we will know exactly what violates that rule and perhaps we could tweak then?

[rovka]

LGTM, thanks! It would be nice to rebase the patch and see the pre-commit CI passing, but then again you're the one dealing with the buildbots if you break anything, so do as you prefer :)

[awarzynski]

Rebase on top of main

[awarzynski]

Mark the tests as unsupported on Windows

Pre-merge testing is failing on Windows. Here is the error message:

flang-new: error: there is no external assembler that can be used on this platform

I will update the commit message accordingly before merging this.

[awarzynski]

Pre-merge CI is 🍏 . If there are no new comments, I'd like to merge this tomorrow.

clang/include/clang/Driver/Options.td

def fno_rtlib_add_rpath: Flag<["-"], "fno-rtlib-add-rpath">, Flags<[NoArgumentUnused]>,
   HelpText<"Do not add -rpath with architecture-specific resource directory to the linker flags">;
 defm openmp_implicit_rpath: BoolFOption<"openmp-implicit-rpath",
   LangOpts<"OpenMP">,
   DefaultTrue,
   PosFlag<SetTrue, [], "Set rpath on OpenMP executables">,
   NegFlag<SetFalse>>;
 def r : Flag<["-"], "r">, Flags<[LinkerInput,NoArgumentUnused]>,
         Group<Link_Group>;
-def save_temps_EQ : Joined<["-", "--"], "save-temps=">, Flags<[CC1Option, NoXarchOption]>,
+def save_temps_EQ : Joined<["-", "--"], "save-temps=">, Flags<[CC1Option, FlangOption, NoXarchOption]>,
   HelpText<"Save intermediate compilation results.">;
-def save_temps : Flag<["-", "--"], "save-temps">, Flags<[NoXarchOption]>,
+def save_temps : Flag<["-", "--"], "save-temps">, Flags<[FlangOption, NoXarchOption]>,
   Alias<save_temps_EQ>, AliasArgs<["cwd"]>,
   HelpText<"Save intermediate compilation results">;
 def save_stats_EQ : Joined<["-", "--"], "save-stats=">, Flags<[NoXarchOption]>,
   HelpText<"Save llvm statistics.">;
 def save_stats : Flag<["-", "--"], "save-stats">, Flags<[NoXarchOption]>,
   Alias<save_stats_EQ>, AliasArgs<["cwd"]>,
   HelpText<"Save llvm statistics.">;
 def via_file_asm : Flag<["-", "--"], "via-file-asm">, InternalDebugOpt,
def w : Flag<["-"], "w">, HelpText<"Suppress all warnings">, Flags<[CC1Option]>,
   MarshallingInfoFlag<DiagnosticOpts<"IgnoreWarnings">>;
 def x : JoinedOrSeparate<["-"], "x">, Flags<[NoXarchOption,CC1Option]>,
   HelpText<"Treat subsequent input files as having type <language>">,
   MetaVarName<"<language>">;
 def y : Joined<["-"], "y">;
 
 defm integrated_as : BoolFOption<"integrated-as",
   CodeGenOpts<"DisableIntegratedAS">, DefaultFalse,
-  NegFlag<SetTrue, [CC1Option], "Disable">, PosFlag<SetFalse, [], "Enable">,
+  NegFlag<SetTrue, [CC1Option, FlangOption], "Disable">, PosFlag<SetFalse, [], "Enable">,
   BothFlags<[], " the integrated assembler">>;
 
 def fintegrated_cc1 : Flag<["-"], "fintegrated-cc1">,
                       Flags<[CoreOption, NoXarchOption]>, Group<f_Group>,
                       HelpText<"Run cc1 in-process">;
 def fno_integrated_cc1 : Flag<["-"], "fno-integrated-cc1">,
                          Flags<[CoreOption, NoXarchOption]>, Group<f_Group>,
                          HelpText<"Spawn a separate process for each cc1">;
 
 def : Flag<["-"], "integrated-as">, Alias<fintegrated_as>, Flags<[NoXarchOption]>;
 def : Flag<["-"], "no-integrated-as">, Alias<fno_integrated_as>,
-      Flags<[CC1Option, NoXarchOption]>;
+      Flags<[CC1Option, FlangOption, NoXarchOption]>;
 
 def working_directory : JoinedOrSeparate<["-"], "working-directory">, Flags<[CC1Option]>,
   HelpText<"Resolve file paths relative to the specified directory">,
   MarshallingInfoString<FileSystemOpts<"WorkingDir">>;
 def working_directory_EQ : Joined<["-"], "working-directory=">, Flags<[CC1Option]>,
   Alias<working_directory>;
 
 // Double dash options, which are usually an alias for one of the previous

clang/include/clang/Driver/Types.def

 TYPE("objective-c++-header",     ObjCXXHeader, PP_ObjCXXHeader, "h",      phases::Preprocess, phases::Precompile)
 TYPE("c++-module",               CXXModule,    PP_CXXModule,    "cppm",   phases::Preprocess, phases::Precompile, phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 TYPE("c++-module-cpp-output",    PP_CXXModule, INVALID,         "iim",    phases::Precompile, phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 
 // Other languages.
 TYPE("ada",                      Ada,          INVALID,         nullptr,  phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 TYPE("assembler",                PP_Asm,       INVALID,         "s",      phases::Assemble, phases::Link)
 TYPE("assembler-with-cpp",       Asm,          PP_Asm,          "S",      phases::Preprocess, phases::Assemble, phases::Link)
-TYPE("f95",                      PP_Fortran,   INVALID,         nullptr,  phases::Compile, phases::Backend, phases::Assemble, phases::Link)
+TYPE("f95",                      PP_Fortran,   INVALID,         "i",      phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 TYPE("f95-cpp-input",            Fortran,      PP_Fortran,      nullptr,  phases::Preprocess, phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 TYPE("java",                     Java,         INVALID,         nullptr,  phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 
 // LLVM IR/LTO types. We define separate types for IR and LTO because LTO
 // outputs should use the standard suffixes.
 TYPE("ir",                       LLVM_IR,      INVALID,         "ll",     phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 TYPE("ir",                       LLVM_BC,      INVALID,         "bc",     phases::Compile, phases::Backend, phases::Assemble, phases::Link)
 TYPE("lto-ir",                   LTO_IR,       INVALID,         "s",      phases::Compile, phases::Backend, phases::Assemble, phases::Link)

flang/test/Driver/driver-help-hidden.f90

 ! CHECK-NEXT: -fintrinsic-modules-path <dir>
 ! CHECK-NEXT:                        Specify where to find the compiled intrinsic modules
 ! CHECK-NEXT: -flang-experimental-exec
 ! CHECK-NEXT:                        Enable support for generating executables (experimental)
 ! CHECK-NEXT: -flarge-sizes          Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! CHECK-NEXT: -flogical-abbreviations Enable logical abbreviations
 ! CHECK-NEXT: -fno-automatic         Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
 ! CHECK-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
+! CHECK-NEXT: -fno-integrated-as     Disable the integrated assembler
 ! CHECK-NEXT: -fopenacc              Enable OpenACC
 ! CHECK-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
 ! CHECK-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
 ! CHECK-NEXT: -help     Display available options
 ! CHECK-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! CHECK-NEXT: -mllvm <value>         Additional arguments to forward to LLVM's option processing
 ! CHECK-NEXT: -mmlir <value>         Additional arguments to forward to MLIR's option processing
 ! CHECK-NEXT: -module-dir <dir>      Put MODULE files in <dir>
 ! CHECK-NEXT: -nocpp                 Disable predefined and command line preprocessor macros
 ! CHECK-NEXT: -o <file> Write output to <file>
 ! CHECK-NEXT: -pedantic              Warn on language extensions
 ! CHECK-NEXT: -print-effective-triple Print the effective target triple
 ! CHECK-NEXT: -print-target-triple    Print the normalized target triple
 ! CHECK-NEXT: -P                     Disable linemarker output in -E mode
+! CHECK-NEXT: -save-temps=<value>    Save intermediate compilation results.
+! CHECK-NEXT: -save-temps            Save intermediate compilation results
 ! CHECK-NEXT: -std=<value>           Language standard to compile for
 ! CHECK-NEXT: -S                     Only run preprocess and compilation steps
 ! CHECK-NEXT: --target=<value>        Generate code for the given target
 ! CHECK-NEXT: -U <macro>             Undefine macro <macro>
 ! CHECK-NEXT: --version Print version information
 ! CHECK-NEXT: -W<warning>            Enable the specified warning
 ! CHECK-NEXT: -Xflang <arg>          Pass <arg> to the flang compiler
 

flang/test/Driver/driver-help.f90

 ! HELP-NEXT: -fimplicit-none        No implicit typing allowed unless overridden by IMPLICIT statements
 ! HELP-NEXT: -finput-charset=<value> Specify the default character set for source files
 ! HELP-NEXT: -fintrinsic-modules-path <dir>
 ! HELP-NEXT:                        Specify where to find the compiled intrinsic modules
 ! HELP-NEXT: -flarge-sizes          Use INTEGER(KIND=8) for the result type in size-related intrinsics
 ! HELP-NEXT: -flogical-abbreviations Enable logical abbreviations
 ! HELP-NEXT: -fno-automatic         Implies the SAVE attribute for non-automatic local objects in subprograms unless RECURSIVE
 ! HELP-NEXT: -fno-color-diagnostics  Disable colors in diagnostics
+! HELP-NEXT: -fno-integrated-as      Disable the integrated assembler
 ! HELP-NEXT: -fopenacc              Enable OpenACC
 ! HELP-NEXT: -fopenmp               Parse OpenMP pragmas and generate parallel code.
 ! HELP-NEXT: -fxor-operator         Enable .XOR. as a synonym of .NEQV.
 ! HELP-NEXT: -help                  Display available options
 ! HELP-NEXT: -I <dir>               Add directory to the end of the list of include search paths
 ! HELP-NEXT: -mllvm <value>         Additional arguments to forward to LLVM's option processing
 ! HELP-NEXT: -mmlir <value>         Additional arguments to forward to MLIR's option processing
 ! HELP-NEXT: -module-dir <dir>      Put MODULE files in <dir>
 ! HELP-NEXT: -nocpp                 Disable predefined and command line preprocessor macros
 ! HELP-NEXT: -o <file>              Write output to <file>
 ! HELP-NEXT: -pedantic              Warn on language extensions
 ! HELP-NEXT: -print-effective-triple Print the effective target triple
 ! HELP-NEXT: -print-target-triple    Print the normalized target triple
 ! HELP-NEXT: -P                     Disable linemarker output in -E mode
+! HELP-NEXT: -save-temps=<value>    Save intermediate compilation results.
+! HELP-NEXT: -save-temps            Save intermediate compilation results
 ! HELP-NEXT: -std=<value>           Language standard to compile for
 ! HELP-NEXT: -S                     Only run preprocess and compilation steps
 ! HELP-NEXT: --target=<value>       Generate code for the given target
 ! HELP-NEXT: -U <macro>             Undefine macro <macro>
 ! HELP-NEXT: --version              Print version information
 ! HELP-NEXT: -W<warning>            Enable the specified warning
 ! HELP-NEXT: -Xflang <arg>          Pass <arg> to the flang compiler
 

flang/test/Driver/fno-integrated-as.f90

+! Tests for the `-fno-integrated-as` flag.
+
+! UNSUPPORTED: system-windows
+
+!--------------------------
+! With `-fno-integrated-as`
+!--------------------------
+! Verify that there _is_ a separate line with an assembler invocation
+! RUN: %flang -c -fno-integrated-as %s -### 2>&1 | FileCheck %s
+! CHECK-LABEL: "-fc1"
+! CHECK-SAME: "-o" "[[assembly_file:.*]].s"
+! CHECK-NEXT: "-o" "{{.*}}.o" "[[assembly_file:.*]].s"
+
+!-----------------------------
+! Without `-fno-integrated-as`
+!-----------------------------
+! Verify that there _is no_ separate line with an assembler invocation
+! RUN: %flang -c %s -### 2>&1 | FileCheck %s -check-prefix=DEFAULT
+! DEFAULT-LABEL: "-fc1"
+! DEFAULT-SAME: "-o" "{{.*}}.o" "{{.*}}fno-integrated-as.f90"

flang/test/Driver/save-temps.f90

+! Tests for the `-save-temps` flag. As `flang` does not implement `-fc1as` (i.e. a driver for the integrated assembler), we need to
+! use `-fno-integrated-as` here.
+
+! UNSUPPORTED: system-windows
+
+!--------------------------
+! Basic case: `-save-temps`
+!--------------------------
+! RUN: %flang -save-temps -fno-integrated-as %s -### 2>&1 | FileCheck %s
+! CHECK: "-o" "save-temps.i"
+! CHECK-NEXT: "-o" "save-temps.bc"
+! CHECK-NEXT: "-o" "save-temps.s"
+! CHECK-NEXT: "-o" "save-temps.o"
+! CHECK-NEXT: "-o" "a.out"
+
+!--------------------------
+! `-save-temps=cwd`
+!--------------------------
+! This should work the same as -save-temps above
+
+! RUN: %flang -save-temps=cwd -fno-integrated-as  %s -### 2>&1 | FileCheck %s -check-prefix=CWD
+! CWD: "-o" "save-temps.i"
+! CWD-NEXT: "-o" "save-temps.bc"
+! CWD-NEXT: "-o" "save-temps.s"
+! CWD-NEXT: "-o" "save-temps.o"
+! CWD-NEXT: "-o" "a.out"
+
+!--------------------------
+! `-save-temps=obj`
+!--------------------------
+! Check that temp files are saved in the same directory as the output file
+! regardless of whether -o is specified.
+
+! RUN: %flang -save-temps=obj -fno-integrated-as -o obj/dir/a.out %s -### 2>&1 | FileCheck %s -check-prefix=CHECK-OBJ
+! CHECK-OBJ: "-o" "obj/dir/save-temps.i"
+! CHECK-OBJ-NEXT: "-o" "obj/dir/save-temps.bc"
+! CHECK-OBJ-NEXT: "-o" "obj/dir/save-temps.s"
+! CHECK-OBJ-NEXT: "-o" "obj/dir/save-temps.o"
+! CHECK-OBJ-NEXT: "-o" "obj/dir/a.out"
+
+! RUN: %flang -save-temps=obj -fno-integrated-as %s -### 2>&1 | FileCheck %s -check-prefix=CHECK-OBJ-NOO
+! CHECK-OBJ-NOO: "-o" "save-temps.i"
+! CHECK-OBJ-NOO-NEXT: "-o" "save-temps.bc"
+! CHECK-OBJ-NOO-NEXT: "-o" "save-temps.s"
+! CHECK-OBJ-NOO-NEXT: "-o" "save-temps.o"
+! CHECK-OBJ-NOO-NEXT: "-o" "a.out"
+
+!--------------------------
+! `-S` without `-save-temps`
+!--------------------------
+! Check for a single `flang -fc1` invocation when NOT using -save-temps.
+! RUN: %flang -S %s -### 2>&1 | FileCheck %s -check-prefix=NO-TEMPS
+! NO-TEMPS: "-fc1"
+! NO-TEMPS-SAME: "-S"
+! NO-TEMPS-SAME: "-o" "save-temps.s"