[Clang] Rework creating offloading toolchains (#125556)

Summary:
This patch reworks how we create offloading toolchains. Previously we
would handle this separately for all the different kinds. This patch
instead changes this to use the target triple and the offloading kind to
determine the proper toolchain. In the old case where the user only
passes `--offload-arch` we instead infer the triple from the passed
arguments. This is a pretty major overhaul but currently passes all the
clang tests with only minor changes to error messages.

Author: jhuber6

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -116,6 +116,8 @@ def err_drv_cuda_host_arch : Error<
   "unsupported architecture '%0' for host compilation">;
 def err_drv_mix_cuda_hip : Error<
   "mixed CUDA and HIP compilation is not supported">;
+def err_drv_mix_offload : Error<
+  "mixed %0 and %1 offloading compilation is not supported">;
 def err_drv_bad_target_id : Error<
   "invalid target ID '%0'; format is a processor name followed by an optional "
   "colon-delimited list of features followed by an enable/disable sign (e.g., "

clang/include/clang/Driver/Driver.h

@@ -355,6 +355,9 @@ class Driver {
   phases::ID getFinalPhase(const llvm::opt::DerivedArgList &DAL,
                            llvm::opt::Arg **FinalPhaseArg = nullptr) const;
 
+  llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
+  executeProgram(llvm::ArrayRef<llvm::StringRef> Args) const;
+
 private:
   /// Certain options suppress the 'no input files' warning.
   LLVM_PREFERRED_TYPE(bool)
@@ -367,10 +370,6 @@ class Driver {
   /// stored in it, and will clean them up when torn down.
   mutable llvm::StringMap<std::unique_ptr<ToolChain>> ToolChains;
 
-  /// The associated offloading architectures with each toolchain.
-  llvm::DenseMap<const ToolChain *, llvm::SmallVector<llvm::StringRef>>
-      OffloadArchs;
-
 private:
   /// TranslateInputArgs - Create a new derived argument list from the input
   /// arguments, after applying the standard argument translations.
@@ -537,8 +536,7 @@ class Driver {
   /// empty string.
   llvm::SmallVector<StringRef>
   getOffloadArchs(Compilation &C, const llvm::opt::DerivedArgList &Args,
-                  Action::OffloadKind Kind, const ToolChain *TC,
-                  bool SpecificToolchain = true) const;
+                  Action::OffloadKind Kind, const ToolChain &TC) const;
 
   /// Check that the file referenced by Value exists. If it doesn't,
   /// issue a diagnostic and return false.

clang/include/clang/Driver/Options.td

@@ -1156,7 +1156,7 @@ def offload_arch_EQ : CommaJoined<["--"], "offload-arch=">,
            "If 'native' is used the compiler will detect locally installed architectures. "
            "For HIP offloading, the device architecture can be followed by target ID features "
            "delimited by a colon (e.g. gfx908:xnack+:sramecc-). May be specified more than once.">;
-def no_offload_arch_EQ : Joined<["--"], "no-offload-arch=">,
+def no_offload_arch_EQ : CommaJoined<["--"], "no-offload-arch=">,
   Visibility<[ClangOption, FlangOption]>,
   HelpText<"Remove CUDA/HIP offloading device architecture (e.g. sm_35, gfx906) from the list of devices to compile for. "
            "'all' resets the list to its default value.">;
@@ -1624,7 +1624,7 @@ defm auto_import : BoolFOption<"auto-import",
 // In the future this option will be supported by other offloading
 // languages and accept other values such as CPU/GPU architectures,
 // offload kinds and target aliases.
-def offload_EQ : CommaJoined<["--"], "offload=">, Flags<[NoXarchOption]>,
+def offload_EQ : CommaJoined<["--"], "offload=">, Flags<[NoXarchOption]>, Alias<offload_targets_EQ>,
   HelpText<"Specify comma-separated list of offloading target triples (CUDA and HIP only)">;
 
 // C++ Coroutines

clang/include/clang/Driver/ToolChain.h

@@ -202,10 +202,6 @@ class ToolChain {
   ToolChain(const Driver &D, const llvm::Triple &T,
             const llvm::opt::ArgList &Args);
 
-  /// Executes the given \p Executable and returns the stdout.
-  llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
-  executeToolChainProgram(StringRef Executable) const;
-
   void setTripleEnvironment(llvm::Triple::EnvironmentType Env);
 
   virtual Tool *buildAssembler() const;