[WebAssembly] Let users know that wasm64 does not exist

[sunfish]

Would it be better to do this check in LLVM, in the backend, with a report_fatal_error?

Clang for its part already supports what we expect wasm64 will need already, and we have a bunch of tests for it, so it'd be nice to keep that code around and tested. And, doing the check in the LLVM backend also means we'll catch users trying to use it from languages other than C/C++.

[aheejin]

+1 on erroring out on the backend side. And how about "wasm64 is not supported"? wasm64... is still a registered target in the frontend, so...

[tlively]

It sounds reasonable to check this from the backend instead.

[tlively]

Closing in favor of D68254.

clang/include/clang/Basic/DiagnosticDriverKinds.td

def err_drv_unknown_stdin_type_clang_cl : Error<
   "use /Tc or /Tp to set input type for standard input">;
 def err_drv_unknown_language : Error<"language not recognized: '%0'">;
 def err_drv_invalid_arch_name : Error<
   "invalid arch name '%0'">;
 def err_drv_invalid_riscv_arch_name : Error<
   "invalid arch name '%0', %1">;
 def err_drv_invalid_riscv_ext_arch_name : Error<
   "invalid arch name '%0', %1 '%2'">;
+def err_drv_invalid_wasm_arch_name : Error<
+  "wasm64 does not exist">;
 def warn_drv_avr_mcu_not_specified : Warning<
   "no target microcontroller specified on command line, cannot "
   "link standard libraries, please pass -mmcu=<mcu name>">,
   InGroup<AVRRtlibLinkingQuirks>;
 def warn_drv_avr_gcc_not_found: Warning<
   "no avr-gcc installation can be found on the system, "
   "cannot link standard libraries">,
   InGroup<AVRRtlibLinkingQuirks>;

clang/lib/Driver/ToolChains/WebAssembly.cpp

 }
 
 WebAssembly::WebAssembly(const Driver &D, const llvm::Triple &Triple,
                          const llvm::opt::ArgList &Args)
     : ToolChain(D, Triple, Args) {
 
   assert(Triple.isArch32Bit() != Triple.isArch64Bit());
 
+  if (Triple.isArch64Bit())
+    getDriver().Diag(diag::err_drv_invalid_wasm_arch_name);
+
   getProgramPaths().push_back(getDriver().getInstalledDir());
 
   if (getTriple().getOS() == llvm::Triple::UnknownOS) {
     // Theoretically an "unknown" OS should mean no standard libraries, however
     // it could also mean that a custom set of libraries is in use, so just add
     // /lib to the search path. Disable multiarch in this case, to discourage
     // paths containing "unknown" from acquiring meanings.
     getFilePaths().push_back(getDriver().SysRoot + "/lib");

clang/test/Preprocessor/wasm-target-features.c

-// RUN: %clang -E -dM %s -o - 2>&1 \
+// RUN: not %clang -E -dM %s -o - 2>&1 \
+// RUN:     -target wasm64-unknown-unknown \
+// RUN:   | FileCheck %s -check-prefix=WASM64
+//
+// WASM64: wasm64 does not exist
+
+// RUN: %clang -E -dM %s -o - 2>&1                   \
 // RUN:     -target wasm32-unknown-unknown -msimd128 \
 // RUN:   | FileCheck %s -check-prefix=SIMD128
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -msimd128 \
-// RUN:   | FileCheck %s -check-prefix=SIMD128
 //
 // SIMD128:#define __wasm_simd128__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -munimplemented-simd128 \
 // RUN:   | FileCheck %s -check-prefix=SIMD128-UNIMPLEMENTED
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -munimplemented-simd128 \
-// RUN:   | FileCheck %s -check-prefix=SIMD128-UNIMPLEMENTED
 //
 // SIMD128-UNIMPLEMENTED:#define __wasm_unimplemented_simd128__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mnontrapping-fptoint \
 // RUN:   | FileCheck %s -check-prefix=NONTRAPPING-FPTOINT
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mnontrapping-fptoint \
-// RUN:   | FileCheck %s -check-prefix=NONTRAPPING-FPTOINT
 //
 // NONTRAPPING-FPTOINT:#define __wasm_nontrapping_fptoint__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -msign-ext \
 // RUN:   | FileCheck %s -check-prefix=SIGN-EXT
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -msign-ext \
-// RUN:   | FileCheck %s -check-prefix=SIGN-EXT
 //
 // SIGN-EXT:#define __wasm_sign_ext__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mexception-handling \
 // RUN:   | FileCheck %s -check-prefix=EXCEPTION-HANDLING
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mexception-handling \
-// RUN:   | FileCheck %s -check-prefix=EXCEPTION-HANDLING
 //
 // EXCEPTION-HANDLING:#define __wasm_exception_handling__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mbulk-memory \
 // RUN:   | FileCheck %s -check-prefix=BULK-MEMORY
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mbulk-memory \
-// RUN:   | FileCheck %s -check-prefix=BULK-MEMORY
 //
 // BULK-MEMORY:#define __wasm_bulk_memory__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -matomics \
 // RUN:   | FileCheck %s -check-prefix=ATOMICS
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -matomics \
-// RUN:   | FileCheck %s -check-prefix=ATOMICS
 //
 // ATOMICS:#define __wasm_atomics__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -pthread \
 // RUN:   | FileCheck %s -check-prefix=PTHREAD
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -pthread \
-// RUN:   | FileCheck %s -check-prefix=PTHREAD
 //
 // PTHREAD:#define __wasm_atomics__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mmutable-globals \
 // RUN:   | FileCheck %s -check-prefix=MUTABLE-GLOBALS
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mmutable-globals \
-// RUN:   | FileCheck %s -check-prefix=MUTABLE-GLOBALS
 //
 // MUTABLE-GLOBALS:#define __wasm_mutable_globals__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mmultivalue \
 // RUN:   | FileCheck %s -check-prefix=MULTIVALUE
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mmultivalue \
-// RUN:   | FileCheck %s -check-prefix=MULTIVALUE
 //
 // MULTIVALUE:#define __wasm_multivalue__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mtail-call \
 // RUN:   | FileCheck %s -check-prefix=TAIL-CALL
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mtail-call \
-// RUN:   | FileCheck %s -check-prefix=TAIL-CALL
 //
 // TAIL-CALL:#define __wasm_tail_call__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=mvp \
 // RUN:   | FileCheck %s -check-prefix=MVP
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mcpu=mvp \
-// RUN:   | FileCheck %s -check-prefix=MVP
 //
 // MVP-NOT:#define __wasm_simd128__
 // MVP-NOT:#define __wasm_unimplemented_simd128__
 // MVP-NOT:#define __wasm_nontrapping_fptoint__
 // MVP-NOT:#define __wasm_sign_ext__
 // MVP-NOT:#define __wasm_exception_handling__
 // MVP-NOT:#define __wasm_bulk_memory__
 // MVP-NOT:#define __wasm_atomics__
 // MVP-NOT:#define __wasm_mutable_globals__
 // MVP-NOT:#define __wasm_multivalue__
 // MVP-NOT:#define __wasm_tail_call__
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=bleeding-edge \
 // RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mcpu=bleeding-edge \
-// RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE
 //
 // BLEEDING-EDGE-DAG:#define __wasm_nontrapping_fptoint__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_sign_ext__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_simd128__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_atomics__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_mutable_globals__ 1{{$}}
 // BLEEDING-EDGE-NOT:#define __wasm_unimplemented_simd128__ 1{{$}}
 // BLEEDING-EDGE-NOT:#define __wasm_multivalue__ 1{{$}}
 // BLEEDING-EDGE-NOT:#define __wasm_tail_call__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=bleeding-edge -mno-simd128 \
 // RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE-NO-SIMD128
-// RUN: %clang -E -dM %s -o - 2>&1 \
-// RUN:     -target wasm64-unknown-unknown -mcpu=bleeding-edge -mno-simd128 \
-// RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE-NO-SIMD128
 //
 // BLEEDING-EDGE-NO-SIMD128-NOT:#define __wasm_simd128__