clang: Forward exception_model flag for bitcode inputs (#146342)

This will enable removal of a hack from the wasm backend
in a future change.

This feels unnecessarily clunky. I would assume something was
automatically parsing this and propagating it in the C++ case,
but I can't seem to find it. In particular it feels wrong that
I need to parse out the individual values, given they are listed
in the options.td file. We should also be parsing and forwarding
every flag that corresponds to something else in TargetOptions,
which requires auditing.

Author: arsenm

clang/lib/Frontend/CompilerInvocation.cpp

@@ -3679,6 +3679,22 @@ static StringRef GetInputKindName(InputKind IK) {
   llvm_unreachable("unknown input language");
 }
 
+static StringRef getExceptionHandlingName(unsigned EHK) {
+  switch (static_cast<LangOptions::ExceptionHandlingKind>(EHK)) {
+  case LangOptions::ExceptionHandlingKind::None:
+  default:
+    return "none";
+  case LangOptions::ExceptionHandlingKind::SjLj:
+    return "sjlj";
+  case LangOptions::ExceptionHandlingKind::DwarfCFI:
+    return "dwarf";
+  case LangOptions::ExceptionHandlingKind::Wasm:
+    return "wasm";
+  }
+
+  llvm_unreachable("covered switch");
+}
+
 void CompilerInvocationBase::GenerateLangArgs(const LangOptions &Opts,
                                               ArgumentConsumer Consumer,
                                               const llvm::Triple &T,
@@ -3694,6 +3710,10 @@ void CompilerInvocationBase::GenerateLangArgs(const LangOptions &Opts,
       GenerateArg(Consumer, OPT_pic_is_pie);
     for (StringRef Sanitizer : serializeSanitizerKinds(Opts.Sanitize))
       GenerateArg(Consumer, OPT_fsanitize_EQ, Sanitizer);
+    if (Opts.ExceptionHandling) {
+      GenerateArg(Consumer, OPT_exception_model,
+                  getExceptionHandlingName(Opts.ExceptionHandling));
+    }
 
     return;
   }
@@ -4002,6 +4022,24 @@ bool CompilerInvocation::ParseLangArgs(LangOptions &Opts, ArgList &Args,
     parseSanitizerKinds("-fsanitize=", Args.getAllArgValues(OPT_fsanitize_EQ),
                         Diags, Opts.Sanitize);
 
+    if (const Arg *A = Args.getLastArg(options::OPT_exception_model)) {
+      std::optional<LangOptions::ExceptionHandlingKind> EMValue =
+          llvm::StringSwitch<std::optional<LangOptions::ExceptionHandlingKind>>(
+              A->getValue())
+              .Case("dwarf", LangOptions::ExceptionHandlingKind::DwarfCFI)
+              .Case("sjlj", LangOptions::ExceptionHandlingKind::SjLj)
+              .Case("wineh", LangOptions::ExceptionHandlingKind::WinEH)
+              .Case("wasm", LangOptions::ExceptionHandlingKind::Wasm)
+              .Case("none", LangOptions::ExceptionHandlingKind::None)
+              .Default(std::nullopt);
+      if (EMValue) {
+        Opts.ExceptionHandling = static_cast<unsigned>(*EMValue);
+      } else {
+        Diags.Report(diag::err_drv_invalid_value)
+            << A->getAsString(Args) << A->getValue();
+      }
+    }
+
     return Diags.getNumErrors() == NumErrorsBefore;
   }
 

clang/test/CodeGen/WebAssembly/wasm-exception-model-flag-parse-ir-input.ll

@@ -0,0 +1,16 @@
+; REQUIRES: webassembly-registered-target
+
+; Check all the options parse
+; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=none %s | FileCheck %s
+; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=wasm %s | FileCheck %s
+; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=dwarf %s | FileCheck %s
+; RUN: %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=sjlj %s | FileCheck %s
+
+; RUN: not %clang_cc1 -triple wasm32 -o - -emit-llvm -exception-model=invalid %s 2>&1 | FileCheck -check-prefix=ERR %s
+
+; CHECK-LABEL: define void @test(
+
+; ERR: error: invalid value 'invalid' in '-exception-model=invalid'
+define void @test() {
+  ret void
+}

clang/test/CodeGen/WebAssembly/wasm-invalid-exception-kinds.ll

@@ -0,0 +1,8 @@
+; RUN: not %clang_cc1 -triple wasm32 -exception-model=arst -S %s 2>&1 | FileCheck -check-prefix=INVALID-VALUE %s
+
+; Make sure invalid values are rejected for -exception-model when the
+; input is IR.
+
+; INVALID-VALUE: error: invalid value 'arst' in '-exception-model=arst'
+
+target triple = "wasm32"

clang/test/Driver/ir-exception-model.c

@@ -0,0 +1,14 @@
+// RUN: %clang -### -target wasm32-unknown-unknown -fwasm-exceptions -c -S -o - %S/Inputs/file.ll 2>&1 | FileCheck %s
+// RUN: %clang -### -target wasm32-unknown-unknown -Xclang -exception-model=wasm -c -S -o - %S/Inputs/file.ll 2>&1 | FileCheck %s
+// RUN: %clang -### -target wasm32-unknown-unknown -Xclang -exception-model=dwarf -c -S -o - %S/Inputs/file.ll 2>&1 | FileCheck -check-prefix=DWARF %s
+// RUN: %clang -### -target wasm32-unknown-unknown -Xclang -exception-model=sjlj -c -S -o - %S/Inputs/file.ll 2>&1 | FileCheck -check-prefix=SJLJ %s
+// RUN: %clang -### -target wasm32-unknown-unknown -Xclang -exception-model=wineh -c -S -o - %S/Inputs/file.ll 2>&1 | FileCheck -check-prefix=WINEH %s
+// RUN: %clang -### -target wasm32-unknown-unknown -Xclang -exception-model=arst -c -S -o - %S/Inputs/file.ll 2>&1 | FileCheck -check-prefix=INVALID %s
+
+// Check that -fwasm-exceptions propagates -exception-model to cc1
+
+// CHECK: "-exception-model=wasm"
+// DWARF: "-exception-model=dwarf"
+// SJLJ: "-exception-model=sjlj"
+// WINEH: "-exception-model=wineh"
+// INVALID: "-exception-model=arst"