Rename EHPersonality::MSVC_Win64SEH to EHPersonality::MSVC_TableSEH. NFC.

[luqmana]

Summary

The types of SEH aren't x86(-32) vs x64 but rather stack-based exception chaining
vs table-based exception handling. x86-32 is the only arch for which Windows
uses the former. 32-bit ARM would use what is called Win64SEH today, which
is a bit confusing so instead let's just rename it to be a bit more clear.

[mstorsjo]

FWIW, definite +1 from me, but I'll let the other reviewers comment as well. There's lots of other cases where things are named "Win64" when it comes to exception handling and unwind info management as well - are you going to clean up that naming as well? And does this imply you're planning on working on ARM unwinding? That'd be awesome.

[compnerd]

The renaming makes sense to me.

[rnk]

My other naming suggestion would be MSVC_SEH_CSpecific, kind of inline with GNU_CXX[_SjLj], and the other would be MSVC_SEH_X86, I suppose. I'm assuming ARM and AArch64 all use a handler called __C_specific_handler?

Seems fine either way.

[mstorsjo]

In D90117#2354170, @rnk wrote:

I'm assuming ARM and AArch64 all use a handler called __C_specific_handler?

Yeah, they do.

[compnerd]

Personally, I think that table based makes more sense, since that is the defining characteristic of the xdata/pdata approach - there is a table that has that information and you look it up (similar to the zero-cost itanium model). This actually mirrors the GNU_CXX_SjLj better - that uses setjmp and longjmp as the mechanism.

[luqmana]

I also think TableSEH is a bit clearer. And yea, I'll try to clean up other similar Win64 cases as I get around.

llvm/include/llvm/Analysis/EHPersonalities.h

enum class EHPersonality {
   Unknown,
   GNU_Ada,
   GNU_C,
   GNU_C_SjLj,
   GNU_CXX,
   GNU_CXX_SjLj,
   GNU_ObjC,
   MSVC_X86SEH,
-  MSVC_Win64SEH,
+  MSVC_TableSEH,
   MSVC_CXX,
   CoreCLR,
   Rust,
   Wasm_CXX
 };
 
 /// See if the given exception handling personality function is one
 /// that we understand.  If so, return a description of it; otherwise return
 /// Unknown.
 EHPersonality classifyEHPersonality(const Value *Pers);
 
 StringRef getEHPersonalityName(EHPersonality Pers);
 
 EHPersonality getDefaultEHPersonality(const Triple &T);
 
 /// Returns true if this personality function catches asynchronous
 /// exceptions.
 inline bool isAsynchronousEHPersonality(EHPersonality Pers) {
   // The two SEH personality functions can catch asynch exceptions. We assume
   // unknown personalities don't catch asynch exceptions.
   switch (Pers) {
   case EHPersonality::MSVC_X86SEH:
-  case EHPersonality::MSVC_Win64SEH:
+  case EHPersonality::MSVC_TableSEH:
     return true;
   default:
     return false;
   }
   llvm_unreachable("invalid enum");
 }
 
 /// Returns true if this is a personality function that invokes
 /// handler funclets (which must return to it).
 inline bool isFuncletEHPersonality(EHPersonality Pers) {
   switch (Pers) {
   case EHPersonality::MSVC_CXX:
   case EHPersonality::MSVC_X86SEH:
-  case EHPersonality::MSVC_Win64SEH:
+  case EHPersonality::MSVC_TableSEH:
   case EHPersonality::CoreCLR:
     return true;
   default:
     return false;
   }
   llvm_unreachable("invalid enum");
 }
 
 /// Returns true if this personality uses scope-style EH IR instructions:
 /// catchswitch, catchpad/ret, and cleanuppad/ret.
 inline bool isScopedEHPersonality(EHPersonality Pers) {
   switch (Pers) {
   case EHPersonality::MSVC_CXX:
   case EHPersonality::MSVC_X86SEH:
-  case EHPersonality::MSVC_Win64SEH:
+  case EHPersonality::MSVC_TableSEH:
   case EHPersonality::CoreCLR:
   case EHPersonality::Wasm_CXX:
     return true;
   default:
     return false;
   }
   llvm_unreachable("invalid enum");
 }

llvm/lib/Analysis/EHPersonalities.cpp

 /// See if the given exception handling personality function is one that we
 /// understand.  If so, return a description of it; otherwise return Unknown.
 EHPersonality llvm::classifyEHPersonality(const Value *Pers) {
   const Function *F =
       Pers ? dyn_cast<Function>(Pers->stripPointerCasts()) : nullptr;
   if (!F)
     return EHPersonality::Unknown;
   return StringSwitch<EHPersonality>(F->getName())
-    .Case("__gnat_eh_personality",     EHPersonality::GNU_Ada)
-    .Case("__gxx_personality_v0",      EHPersonality::GNU_CXX)
-    .Case("__gxx_personality_seh0",    EHPersonality::GNU_CXX)
-    .Case("__gxx_personality_sj0",     EHPersonality::GNU_CXX_SjLj)
-    .Case("__gcc_personality_v0",      EHPersonality::GNU_C)
-    .Case("__gcc_personality_seh0",    EHPersonality::GNU_C)
-    .Case("__gcc_personality_sj0",     EHPersonality::GNU_C_SjLj)
-    .Case("__objc_personality_v0",     EHPersonality::GNU_ObjC)
-    .Case("_except_handler3",          EHPersonality::MSVC_X86SEH)
-    .Case("_except_handler4",          EHPersonality::MSVC_X86SEH)
-    .Case("__C_specific_handler",      EHPersonality::MSVC_Win64SEH)
-    .Case("__CxxFrameHandler3",        EHPersonality::MSVC_CXX)
-    .Case("ProcessCLRException",       EHPersonality::CoreCLR)
-    .Case("rust_eh_personality",       EHPersonality::Rust)
+      .Case("__gnat_eh_personality", EHPersonality::GNU_Ada)
+      .Case("__gxx_personality_v0", EHPersonality::GNU_CXX)
+      .Case("__gxx_personality_seh0", EHPersonality::GNU_CXX)
+      .Case("__gxx_personality_sj0", EHPersonality::GNU_CXX_SjLj)
+      .Case("__gcc_personality_v0", EHPersonality::GNU_C)
+      .Case("__gcc_personality_seh0", EHPersonality::GNU_C)
+      .Case("__gcc_personality_sj0", EHPersonality::GNU_C_SjLj)
+      .Case("__objc_personality_v0", EHPersonality::GNU_ObjC)
+      .Case("_except_handler3", EHPersonality::MSVC_X86SEH)
+      .Case("_except_handler4", EHPersonality::MSVC_X86SEH)
+      .Case("__C_specific_handler", EHPersonality::MSVC_TableSEH)
+      .Case("__CxxFrameHandler3", EHPersonality::MSVC_CXX)
+      .Case("ProcessCLRException", EHPersonality::CoreCLR)
+      .Case("rust_eh_personality", EHPersonality::Rust)
       .Case("__gxx_wasm_personality_v0", EHPersonality::Wasm_CXX)
       .Default(EHPersonality::Unknown);
 }
 
 StringRef llvm::getEHPersonalityName(EHPersonality Pers) {
   switch (Pers) {
   case EHPersonality::GNU_Ada:       return "__gnat_eh_personality";
   case EHPersonality::GNU_CXX:       return "__gxx_personality_v0";
   case EHPersonality::GNU_CXX_SjLj:  return "__gxx_personality_sj0";
   case EHPersonality::GNU_C:         return "__gcc_personality_v0";
   case EHPersonality::GNU_C_SjLj:    return "__gcc_personality_sj0";
   case EHPersonality::GNU_ObjC:      return "__objc_personality_v0";
   case EHPersonality::MSVC_X86SEH:   return "_except_handler3";
-  case EHPersonality::MSVC_Win64SEH: return "__C_specific_handler";
+  case EHPersonality::MSVC_TableSEH:
+    return "__C_specific_handler";
   case EHPersonality::MSVC_CXX:      return "__CxxFrameHandler3";
   case EHPersonality::CoreCLR:       return "ProcessCLRException";
   case EHPersonality::Rust:          return "rust_eh_personality";
   case EHPersonality::Wasm_CXX:      return "__gxx_wasm_personality_v0";
   case EHPersonality::Unknown:       llvm_unreachable("Unknown EHPersonality!");
   }
 
   llvm_unreachable("Invalid EHPersonality!");

llvm/lib/CodeGen/AsmPrinter/WinException.cpp

void WinException::endFunction(const MachineFunction *MF) {
   // that we can emit the right table data.
   if (!isFuncletEHPersonality(Per)) {
     MachineFunction *NonConstMF = const_cast<MachineFunction*>(MF);
     NonConstMF->tidyLandingPads();
   }
 
   endFuncletImpl();
 
-  // endFunclet will emit the necessary .xdata tables for x64 SEH.
-  if (Per == EHPersonality::MSVC_Win64SEH && MF->hasEHFunclets())
+  // endFunclet will emit the necessary .xdata tables for table-based SEH.
+  if (Per == EHPersonality::MSVC_TableSEH && MF->hasEHFunclets())
     return;
 
   if (shouldEmitPersonality || shouldEmitLSDA) {
     Asm->OutStreamer->PushSection();
 
     // Just switch sections to the right xdata section.
     MCSection *XData = Asm->OutStreamer->getAssociatedXDataSection(
         Asm->OutStreamer->getCurrentSectionOnly());
     Asm->OutStreamer->SwitchSection(XData);
 
     // Emit the tables appropriate to the personality function in use. If we
     // don't recognize the personality, assume it uses an Itanium-style LSDA.
-    if (Per == EHPersonality::MSVC_Win64SEH)
+    if (Per == EHPersonality::MSVC_TableSEH)
       emitCSpecificHandlerTable(MF);
     else if (Per == EHPersonality::MSVC_X86SEH)
       emitExceptHandlerTable(MF);
     else if (Per == EHPersonality::MSVC_CXX)
       emitCXXFrameHandler3Table(MF);
     else if (Per == EHPersonality::CoreCLR)
       emitCLRExceptionTable(MF);
     else
if (Per == EHPersonality::MSVC_CXX && shouldEmitPersonality &&
       Asm->OutStreamer->EmitWinEHHandlerData();
 
       // If this is a C++ catch funclet (or the parent function),
       // emit a reference to the LSDA for the parent function.
       StringRef FuncLinkageName = GlobalValue::dropLLVMManglingEscape(F.getName());
       MCSymbol *FuncInfoXData = Asm->OutContext.getOrCreateSymbol(
           Twine("$cppxdata$", FuncLinkageName));
       Asm->OutStreamer->emitValue(create32bitRef(FuncInfoXData), 4);
-    } else if (Per == EHPersonality::MSVC_Win64SEH && MF->hasEHFunclets() &&
+    } else if (Per == EHPersonality::MSVC_TableSEH && MF->hasEHFunclets() &&
                !CurrentFuncletEntry->isEHFuncletEntry()) {
       // Emit an UNWIND_INFO struct describing the prologue.
       Asm->OutStreamer->EmitWinEHHandlerData();
 
       // If this is the parent function in Win64 SEH, emit the LSDA immediately
       // following .seh_handlerdata.
       emitCSpecificHandlerTable(MF);
     } else if (shouldEmitPersonality || shouldEmitLSDA) {

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

static bool isCatchAll(EHPersonality Personality, Constant *TypeInfo) {
   case EHPersonality::GNU_Ada:
     // While __gnat_all_others_value will match any Ada exception, it doesn't
     // match foreign exceptions (or didn't, before gcc-4.7).
     return false;
   case EHPersonality::GNU_CXX:
   case EHPersonality::GNU_CXX_SjLj:
   case EHPersonality::GNU_ObjC:
   case EHPersonality::MSVC_X86SEH:
-  case EHPersonality::MSVC_Win64SEH:
+  case EHPersonality::MSVC_TableSEH:
   case EHPersonality::MSVC_CXX:
   case EHPersonality::CoreCLR:
   case EHPersonality::Wasm_CXX:
     return TypeInfo->isNullValue();
   }
   llvm_unreachable("invalid enum");
 }