[ms] [llvm-ml] Add support for nested PROC/ENDP pairs

[epastor]

Summary

This is believed to match behavior by ML.EXE and ML64.EXE.

[thakis]

Test?

[epastor]

Add tests

[epastor]

Add support for case-insensitive PROC/ENDP matching

[thakis]

Thanks!

I wonder if ml allows nested procs to refer to the parameters of the outer proc – then we'd have to handle activation records like gcc creates them for its nested functions.

But we don't even implement parameters for proc at all, so that's moot for now :)

[epastor]

In D131522#3713909, @thakis wrote:

Thanks!

I wonder if ml allows nested procs to refer to the parameters of the outer proc – then we'd have to handle activation records like gcc creates them for its nested functions.

But we don't even implement parameters for proc at all, so that's moot for now :)

"Good" news - if you provide arguments to PROC that would require prologue/epilogue support (even if prologues and epilogues are disabled), nesting is suddenly disallowed. This is true if the arguments are provided to the inner PROC, the outer PROC, or both. So this will never come up... when we add parameter support, we'll just need to block nesting when parameters are provided.

[epastor]

Fix a missing negation

llvm/lib/MC/MCParser/COFFMasmParser.cpp

class COFFMasmParser : public MCAsmParserExtension {
   bool ParseSectionDirectiveUninitializedData(StringRef, SMLoc) {
     return ParseSectionSwitch(".bss",
                               COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA
                             | COFF::IMAGE_SCN_MEM_READ
                             | COFF::IMAGE_SCN_MEM_WRITE,
                               SectionKind::getBSS());
   }
 
-  StringRef CurrentProcedure;
-  bool CurrentProcedureFramed;
+  /// Stack of active procedure definitions.
+  SmallVector<StringRef, 1> CurrentProcedures;
+  SmallVector<bool, 1> CurrentProceduresFramed;
 
 public:
   COFFMasmParser() = default;
 };
 
 } // end anonymous namespace.
 
 bool COFFMasmParser::ParseSectionSwitch(StringRef SectionName,
bool COFFMasmParser::ParseDirectiveProc(StringRef Directive, SMLoc Loc) {
   if (getLexer().is(AsmToken::Identifier) &&
       getTok().getString().equals_insensitive("frame")) {
     Lex();
     Framed = true;
     getStreamer().emitWinCFIStartProc(Sym, Loc);
   }
   getStreamer().emitLabel(Sym, Loc);
 
-  CurrentProcedure = Label;
-  CurrentProcedureFramed = Framed;
+  CurrentProcedures.push_back(Label);
+  CurrentProceduresFramed.push_back(Framed);
   return false;
 }
 bool COFFMasmParser::ParseDirectiveEndProc(StringRef Directive, SMLoc Loc) {
   StringRef Label;
   SMLoc LabelLoc = getTok().getLoc();
   if (getParser().parseIdentifier(Label))
     return Error(LabelLoc, "expected identifier for procedure end");
 
-  if (CurrentProcedure.empty())
+  if (CurrentProcedures.empty())
     return Error(Loc, "endp outside of procedure block");
-  else if (CurrentProcedure != Label)
+  else if (!CurrentProcedures.back().equals_insensitive(Label))
     return Error(LabelLoc, "endp does not match current procedure '" +
-                               CurrentProcedure + "'");
+                               CurrentProcedures.back() + "'");
 
-  if (CurrentProcedureFramed) {
+  if (CurrentProceduresFramed.back()) {
     getStreamer().emitWinCFIEndProc(Loc);
   }
-  CurrentProcedure = "";
-  CurrentProcedureFramed = false;
+  CurrentProcedures.pop_back();
+  CurrentProceduresFramed.pop_back();
   return false;
 }
 
 bool COFFMasmParser::ParseDirectiveAlias(StringRef Directive, SMLoc Loc) {
   std::string AliasName, ActualName;
   if (getTok().isNot(AsmToken::Less) ||
       getParser().parseAngleBracketString(AliasName))
     return Error(getTok().getLoc(), "expected <aliasName>");

llvm/test/tools/llvm-ml/nested_proc.asm

+; RUN: llvm-ml -m32 -filetype=s %s /Fo - | FileCheck %s
+; RUN: llvm-ml -m64 -filetype=s %s /Fo - | FileCheck %s
+
+.code
+
+t1 PROC
+  xor eax, eax
+t1_nested PROC
+  ret
+t1_nested ENDP
+t1 ENDP
+
+; CHECK-LABEL: t1:
+; CHECK: xor eax, eax
+; CHECK: t1_nested:
+; CHECK: ret
+
+t2 PROC
+  xor eax, eax
+t2_nested PROC
+  ret
+T2_nEsTeD ENDP
+t2 ENDP
+
+; CHECK-LABEL: t2:
+; CHECK: xor eax, eax
+; CHECK: t2_nested:
+; CHECK: ret
+
+END

llvm/test/tools/llvm-ml/nested_proc_errors.asm

+; RUN: not llvm-ml -filetype=s %s /Fo - 2>&1 | FileCheck %s --implicit-check-not=error:
+
+.code
+
+t1 PROC
+  xor eax, eax
+t1_nested PROC
+  ret
+t1 ENDP
+t1_nested ENDP
+; CHECK: :[[# @LINE - 2]]:1: error: endp does not match current procedure 't1_nested'
+
+END