[codeview] Add .cv_string directive for testing purposes

The main use case for this directive is to allow assembly writers to
write their own FPO data strings without going through the .cv_fpo*
directive family.

I'm experimenting with different RPN programs to fix PR38857, and I
figured I should go ahead and make this directive permanent.

llvm-svn: 341712

llvm/lib/MC/MCParser/AsmParser.cpp

@@ -467,6 +467,7 @@ private:
     DK_CV_INLINE_LINETABLE,
     DK_CV_DEF_RANGE,
     DK_CV_STRINGTABLE,
+    DK_CV_STRING,
     DK_CV_FILECHECKSUMS,
     DK_CV_FILECHECKSUM_OFFSET,
     DK_CV_FPO_DATA,
@@ -538,7 +539,7 @@ private:
   bool parseDirectiveStabs();
 
   // ".cv_file", ".cv_func_id", ".cv_inline_site_id", ".cv_loc", ".cv_linetable",
-  // ".cv_inline_linetable", ".cv_def_range"
+  // ".cv_inline_linetable", ".cv_def_range", ".cv_string"
   bool parseDirectiveCVFile();
   bool parseDirectiveCVFuncId();
   bool parseDirectiveCVInlineSiteId();
@@ -546,6 +547,7 @@ private:
   bool parseDirectiveCVLinetable();
   bool parseDirectiveCVInlineLinetable();
   bool parseDirectiveCVDefRange();
+  bool parseDirectiveCVString();
   bool parseDirectiveCVStringTable();
   bool parseDirectiveCVFileChecksums();
   bool parseDirectiveCVFileChecksumOffset();
@@ -2029,6 +2031,8 @@ bool AsmParser::parseStatement(ParseStatementInfo &Info,
       return parseDirectiveCVInlineLinetable();
     case DK_CV_DEF_RANGE:
       return parseDirectiveCVDefRange();
+    case DK_CV_STRING:
+      return parseDirectiveCVString();
     case DK_CV_STRINGTABLE:
       return parseDirectiveCVStringTable();
     case DK_CV_FILECHECKSUMS:
@@ -3813,6 +3817,20 @@ bool AsmParser::parseDirectiveCVDefRange() {
   return false;
 }
 
+/// parseDirectiveCVString
+/// ::= .cv_stringtable "string"
+bool AsmParser::parseDirectiveCVString() {
+  std::string Data;
+  if (checkForValidSection() || parseEscapedString(Data))
+    return addErrorSuffix(" in '.cv_string' directive");
+
+  // Put the string in the table and emit the offset.
+  std::pair<StringRef, unsigned> Insertion =
+      getCVContext().addToStringTable(Data);
+  getStreamer().EmitIntValue(Insertion.second, 4);
+  return false;
+}
+
 /// parseDirectiveCVStringTable
 /// ::= .cv_stringtable
 bool AsmParser::parseDirectiveCVStringTable() {
@@ -5238,6 +5256,7 @@ void AsmParser::initializeDirectiveKindMap() {
   DirectiveKindMap[".cv_inline_linetable"] = DK_CV_INLINE_LINETABLE;
   DirectiveKindMap[".cv_inline_site_id"] = DK_CV_INLINE_SITE_ID;
   DirectiveKindMap[".cv_def_range"] = DK_CV_DEF_RANGE;
+  DirectiveKindMap[".cv_string"] = DK_CV_STRING;
   DirectiveKindMap[".cv_stringtable"] = DK_CV_STRINGTABLE;
   DirectiveKindMap[".cv_filechecksums"] = DK_CV_FILECHECKSUMS;
   DirectiveKindMap[".cv_filechecksumoffset"] = DK_CV_FILECHECKSUM_OFFSET;

llvm/test/MC/COFF/cv-string.s

@@ -0,0 +1,69 @@
+# RUN: llvm-mc -triple=i686-windows-msvc %s -filetype=obj -o %t.obj
+# RUN: llvm-readobj -codeview %t.obj | FileCheck %s
+
+# The .cv_string directive mainly exists as a convenience for manually writing
+# FPO data in assembler. Test that we can write FPO data using this directive,
+# and that the string comes out in the dumper.
+
+# void g(int);
+# void f(int x) {
+#   g(x+1);
+# }
+
+# CHECK: FrameFunc [
+# CHECK-NEXT: abc =
+# CHECK-NEXT: def =
+# CHECK-NEXT: ghi =
+# CHECK-NEXT: ]
+
+	.text
+	.def	 @feat.00;
+	.scl	3;
+	.type	0;
+	.endef
+	.globl	@feat.00
+.set @feat.00, 1
+	.def	 _f;
+	.scl	2;
+	.type	32;
+	.endef
+	.globl	_f                      # -- Begin function f
+	.p2align	4, 0x90
+_f:                                     # @f
+Lfunc_begin0:
+# %bb.0:                                # %entry
+	pushl	%ebp
+	movl	%esp, %ebp
+	subl	$8, %esp
+	movl	8(%ebp), %eax
+	movl	8(%ebp), %ecx
+	addl	$1, %ecx
+	movl	%ecx, (%esp)
+	movl	%eax, -4(%ebp)          # 4-byte Spill
+	calll	_g
+	addl	$8, %esp
+	popl	%ebp
+	retl
+Lfunc_end0:
+                                        # -- End function
+	.section	.debug$S,"dr"
+	.p2align	2
+	.long	4                       # Debug section magic
+
+	# Open coded frame data
+	.long	245
+	.long	Lfoo_fpo_end-Lfoo_fpo_begin           # Subsection size
+Lfoo_fpo_begin:
+	.long _f
+	.long 0
+	.long Lfunc_end0-Lfunc_begin0
+	.long 24 # LocalSize
+	.long 0 # ParamSize
+	.long 0 # MaxStackSize
+	.cv_string "abc = def = ghi = "
+	.short 0 # PrologSize
+	.short 0 # SavedRegSize
+	.long 0x4 # Flags
+Lfoo_fpo_end:
+	.p2align	2
+	.cv_stringtable                 # String table