From bc3b27ccd964df7627ecff4a62715ff72f1c4a7f Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Sat, 12 May 2012 11:21:46 +0000
Subject: [PATCH] AsmParser: Add support for the .purgem directive.

Based on a patch by Team PaX.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@156709 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/MC/MCParser/AsmParser.cpp | 23 +++++++++++++++++++++++
 test/MC/AsmParser/purgem.s    | 12 ++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 test/MC/AsmParser/purgem.s

diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 8ac0fd244c0..109ce5b4f24 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -336,6 +336,7 @@ public:
     AddDirectiveHandler<&GenericAsmParser::ParseDirectiveMacro>(".macro");
     AddDirectiveHandler<&GenericAsmParser::ParseDirectiveEndMacro>(".endm");
     AddDirectiveHandler<&GenericAsmParser::ParseDirectiveEndMacro>(".endmacro");
+    AddDirectiveHandler<&GenericAsmParser::ParseDirectivePurgeMacro>(".purgem");
 
     AddDirectiveHandler<&GenericAsmParser::ParseDirectiveLEB128>(".sleb128");
     AddDirectiveHandler<&GenericAsmParser::ParseDirectiveLEB128>(".uleb128");
@@ -367,6 +368,7 @@ public:
   bool ParseDirectiveMacrosOnOff(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveMacro(StringRef, SMLoc DirectiveLoc);
   bool ParseDirectiveEndMacro(StringRef, SMLoc DirectiveLoc);
+  bool ParseDirectivePurgeMacro(StringRef, SMLoc DirectiveLoc);
 
   bool ParseDirectiveLEB128(StringRef, SMLoc);
 };
@@ -3083,6 +3085,27 @@ bool GenericAsmParser::ParseDirectiveEndMacro(StringRef Directive,
                   "no current macro definition");
 }
 
+/// ParseDirectivePurgeMacro
+/// ::= .purgem
+bool GenericAsmParser::ParseDirectivePurgeMacro(StringRef Directive,
+                                                SMLoc DirectiveLoc) {
+  StringRef Name;
+  if (getParser().ParseIdentifier(Name))
+    return TokError("expected identifier in '.purgem' directive");
+
+  if (getLexer().isNot(AsmToken::EndOfStatement))
+    return TokError("unexpected token in '.purgem' directive");
+
+  StringMap<Macro*>::iterator I = getParser().MacroMap.find(Name);
+  if (I == getParser().MacroMap.end())
+    return Error(DirectiveLoc, "macro '" + Name + "' is not defined");
+
+  // Undefine the macro.
+  delete I->getValue();
+  getParser().MacroMap.erase(I);
+  return false;
+}
+
 bool GenericAsmParser::ParseDirectiveLEB128(StringRef DirName, SMLoc) {
   getParser().CheckForValidSection();
 
diff --git a/test/MC/AsmParser/purgem.s b/test/MC/AsmParser/purgem.s
new file mode 100644
index 00000000000..46004eeda38
--- /dev/null
+++ b/test/MC/AsmParser/purgem.s
@@ -0,0 +1,12 @@
+# RUN: not llvm-mc -triple i386-unknown-unknown %s |& FileCheck %s
+
+.macro foo
+.err
+.endm
+
+.purgem bar
+# CHECK: error: macro 'bar' is not defined
+
+.purgem foo
+foo
+# CHECK: error: invalid instruction mnemonic 'foo'