Keep empty assembly macro argument values in the middle of the list.

Empty macro arguments at the end of the list should be as-if not specified at
all, but those in the middle of the list need to be kept so as not to screw
up the positional numbering. E.g.:
.macro foo
foo_-bash___:
  nop
.endm

foo 1, 2, 3, 4
foo 1, , 3, 4

Should create two labels, "foo_1_2_3_4" and "foo_1__3_4".

rdar://11948769

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161002 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 20 insertions, 2 deletions

diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 2daad0a851..4985bd5125 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -1597,8 +1597,8 @@ bool AsmParser::ParseMacroArguments(const Macro *M,
     if (ParseMacroArgument(MA))
       return true;
 
-    if (!MA.empty())
-      A.push_back(MA);
+    A.push_back(MA);
+
     if (Lexer.is(AsmToken::EndOfStatement))
       return false;
 
@@ -1619,6 +1619,12 @@ bool AsmParser::HandleMacroEntry(StringRef Name, SMLoc NameLoc,
   if (ParseMacroArguments(M, MacroArguments))
     return true;
 
+  // Remove any trailing empty arguments. Do this after-the-fact as we have
+  // to keep empty arguments in the middle of the list or positionality
+  // gets off. e.g.,  "foo 1, , 2" vs. "foo 1, 2,"
+  while (!MacroArguments.empty() && MacroArguments.back().empty())
+    MacroArguments.pop_back();
+
   // Macro instantiation is lexical, unfortunately. We construct a new buffer
   // to hold the macro body with substitutions.
   SmallString<256> Buf;
diff --git a/test/MC/AsmParser/macro-args.s b/test/MC/AsmParser/macro-args.s
index 13b197a55a..6d084213e4 100644
--- a/test/MC/AsmParser/macro-args.s
+++ b/test/MC/AsmParser/macro-args.s
@@ -42,3 +42,15 @@ top bar, 42
 // CHECK-NOT: fred
 // CHECK: _bar
 // CHECK-NEXT: fred = 42
+
+
+.macro foo
+foo_$0_$1_$2_$3:
+  nop
+.endm
+
+foo 1, 2, 3, 4
+foo 1, , 3, 4
+
+// CHECK: foo_1_2_3_4:
+// CHECK: foo_1__3_4: