IR: Change inalloca's grammar a bit

The grammar for LLVM IR is not well specified in any document but seems
to obey the following rules:

 - Attributes which have parenthesized arguments are never preceded by
   commas.  This form of attribute is the only one which ever has
   optional arguments.  However, not all of these attributes support
   optional arguments: 'thread_local' supports an optional argument but
   'addrspace' does not.  Interestingly, 'addrspace' is documented as
   being a "qualifier".  What constitutes a qualifier?  I cannot find a
   definition.

 - Some attributes use a space between the keyword and the value.
   Examples of this form are 'align' and 'section'.  These are always
   preceded by a comma.

 - Otherwise, the attribute has no argument.  These attributes do not
   have a preceding comma.

Sometimes an attribute goes before the instruction, between the
instruction and it's type, or after it's type.  'atomicrmw' has
'volatile' between the instruction and the type while 'call' has 'tail'
preceding the instruction.

With all this in mind, it seems most consistent for 'inalloca' on an
'inalloca' instruction to occur before between the instruction and the
type.  Unlike the current formulation, there would be no preceding
comma.  The combination 'alloca inalloca' doesn't look particularly
appetizing, perhaps a better spelling of 'inalloca' is down the road.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203376 91177308-0d34-0410-b5e6-96231b3b80d8

lib/AsmParser/LLParser.cpp

@@ -707,7 +707,8 @@ bool LLParser::ParseAlias(const std::string &Name, LocTy NameLoc,
 ///       OptionalThreadLocal OptionalAddrSpace OptionalUnNammedAddr
 ///       OptionalExternallyInitialized GlobalType Type Const
 ///
-/// Everything through visibility has been parsed already.
+/// Everything up to and including OptionalDLLStorageClass has been parsed
+/// already.
 ///
 bool LLParser::ParseGlobal(const std::string &Name, LocTy NameLoc,
                            unsigned Linkage, bool HasLinkage,
@@ -4071,33 +4072,27 @@ bool LLParser::ParseCall(Instruction *&Inst, PerFunctionState &PFS,
 //===----------------------------------------------------------------------===//
 
 /// ParseAlloc
-///   ::= 'alloca' Type (',' 'inalloca')? (',' TypeAndValue)? (',' OptionalInfo)?
+///   ::= 'alloca' 'inalloca'? Type (',' TypeAndValue)? (',' 'align' i32)?
 int LLParser::ParseAlloc(Instruction *&Inst, PerFunctionState &PFS) {
   Value *Size = 0;
   LocTy SizeLoc;
   unsigned Alignment = 0;
-  bool IsInAlloca = false;
   Type *Ty = 0;
+
+  bool IsInAlloca = EatIfPresent(lltok::kw_inalloca);
+
   if (ParseType(Ty)) return true;
 
   bool AteExtraComma = false;
   if (EatIfPresent(lltok::comma)) {
-    bool HaveComma = true;
-    if (EatIfPresent(lltok::kw_inalloca)) {
-      IsInAlloca = true;
-      HaveComma = EatIfPresent(lltok::comma);
-    }
-
-    if (HaveComma) {
-      if (Lex.getKind() == lltok::kw_align) {
-        if (ParseOptionalAlignment(Alignment)) return true;
-      } else if (Lex.getKind() == lltok::MetadataVar) {
-        AteExtraComma = true;
-      } else {
-        if (ParseTypeAndValue(Size, SizeLoc, PFS) ||
-            ParseOptionalCommaAlign(Alignment, AteExtraComma))
-          return true;
-      }
+    if (Lex.getKind() == lltok::kw_align) {
+      if (ParseOptionalAlignment(Alignment)) return true;
+    } else if (Lex.getKind() == lltok::MetadataVar) {
+      AteExtraComma = true;
+    } else {
+      if (ParseTypeAndValue(Size, SizeLoc, PFS) ||
+          ParseOptionalCommaAlign(Alignment, AteExtraComma))
+        return true;
     }
   }