Reapply r179115, but use parsePrimaryExpression a little more judiciously.

Test cases that regressed due to r179115, plus a few more, were added in
r179182.  Original commit message below:

[ms-inline asm] Use parsePrimaryExpr in lieu of parseExpression if we need to
parse an identifier.  Otherwise, parseExpression may parse multiple tokens,
which makes it impossible to properly compute an immediate displacement.
An example of such a case is the source operand (i.e., [Symbol + ImmDisp]) in
the below example:

 __asm mov eax, [Symbol + ImmDisp]

Part of rdar://13611297

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179187 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 15 insertions, 3 deletions

diff --git a/include/llvm/MC/MCParser/MCAsmParser.h b/include/llvm/MC/MCParser/MCAsmParser.h
index d7e3902ac4..601f8f7734 100644
--- a/include/llvm/MC/MCParser/MCAsmParser.h
+++ b/include/llvm/MC/MCParser/MCAsmParser.h
@@ -151,6 +151,13 @@ public:
   virtual bool parseExpression(const MCExpr *&Res, SMLoc &EndLoc) = 0;
   bool parseExpression(const MCExpr *&Res);
 
+  /// parsePrimaryExpr - Parse a primary expression.
+  ///
+  /// @param Res - The value of the expression. The result is undefined
+  /// on error.
+  /// @result - False on success.
+  virtual bool parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) = 0;
+
   /// parseParenExpression - Parse an arbitrary expression, assuming that an
   /// initial '(' has already been consumed.
   ///
diff --git a/lib/MC/MCParser/AsmParser.cpp b/lib/MC/MCParser/AsmParser.cpp
index 14577f79be..c50177cb0a 100644
--- a/lib/MC/MCParser/AsmParser.cpp
+++ b/lib/MC/MCParser/AsmParser.cpp
@@ -221,6 +221,7 @@ public:
 
   bool parseExpression(const MCExpr *&Res);
   virtual bool parseExpression(const MCExpr *&Res, SMLoc &EndLoc);
+  virtual bool parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc);
   virtual bool parseParenExpression(const MCExpr *&Res, SMLoc &EndLoc);
   virtual bool parseAbsoluteExpression(int64_t &Res);
 
@@ -869,6 +870,10 @@ bool AsmParser::parseExpression(const MCExpr *&Res) {
   return parseExpression(Res, EndLoc);
 }
 
+bool AsmParser::parsePrimaryExpr(const MCExpr *&Res, SMLoc &EndLoc) {
+  return ParsePrimaryExpr(Res, EndLoc);
+}
+
 const MCExpr *
 AsmParser::ApplyModifierToExpr(const MCExpr *E,
                                MCSymbolRefExpr::VariantKind Variant) {
diff --git a/lib/Target/X86/AsmParser/X86AsmParser.cpp b/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 60a02702eb..ba19a9bcdb 100644
--- a/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -1182,7 +1182,7 @@ X86Operand *X86AsmParser::ParseIntelBracExpression(unsigned SegReg,
         SM.onRegister(TmpReg);
         UpdateLocLex = false;
         break;
-      } else if (!getParser().parseExpression(Disp, End)) {
+      } else if (!getParser().parsePrimaryExpr(Disp, End)) {
         SM.onDispExpr();
         UpdateLocLex = false;
         break;
@@ -1401,7 +1401,7 @@ X86Operand *X86AsmParser::ParseIntelOffsetOfOperator() {
 
   const MCExpr *Val;
   SMLoc Start = Tok.getLoc(), End;
-  if (getParser().parseExpression(Val, End))
+  if (getParser().parsePrimaryExpr(Val, End))
     return ErrorOperand(Start, "Unable to parse expression!");
 
   // Don't emit the offset operator.
@@ -1437,7 +1437,7 @@ X86Operand *X86AsmParser::ParseIntelOperator(unsigned OpKind) {
 
   const MCExpr *Val;
   SMLoc Start = Tok.getLoc(), End;
-  if (getParser().parseExpression(Val, End))
+  if (getParser().parsePrimaryExpr(Val, End))
     return 0;
 
   unsigned Length = 0, Size = 0, Type = 0;