MS asm: Attempt to parse variables followed by a bracketed displacement

This is required to include MSVC's <atomic> header, which we do now in
LLVM.

Tests forthcoming in Clang, since that's where we test semantic inline
asm changes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@202865 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 34 insertions, 2 deletions

diff --git a/lib/Target/X86/AsmParser/X86AsmParser.cpp b/lib/Target/X86/AsmParser/X86AsmParser.cpp
index 59d78461f4..fdd538450b 100644
--- a/lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ b/lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -1307,6 +1307,7 @@ X86Operand *X86AsmParser::ParseIntelMemOperand(int64_t ImmDisp, SMLoc Start,
   // Parse ImmDisp [ BaseReg + Scale*IndexReg + Disp ].
   if (getLexer().is(AsmToken::LBrac))
     return ParseIntelBracExpression(/*SegReg=*/0, Start, ImmDisp, Size);
+  assert(ImmDisp == 0);
 
   const MCExpr *Val;
   if (!isParsingInlineAsm()) {
@@ -1321,8 +1322,39 @@ X86Operand *X86AsmParser::ParseIntelMemOperand(int64_t ImmDisp, SMLoc Start,
   if (ParseIntelIdentifier(Val, Identifier, Info,
                            /*Unevaluated=*/false, End))
     return 0;
-  return CreateMemForInlineAsm(/*SegReg=*/0, Val, /*BaseReg=*/0, /*IndexReg=*/0,
-                               /*Scale=*/1, Start, End, Size, Identifier, Info);
+
+  if (!getLexer().is(AsmToken::LBrac))
+    return CreateMemForInlineAsm(/*SegReg=*/0, Val, /*BaseReg=*/0, /*IndexReg=*/0,
+                                 /*Scale=*/1, Start, End, Size, Identifier, Info);
+
+  Parser.Lex(); // Eat '['
+
+  // Parse Identifier [ ImmDisp ]
+  IntelExprStateMachine SM(/*ImmDisp=*/0, /*StopOnLBrac=*/true,
+                           /*AddImmPrefix=*/false);
+  if (ParseIntelExpression(SM, End))
+    return 0;
+
+  if (SM.getSym()) {
+    Error(Start, "cannot use more than one symbol in memory operand");
+    return 0;
+  }
+  if (SM.getBaseReg()) {
+    Error(Start, "cannot use base register with variable reference");
+    return 0;
+  }
+  if (SM.getIndexReg()) {
+    Error(Start, "cannot use index register with variable reference");
+    return 0;
+  }
+
+  const MCExpr *Disp = MCConstantExpr::Create(SM.getImm(), getContext());
+  // BaseReg is non-zero to avoid assertions.  In the context of inline asm,
+  // we're pointing to a local variable in memory, so the base register is
+  // really the frame or stack pointer.
+  return X86Operand::CreateMem(/*SegReg=*/0, Disp, /*BaseReg=*/1, /*IndexReg=*/0,
+                               /*Scale=*/1, Start, End, Size, Identifier,
+                               Info.OpDecl);
 }
 
 /// Parse the '.' operator.