[PATCH] D11512: Fix conflict for referencing "flags" variable in X86 assembly syntax

[Marina Yatsina]

myatsina created this revision.
myatsina added reviewers: rnk, MatzeB.
myatsina added a subscriber: llvm-commits.
myatsina set the repository for this revision to rL LLVM.

This asm instruction passes compilation:
mov eax, flags2

This asm instruction fails compilation:
mov eax, flags

When parsing the latter, the X86AsmParser “flags” should be matched to a memory location and not to the implicit EFLAGS register.

Repository:
  rL LLVM

http://reviews.llvm.org/D11512

Files:
  lib/Target/X86/AsmParser/X86AsmParser.cpp

Index: lib/Target/X86/AsmParser/X86AsmParser.cpp
===================================================================
--- lib/Target/X86/AsmParser/X86AsmParser.cpp
+++ lib/Target/X86/AsmParser/X86AsmParser.cpp
@@ -805,6 +805,7 @@
         CreateX86AsmInstrumentation(Options, Parser.getContext(), STI));
   }
 
+  unsigned FixMatchedRegister(unsigned RegNo);
   bool ParseRegister(unsigned &RegNo, SMLoc &StartLoc, SMLoc &EndLoc) override;
 
   void SetFrameRegister(unsigned RegNo) override;
@@ -882,6 +883,16 @@
   return true;
 }
 
+unsigned X86AsmParser::FixMatchedRegister(unsigned RegNo) {
+
+  if (isParsingInlineAsm() && RegNo == X86::EFLAGS) {
+    // Cannot address reg called "flags" - this is just an identifier!
+    return 0;
+  }
+
+  return RegNo;
+}
+
 bool X86AsmParser::ParseRegister(unsigned &RegNo,
                                  SMLoc &StartLoc, SMLoc &EndLoc) {
   MCAsmParser &Parser = getParser();
@@ -909,6 +920,8 @@
   if (RegNo == 0)
     RegNo = MatchRegisterName(Tok.getString().lower());
 
+  RegNo = FixMatchedRegister(RegNo);
+
   if (!is64BitMode()) {
     // FIXME: This should be done using Requires<Not64BitMode> and
     // Requires<In64BitMode> so "eiz" usage in 64-bit instructions can be also


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