Update clang filtering for mxcsr

[andrew.w.kaylor]

Summary

This patch updates the clang function that filters the mxcsr register name to recognize that mxcsr is being split into two pseduo-registers that model the control and status bits separately.

[ahatanak]

Is it possible to add a test case (possibly in CodeGen)?

[andrew.w.kaylor]

In D30662#693559, @ahatanak wrote:

Is it possible to add a test case (possibly in CodeGen)?

This is covered by CodeGen/ms-inline-asm.c, which Reid added after I broke this adding the mxcsr register a couple of weeks ago.

[rnk]

I think we should really change this code to filter out clobber registers that do not name valid gcc inline asm clobbers. That's basically what we require later. I think if you change this condition to just check Target.isValidGCCRegisterName.

[ahatanak]

In D30662#693609, @andrew.w.kaylor wrote:

In D30662#693559, @ahatanak wrote:

Is it possible to add a test case (possibly in CodeGen)?

This is covered by CodeGen/ms-inline-asm.c, which Reid added after I broke this adding the mxcsr register a couple of weeks ago.

I see, thanks.

lib/Parse/ParseStmtAsm.cpp

StmtResult Parser::ParseMicrosoftAsmStatement(SourceLocation AsmLoc) {
   SmallVector<std::string, 4> Clobbers;
   if (Parser->parseMSInlineAsm(AsmLoc.getPtrEncoding(), AsmStringIR, NumOutputs,
                                NumInputs, OpExprs, Constraints, Clobbers,
                                MII.get(), IP.get(), Callback))
     return StmtError();
 
   // Filter out "fpsw" and "mxcsr". They aren't valid GCC asm clobber
   // constraints. Clang always adds fpsr to the clobber list anyway.
+  // Note that mxcsr is modeled as two separate registers.
   llvm::erase_if(Clobbers, [](const std::string &C) {
-    return C == "fpsw" || C == "mxcsr";
+    return C == "fpsw" || C == "mxcsr_c" || C == "mxcsr_s";
   });
 
   // Build the vector of clobber StringRefs.
   ClobberRefs.insert(ClobberRefs.end(), Clobbers.begin(), Clobbers.end());
 
   // Recast the void pointers and build the vector of constraint StringRefs.
   unsigned NumExprs = NumOutputs + NumInputs;
   ConstraintRefs.resize(NumExprs);