[MC] Add Subtarget for MAsmParser call to emitCodeAlignment

[peter.smith]

Summary

The call to emitCodeAlignment was missing a STI which is required after D45962.

Should fix the problem reported in D45962 https://reviews.llvm.org/D45962#2988712

emitCodeAlignment has a default parameter of 0 for MaxBytesToEmit. Explicitly passing 0 here was interpreted as as nullptr for the STI. This could possibly be avoided by taking STI as a const reference in emitCodeAlignment. This could be done as a follow up patch to get the fix for the problem resolved.

[mstorsjo]

LGTM, thanks!

I'll leave it as a separate change for @epastor or myself to add a testcase for llvm-ml that covers that codepath.

[mstorsjo]

Thanks for getting to it so quickly!

[epastor]

This code is similar to code in AsmParser.cpp (https://github.com/llvm-mirror/llvm/blob/master/lib/MC/MCParser/AsmParser.cpp#L3344-L3351) - looks like that will probably need an update as well, to keep MaxBytesToFill from being interpreted as a pointer?

[peter.smith]

In D109425#2989305, @epastor wrote:

This code is similar to code in AsmParser.cpp (https://github.com/llvm-mirror/llvm/blob/master/lib/MC/MCParser/AsmParser.cpp#L3344-L3351) - looks like that will probably need an update as well, to keep MaxBytesToFill from being interpreted as a pointer?

Yes, I managed to catch that one in D45961 that reference from llvm-mirror might be a little bit out of date. I think https://github.com/llvm/llvm-project/blob/main/llvm/lib/MC/MCParser/AsmParser.cpp#L3457 is where the code is now. Hope I've not missed something.

[epastor]

In D109425#2989346, @peter.smith wrote:

In D109425#2989305, @epastor wrote:

This code is similar to code in AsmParser.cpp (https://github.com/llvm-mirror/llvm/blob/master/lib/MC/MCParser/AsmParser.cpp#L3344-L3351) - looks like that will probably need an update as well, to keep MaxBytesToFill from being interpreted as a pointer?

Yes, I managed to catch that one in D45961 that reference from llvm-mirror might be a little bit out of date. I think https://github.com/llvm/llvm-project/blob/main/llvm/lib/MC/MCParser/AsmParser.cpp#L3457 is where the code is now. Hope I've not missed something.

Great, looks good!

llvm/lib/MC/MCParser/MasmParser.cpp

if (StructInProgress.empty()) {
     if (checkForValidSection())
       return true;
 
     // Check whether we should use optimal code alignment for this align
     // directive.
     const MCSection *Section = getStreamer().getCurrentSectionOnly();
     assert(Section && "must have section to emit alignment");
     if (Section->UseCodeAlign()) {
-      getStreamer().emitCodeAlignment(Alignment, /*MaxBytesToEmit=*/0);
+      getStreamer().emitCodeAlignment(Alignment, &getTargetParser().getSTI(),
+                                      /*MaxBytesToEmit=*/0);
     } else {
       // FIXME: Target specific behavior about how the "extra" bytes are filled.
       getStreamer().emitValueToAlignment(Alignment, /*Value=*/0,
                                          /*ValueSize=*/1,
                                          /*MaxBytesToEmit=*/0);
     }
   } else {
     // Align the next field of this struct