Enable StackMap Serialization for COFF

[swaroop.sridhar]

Summary

This change turns on the emission of __LLVM_Stackmaps section when generating a COFF binary.

[sanjoy]

LGTM -- I'll trust you got the flags for the COFF section right.

lib/MC/MCObjectFileInfo.cpp

737

The formatting looks a little bit off here -- can you please run this change through clang-format?

[pgavlin]

LGTM as well.

[swaroop.sridhar]

Checked in as revision 240613

[AndyAyers]

I'm not sure about the COFF flags. Not something that needs to be fixed right away though.

lib/MC/MCObjectFileInfo.cpp

740

I wonder if the stackmap data really needs to be in a loadable section (in other words, memory resident when the code it refers to is executing), or if this should be some kind of client determined thing.

Certainly for LLILC's purposes it doesn't need to be loadable, since we'll translate it to another format.

lib/MC/MCObjectFileInfo.cpp

       ".tls$", COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ |
                    COFF::IMAGE_SCN_MEM_WRITE,
       SectionKind::getDataRel());
+    
+  StackMapSection = Ctx->getCOFFSection(
+    ".llvm_stackmaps", 
+    COFF::IMAGE_SCN_CNT_INITIALIZED_DATA | COFF::IMAGE_SCN_MEM_READ,
+    SectionKind::getReadOnly());    
 }
 
 void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple,

lib/Target/X86/X86AsmPrinter.cpp

       for (auto & Symbol : DLLExportedFns)
         GenerateExportDirective(Symbol, /*IsData=*/false);
     }
+
+    SM.serializeToStackMapSection();
   }
 
   if (TT.isOSBinFormatELF()) {

test/CodeGen/X86/statepoint-stackmap-format.ll

-; RUN: llc < %s | FileCheck %s
+; RUN: llc < %s -mtriple="x86_64-pc-linux-gnu" | FileCheck %s
+; RUN: llc < %s -mtriple="x86_64-pc-win64-coff" | FileCheck %s
+
 ; This test is a sanity check to ensure statepoints are generating StackMap
 ; sections correctly.  This is not intended to be a rigorous test of the 
 ; StackMap format (see the stackmap tests for that).
 
 target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-pc-linux-gnu"
 
 declare zeroext i1 @return_i1()