Emit the correct flags for the PROC CodeView Debug Symbol

The S_LPROC32_ID and S_GPROC32_ID CodeView Debug Symbols have a flags
field which LLVM has had the values for (in the ProcSymFlags enum) but
has never actually set.

These flags are used by Microsoft-internal tooling that leverages debug
information to do binary analysis.

Modified LLVM to set the correct flags:

- ProcSymFlags::HasOptimizedDebugInfo - always set, as this indicates that
debug info is present for optimized builds (if debug info is not emitted
for optimized builds, then LLVM won't emit a debug symbol at all).
- ProcSymFlags::IsNoReturn and ProcSymFlags::IsNoInline - set if the
function has the NoReturn or NoInline attributes respectively.
- ProcSymFlags::HasFP - set if the function requires a frame pointer (per
TargetFrameLowering::hasFP).

Per discussion in review, XFAIL'ing lldb test until someone working on
lldb has a chance to look at it.

Differential Revision: https://reviews.llvm.org/D148761

1 files changed, 9 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index ce5fe61..8161de5 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -1160,7 +1160,14 @@ void CodeViewDebug::emitDebugInfoForFunction(const Function *GV,
     OS.AddComment("Function section index");
     OS.emitCOFFSectionIndex(Fn);
     OS.AddComment("Flags");
-    OS.emitInt8(0);
+    ProcSymFlags ProcFlags = ProcSymFlags::HasOptimizedDebugInfo;
+    if (FI.HasFramePointer)
+      ProcFlags |= ProcSymFlags::HasFP;
+    if (GV->hasFnAttribute(Attribute::NoReturn))
+      ProcFlags |= ProcSymFlags::IsNoReturn;
+    if (GV->hasFnAttribute(Attribute::NoInline))
+      ProcFlags |= ProcSymFlags::IsNoInline;
+    OS.emitInt8(static_cast<uint8_t>(ProcFlags));
     // Emit the function display name as a null-terminated string.
     OS.AddComment("Function name");
     // Truncate the name so we won't overflow the record length field.
@@ -1480,6 +1487,7 @@ void CodeViewDebug::beginFunctionImpl(const MachineFunction *MF) {
       CurFn->EncodedLocalFramePtrReg = EncodedFramePtrReg::StackPtr;
       CurFn->EncodedParamFramePtrReg = EncodedFramePtrReg::StackPtr;
     } else {
+      CurFn->HasFramePointer = true;
       // If there is an FP, parameters are always relative to it.
       CurFn->EncodedParamFramePtrReg = EncodedFramePtrReg::FramePtr;
       if (CurFn->HasStackRealignment) {