[codeview] Emit parameter variables in the right order

Clang emits them in reverse order to conform to the ABI, which requires
left-to-right destruction. As a result, the order doesn't fall out
naturally, and we have to sort things out in the backend.

Fixes PR28213

llvm-svn: 273696

2 files changed, 25 insertions, 4 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index ca2482a5646..e01ee0984ed 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -504,8 +504,7 @@ void CodeViewDebug::emitInlinedCallSite(const FunctionInfo &FI,
 
   OS.EmitLabel(InlineEnd);
 
-  for (const LocalVariable &Var : Site.InlinedLocals)
-    emitLocalVariable(Var);
+  emitLocalVariableList(Site.InlinedLocals);
 
   // Recurse on child inlined call sites before closing the scope.
   for (const DILocation *ChildSite : Site.ChildSites) {
@@ -608,8 +607,7 @@ void CodeViewDebug::emitDebugInfoForFunction(const Function *GV,
     emitNullTerminatedSymbolName(OS, FuncName);
     OS.EmitLabel(ProcRecordEnd);
 
-    for (const LocalVariable &Var : FI.Locals)
-      emitLocalVariable(Var);
+    emitLocalVariableList(FI.Locals);
 
     // Emit inlined call site information. Only emit functions inlined directly
     // into the parent function. We'll emit the other sites recursively as part
@@ -1680,6 +1678,25 @@ void CodeViewDebug::emitDeferredCompleteTypes() {
   }
 }
 
+void CodeViewDebug::emitLocalVariableList(ArrayRef<LocalVariable> Locals) {
+  // Get the sorted list of parameters and emit them first.
+  SmallVector<const LocalVariable *, 6> Params;
+  for (const LocalVariable &L : Locals)
+    if (L.DIVar->isParameter())
+      Params.push_back(&L);
+  std::sort(Params.begin(), Params.end(),
+            [](const LocalVariable *L, const LocalVariable *R) {
+              return L->DIVar->getArg() < R->DIVar->getArg();
+            });
+  for (const LocalVariable *L : Params)
+    emitLocalVariable(*L);
+
+  // Next emit all non-parameters in the order that we found them.
+  for (const LocalVariable &L : Locals)
+    if (!L.DIVar->isParameter())
+      emitLocalVariable(L);
+}
+
 void CodeViewDebug::emitLocalVariable(const LocalVariable &Var) {
   // LocalSym record, see SymbolRecord.h for more info.
   MCSymbol *LocalBegin = MMI->getContext().createTempSymbol(),
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
index 53493725c13..51dd5df1027 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -220,6 +220,10 @@ class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
   /// particular, locals from inlined code live inside the inlining site.
   void recordLocalVariable(LocalVariable &&Var, const DILocation *Loc);
 
+  /// Emits local variables in the appropriate order.
+  void emitLocalVariableList(ArrayRef<LocalVariable> Locals);
+
+  /// Emits an S_LOCAL record and its associated defined ranges.
   void emitLocalVariable(const LocalVariable &Var);
 
   /// Translates the DIType to codeview if necessary and returns a type index