Ignore all duplicate frame index expression

Some passes might duplicate calls to llvm.dbg.declare creating
duplicate frame index expression which currently trigger an assertion
which is meant to catch erroneous, overlapping fragment declarations.
But identical frame index expressions are just redundant and don't
actually conflict with each other, so we can be more lenient and just
ignore the duplicates.

Reviewers: aprantl, rnk

Subscribers: llvm-commits, JDevlieghere

Differential Revision: https://reviews.llvm.org/D38540

Author: Björn Steinbrink

lib/CodeGen/AsmPrinter/DwarfDebug.cpp

@@ -205,9 +205,34 @@ ArrayRef<DbgVariable::FrameIndexExpr> DbgVariable::getFrameIndexExprs() const {
               return A.Expr->getFragmentInfo()->OffsetInBits <
                      B.Expr->getFragmentInfo()->OffsetInBits;
             });
+
   return FrameIndexExprs;
 }
 
+void DbgVariable::addMMIEntry(const DbgVariable &V) {
+  assert(DebugLocListIndex == ~0U && !MInsn && "not an MMI entry");
+  assert(V.DebugLocListIndex == ~0U && !V.MInsn && "not an MMI entry");
+  assert(V.Var == Var && "conflicting variable");
+  assert(V.IA == IA && "conflicting inlined-at location");
+
+  assert(!FrameIndexExprs.empty() && "Expected an MMI entry");
+  assert(!V.FrameIndexExprs.empty() && "Expected an MMI entry");
+
+  for (const auto &FIE : V.FrameIndexExprs)
+    // Ignore duplicate entries.
+    if (llvm::none_of(FrameIndexExprs, [&](const FrameIndexExpr &Other) {
+          return FIE.FI == Other.FI && FIE.Expr == Other.Expr;
+        }))
+      FrameIndexExprs.push_back(FIE);
+
+  assert((FrameIndexExprs.size() == 1 ||
+          llvm::all_of(FrameIndexExprs,
+                       [](FrameIndexExpr &FIE) {
+                         return FIE.Expr && FIE.Expr->isFragment();
+                       })) &&
+         "conflicting locations for variable");
+}
+
 static const DwarfAccelTable::Atom TypeAtoms[] = {
     DwarfAccelTable::Atom(dwarf::DW_ATOM_die_offset, dwarf::DW_FORM_data4),
     DwarfAccelTable::Atom(dwarf::DW_ATOM_die_tag, dwarf::DW_FORM_data2),

lib/CodeGen/AsmPrinter/DwarfDebug.h

@@ -124,23 +124,7 @@ class DbgVariable {
   /// Get the FI entries, sorted by fragment offset.
   ArrayRef<FrameIndexExpr> getFrameIndexExprs() const;
   bool hasFrameIndexExprs() const { return !FrameIndexExprs.empty(); }
-
-  void addMMIEntry(const DbgVariable &V) {
-    assert(DebugLocListIndex == ~0U && !MInsn && "not an MMI entry");
-    assert(V.DebugLocListIndex == ~0U && !V.MInsn && "not an MMI entry");
-    assert(V.Var == Var && "conflicting variable");
-    assert(V.IA == IA && "conflicting inlined-at location");
-
-    assert(!FrameIndexExprs.empty() && "Expected an MMI entry");
-    assert(!V.FrameIndexExprs.empty() && "Expected an MMI entry");
-
-    FrameIndexExprs.append(V.FrameIndexExprs.begin(), V.FrameIndexExprs.end());
-    assert(all_of(FrameIndexExprs,
-                  [](FrameIndexExpr &FIE) {
-                    return FIE.Expr && FIE.Expr->isFragment();
-                  }) &&
-           "conflicting locations for variable");
-  }
+  void addMMIEntry(const DbgVariable &V);
 
   // Translate tag to proper Dwarf tag.
   dwarf::Tag getTag() const {