[PATCH] D83896: [DebugInfo] Add replaceArg function for removing duplicates from DBG_VALUE_LIST expressions

[Stephen Tozer via Phabricator via llvm-commits]

StephenTozer updated this revision to Diff 310173.
StephenTozer added a comment.
Herald added a subscriber: dexonsmith.

Rebased to recent master, no actual changes.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D83896/new/

https://reviews.llvm.org/D83896

Files:
  llvm/include/llvm/IR/DebugInfoMetadata.h
  llvm/lib/IR/DebugInfoMetadata.cpp
  llvm/unittests/IR/MetadataTest.cpp


Index: llvm/unittests/IR/MetadataTest.cpp
===================================================================
--- llvm/unittests/IR/MetadataTest.cpp
+++ llvm/unittests/IR/MetadataTest.cpp
@@ -2862,6 +2862,33 @@
 #undef EXPECT_INVALID_FRAGMENT
 }
 
+TEST_F(DIExpressionTest, replaceArg) {
+#define EXPECT_REPLACE_ARG_EQ(Expr, OldArg, NewArg, ...)                       \
+  do {                                                                         \
+    ArrayRef<uint64_t> Expected({__VA_ARGS__});                                \
+    DIExpression *Expression = DIExpression::replaceArg(Expr, OldArg, NewArg); \
+    EXPECT_EQ(Expression->getElements(), Expected);                            \
+  } while (false)
+
+  auto N = DIExpression::get(
+      Context, {dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_LLVM_arg, 1,
+                dwarf::DW_OP_plus, dwarf::DW_OP_LLVM_arg, 2, dwarf::DW_OP_mul});
+  EXPECT_REPLACE_ARG_EQ(N, 0, 1, dwarf::DW_OP_LLVM_arg, 0,
+                        dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_plus,
+                        dwarf::DW_OP_LLVM_arg, 1, dwarf::DW_OP_mul);
+  EXPECT_REPLACE_ARG_EQ(N, 0, 2, dwarf::DW_OP_LLVM_arg, 1,
+                        dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_plus,
+                        dwarf::DW_OP_LLVM_arg, 1, dwarf::DW_OP_mul);
+  EXPECT_REPLACE_ARG_EQ(N, 2, 0, dwarf::DW_OP_LLVM_arg, 0,
+                        dwarf::DW_OP_LLVM_arg, 1, dwarf::DW_OP_plus,
+                        dwarf::DW_OP_LLVM_arg, 0, dwarf::DW_OP_mul);
+  EXPECT_REPLACE_ARG_EQ(N, 2, 1, dwarf::DW_OP_LLVM_arg, 0,
+                        dwarf::DW_OP_LLVM_arg, 1, dwarf::DW_OP_plus,
+                        dwarf::DW_OP_LLVM_arg, 1, dwarf::DW_OP_mul);
+
+#undef EXPECT_REPLACE_ARG_EQ
+}
+
 typedef MetadataTest DIObjCPropertyTest;
 
 TEST_F(DIObjCPropertyTest, get) {
Index: llvm/lib/IR/DebugInfoMetadata.cpp
===================================================================
--- llvm/lib/IR/DebugInfoMetadata.cpp
+++ llvm/lib/IR/DebugInfoMetadata.cpp
@@ -1296,6 +1296,28 @@
   return DIExpression::get(Expr->getContext(), NewOps);
 }
 
+DIExpression *DIExpression::replaceArg(const DIExpression *Expr,
+                                       uint64_t OldArg, uint64_t NewArg) {
+  assert(Expr && "Can't replace args in this expression");
+
+  SmallVector<uint64_t, 8> NewOps;
+
+  for (auto Op : Expr->expr_ops()) {
+    if (Op.getOp() != dwarf::DW_OP_LLVM_arg || Op.getArg(0) < OldArg) {
+      Op.appendToVector(NewOps);
+      continue;
+    }
+    NewOps.push_back(dwarf::DW_OP_LLVM_arg);
+    uint64_t Arg = Op.getArg(0) == OldArg ? NewArg : Op.getArg(0);
+    // OldArg has been deleted from the Op list, so decrement all indices
+    // greater than it.
+    if (Arg > OldArg)
+      --Arg;
+    NewOps.push_back(Arg);
+  }
+  return DIExpression::get(Expr->getContext(), NewOps);
+}
+
 DIExpression *DIExpression::prependOpcodes(const DIExpression *Expr,
                                            SmallVectorImpl<uint64_t> &Ops,
                                            bool StackValue,
Index: llvm/include/llvm/IR/DebugInfoMetadata.h
===================================================================
--- llvm/include/llvm/IR/DebugInfoMetadata.h
+++ llvm/include/llvm/IR/DebugInfoMetadata.h
@@ -2773,8 +2773,17 @@
   /// modify a specific location used by \p Expr, such as when salvaging that
   /// location.
   static DIExpression *appendOpsToArg(const DIExpression *Expr,
-                                      ArrayRef<uint64_t> Ops, unsigned ArgNo,
-                                      bool StackValue = false);
+                                      ArrayRef<uint64_t> Ops, unsigned ArgNo,
+                                      bool StackValue = false);
+
+  /// Create a copy of \p Expr with each instance of
+  /// `DW_OP_LLVM_arg, \p OldArg` replaced with `DW_OP_LLVM_arg, \p NewArg`,
+  /// and each instance of `DW_OP_LLVM_arg, Arg` with `DW_OP_LLVM_arg, Arg - 1`
+  /// for all Arg > \p OldArg.
+  /// This is used when replacing one of the operands of a debug value list
+  /// with another operand in the same list and deleting the old operand.
+  static DIExpression *replaceArg(const DIExpression *Expr, uint64_t OldArg,
+                                  uint64_t NewArg);
 
   /// Create a DIExpression to describe one part of an aggregate variable that
   /// is fragmented across multiple Values. The DW_OP_LLVM_fragment operation


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