[Lldb-commits] [lldb] [lldb] Support negative function offsets in UnwindPlans (PR #134662)

[Pavel Labath via lldb-commits]

https://github.com/labath created https://github.com/llvm/llvm-project/pull/134662

These are needed for functions whose entry point is not their lowest address.

>From 10a1029d776bf5dcae5fe69a72883916de7c4b5f Mon Sep 17 00:00:00 2001
From: Pavel Labath <pavel at labath.sk>
Date: Fri, 4 Apr 2025 11:37:34 +0200
Subject: [PATCH] [lldb] Support negative function offsets in UnwindPlans

These are needed for functions whose entry point is not their lowest
address.
---
 lldb/include/lldb/Symbol/UnwindPlan.h                  | 10 +++++-----
 .../UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp |  5 +++--
 lldb/source/Symbol/DWARFCallFrameInfo.cpp              |  2 +-
 lldb/source/Symbol/UnwindPlan.cpp                      |  6 +++---
 lldb/unittests/Symbol/UnwindPlanTest.cpp               |  5 +++++
 5 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/lldb/include/lldb/Symbol/UnwindPlan.h b/lldb/include/lldb/Symbol/UnwindPlan.h
index 6640a23a3e868..410289851a879 100644
--- a/lldb/include/lldb/Symbol/UnwindPlan.h
+++ b/lldb/include/lldb/Symbol/UnwindPlan.h
@@ -356,11 +356,11 @@ class UnwindPlan {
 
     void RemoveRegisterInfo(uint32_t reg_num);
 
-    lldb::addr_t GetOffset() const { return m_offset; }
+    int64_t GetOffset() const { return m_offset; }
 
-    void SetOffset(lldb::addr_t offset) { m_offset = offset; }
+    void SetOffset(int64_t offset) { m_offset = offset; }
 
-    void SlideOffset(lldb::addr_t offset) { m_offset += offset; }
+    void SlideOffset(int64_t offset) { m_offset += offset; }
 
     const FAValue &GetCFAValue() const { return m_cfa_value; }
     FAValue &GetCFAValue() { return m_cfa_value; }
@@ -420,7 +420,7 @@ class UnwindPlan {
 
   protected:
     typedef std::map<uint32_t, AbstractRegisterLocation> collection;
-    lldb::addr_t m_offset = 0; // Offset into the function for this row
+    int64_t m_offset = 0; // Offset into the function for this row
 
     FAValue m_cfa_value;
     FAValue m_afa_value;
@@ -472,7 +472,7 @@ class UnwindPlan {
   // practice, the UnwindPlan for a function with no known start address will be
   // the architectural default UnwindPlan which will only have one row.
   const UnwindPlan::Row *
-  GetRowForFunctionOffset(std::optional<int> offset) const;
+  GetRowForFunctionOffset(std::optional<int64_t> offset) const;
 
   lldb::RegisterKind GetRegisterKind() const { return m_register_kind; }
 
diff --git a/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp
index 3eaa2f33fce3e..aaff278ca31e2 100644
--- a/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp
+++ b/lldb/source/Plugins/UnwindAssembly/x86/x86AssemblyInspectionEngine.cpp
@@ -1390,11 +1390,12 @@ bool x86AssemblyInspectionEngine::AugmentUnwindPlanFromCallSite(
 
     // If we already have one row for this instruction, we can continue.
     while (row_id < unwind_plan.GetRowCount() &&
-           unwind_plan.GetRowAtIndex(row_id)->GetOffset() <= offset) {
+           unwind_plan.GetRowAtIndex(row_id)->GetOffset() <=
+               static_cast<int64_t>(offset)) {
       row_id++;
     }
     const UnwindPlan::Row *original_row = unwind_plan.GetRowAtIndex(row_id - 1);
-    if (original_row->GetOffset() == offset) {
+    if (original_row->GetOffset() == static_cast<int64_t>(offset)) {
       row = *original_row;
       continue;
     }
diff --git a/lldb/source/Symbol/DWARFCallFrameInfo.cpp b/lldb/source/Symbol/DWARFCallFrameInfo.cpp
index 957818e8d077f..dca3f665b0b80 100644
--- a/lldb/source/Symbol/DWARFCallFrameInfo.cpp
+++ b/lldb/source/Symbol/DWARFCallFrameInfo.cpp
@@ -765,7 +765,7 @@ bool DWARFCallFrameInfo::FDEToUnwindPlan(dw_offset_t dwarf_offset,
                      __FUNCTION__, dwarf_offset, startaddr.GetFileAddress());
             break;
           }
-          lldb::addr_t offset = row.GetOffset();
+          int64_t offset = row.GetOffset();
           row = std::move(stack.back());
           stack.pop_back();
           row.SetOffset(offset);
diff --git a/lldb/source/Symbol/UnwindPlan.cpp b/lldb/source/Symbol/UnwindPlan.cpp
index cfa8eefaa55bb..33aba0a859d5c 100644
--- a/lldb/source/Symbol/UnwindPlan.cpp
+++ b/lldb/source/Symbol/UnwindPlan.cpp
@@ -398,10 +398,10 @@ void UnwindPlan::AppendRow(Row row) {
 }
 
 struct RowLess {
-  bool operator()(addr_t a, const UnwindPlan::RowSP &b) const {
+  bool operator()(int64_t a, const UnwindPlan::RowSP &b) const {
     return a < b->GetOffset();
   }
-  bool operator()(const UnwindPlan::RowSP &a, addr_t b) const {
+  bool operator()(const UnwindPlan::RowSP &a, int64_t b) const {
     return a->GetOffset() < b;
   }
 };
@@ -418,7 +418,7 @@ void UnwindPlan::InsertRow(Row row, bool replace_existing) {
 }
 
 const UnwindPlan::Row *
-UnwindPlan::GetRowForFunctionOffset(std::optional<int> offset) const {
+UnwindPlan::GetRowForFunctionOffset(std::optional<int64_t> offset) const {
   auto it = offset ? llvm::upper_bound(m_row_list, *offset, RowLess())
                    : m_row_list.end();
   if (it == m_row_list.begin())
diff --git a/lldb/unittests/Symbol/UnwindPlanTest.cpp b/lldb/unittests/Symbol/UnwindPlanTest.cpp
index fa8bb153e9247..08aa5b2dd84bb 100644
--- a/lldb/unittests/Symbol/UnwindPlanTest.cpp
+++ b/lldb/unittests/Symbol/UnwindPlanTest.cpp
@@ -24,6 +24,7 @@ static UnwindPlan::Row make_simple_row(addr_t offset, uint64_t cfa_value) {
 TEST(UnwindPlan, InsertRow) {
   UnwindPlan::Row row1 = make_simple_row(0, 42);
   UnwindPlan::Row row2 = make_simple_row(0, 47);
+  UnwindPlan::Row row3 = make_simple_row(-1, 4242);
 
   UnwindPlan plan(eRegisterKindGeneric);
   plan.InsertRow(row1);
@@ -34,6 +35,10 @@ TEST(UnwindPlan, InsertRow) {
 
   plan.InsertRow(row2, /*replace_existing=*/true);
   EXPECT_THAT(plan.GetRowForFunctionOffset(0), testing::Pointee(row2));
+
+  EXPECT_THAT(plan.GetRowForFunctionOffset(-1), nullptr);
+  plan.InsertRow(row3);
+  EXPECT_THAT(plan.GetRowForFunctionOffset(-1), testing::Pointee(row3));
 }
 
 TEST(UnwindPlan, GetRowForFunctionOffset) {