[PATCH] D75189: [DebugInfo] Add check for .debug_line minimum_instruction_length of 0

[James Henderson via Phabricator via llvm-commits]

jhenderson created this revision.
jhenderson added reviewers: ikudrin, labath, probinson, dblaikie, JDevlieghere.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.

If the minimum_instruction_length of a debug line program is 0, no address advancing via special opcodes, DW_LNS_const_add_pc, and DW_LNS_advance_pc can occur, since the minimum_instruction_length is used in a multiplication. This patch adds a warning reporting when this issue occurs.

Depends on D74819 <https://reviews.llvm.org/D74819>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D75189

Files:
  llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
  llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp


Index: llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
===================================================================
--- llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
+++ llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
@@ -993,6 +993,39 @@
     Values(std::make_tuple(0, true),       // Test zero value (error).
            std::make_tuple(14, false)), ); // Test non-zero value (no error).
 
+struct BadMinInstLenFixture : public TestWithParam<std::tuple<uint8_t, bool>>,
+                              public AdjustAddressFixtureBase {
+  void SetUp() { std::tie(MinInstLength, IsErrorExpected) = GetParam(); }
+
+  uint64_t editPrologue(LineTable &LT) override {
+    DWARFDebugLine::Prologue Prologue = LT.createBasicPrologue();
+    Prologue.MinInstLength = MinInstLength;
+    LT.setPrologue(Prologue);
+    return Prologue.TotalLength + Prologue.sizeofTotalLength();
+  }
+
+  uint64_t getAdjustedAddr(uint64_t Base, uint64_t ConstIncr,
+                           uint64_t SpecialIncr,
+                           uint64_t AdvanceIncr) override {
+    return MinInstLength != 0 ? AdjustAddressFixtureBase::getAdjustedAddr(
+                                    Base, ConstIncr, SpecialIncr, AdvanceIncr)
+                              : Base;
+  }
+
+  uint8_t MinInstLength;
+};
+
+TEST_P(BadMinInstLenFixture, MinInstLengthProblemsReportedCorrectly) {
+  runTest(/*CheckAdvancePC=*/true,
+          "but the prologue minimum_instruction_length value is 0, which "
+          "prevents any address advancing");
+}
+
+INSTANTIATE_TEST_CASE_P(
+    BadMinInstLenParams, BadMinInstLenFixture,
+    Values(std::make_tuple(0, true),      // Test zero value (error).
+           std::make_tuple(1, false)), ); // Test non-zero value (no error).
+
 TEST_F(DebugLineBasicFixture, ParserParsesCorrectly) {
   if (!setupGenerator())
     return;
Index: llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
===================================================================
--- llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
@@ -613,6 +613,14 @@
         ", but the prologue maximum_operations_per_instruction value is %" PRId8
         ", which is unsupported. Assuming a value of 1 instead",
         TableOffset, OpcodeName.data(), OpcodeOffset, Prologue.MaxOpsPerInst));
+  if (ReportAdvanceAddrProblem && Prologue.MinInstLength == 0)
+    ErrorHandler(
+        createStringError(errc::invalid_argument,
+                          "line table program at offset 0x%8.8" PRIx64
+                          " contains a %s opcode at offset 0x%8.8" PRIx64
+                          ", but the prologue minimum_instruction_length value "
+                          "is 0, which prevents any address advancing",
+                          TableOffset, OpcodeName.data(), OpcodeOffset));
   ReportAdvanceAddrProblem = false;
   return OperationAdvance * Prologue.MinInstLength;
 }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D75189.246747.patch
Type: text/x-patch
Size: 2939 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200226/7daf47d7/attachment.bin>