Reapply "[DebugLine] Correct debug line emittion" (#158343) #158379
+64
−49
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This reverts commit aabf18d.
|
@llvm/pr-subscribers-llvm-mc @llvm/pr-subscribers-debuginfo Author: Peter Rong (DataCorrupted) ChangesThis reverts commit aabf18d. This PR reapplies the original patch with the incorrect test removed. Context#99710 introduced Both rows having PC 0x0 is incorrect, and parsers won't be able to parse them. See more explanation why this is wrong in #154851. DesignThis PR attempts to fix this by advancing the PC to the next available Label, and advance to the end of the section if no Label is available. Implementation
NoteThis fix should render #154986 and #154851 obsolete, they were temporary fixes and don't resolve the root cause. Full diff: https://github.com/llvm/llvm-project/pull/158379.diff 3 Files Affected:
diff --git a/llvm/lib/MC/MCDwarf.cpp b/llvm/lib/MC/MCDwarf.cpp
index e7c0d37e8f99b..e8f000a584839 100644
--- a/llvm/lib/MC/MCDwarf.cpp
+++ b/llvm/lib/MC/MCDwarf.cpp
@@ -181,7 +181,7 @@ void MCDwarfLineTable::emitOne(
unsigned FileNum, LastLine, Column, Flags, Isa, Discriminator;
bool IsAtStartSeq;
- MCSymbol *LastLabel;
+ MCSymbol *PrevLabel;
auto init = [&]() {
FileNum = 1;
LastLine = 1;
@@ -189,21 +189,31 @@ void MCDwarfLineTable::emitOne(
Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
Isa = 0;
Discriminator = 0;
- LastLabel = nullptr;
+ PrevLabel = nullptr;
IsAtStartSeq = true;
};
init();
// Loop through each MCDwarfLineEntry and encode the dwarf line number table.
bool EndEntryEmitted = false;
- for (const MCDwarfLineEntry &LineEntry : LineEntries) {
- MCSymbol *Label = LineEntry.getLabel();
+ for (auto It = LineEntries.begin(); It != LineEntries.end(); ++It) {
+ auto LineEntry = *It;
+ MCSymbol *CurrLabel = LineEntry.getLabel();
const MCAsmInfo *asmInfo = MCOS->getContext().getAsmInfo();
if (LineEntry.LineStreamLabel) {
if (!IsAtStartSeq) {
- MCOS->emitDwarfLineEndEntry(Section, LastLabel,
- /*EndLabel =*/LastLabel);
+ auto *Label = CurrLabel;
+ auto NextIt = It + 1;
+ // LineEntry with a null Label is probably a fake LineEntry we added
+ // when `-emit-func-debug-line-table-offsets` in order to terminate the
+ // sequence. Look for the next Label if possible, otherwise we will set
+ // the PC to the end of the section.
+ if (!Label && NextIt != LineEntries.end()) {
+ Label = NextIt->getLabel();
+ }
+ MCOS->emitDwarfLineEndEntry(Section, PrevLabel,
+ /*EndLabel =*/Label);
init();
}
MCOS->emitLabel(LineEntry.LineStreamLabel, LineEntry.StreamLabelDefLoc);
@@ -211,7 +221,7 @@ void MCDwarfLineTable::emitOne(
}
if (LineEntry.IsEndEntry) {
- MCOS->emitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, Label,
+ MCOS->emitDwarfAdvanceLineAddr(INT64_MAX, PrevLabel, CurrLabel,
asmInfo->getCodePointerSize());
init();
EndEntryEmitted = true;
@@ -258,12 +268,12 @@ void MCDwarfLineTable::emitOne(
// At this point we want to emit/create the sequence to encode the delta in
// line numbers and the increment of the address from the previous Label
// and the current Label.
- MCOS->emitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label,
+ MCOS->emitDwarfAdvanceLineAddr(LineDelta, PrevLabel, CurrLabel,
asmInfo->getCodePointerSize());
Discriminator = 0;
LastLine = LineEntry.getLine();
- LastLabel = Label;
+ PrevLabel = CurrLabel;
IsAtStartSeq = false;
}
@@ -273,7 +283,7 @@ void MCDwarfLineTable::emitOne(
// does not track ranges nor terminate the line table. In that case,
// conservatively use the section end symbol to end the line table.
if (!EndEntryEmitted && !IsAtStartSeq)
- MCOS->emitDwarfLineEndEntry(Section, LastLabel);
+ MCOS->emitDwarfLineEndEntry(Section, PrevLabel);
}
void MCDwarfLineTable::endCurrentSeqAndEmitLineStreamLabel(MCStreamer *MCOS,
diff --git a/llvm/test/DebugInfo/X86/DW_AT_LLVM_stmt_seq_sec_offset.ll b/llvm/test/DebugInfo/X86/DW_AT_LLVM_stmt_seq_sec_offset.ll
index 58f6495924b90..f17c6e5429b6b 100644
--- a/llvm/test/DebugInfo/X86/DW_AT_LLVM_stmt_seq_sec_offset.ll
+++ b/llvm/test/DebugInfo/X86/DW_AT_LLVM_stmt_seq_sec_offset.ll
@@ -14,7 +14,7 @@
; STMT_SEQ: DW_AT_LLVM_stmt_sequence [DW_FORM_sec_offset] (0x00000043)
; STMT_SEQ: DW_AT_name {{.*}}func01
; STMT_SEQ: DW_TAG_subprogram [[[ABBREV_CODE2]]]
-; STMT_SEQ: DW_AT_LLVM_stmt_sequence [DW_FORM_sec_offset] (0x00000056)
+; STMT_SEQ: DW_AT_LLVM_stmt_sequence [DW_FORM_sec_offset] (0x00000058)
; STMT_SEQ: DW_AT_name {{.*}}main
;; Check the entire line sequence to see that it's correct
@@ -29,22 +29,23 @@
; STMT_SEQ-NEXT: 0x00000050: 05 DW_LNS_set_column (3)
; STMT_SEQ-NEXT: 0x00000052: 67 address += 6, line += 1, op-index += 0
; STMT_SEQ-NEXT: 0x0000000000000006 6 3 0 0 0 0 is_stmt
-; STMT_SEQ-NEXT: 0x00000053: 00 DW_LNE_end_sequence
-; STMT_SEQ-NEXT: 0x0000000000000006 6 3 0 0 0 0 is_stmt end_sequence
-; STMT_SEQ-NEXT: 0x00000056: 04 DW_LNS_set_file (0)
-; STMT_SEQ-NEXT: 0x00000058: 00 DW_LNE_set_address (0x00000008)
-; STMT_SEQ-NEXT: 0x0000005f: 03 DW_LNS_advance_line (10)
-; STMT_SEQ-NEXT: 0x00000061: 01 DW_LNS_copy
+; STMT_SEQ-NEXT: 0x00000053: 02 DW_LNS_advance_pc (addr += 2, op-index += 0)
+; STMT_SEQ-NEXT: 0x00000055: 00 DW_LNE_end_sequence
+; STMT_SEQ-NEXT: 0x0000000000000008 6 3 0 0 0 0 is_stmt end_sequence
+; STMT_SEQ-NEXT: 0x00000058: 04 DW_LNS_set_file (0)
+; STMT_SEQ-NEXT: 0x0000005a: 00 DW_LNE_set_address (0x00000008)
+; STMT_SEQ-NEXT: 0x00000061: 03 DW_LNS_advance_line (10)
+; STMT_SEQ-NEXT: 0x00000063: 01 DW_LNS_copy
; STMT_SEQ-NEXT: 0x0000000000000008 10 0 0 0 0 0 is_stmt
-; STMT_SEQ-NEXT: 0x00000062: 05 DW_LNS_set_column (10)
-; STMT_SEQ-NEXT: 0x00000064: 0a DW_LNS_set_prologue_end
-; STMT_SEQ-NEXT: 0x00000065: 83 address += 8, line += 1, op-index += 0
+; STMT_SEQ-NEXT: 0x00000064: 05 DW_LNS_set_column (10)
+; STMT_SEQ-NEXT: 0x00000066: 0a DW_LNS_set_prologue_end
+; STMT_SEQ-NEXT: 0x00000067: 83 address += 8, line += 1, op-index += 0
; STMT_SEQ-NEXT: 0x0000000000000010 11 10 0 0 0 0 is_stmt prologue_end
-; STMT_SEQ-NEXT: 0x00000066: 05 DW_LNS_set_column (3)
-; STMT_SEQ-NEXT: 0x00000068: 9f address += 10, line += 1, op-index += 0
+; STMT_SEQ-NEXT: 0x00000068: 05 DW_LNS_set_column (3)
+; STMT_SEQ-NEXT: 0x0000006a: 9f address += 10, line += 1, op-index += 0
; STMT_SEQ-NEXT: 0x000000000000001a 12 3 0 0 0 0 is_stmt
-; STMT_SEQ-NEXT: 0x00000069: 02 DW_LNS_advance_pc (addr += 5, op-index += 0)
-; STMT_SEQ-NEXT: 0x0000006b: 00 DW_LNE_end_sequence
+; STMT_SEQ-NEXT: 0x0000006b: 02 DW_LNS_advance_pc (addr += 5, op-index += 0)
+; STMT_SEQ-NEXT: 0x0000006d: 00 DW_LNE_end_sequence
; STMT_SEQ-NEXT: 0x000000000000001f 12 3 0 0 0 0 is_stmt end_sequence
; generated from:
diff --git a/llvm/test/MC/ELF/debug-loc-label.s b/llvm/test/MC/ELF/debug-loc-label.s
index 6b5d04777bef4..4200b1192107b 100644
--- a/llvm/test/MC/ELF/debug-loc-label.s
+++ b/llvm/test/MC/ELF/debug-loc-label.s
@@ -17,43 +17,47 @@
# CHECK-LINE-TABLE-NEXT: 0x0000002a: 00 DW_LNE_set_address (0x0000000000000000)
# CHECK-LINE-TABLE-NEXT: 0x00000035: 01 DW_LNS_copy
# CHECK-LINE-TABLE-NEXT: 0x0000000000000000 1 1 1 0 0 0 is_stmt
-# CHECK-LINE-TABLE-NEXT: 0x00000036: 00 DW_LNE_end_sequence
-# CHECK-LINE-TABLE-NEXT: 0x0000000000000000 1 1 1 0 0 0 is_stmt end_sequence
-# CHECK-LINE-TABLE-NEXT: 0x00000039: 05 DW_LNS_set_column (2)
-# CHECK-LINE-TABLE-NEXT: 0x0000003b: 00 DW_LNE_set_address (0x0000000000000008)
-# CHECK-LINE-TABLE-NEXT: 0x00000046: 01 DW_LNS_copy
+# CHECK-LINE-TABLE-NEXT: 0x00000036: 02 DW_LNS_advance_pc (addr += 8, op-index += 0)
+# CHECK-LINE-TABLE-NEXT: 0x00000038: 00 DW_LNE_end_sequence
+# CHECK-LINE-TABLE-NEXT: 0x0000000000000008 1 1 1 0 0 0 is_stmt end_sequence
+# CHECK-LINE-TABLE-NEXT: 0x0000003b: 05 DW_LNS_set_column (2)
+# CHECK-LINE-TABLE-NEXT: 0x0000003d: 00 DW_LNE_set_address (0x0000000000000008)
+# CHECK-LINE-TABLE-NEXT: 0x00000048: 01 DW_LNS_copy
# CHECK-LINE-TABLE-NEXT: 0x0000000000000008 1 2 1 0 0 0 is_stmt
-# CHECK-LINE-TABLE-NEXT: 0x00000047: 00 DW_LNE_end_sequence
-# CHECK-LINE-TABLE-NEXT: 0x0000000000000008 1 2 1 0 0 0 is_stmt end_sequence
-# CHECK-LINE-TABLE-NEXT: 0x0000004a: 05 DW_LNS_set_column (3)
-# CHECK-LINE-TABLE-NEXT: 0x0000004c: 00 DW_LNE_set_address (0x0000000000000010)
-# CHECK-LINE-TABLE-NEXT: 0x00000057: 01 DW_LNS_copy
+# CHECK-LINE-TABLE-NEXT: 0x00000049: 02 DW_LNS_advance_pc (addr += 8, op-index += 0)
+# CHECK-LINE-TABLE-NEXT: 0x0000004b: 00 DW_LNE_end_sequence
+# CHECK-LINE-TABLE-NEXT: 0x0000000000000010 1 2 1 0 0 0 is_stmt end_sequence
+# CHECK-LINE-TABLE-NEXT: 0x0000004e: 05 DW_LNS_set_column (3)
+# CHECK-LINE-TABLE-NEXT: 0x00000050: 00 DW_LNE_set_address (0x0000000000000010)
+# CHECK-LINE-TABLE-NEXT: 0x0000005b: 01 DW_LNS_copy
# CHECK-LINE-TABLE-NEXT: 0x0000000000000010 1 3 1 0 0 0 is_stmt
-# CHECK-LINE-TABLE-NEXT: 0x00000058: 00 DW_LNE_end_sequence
-# CHECK-LINE-TABLE-NEXT: 0x0000000000000010 1 3 1 0 0 0 is_stmt end_sequence
-# CHECK-LINE-TABLE-NEXT: 0x0000005b: 05 DW_LNS_set_column (4)
-# CHECK-LINE-TABLE-NEXT: 0x0000005d: 00 DW_LNE_set_address (0x0000000000000018)
-# CHECK-LINE-TABLE-NEXT: 0x00000068: 01 DW_LNS_copy
+# CHECK-LINE-TABLE-NEXT: 0x0000005c: 02 DW_LNS_advance_pc (addr += 8, op-index += 0)
+# CHECK-LINE-TABLE-NEXT: 0x0000005e: 00 DW_LNE_end_sequence
+# CHECK-LINE-TABLE-NEXT: 0x0000000000000018 1 3 1 0 0 0 is_stmt end_sequence
+# CHECK-LINE-TABLE-NEXT: 0x00000061: 05 DW_LNS_set_column (4)
+# CHECK-LINE-TABLE-NEXT: 0x00000063: 00 DW_LNE_set_address (0x0000000000000018)
+# CHECK-LINE-TABLE-NEXT: 0x0000006e: 01 DW_LNS_copy
# CHECK-LINE-TABLE-NEXT: 0x0000000000000018 1 4 1 0 0 0 is_stmt
-# CHECK-LINE-TABLE-NEXT: 0x00000069: 05 DW_LNS_set_column (5)
-# CHECK-LINE-TABLE-NEXT: 0x0000006b: 01 DW_LNS_copy
+# CHECK-LINE-TABLE-NEXT: 0x0000006f: 05 DW_LNS_set_column (5)
+# CHECK-LINE-TABLE-NEXT: 0x00000071: 01 DW_LNS_copy
# CHECK-LINE-TABLE-NEXT: 0x0000000000000018 1 5 1 0 0 0 is_stmt
-# CHECK-LINE-TABLE-NEXT: 0x0000006c: 00 DW_LNE_end_sequence
-# CHECK-LINE-TABLE-NEXT: 0x0000000000000018 1 5 1 0 0 0 is_stmt end_sequence
+# CHECK-LINE-TABLE-NEXT: 0x00000072: 02 DW_LNS_advance_pc (addr += 8, op-index += 0)
+# CHECK-LINE-TABLE-NEXT: 0x00000074: 00 DW_LNE_end_sequence
+# CHECK-LINE-TABLE-NEXT: 0x0000000000000020 1 5 1 0 0 0 is_stmt end_sequence
# CHECK-SYM: Symbol table '.symtab' contains 9 entries:
# CHECK-SYM-NEXT: Num: Value Size Type Bind Vis Ndx Name
# CHECK-SYM-NEXT: 0: 0000000000000000 0 NOTYPE LOCAL DEFAULT UND
# CHECK-SYM-NEXT: 1: 0000000000000000 0 FILE LOCAL DEFAULT ABS test.c
# CHECK-SYM-NEXT: 2: 0000000000000000 0 SECTION LOCAL DEFAULT 2 .text
-# CHECK-SYM-NEXT: 3: 0000000000000039 0 NOTYPE LOCAL DEFAULT 3 my_label_02
-# CHECK-SYM-NEXT: 4: 000000000000004a 0 NOTYPE LOCAL DEFAULT 3 my_label_03
-# CHECK-SYM-NEXT: 5: 000000000000005b 0 NOTYPE LOCAL DEFAULT 3 my_label_04
-# CHECK-SYM-NEXT: 6: 000000000000004a 0 NOTYPE LOCAL DEFAULT 3 my_label_03.1
-# CHECK-SYM-NEXT: 7: 000000000000006f 0 NOTYPE LOCAL DEFAULT 3 my_label_05
+# CHECK-SYM-NEXT: 3: 000000000000003b 0 NOTYPE LOCAL DEFAULT 3 my_label_02
+# CHECK-SYM-NEXT: 4: 000000000000004e 0 NOTYPE LOCAL DEFAULT 3 my_label_03
+# CHECK-SYM-NEXT: 5: 0000000000000061 0 NOTYPE LOCAL DEFAULT 3 my_label_04
+# CHECK-SYM-NEXT: 6: 000000000000004e 0 NOTYPE LOCAL DEFAULT 3 my_label_03.1
+# CHECK-SYM-NEXT: 7: 0000000000000077 0 NOTYPE LOCAL DEFAULT 3 my_label_05
# CHECK-SYM-NEXT: 8: 0000000000000000 0 FUNC GLOBAL DEFAULT 2 foo
-# CHECK-OFFSETS: 0000 39000000 4a000000 5b000000
+# CHECK-OFFSETS: 0000 3b000000 4e000000 61000000
.text
.file "test.c"
|
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This reverts commit aabf18d.
#157529 included a test that used clang, which doesn't exists in some CI. #158343 reverts it.
This PR reapplies the original patch with the incorrect test removed.
Context
#99710 introduced
.loc_labelso we can terminate a line sequence. However, it did not advance PC properly. This is problematic for 1-instruction functions as it will have zero-length sequence. The test checked in that PR shows the problem:Both rows having PC 0x0 is incorrect, and parsers won't be able to parse them. See more explanation why this is wrong in #154851.
Design
This PR attempts to fix this by advancing the PC to the next available Label, and advance to the end of the section if no Label is available.
Implementation
emitDwarfLineEndEntrywill advance PC to theCurrLabelCurrLabelis null, its probably a fake LineEntry we introduced in [DebugInfo][DWARF] Emit Per-Function Line Table Offsets and End Sequences #110192. In that case look for the next LabelnullandemitDwarfLineEndEntryis smart enough to advance PC to the end of the sectionLastLabeltoPrevLabel, "last" can mean "previous" or "final", this is ambigous.Note
This fix should render #154986 and #154851 obsolete, they were temporary fixes and don't resolve the root cause.