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Omit .debug_aranges if it is empty #99897

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Merged
merged 1 commit into from
Jul 22, 2024
Merged

Omit .debug_aranges if it is empty #99897

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6 changes: 4 additions & 2 deletions llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2990,6 +2990,9 @@ struct ArangeSpan {
// Emit a debug aranges section, containing a CU lookup for any
// address we can tie back to a CU.
void DwarfDebug::emitDebugARanges() {
if (ArangeLabels.empty())
return;

// Provides a unique id per text section.
MapVector<MCSection *, SmallVector<SymbolCU, 8>> SectionMap;

Expand All @@ -3012,8 +3015,7 @@ void DwarfDebug::emitDebugARanges() {
for (auto &I : SectionMap) {
MCSection *Section = I.first;
SmallVector<SymbolCU, 8> &List = I.second;
if (List.size() < 1)
continue;
assert(!List.empty());
Comment on lines -3015 to +3018
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After convincing myself that any List must be non-empty, I was confident that the early return could be placed above this loop. I replaced the dead check with an assert to avoid similar head scratching in future.

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I believe the assert is appropriate even without the early return. If ArangeLabels is empty, SectionMap will also be empty, and the loop body will not execute.

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Yep, agreed. Just wanted to explain why I touched this seemingly unrelated part, for posterity.


// If we have no section (e.g. common), just write out
// individual spans for each symbol.
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2 changes: 1 addition & 1 deletion llvm/test/DebugInfo/omit-empty.ll
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@@ -1,4 +1,4 @@
; RUN: %llc_dwarf %s -filetype=obj -o - | llvm-objdump -h - | FileCheck %s
; RUN: %llc_dwarf %s -filetype=obj -generate-arange-section -o - | llvm-objdump -h - | FileCheck %s
; REQUIRES: object-emission

; CHECK-NOT: .debug_
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