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Suppress spurious warnings due to R_RISCV_SET_ULEB128
llvm-objdump -S issues unnecessary warnings for RISC-V relocatable files containing .debug_loclists or .debug_rnglists sections with ULEB128 relocations. This occurred because `DWARFObjInMemory` verifies support for all relocation types, triggering warnings for unsupported ones. ``` % llvm-objdump -S a.o ... 0000000000000000 <foo>: warning: failed to compute relocation: R_RISCV_SUB_ULEB128, Invalid data was encountered while parsing the file warning: failed to compute relocation: R_RISCV_SET_ULEB128, Invalid data was encountered while parsing the file ... ``` This change fixes #101544 by declaring support for the two ULEB128 relocation types, silencing the spurious warnings. --- In DWARF v5 builds, DW_LLE_offset_pair/DW_RLE_offset_pair might be generated in .debug_loclists/.debug_rnglists with ULEB128 relocations. They are only read by llvm-dwarfdump to dump section content and verbose DW_AT_location/DW_AT_ranges output for relocatable files. The DebugInfoDWARF user (e.g. DWARFDebugRnglists.cpp) calls `Data.getULEB128` without checking the ULEB128 relocations, as the unrelocated value holds meaning (refer to the assembler implementation https://reviews.llvm.org/D157657). This differs from `.quad .Lfoo`, which requires relocation reading (e.g. https://reviews.llvm.org/D74404). Pull Request: #101607
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‎llvm/lib/Object/RelocationResolver.cpp

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@@ -457,6 +457,12 @@ static bool supportsRISCV(uint64_t Type) {
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case ELF::R_RISCV_SUB32:
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case ELF::R_RISCV_ADD64:
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case ELF::R_RISCV_SUB64:
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// Because the unrelocated value generated by .uleb128 A-B (used by
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// loclists/rnglists) is meaningful, DebugInfoDWARF does not inspect the
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// relocations. We declare support for the two relocation types without an
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// (unreachable) implementation.
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case ELF::R_RISCV_SET_ULEB128:
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case ELF::R_RISCV_SUB_ULEB128:
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return true;
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default:
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return false;

‎llvm/test/tools/llvm-objdump/ELF/RISCV/source-interleave.ll

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; RUN: rm -rf %t && split-file %s %t && cd %t
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; RUN: llc -filetype=obj a.ll -o a.o
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; RUN: llvm-readelf -r a.o 2>err | FileCheck %s --check-prefix=RELOC
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; RUN: llvm-objdump -Sl --no-show-raw-insn a.o 2>err | FileCheck %s
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;; Test that ULEB128 relocs do not lead to spurious warnings.
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;; https://github.com/llvm/llvm-project/issues/101544
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; RUN: count 0 < err
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; RELOC: Relocation section '.rela.debug_loclists'
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; RELOC: R_RISCV_SET_ULEB128
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; RELOC-NEXT: R_RISCV_SUB_ULEB128
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; CHECK: ; foo():
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; CHECK-NEXT: /proc/self/cwd/a.c:2
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; CHECK-NEXT: ; int foo(int x) {
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; CHECK-NEXT: 0: addi sp, sp, -0x10
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; CHECK-NEXT: 2: sd ra, 0x8(sp)
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; CHECK-NEXT: /proc/self/cwd/a.c:3
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; CHECK-NEXT: ; ext();
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; CHECK-NEXT: 4: auipc ra, 0x0
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;--- a.c
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int ext(void);
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int foo(int x) {
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ext();
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return 0;
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}
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int ext(void);
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void foo2() {
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{
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int ret = ext();
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if (__builtin_expect(ret, 0))
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ext();
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}
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}
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;--- gen
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clang --target=riscv64-linux -S -emit-llvm -g -O1 a.c -o - | sed -E '/^attribute/s/,-[-0-9a-z]+//g'
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;--- a.ll
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; ModuleID = 'a.c'
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source_filename = "a.c"
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target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128"
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target triple = "riscv64-unknown-linux"
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; Function Attrs: nounwind uwtable
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define dso_local noundef signext i32 @foo(i32 noundef signext %x) local_unnamed_addr #0 !dbg !13 {
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entry:
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#dbg_value(i32 %x, !18, !DIExpression(), !19)
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%call = tail call signext i32 @ext() #2, !dbg !20
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ret i32 0, !dbg !21
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}
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declare !dbg !22 signext i32 @ext() local_unnamed_addr #1
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; Function Attrs: nounwind uwtable
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define dso_local void @foo2() local_unnamed_addr #0 !dbg !25 {
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entry:
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%call = tail call signext i32 @ext() #2, !dbg !31
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#dbg_value(i32 %call, !29, !DIExpression(), !32)
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%tobool.not = icmp eq i32 %call, 0, !dbg !33
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br i1 %tobool.not, label %if.end, label %if.then, !dbg !35, !prof !36
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if.then: ; preds = %entry
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%call1 = tail call signext i32 @ext() #2, !dbg !37
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br label %if.end, !dbg !37
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if.end: ; preds = %if.then, %entry
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ret void, !dbg !38
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}
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attributes #0 = { nounwind uwtable "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic-rv64" "target-features"="+64bit,+a,+c,+d,+f,+m,+relax,+zicsr,+zmmul" }
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attributes #1 = { "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic-rv64" "target-features"="+64bit,+a,+c,+d,+f,+m,+relax,+zicsr,+zmmul" }
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attributes #2 = { nounwind }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2, !3, !4, !5, !6, !8, !9, !10, !11, !12}
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!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
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!1 = !DIFile(filename: "a.c", directory: "/proc/self/cwd", checksumkind: CSK_MD5, checksum: "4791066d0b0e4fd9c4b4df1c56f349cb")
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!2 = !{i32 7, !"Dwarf Version", i32 5}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = !{i32 1, !"wchar_size", i32 4}
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!5 = !{i32 1, !"target-abi", !"lp64d"}
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!6 = !{i32 6, !"riscv-isa", !7}
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!7 = !{!"rv64i2p1_m2p0_a2p1_f2p2_d2p2_c2p0_zicsr2p0_zmmul1p0"}
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!8 = !{i32 8, !"PIC Level", i32 2}
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!9 = !{i32 7, !"PIE Level", i32 2}
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!10 = !{i32 7, !"uwtable", i32 2}
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!11 = !{i32 8, !"SmallDataLimit", i32 8}
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!12 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
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!13 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 2, type: !14, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !17)
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!14 = !DISubroutineType(types: !15)
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!15 = !{!16, !16}
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!16 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!17 = !{!18}
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!18 = !DILocalVariable(name: "x", arg: 1, scope: !13, file: !1, line: 2, type: !16)
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!19 = !DILocation(line: 0, scope: !13)
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!20 = !DILocation(line: 3, column: 3, scope: !13)
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!21 = !DILocation(line: 4, column: 3, scope: !13)
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!22 = !DISubprogram(name: "ext", scope: !1, file: !1, line: 1, type: !23, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
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!23 = !DISubroutineType(types: !24)
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!24 = !{!16}
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!25 = distinct !DISubprogram(name: "foo2", scope: !1, file: !1, line: 8, type: !26, scopeLine: 8, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !28)
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!26 = !DISubroutineType(types: !27)
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!27 = !{null}
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!28 = !{!29}
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!29 = !DILocalVariable(name: "ret", scope: !30, file: !1, line: 10, type: !16)
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!30 = distinct !DILexicalBlock(scope: !25, file: !1, line: 9, column: 3)
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!31 = !DILocation(line: 10, column: 15, scope: !30)
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!32 = !DILocation(line: 0, scope: !30)
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!33 = !DILocation(line: 11, column: 9, scope: !34)
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!34 = distinct !DILexicalBlock(scope: !30, file: !1, line: 11, column: 9)
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!35 = !DILocation(line: 11, column: 9, scope: !30)
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!36 = !{!"branch_weights", !"expected", i32 2000, i32 1}
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!37 = !DILocation(line: 12, column: 7, scope: !34)
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!38 = !DILocation(line: 14, column: 1, scope: !25)

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