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[WebAssembly][Object] Record section start offsets at start of payload (
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#76188)

LLVM ObjectFile currently records the start offsets of sections as the
start of the section header, whereas most other tools (WABT, emscripten,
wasm-tools) record it as the start of the section content, after the
header. This affects binutils tools such as objdump and nm, but not
compilation/assembly (since that is driven by symbols and assembler
labels which already have their values inside the section payload rather
in the header. This patch updates LLVM to match the other tools.
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@dschuff
dschuff committed Dec 21, 2023
1 parent 0110245 commit 35a5df2
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Showing 7 changed files with 58 additions and 58 deletions.
2 changes: 1 addition & 1 deletion llvm/lib/Object/WasmObjectFile.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -265,14 +265,14 @@ static wasm::WasmTableType readTableType(WasmObjectFile::ReadContext &Ctx) {

static Error readSection(WasmSection &Section, WasmObjectFile::ReadContext &Ctx,
WasmSectionOrderChecker &Checker) {
Section.Offset = Ctx.Ptr - Ctx.Start;
Section.Type = readUint8(Ctx);
LLVM_DEBUG(dbgs() << "readSection type=" << Section.Type << "\n");
// When reading the section's size, store the size of the LEB used to encode
// it. This allows objcopy/strip to reproduce the binary identically.
const uint8_t *PreSizePtr = Ctx.Ptr;
uint32_t Size = readVaruint32(Ctx);
Section.HeaderSecSizeEncodingLen = Ctx.Ptr - PreSizePtr;
Section.Offset = Ctx.Ptr - Ctx.Start;
if (Size == 0)
return make_error<StringError>("zero length section",
object_error::parse_failed);
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6 changes: 3 additions & 3 deletions llvm/test/MC/WebAssembly/custom-sections.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -15,18 +15,18 @@ target triple = "wasm32-unknown-unknown"
; CHECK: Section {
; CHECK: Type: CUSTOM (0x0)
; CHECK: Size: 3
; CHECK: Offset: 38
; CHECK: Offset: 44
; CHECK: Name: red
; CHECK: }
; CHECK: Section {
; CHECK: Type: CUSTOM (0x0)
; CHECK: Size: 6
; CHECK: Offset: 51
; CHECK: Offset: 57
; CHECK: Name: green
; CHECK: }
; CHECK: Section {
; CHECK: Type: CUSTOM (0x0)
; CHECK: Size: 25
; CHECK: Offset: 84
; CHECK: Offset: 90
; CHECK: Name: producers
; CHECK: }
44 changes: 22 additions & 22 deletions llvm/test/MC/WebAssembly/debug-info.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -7,37 +7,37 @@
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: TYPE (0x1)
; CHECK-NEXT: Size: 4
; CHECK-NEXT: Offset: 8
; CHECK-NEXT: Offset: 14
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: IMPORT (0x2)
; CHECK-NEXT: Size: 81
; CHECK-NEXT: Offset: 18
; CHECK-NEXT: Offset: 24
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: FUNCTION (0x3)
; CHECK-NEXT: Size: 2
; CHECK-NEXT: Offset: 105
; CHECK-NEXT: Offset: 111
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: ELEM (0x9)
; CHECK-NEXT: Size: 7
; CHECK-NEXT: Offset: 113
; CHECK-NEXT: Offset: 119
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: DATACOUNT (0xC)
; CHECK-NEXT: Size: 1
; CHECK-NEXT: Offset: 126
; CHECK-NEXT: Offset: 132
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CODE (0xA)
; CHECK-NEXT: Size: 4
; CHECK-NEXT: Offset: 133
; CHECK-NEXT: Offset: 139
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: DATA (0xB)
; CHECK-NEXT: Size: 19
; CHECK-NEXT: Offset: 143
; CHECK-NEXT: Offset: 149
; CHECK-NEXT: Segments [
; CHECK-NEXT: Segment {
; CHECK-NEXT: Name: .data.foo
Expand All @@ -54,91 +54,91 @@
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 86
; CHECK-NEXT: Offset: 168
; CHECK-NEXT: Offset: 174
; CHECK-NEXT: Name: .debug_abbrev
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 114
; CHECK-NEXT: Offset: 274
; CHECK-NEXT: Offset: 280
; CHECK-NEXT: Name: .debug_info
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 48
; CHECK-NEXT: Offset: 406
; CHECK-NEXT: Offset: 412
; CHECK-NEXT: Name: .debug_aranges
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 121
; CHECK-NEXT: Offset: 475
; CHECK-NEXT: Offset: 481
; CHECK-NEXT: Name: .debug_str
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 42
; CHECK-NEXT: Offset: 613
; CHECK-NEXT: Offset: 619
; CHECK-NEXT: Name: .debug_pubnames
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 26
; CHECK-NEXT: Offset: 677
; CHECK-NEXT: Offset: 683
; CHECK-NEXT: Name: .debug_pubtypes
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 56
; CHECK-NEXT: Offset: 725
; CHECK-NEXT: Offset: 731
; CHECK-NEXT: Name: .debug_line
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 91
; CHECK-NEXT: Offset: 799
; CHECK-NEXT: Offset: 805
; CHECK-NEXT: Name: linking
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 9
; CHECK-NEXT: Offset: 904
; CHECK-NEXT: Offset: 910
; CHECK-NEXT: Name: reloc.DATA
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 61
; CHECK-NEXT: Offset: 930
; CHECK-NEXT: Offset: 936
; CHECK-NEXT: Name: reloc..debug_info
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 18
; CHECK-NEXT: Offset: 1015
; CHECK-NEXT: Offset: 1021
; CHECK-NEXT: Name: reloc..debug_aranges
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 6
; CHECK-NEXT: Offset: 1060
; CHECK-NEXT: Offset: 1066
; CHECK-NEXT: Name: reloc..debug_pubnames
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 6
; CHECK-NEXT: Offset: 1094
; CHECK-NEXT: Offset: 1100
; CHECK-NEXT: Name: reloc..debug_pubtypes
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 6
; CHECK-NEXT: Offset: 1128
; CHECK-NEXT: Offset: 1134
; CHECK-NEXT: Name: reloc..debug_line
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 77
; CHECK-NEXT: Offset: 1158
; CHECK-NEXT: Offset: 1164
; CHECK-NEXT: Name: producers
; CHECK-NEXT: }
; CHECK-NEXT:]
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46 changes: 23 additions & 23 deletions llvm/test/MC/WebAssembly/debug-info64.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -7,37 +7,37 @@
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: TYPE (0x1)
; CHECK-NEXT: Size: 4
; CHECK-NEXT: Offset: 8
; CHECK-NEXT: Offset: 14
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: IMPORT (0x2)
; CHECK-NEXT: Size: 81
; CHECK-NEXT: Offset: 18
; CHECK-NEXT: Offset: 24
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: FUNCTION (0x3)
; CHECK-NEXT: Size: 2
; CHECK-NEXT: Offset: 105
; CHECK-NEXT: Offset: 111
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: ELEM (0x9)
; CHECK-NEXT: Size: 7
; CHECK-NEXT: Offset: 113
; CHECK-NEXT: Offset: 119
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: DATACOUNT (0xC)
; CHECK-NEXT: Size: 1
; CHECK-NEXT: Offset: 126
; CHECK-NEXT: Offset: 132
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CODE (0xA)
; CHECK-NEXT: Size: 4
; CHECK-NEXT: Offset: 133
; CHECK-NEXT: Offset: 139
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: DATA (0xB)
; CHECK-NEXT: Size: 27
; CHECK-NEXT: Offset: 143
; CHECK-NEXT: Offset: 149
; CHECK-NEXT: Segments [
; CHECK-NEXT: Segment {
; CHECK-NEXT: Name: .data.foo
Expand All @@ -54,97 +54,97 @@
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 86
; CHECK-NEXT: Offset: 176
; CHECK-NEXT: Offset: 182
; CHECK-NEXT: Name: .debug_abbrev
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 130
; CHECK-NEXT: Offset: 282
; CHECK-NEXT: Offset: 288
; CHECK-NEXT: Name: .debug_info
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 80
; CHECK-NEXT: Offset: 430
; CHECK-NEXT: Offset: 436
; CHECK-NEXT: Name: .debug_aranges
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 121
; CHECK-NEXT: Offset: 531
; CHECK-NEXT: Offset: 537
; CHECK-NEXT: Name: .debug_str
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 42
; CHECK-NEXT: Offset: 669
; CHECK-NEXT: Offset: 675
; CHECK-NEXT: Name: .debug_pubnames
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 26
; CHECK-NEXT: Offset: 733
; CHECK-NEXT: Offset: 739
; CHECK-NEXT: Name: .debug_pubtypes
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 60
; CHECK-NEXT: Offset: 781
; CHECK-NEXT: Offset: 787
; CHECK-NEXT: Name: .debug_line
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 91
; CHECK-NEXT: Offset: 859
; CHECK-NEXT: Offset: 865
; CHECK-NEXT: Name: linking
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 9
; CHECK-NEXT: Offset: 964
; CHECK-NEXT: Offset: 970
; CHECK-NEXT: Name: reloc.DATA
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 61
; CHECK-NEXT: Offset: 990
; CHECK-NEXT: Offset: 996
; CHECK-NEXT: Name: reloc..debug_info
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 18
; CHECK-NEXT: Offset: 1075
; CHECK-NEXT: Offset: 1081
; CHECK-NEXT: Name: reloc..debug_aranges
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 6
; CHECK-NEXT: Offset: 1120
; CHECK-NEXT: Offset: 1126
; CHECK-NEXT: Name: reloc..debug_pubnames
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 6
; CHECK-NEXT: Offset: 1154
; CHECK-NEXT: Offset: 1160
; CHECK-NEXT: Name: reloc..debug_pubtypes
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 6
; CHECK-NEXT: Offset: 1188
; CHECK-NEXT: Offset: 1194
; CHECK-NEXT: Name: reloc..debug_line
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 77
; CHECK-NEXT: Offset: 1218
; CHECK-NEXT: Offset: 1224
; CHECK-NEXT: Name: producers
; CHECK-NEXT: }
; CHECK-NEXT: Section {
; CHECK-NEXT: Type: CUSTOM (0x0)
; CHECK-NEXT: Size: 11
; CHECK-NEXT: Offset: 1311
; CHECK-NEXT: Offset: 1317
; CHECK-NEXT: Name: target_features
; CHECK-NEXT: }
; CHECK-NEXT: ]
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2 changes: 1 addition & 1 deletion llvm/test/MC/WebAssembly/tag-section.ll
View file
Original file line number Diff line number Diff line change
Expand Up @@ -53,4 +53,4 @@ define i32 @test_throw1(ptr %p) {

; SEC: Type: TAG (0xD)
; SEC-NEXT: Size: 3
; SEC-NEXT: Offset: 63
; SEC-NEXT: Offset: 69
2 changes: 1 addition & 1 deletion llvm/test/tools/llvm-readobj/wasm/globals.test
View file
Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ Sections:
# CHECK: Section {
# CHECK-NEXT: Type: DATA (0xB)
# CHECK-NEXT: Size: 7
# CHECK-NEXT: Offset: 8
# CHECK-NEXT: Offset: 14
# CHECK-NEXT: Segments [
# CHECK-NEXT: Segment {
# CHECK-NEXT: Size: 1
Expand Down

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