[LLD][COFF] Allow symbols with empty chunks to have no associated output section #149523
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…put section If a chunk is empty and there are no other non-empty chunks in the same section, removeEmptySections() will remove the entire section. In this case, use a section index of 0, as the MSVC linker does, instead of asserting.
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This issue was reported to cause problems when building Wine: In that case, it involved the recently introduced |
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@llvm/pr-subscribers-lld-coff @llvm/pr-subscribers-platform-windows Author: Jacek Caban (cjacek) ChangesIf a chunk is empty and there are no other non-empty chunks in the same section, Full diff: https://github.com/llvm/llvm-project/pull/149523.diff 2 Files Affected:
diff --git a/lld/COFF/PDB.cpp b/lld/COFF/PDB.cpp
index a54ea403ba2ec..94eeae2797971 100644
--- a/lld/COFF/PDB.cpp
+++ b/lld/COFF/PDB.cpp
@@ -1135,9 +1135,12 @@ static pdb::BulkPublic createPublic(COFFLinkerContext &ctx, Defined *def) {
pub.setFlags(flags);
OutputSection *os = ctx.getOutputSection(def->getChunk());
- assert(os && "all publics should be in final image");
- pub.Offset = def->getRVA() - os->getRVA();
- pub.Segment = os->sectionIndex;
+ assert((os || !def->getChunk()->getSize()) &&
+ "all publics should be in final image");
+ if (os) {
+ pub.Offset = def->getRVA() - os->getRVA();
+ pub.Segment = os->sectionIndex;
+ }
return pub;
}
diff --git a/lld/test/COFF/pdb-empty-sec.s b/lld/test/COFF/pdb-empty-sec.s
new file mode 100644
index 0000000000000..0d61447b76651
--- /dev/null
+++ b/lld/test/COFF/pdb-empty-sec.s
@@ -0,0 +1,19 @@
+// REQUIRES: x86
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
+// RUN: lld-link -dll -noentry -debug %t.obj -out:%t.dll
+// RUN: llvm-pdbutil dump -publics %t.pdb | FileCheck %s
+
+// CHECK: Records
+// CHECK-NEXT: 0 | S_PUB32 [size = 20] `func`
+// CHECK-NEXT: flags = none, addr = 0001:0000
+// CHECK-NEXT: 20 | S_PUB32 [size = 20] `sym`
+// CHECK-NEXT: flags = none, addr = 0000:0000
+
+ .globl sym
+ .data
+sym:
+ .text
+ .globl func
+func:
+ ret
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@llvm/pr-subscribers-lld Author: Jacek Caban (cjacek) ChangesIf a chunk is empty and there are no other non-empty chunks in the same section, Full diff: https://github.com/llvm/llvm-project/pull/149523.diff 2 Files Affected:
diff --git a/lld/COFF/PDB.cpp b/lld/COFF/PDB.cpp
index a54ea403ba2ec..94eeae2797971 100644
--- a/lld/COFF/PDB.cpp
+++ b/lld/COFF/PDB.cpp
@@ -1135,9 +1135,12 @@ static pdb::BulkPublic createPublic(COFFLinkerContext &ctx, Defined *def) {
pub.setFlags(flags);
OutputSection *os = ctx.getOutputSection(def->getChunk());
- assert(os && "all publics should be in final image");
- pub.Offset = def->getRVA() - os->getRVA();
- pub.Segment = os->sectionIndex;
+ assert((os || !def->getChunk()->getSize()) &&
+ "all publics should be in final image");
+ if (os) {
+ pub.Offset = def->getRVA() - os->getRVA();
+ pub.Segment = os->sectionIndex;
+ }
return pub;
}
diff --git a/lld/test/COFF/pdb-empty-sec.s b/lld/test/COFF/pdb-empty-sec.s
new file mode 100644
index 0000000000000..0d61447b76651
--- /dev/null
+++ b/lld/test/COFF/pdb-empty-sec.s
@@ -0,0 +1,19 @@
+// REQUIRES: x86
+
+// RUN: llvm-mc -filetype=obj -triple=x86_64-windows %s -o %t.obj
+// RUN: lld-link -dll -noentry -debug %t.obj -out:%t.dll
+// RUN: llvm-pdbutil dump -publics %t.pdb | FileCheck %s
+
+// CHECK: Records
+// CHECK-NEXT: 0 | S_PUB32 [size = 20] `func`
+// CHECK-NEXT: flags = none, addr = 0001:0000
+// CHECK-NEXT: 20 | S_PUB32 [size = 20] `sym`
+// CHECK-NEXT: flags = none, addr = 0000:0000
+
+ .globl sym
+ .data
+sym:
+ .text
+ .globl func
+func:
+ ret
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cjacek
referenced
this pull request
in mstorsjo/llvm-mingw
Jul 18, 2025
Relevant changes include: - Lots of work for supporting ARM64EC and ARM64X - LLD now produces more compact string tables in executables (only relevant when including debug symbols) - llvm-rc now supports multiplication/division expressions, like GNU windres - Improved support for armv7 and aarch64 in libunwind (for Itanium ABI "forced unwinding", which I'm not aware of being used in practice anywhere) - Made the libunwind, libcxxabi, libcxx and compiler-rt tests pass on armv7 and aarch64 mingw - Made the llvm/clang tests pass on aarch64 mingw
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If a chunk is empty and there are no other non-empty chunks in the same section,
removeEmptySections()will remove the entire section. In this case, use a section index of 0, as the MSVC linker does, instead of asserting.