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@llvm-beanz llvm-beanz commented Sep 21, 2025

This adds support for the -dump-section=<section>=<file> flag for the DXContainer file format. This flag dumps the contents of a named section to the specified file.

This flag is particularly handy for ripping DXIL bitcode out of the object files so that we can use LLVM tools to inspect and operate on the bitcode. To facilitate that workflow this flag also strips the program headers from parts containing DXIL so that the resulting file is a valid bitcode file.

This adds support for the -dump-section=<section>=<file> flag for the
DXContainer file format. This flag dumps the contents of a named section
to the specified file.

This flag is particularly handy for ripping DXIL bitcode out of the
object files so that we can use LLVM tools to inspect and operate on
the bitcode. To facilitate that workflow this flag also strips the
program headers from parts containing DXIL so that the resulting file is
a valid bitcode file.
../llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp
../llvm/test/tools/llvm-objcopy/DXContainer/dump-section.yaml
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llvmbot commented Sep 21, 2025

@llvm/pr-subscribers-llvm-binary-utilities

@llvm/pr-subscribers-backend-directx

Author: Chris B (llvm-beanz)

Changes

This adds support for the -dump-section=<section>=<file> flag for the DXContainer file format. This flag dumps the contents of a named section to the specified file.

This flag is particularly handy for ripping DXIL bitcode out of the object files so that we can use LLVM tools to inspect and operate on the bitcode. To facilitate that workflow this flag also strips the program headers from parts containing DXIL so that the resulting file is a valid bitcode file.


Patch is 21.45 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/159999.diff

3 Files Affected:

  • (modified) llvm/lib/ObjCopy/ConfigManager.cpp (+8-8)
  • (modified) llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp (+35)
  • (added) llvm/test/tools/llvm-objcopy/DXContainer/dump-section.yaml (+283)
diff --git a/llvm/lib/ObjCopy/ConfigManager.cpp b/llvm/lib/ObjCopy/ConfigManager.cpp
index eef8a2190c4d2..6b7b4f116f583 100644
--- a/llvm/lib/ObjCopy/ConfigManager.cpp
+++ b/llvm/lib/ObjCopy/ConfigManager.cpp
@@ -122,14 +122,14 @@ ConfigManager::getDXContainerConfig() const {
   if (!Common.AddGnuDebugLink.empty() || !Common.SplitDWO.empty() ||
       !Common.AllocSectionsPrefix.empty() ||
       Common.DiscardMode != DiscardType::None || !Common.AddSection.empty() ||
-      !Common.DumpSection.empty() || !Common.KeepSection.empty() ||
-      !Common.SectionsToRename.empty() || !Common.SetSectionAlignment.empty() ||
-      !Common.SetSectionFlags.empty() || !Common.SetSectionType.empty() ||
-      Common.ExtractDWO || Common.OnlyKeepDebug || Common.StripAllGNU ||
-      Common.StripDWO || Common.StripDebug || Common.StripNonAlloc ||
-      Common.StripSections || Common.StripUnneeded ||
-      Common.DecompressDebugSections || Common.GapFill != 0 ||
-      Common.PadTo != 0 || Common.ChangeSectionLMAValAll != 0 ||
+      !Common.KeepSection.empty() || !Common.SectionsToRename.empty() ||
+      !Common.SetSectionAlignment.empty() || !Common.SetSectionFlags.empty() ||
+      !Common.SetSectionType.empty() || Common.ExtractDWO ||
+      Common.OnlyKeepDebug || Common.StripAllGNU || Common.StripDWO ||
+      Common.StripDebug || Common.StripNonAlloc || Common.StripSections ||
+      Common.StripUnneeded || Common.DecompressDebugSections ||
+      Common.GapFill != 0 || Common.PadTo != 0 ||
+      Common.ChangeSectionLMAValAll != 0 ||
       !Common.ChangeSectionAddress.empty()) {
     return createStringError(llvm::errc::invalid_argument,
                              "option is not supported for DXContainer");
diff --git a/llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp b/llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp
index d7f3c0d1f7b36..e41f3fe6bedb2 100644
--- a/llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp
+++ b/llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp
@@ -9,8 +9,10 @@
 #include "llvm/ObjCopy/DXContainer/DXContainerObjcopy.h"
 #include "DXContainerReader.h"
 #include "DXContainerWriter.h"
+#include "llvm/BinaryFormat/DXContainer.h"
 #include "llvm/ObjCopy/CommonConfig.h"
 #include "llvm/ObjCopy/DXContainer/DXContainerConfig.h"
+#include "llvm/Support/FileOutputBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 
 namespace llvm {
@@ -42,7 +44,40 @@ static Error extractPartAsObject(StringRef PartName, StringRef OutFilename,
                          "part '%s' not found", PartName.str().c_str());
 }
 
+static Error dumpPartToFile(StringRef PartName, StringRef Filename,
+                            StringRef InputFilename, Object &Obj) {
+  for (const Part &P : Obj.Parts) {
+    if (P.Name == PartName) {
+      ArrayRef<uint8_t> Contents = P.Data;
+      // For parts containing llvm bitcode, don't dump the program headers so
+      // that we get a valid .bc file.
+      if (PartName == "DXIL" || PartName == "STAT")
+        Contents = Contents.drop_front(sizeof(llvm::dxbc::ProgramHeader));
+      Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
+          FileOutputBuffer::create(Filename, Contents.size());
+      if (!BufferOrErr)
+        return createFileError(Filename, BufferOrErr.takeError());
+      std::unique_ptr<FileOutputBuffer> Buf = std::move(*BufferOrErr);
+      llvm::copy(Contents, Buf->getBufferStart());
+      if (Error E = Buf->commit())
+        return createFileError(Filename, std::move(E));
+      return Error::success();
+    }
+  }
+  return createFileError(Filename,
+                         std::make_error_code(std::errc::invalid_argument),
+                         "part '%s' not found", PartName.str().c_str());
+}
+
 static Error handleArgs(const CommonConfig &Config, Object &Obj) {
+  for (StringRef Flag : Config.DumpSection) {
+    StringRef SecName;
+    StringRef FileName;
+    std::tie(SecName, FileName) = Flag.split("=");
+    if (Error E = dumpPartToFile(SecName, FileName, Config.InputFilename, Obj))
+      return E;
+  }
+
   // Extract all sections before any modifications.
   for (StringRef Flag : Config.ExtractSection) {
     StringRef SectionName;
diff --git a/llvm/test/tools/llvm-objcopy/DXContainer/dump-section.yaml b/llvm/test/tools/llvm-objcopy/DXContainer/dump-section.yaml
new file mode 100644
index 0000000000000..faaf59b61638d
--- /dev/null
+++ b/llvm/test/tools/llvm-objcopy/DXContainer/dump-section.yaml
@@ -0,0 +1,283 @@
+# RUN: yaml2obj %s -o %t.dxbc
+# RUN: llvm-objcopy --dump-section=DXIL=%t.bc %t.dxbc
+# RUN: llvm-dis %t.bc -o - | FileCheck %s
+# RUN: wc -c %t.bc | FileCheck %s --check-prefix=DXIL-SIZE
+
+# Verify that when dumping the DXIL part we get a valid bitcode file.
+# CHECK: define void @main()
+# Verify the size of the bitcode data.
+# DXIL-SIZE: 1708
+
+# Dump the PSV0 part and verify its size.
+# RUN: llvm-objcopy --dump-section=PSV0=%t.psv0 %t.dxbc
+# RUN: wc -c %t.psv0 | FileCheck %s --check-prefix=PSV0-SIZE
+# PSV0-SIZE: 76
+--- !dxcontainer
+Header:
+  Hash:            [ 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0,
+                     0x0, 0x0, 0x0, 0x0, 0x0, 0x0 ]
+  Version:
+    Major:           1
+    Minor:           0
+  FileSize:        1956
+  PartCount:       6
+  PartOffsets:     [ 56, 1796, 1812, 1840, 1856, 1872 ]
+Parts:
+  - Name:            DXIL
+    Size:            1732
+    Program:
+      MajorVersion:    6
+      MinorVersion:    0
+      ShaderKind:      5
+      Size:            433
+      DXILMajorVersion: 1
+      DXILMinorVersion: 0
+      DXILSize:        1708
+      DXIL:            [ 0x42, 0x43, 0xC0, 0xDE, 0x21, 0xC, 0x0, 0x0, 0xA8,
+                         0x1, 0x0, 0x0, 0xB, 0x82, 0x20, 0x0, 0x2, 0x0,
+                         0x0, 0x0, 0x13, 0x0, 0x0, 0x0, 0x7, 0x81, 0x23,
+                         0x91, 0x41, 0xC8, 0x4, 0x49, 0x6, 0x10, 0x32,
+                         0x39, 0x92, 0x1, 0x84, 0xC, 0x25, 0x5, 0x8, 0x19,
+                         0x1E, 0x4, 0x8B, 0x62, 0x80, 0x10, 0x45, 0x2,
+                         0x42, 0x92, 0xB, 0x42, 0x84, 0x10, 0x32, 0x14,
+                         0x38, 0x8, 0x18, 0x4B, 0xA, 0x32, 0x42, 0x88,
+                         0x48, 0x90, 0x14, 0x20, 0x43, 0x46, 0x88, 0xA5,
+                         0x0, 0x19, 0x32, 0x42, 0xE4, 0x48, 0xE, 0x90,
+                         0x11, 0x22, 0xC4, 0x50, 0x41, 0x51, 0x81, 0x8C,
+                         0xE1, 0x83, 0xE5, 0x8A, 0x4, 0x21, 0x46, 0x6,
+                         0x51, 0x18, 0x0, 0x0, 0x4, 0x0, 0x0, 0x0, 0x1B,
+                         0x90, 0xE0, 0xFF, 0xFF, 0xFF, 0xFF, 0x7, 0xC0,
+                         0x1, 0x24, 0x80, 0x2, 0x0, 0x0, 0x0, 0x49, 0x18,
+                         0x0, 0x0, 0x1, 0x0, 0x0, 0x0, 0x13, 0x82, 0x0,
+                         0x0, 0x89, 0x20, 0x0, 0x0, 0x11, 0x0, 0x0, 0x0,
+                         0x32, 0x22, 0x8, 0x9, 0x20, 0x64, 0x85, 0x4, 0x13,
+                         0x22, 0xA4, 0x84, 0x4, 0x13, 0x22, 0xE3, 0x84,
+                         0xA1, 0x90, 0x14, 0x12, 0x4C, 0x88, 0x8C, 0xB,
+                         0x84, 0x84, 0x4C, 0x10, 0x20, 0x73, 0x4, 0x8,
+                         0xC1, 0x65, 0xC3, 0x85, 0x2C, 0xE8, 0x3, 0x40,
+                         0x14, 0x91, 0x4E, 0xD1, 0x4A, 0x48, 0x44, 0x54,
+                         0x11, 0xC3, 0x9, 0x30, 0xC4, 0x18, 0x1, 0x30,
+                         0x2, 0x50, 0x82, 0x21, 0x1A, 0x8, 0x98, 0x23,
+                         0x0, 0x3, 0x0, 0x13, 0x14, 0x72, 0xC0, 0x87, 0x74,
+                         0x60, 0x87, 0x36, 0x68, 0x87, 0x79, 0x68, 0x3,
+                         0x72, 0xC0, 0x87, 0xD, 0xAE, 0x50, 0xE, 0x6D,
+                         0xD0, 0xE, 0x7A, 0x50, 0xE, 0x6D, 0x0, 0xF, 0x7A,
+                         0x30, 0x7, 0x72, 0xA0, 0x7, 0x73, 0x20, 0x7, 0x6D,
+                         0x90, 0xE, 0x71, 0xA0, 0x7, 0x73, 0x20, 0x7, 0x6D,
+                         0x90, 0xE, 0x78, 0xA0, 0x7, 0x78, 0xD0, 0x6, 0xE9,
+                         0x10, 0x7, 0x76, 0xA0, 0x7, 0x71, 0x60, 0x7, 0x6D,
+                         0x90, 0xE, 0x73, 0x20, 0x7, 0x7A, 0x30, 0x7, 0x72,
+                         0xD0, 0x6, 0xE9, 0x60, 0x7, 0x74, 0xA0, 0x7, 0x76,
+                         0x40, 0x7, 0x6D, 0x60, 0xE, 0x71, 0x60, 0x7, 0x7A,
+                         0x10, 0x7, 0x76, 0xD0, 0x6, 0xE6, 0x30, 0x7, 0x72,
+                         0xA0, 0x7, 0x73, 0x20, 0x7, 0x6D, 0x60, 0xE, 0x76,
+                         0x40, 0x7, 0x7A, 0x60, 0x7, 0x74, 0xD0, 0x6, 0xEE,
+                         0x80, 0x7, 0x7A, 0x10, 0x7, 0x76, 0xA0, 0x7, 0x73,
+                         0x20, 0x7, 0x7A, 0x60, 0x7, 0x74, 0x30, 0xE4,
+                         0x21, 0x0, 0x0, 0x8, 0x0, 0x0, 0x0, 0x2, 0x0,
+                         0x0, 0x0, 0x20, 0xB, 0x4, 0x7, 0x0, 0x0, 0x0,
+                         0x32, 0x1E, 0x98, 0xC, 0x19, 0x11, 0x4C, 0x90,
+                         0x8C, 0x9, 0x26, 0x47, 0xC6, 0x4, 0x43, 0xBA,
+                         0x12, 0x28, 0x88, 0x62, 0x18, 0x1, 0x28, 0x84,
+                         0x22, 0x0, 0x0, 0x0, 0x79, 0x18, 0x0, 0x0, 0xE5,
+                         0x0, 0x0, 0x0, 0x33, 0x8, 0x80, 0x1C, 0xC4, 0xE1,
+                         0x1C, 0x66, 0x14, 0x1, 0x3D, 0x88, 0x43, 0x38,
+                         0x84, 0xC3, 0x8C, 0x42, 0x80, 0x7, 0x79, 0x78,
+                         0x7, 0x73, 0x98, 0x71, 0xC, 0xE6, 0x0, 0xF, 0xED,
+                         0x10, 0xE, 0xF4, 0x80, 0xE, 0x33, 0xC, 0x42, 0x1E,
+                         0xC2, 0xC1, 0x1D, 0xCE, 0xA1, 0x1C, 0x66, 0x30,
+                         0x5, 0x3D, 0x88, 0x43, 0x38, 0x84, 0x83, 0x1B,
+                         0xCC, 0x3, 0x3D, 0xC8, 0x43, 0x3D, 0x8C, 0x3,
+                         0x3D, 0xCC, 0x78, 0x8C, 0x74, 0x70, 0x7, 0x7B,
+                         0x8, 0x7, 0x79, 0x48, 0x87, 0x70, 0x70, 0x7, 0x7A,
+                         0x70, 0x3, 0x76, 0x78, 0x87, 0x70, 0x20, 0x87,
+                         0x19, 0xCC, 0x11, 0xE, 0xEC, 0x90, 0xE, 0xE1,
+                         0x30, 0xF, 0x6E, 0x30, 0xF, 0xE3, 0xF0, 0xE, 0xF0,
+                         0x50, 0xE, 0x33, 0x10, 0xC4, 0x1D, 0xDE, 0x21,
+                         0x1C, 0xD8, 0x21, 0x1D, 0xC2, 0x61, 0x1E, 0x66,
+                         0x30, 0x89, 0x3B, 0xBC, 0x83, 0x3B, 0xD0, 0x43,
+                         0x39, 0xB4, 0x3, 0x3C, 0xBC, 0x83, 0x3C, 0x84,
+                         0x3, 0x3B, 0xCC, 0xF0, 0x14, 0x76, 0x60, 0x7,
+                         0x7B, 0x68, 0x7, 0x37, 0x68, 0x87, 0x72, 0x68,
+                         0x7, 0x37, 0x80, 0x87, 0x70, 0x90, 0x87, 0x70,
+                         0x60, 0x7, 0x76, 0x28, 0x7, 0x76, 0xF8, 0x5, 0x76,
+                         0x78, 0x87, 0x77, 0x80, 0x87, 0x5F, 0x8, 0x87,
+                         0x71, 0x18, 0x87, 0x72, 0x98, 0x87, 0x79, 0x98,
+                         0x81, 0x2C, 0xEE, 0xF0, 0xE, 0xEE, 0xE0, 0xE,
+                         0xF5, 0xC0, 0xE, 0xEC, 0x30, 0x3, 0x62, 0xC8,
+                         0xA1, 0x1C, 0xE4, 0xA1, 0x1C, 0xCC, 0xA1, 0x1C,
+                         0xE4, 0xA1, 0x1C, 0xDC, 0x61, 0x1C, 0xCA, 0x21,
+                         0x1C, 0xC4, 0x81, 0x1D, 0xCA, 0x61, 0x6, 0xD6,
+                         0x90, 0x43, 0x39, 0xC8, 0x43, 0x39, 0x98, 0x43,
+                         0x39, 0xC8, 0x43, 0x39, 0xB8, 0xC3, 0x38, 0x94,
+                         0x43, 0x38, 0x88, 0x3, 0x3B, 0x94, 0xC3, 0x2F,
+                         0xBC, 0x83, 0x3C, 0xFC, 0x82, 0x3B, 0xD4, 0x3,
+                         0x3B, 0xB0, 0xC3, 0xC, 0xC7, 0x69, 0x87, 0x70,
+                         0x58, 0x87, 0x72, 0x70, 0x83, 0x74, 0x68, 0x7,
+                         0x78, 0x60, 0x87, 0x74, 0x18, 0x87, 0x74, 0xA0,
+                         0x87, 0x19, 0xCE, 0x53, 0xF, 0xEE, 0x0, 0xF, 0xF2,
+                         0x50, 0xE, 0xE4, 0x90, 0xE, 0xE3, 0x40, 0xF, 0xE1,
+                         0x20, 0xE, 0xEC, 0x50, 0xE, 0x33, 0x20, 0x28,
+                         0x1D, 0xDC, 0xC1, 0x1E, 0xC2, 0x41, 0x1E, 0xD2,
+                         0x21, 0x1C, 0xDC, 0x81, 0x1E, 0xDC, 0xE0, 0x1C,
+                         0xE4, 0xE1, 0x1D, 0xEA, 0x1, 0x1E, 0x66, 0x18,
+                         0x51, 0x38, 0xB0, 0x43, 0x3A, 0x9C, 0x83, 0x3B,
+                         0xCC, 0x50, 0x24, 0x76, 0x60, 0x7, 0x7B, 0x68,
+                         0x7, 0x37, 0x60, 0x87, 0x77, 0x78, 0x7, 0x78,
+                         0x98, 0x51, 0x4C, 0xF4, 0x90, 0xF, 0xF0, 0x50,
+                         0xE, 0x33, 0x1E, 0x6A, 0x1E, 0xCA, 0x61, 0x1C,
+                         0xE8, 0x21, 0x1D, 0xDE, 0xC1, 0x1D, 0x7E, 0x1,
+                         0x1E, 0xE4, 0xA1, 0x1C, 0xCC, 0x21, 0x1D, 0xF0,
+                         0x61, 0x6, 0x54, 0x85, 0x83, 0x38, 0xCC, 0xC3,
+                         0x3B, 0xB0, 0x43, 0x3D, 0xD0, 0x43, 0x39, 0xFC,
+                         0xC2, 0x3C, 0xE4, 0x43, 0x3B, 0x88, 0xC3, 0x3B,
+                         0xB0, 0xC3, 0x8C, 0xC5, 0xA, 0x87, 0x79, 0x98,
+                         0x87, 0x77, 0x18, 0x87, 0x74, 0x8, 0x7, 0x7A,
+                         0x28, 0x7, 0x72, 0x98, 0x81, 0x5C, 0xE3, 0x10,
+                         0xE, 0xEC, 0xC0, 0xE, 0xE5, 0x50, 0xE, 0xF3, 0x30,
+                         0x23, 0xC1, 0xD2, 0x41, 0x1E, 0xE4, 0xE1, 0x17,
+                         0xD8, 0xE1, 0x1D, 0xDE, 0x1, 0x1E, 0x66, 0x48,
+                         0x19, 0x3B, 0xB0, 0x83, 0x3D, 0xB4, 0x83, 0x1B,
+                         0x84, 0xC3, 0x38, 0x8C, 0x43, 0x39, 0xCC, 0xC3,
+                         0x3C, 0xB8, 0xC1, 0x39, 0xC8, 0xC3, 0x3B, 0xD4,
+                         0x3, 0x3C, 0xCC, 0x48, 0xB4, 0x71, 0x8, 0x7, 0x76,
+                         0x60, 0x7, 0x71, 0x8, 0x87, 0x71, 0x58, 0x87,
+                         0x19, 0xDB, 0xC6, 0xE, 0xEC, 0x60, 0xF, 0xED,
+                         0xE0, 0x6, 0xF0, 0x20, 0xF, 0xE5, 0x30, 0xF, 0xE5,
+                         0x20, 0xF, 0xF6, 0x50, 0xE, 0x6E, 0x10, 0xE, 0xE3,
+                         0x30, 0xE, 0xE5, 0x30, 0xF, 0xF3, 0xE0, 0x6, 0xE9,
+                         0xE0, 0xE, 0xE4, 0x50, 0xE, 0xF8, 0x30, 0x23,
+                         0xE2, 0xEC, 0x61, 0x1C, 0xC2, 0x81, 0x1D, 0xD8,
+                         0xE1, 0x17, 0xEC, 0x21, 0x1D, 0xE6, 0x21, 0x1D,
+                         0xC4, 0x21, 0x1D, 0xD8, 0x21, 0x1D, 0xE8, 0x21,
+                         0x1F, 0x66, 0x20, 0x9D, 0x3B, 0xBC, 0x43, 0x3D,
+                         0xB8, 0x3, 0x39, 0x94, 0x83, 0x39, 0xCC, 0x58,
+                         0xBC, 0x70, 0x70, 0x7, 0x77, 0x78, 0x7, 0x7A,
+                         0x8, 0x7, 0x7A, 0x48, 0x87, 0x77, 0x70, 0x87,
+                         0x19, 0xCB, 0xE7, 0xE, 0xEF, 0x30, 0xF, 0xE1,
+                         0xE0, 0xE, 0xE9, 0x40, 0xF, 0xE9, 0xA0, 0xF, 0xE5,
+                         0x30, 0xC3, 0x1, 0x3, 0x73, 0xA8, 0x7, 0x77, 0x18,
+                         0x87, 0x5F, 0x98, 0x87, 0x70, 0x70, 0x87, 0x74,
+                         0xA0, 0x87, 0x74, 0xD0, 0x87, 0x72, 0x98, 0x81,
+                         0x84, 0x41, 0x39, 0xE0, 0xC3, 0x38, 0xB0, 0x43,
+                         0x3D, 0x90, 0x43, 0x39, 0xCC, 0x40, 0xC4, 0xA0,
+                         0x1D, 0xCA, 0xA1, 0x1D, 0xE0, 0x41, 0x1E, 0xDE,
+                         0xC1, 0x1C, 0x66, 0x24, 0x63, 0x30, 0xE, 0xE1,
+                         0xC0, 0xE, 0xEC, 0x30, 0xF, 0xE9, 0x40, 0xF, 0xE5,
+                         0x30, 0x43, 0x21, 0x83, 0x75, 0x18, 0x7, 0x73,
+                         0x48, 0x87, 0x5F, 0xA0, 0x87, 0x7C, 0x80, 0x87,
+                         0x72, 0x98, 0xB1, 0x94, 0x1, 0x3C, 0x8C, 0xC3,
+                         0x3C, 0x94, 0xC3, 0x38, 0xD0, 0x43, 0x3A, 0xBC,
+                         0x83, 0x3B, 0xCC, 0xC3, 0x8C, 0xC5, 0xC, 0x48,
+                         0x21, 0x15, 0x42, 0x61, 0x1E, 0xE6, 0x21, 0x1D,
+                         0xCE, 0xC1, 0x1D, 0x52, 0x81, 0x14, 0x66, 0x4C,
+                         0x67, 0x30, 0xE, 0xEF, 0x20, 0xF, 0xEF, 0xE0,
+                         0x6, 0xEF, 0x50, 0xF, 0xF4, 0x30, 0xF, 0xE9, 0x40,
+                         0xE, 0xE5, 0xE0, 0x6, 0xE6, 0x20, 0xF, 0xE1, 0xD0,
+                         0xE, 0xE5, 0x30, 0xA3, 0x40, 0x83, 0x76, 0x68,
+                         0x7, 0x79, 0x8, 0x87, 0x19, 0x52, 0x1A, 0xB8,
+                         0xC3, 0x3B, 0x84, 0x3, 0x3B, 0xA4, 0x43, 0x38,
+                         0xCC, 0x83, 0x1B, 0x84, 0x3, 0x39, 0x90, 0x83,
+                         0x3C, 0xCC, 0x3, 0x3C, 0x84, 0xC3, 0x38, 0x94,
+                         0xC3, 0xC, 0x46, 0xD, 0xC6, 0x21, 0x1C, 0xD8,
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+                         0x20, 0x0, 0x0, 0...
[truncated]

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Largely LGTM, I will note the pr description seems incomplete/mis-typed

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nit: file naming convention seems to be .test

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I'm okay with switching to .yaml for DXContainer tests, if you prefer (as long as they contain YAML, obviosuly). At the time llvm-objcopy was being brought up,".yaml" wasn't recognised as a test file extension, hence the generic ".test" was used.

std::unique_ptr<FileOutputBuffer> Buf = std::move(*BufferOrErr);
llvm::copy(Contents, Buf->getBufferStart());
if (Error E = Buf->commit())
return createFileError(Filename, std::move(E));
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ELF behaviour is to create an error if the contents are empty. I am not sure if that is generated here? Can we add a test-case to demonstrate that error is generated

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I'm okay with switching to .yaml for DXContainer tests, if you prefer (as long as they contain YAML, obviosuly). At the time llvm-objcopy was being brought up,".yaml" wasn't recognised as a test file extension, hence the generic ".test" was used.

Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
FileOutputBuffer::create(Filename, Contents.size());
if (!BufferOrErr)
return createFileError(Filename, BufferOrErr.takeError());
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Test cases for this and other error paths are required.

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I assume it's not practical to test both the create and commit error paths? (I see one is tested, but not the other).

../llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp
../llvm/test/tools/llvm-objcopy/DXContainer/dump-section-errors.yaml
../llvm/test/tools/llvm-objcopy/DXContainer/dump-section.yaml
Expected<std::unique_ptr<FileOutputBuffer>> BufferOrErr =
FileOutputBuffer::create(Filename, Contents.size());
if (!BufferOrErr)
return createFileError(Filename, BufferOrErr.takeError());
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I assume it's not practical to test both the create and commit error paths? (I see one is tested, but not the other).

../llvm/test/tools/llvm-objcopy/DXContainer/dump-section-errors.yaml
../llvm/test/tools/llvm-objcopy/DXContainer/dump-section.yaml
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LGTM. Probably worth waiting for a DXContainer expert to sign off too.

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LGTM. Just a few take it or leave it nitpicks.

Comment on lines 49 to 50
for (const Part &P : Obj.Parts) {
if (P.Name == PartName) {
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This seems like a weird pattern for this. Why not use find_if and return early if it isn't found instead?

  auto PartIter = llvm::find_if(
      Obj.Parts, [&PartName](const Part &P) { return P.Name == PartName; });
  if (PartIter == Obj.Parts.end())
    return createFileError(...);

@@ -0,0 +1,27 @@
# RUN: yaml2obj %s -o %t.dxbc
# RUN: not llvm-objcopy --dump-section=FKE0=%t.fek0 %t.dxbc 2>&1 | FileCheck %s --check-prefix=CHECK-EMPTY -DFILE=%t.fek0
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FileCheck has a CHECK-EMPTY directive so this prefix could be confusing / ambiguous. Might be worth a different name to avoid that.

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As the one who implemented CHECK-EMPTY, I should have seen that 😂

llvm-beanz and others added 2 commits October 10, 2025 12:07
../llvm/lib/ObjCopy/DXContainer/DXContainerObjcopy.cpp
../llvm/test/tools/llvm-objcopy/DXContainer/dump-section-errors.yaml
@llvm-beanz llvm-beanz merged commit da5fb5e into llvm:main Oct 14, 2025
10 checks passed
llvm-beanz added a commit that referenced this pull request Oct 14, 2025
This fixes a build regression on big endian systems introduced in
#159999.
akadutta pushed a commit to akadutta/llvm-project that referenced this pull request Oct 14, 2025
This adds support for the `-dump-section=<section>=<file>` flag for the
DXContainer file format. This flag dumps the contents of a named section
to the specified file.

This flag is particularly handy for ripping DXIL bitcode out of the
object files so that we can use LLVM tools to inspect and operate on the
bitcode. To facilitate that workflow this flag also strips the program
headers from parts containing DXIL so that the resulting file is a valid
bitcode file.

---------

Co-authored-by: Justin Bogner <[email protected]>
akadutta pushed a commit to akadutta/llvm-project that referenced this pull request Oct 14, 2025
This fixes a build regression on big endian systems introduced in
llvm#159999.
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5 participants