Don't preserve debug metadata with --spirv-preserve-auxdata (#2102)

It's duplicating existing information in the SPIR-V and it has complex structure.

Signed-off-by: Sarnie, Nick <[email protected]>

Original commit:
KhronosGroup/SPIRV-LLVM-Translator@d498f48

Author: sarnex

llvm-spirv/lib/SPIRV/SPIRVWriter.cpp

@@ -1107,11 +1107,12 @@ void LLVMToSPIRVBase::transAuxDataInst(SPIRVFunction *BF, Function *F) {
   for (const auto &MD : AllMD) {
     std::string MDName = MDNames[MD.first].str();
 
-    // spirv.Decorations and spirv.ParameterDecorations are handled
-    // elsewhere for both forward and reverse translation and are complicated
-    // to support here, so just skip them.
+    // spirv.Decorations, spirv.ParameterDecorations and debug information are
+    // handled elsewhere for both forward and reverse translation and are
+    // complicated to support here, so just skip them.
     if (MDName == SPIRV_MD_DECORATIONS ||
-        MDName == SPIRV_MD_PARAMETER_DECORATIONS)
+        MDName == SPIRV_MD_PARAMETER_DECORATIONS ||
+        MD.first == LLVMContext::MD_dbg)
       continue;
 
     // Format for metadata is:

llvm-spirv/test/extensions/KHR/SPV_KHR_non_semantic_info/preserve-all-function-metadata-debug.ll

@@ -0,0 +1,28 @@
+; RUN: llvm-as < %s -o %t.bc
+; RUN: llvm-spirv %t.bc -spirv-text --spirv-preserve-auxdata -o - | FileCheck %s --check-prefix=CHECK-SPIRV
+
+; CHECK-SPIRV: Capability
+; CHECK-SPIRV-NOT: NonSemanticAuxData
+; CHECK-SPIRV: FunctionEnd
+target triple = "spir64-unknown-unknown"
+
+define spir_func void @foo() #1 !dbg !4 {
+ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang 16.0.0", isOptimized: false, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "foo.c", directory: "./")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !6, isLocal: false, isDefinition: true, scopeLine: 2, isOptimized: false, unit: !0, retainedNodes: !5)
+!5 = !{!9}
+!6 = !DISubroutineType(types: !7)
+!7 = !{!8, !8, !8}
+!8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!9 = !DILabel(scope: !4, name: "top", file: !1, line: 4)
+!10 = !DILocation(line: 4, column: 1, scope: !4)
+!11 = !DILabel(scope: !4, name: "done", file: !1, line: 7)
+!12 = !DILocation(line: 7, column: 1, scope: !4)