Support btf_tag annotations

Fixes #188.

disasm-test/tests/btf-tag-dicompositetype.at-least-llvm14.ll

@@ -0,0 +1,10 @@
+;; https://github.com/llvm/llvm-project/blob/0b32dca12ef4d82af71f86a70c49806e5b81ead2/llvm/test/Bitcode/attr-btf_tag-dicomposite.ll
+
+!3 = !DIFile(filename: "struct.c", directory: "/home/yhs/work/tests/llvm/btf_tag")
+!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t", file: !3, line: 1, size: 32, elements: !7, annotations: !10)
+!7 = !{!8}
+!8 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !6, file: !3, line: 1, baseType: !9, size: 32)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !{!11, !12}
+!11 = !{!"btf_tag", !"a"}
+!12 = !{!"btf_tag", !"b"}

disasm-test/tests/btf-tag-diderivedtype.at-least-llvm14.ll

@@ -0,0 +1,10 @@
+;; Adapted from https://github.com/llvm/llvm-project/blob/430e22388173c96da6777fccb9735a6e8ee3ea1c/llvm/test/Bitcode/attr-btf_tag-field.ll
+
+!1 = !DIFile(filename: "attr-btf_tag-field.c", directory: "/home/yhs/work/tests/llvm/btf_tag")
+!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!14 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t1", file: !1, line: 7, size: 32, elements: !15)
+!15 = !{!16}
+!16 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !14, file: !1, line: 8, baseType: !12, size: 32, annotations: !17)
+!17 = !{!18, !19}
+!18 = !{!"btf_tag", !"tag1"}
+!19 = !{!"btf_tag", !"tag2"}

disasm-test/tests/btf-tag-diglobalvariable.at-least-llvm14.ll

@@ -0,0 +1,15 @@
+;; Adapted from https://github.com/llvm/llvm-project/blob/30c288489ae51a3e0819241f367eeae6df2b09e7/llvm/test/Bitcode/attr-btf_tag-diglobalvariable.ll
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "g1", scope: !2, file: !3, line: 7, type: !6, isLocal: false, isDefinition: true, annotations: !10)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 13.0.0 (https://github.com/llvm/llvm-project.git 47af5574a87dc298b5c6c36ff6a969c8c77c8499)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, splitDebugInlining: false, nameTableKind: None)
+!3 = !DIFile(filename: "t.c", directory: "/home/yhs/work/tests/llvm/btf_tag")
+!4 = !{}
+!5 = !{!0}
+!6 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "t1", file: !3, line: 4, size: 32, elements: !7)
+!7 = !{!8}
+!8 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !6, file: !3, line: 5, baseType: !9, size: 32)
+!9 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!10 = !{!11, !12}
+!11 = !{!"btf_tag", !"tag1"}
+!12 = !{!"btf_tag", !"tag2"}

disasm-test/tests/btf-tag-dilocalvariable.at-least-llvm14.ll

@@ -0,0 +1,14 @@
+;; Adapted from https://github.com/llvm/llvm-project/blob/1bebc31c617d1a0773f1d561f02dd17c5e83b23b/llvm/test/Bitcode/attr-btf_tag-parameter.ll
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 13.0.0 (https://github.com/llvm/llvm-project.git c9e3139e00bcef23b236a02890b909a130d1b3d9)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "func.c", directory: "/home/yhs/work/tests/llvm/btf_tag")
+!2 = !{}
+!8 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !9, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!11, !11}
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !{!13}
+!13 = !DILocalVariable(name: "a", arg: 1, scope: !8, file: !1, line: 1, type: !11, annotations: !14)
+!14 = !{!15, !16}
+!15 = !{!"btf_tag", !"a"}
+!16 = !{!"btf_tag", !"b"}

disasm-test/tests/btf-tag-disubprogram.at-least-llvm14.ll

@@ -0,0 +1,15 @@
+;; Adapted from https://github.com/llvm/llvm-project/blob/d383df32c0d5bcdc8c160ecdd7174399aa3c5395/llvm/test/Bitcode/attr-btf_tag-disubprogram.ll
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 13.0.0 (https://github.com/llvm/llvm-project.git a6dd9d402a04d53403664bbb47771f2573c7ade0)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "func.c", directory: "/home/yhs/work/tests/llvm/btf_tag")
+!2 = !{}
+!7 = !{!"clang version 13.0.0 (https://github.com/llvm/llvm-project.git a6dd9d402a04d53403664bbb47771f2573c7ade0)"}
+!8 = distinct !DISubprogram(name: "f", scope: !1, file: !1, line: 1, type: !9, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12, annotations: !14)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!11, !11}
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !{!13}
+!13 = !DILocalVariable(name: "a", arg: 1, scope: !8, file: !1, line: 1, type: !11)
+!14 = !{!15, !16}
+!15 = !{!"btf_tag", !"a"}
+!16 = !{!"btf_tag", !"b"}

src/Data/LLVM/BitCode/IR/Metadata.hs

@@ -592,7 +592,7 @@ parseMetadataEntry vt mt pm (fromEntry -> Just r) =
         (addDebugInfo isDistinct (DebugInfoFile diFile)) pm
 
     17 -> label "METADATA_DERIVED_TYPE" $ do
-      assertRecordSizeBetween 12 13
+      assertRecordSizeBetween 12 14
       ctx        <- getContext
       isDistinct <- parseField r 0 nonzero
       didt       <- DIDerivedType
@@ -610,11 +610,14 @@ parseMetadataEntry vt mt pm (fromEntry -> Just r) =
         <*> (if length (recordFields r) <= 12
              then pure Nothing
              else Just                 <$> parseField r 12 numeric) -- didtDwarfAddressSpace
+        <*> (if length (recordFields r) <= 13
+             then pure Nothing
+             else mdForwardRefOrNull ctx mt <$> parseField r 13 numeric) -- didtAnnotations
       return $! updateMetadataTable
         (addDebugInfo isDistinct (DebugInfoDerivedType didt)) pm
 
     18 -> label "METADATA_COMPOSITE_TYPE" $ do
-      assertRecordSizeBetween 16 21
+      assertRecordSizeBetween 16 22
       ctx        <- getContext
       isDistinct <- parseField r 0 nonzero
       dict       <- DICompositeType
@@ -648,6 +651,9 @@ parseMetadataEntry vt mt pm (fromEntry -> Just r) =
         <*> (if length (recordFields r) <= 20
              then pure Nothing
              else mdForwardRefOrNull ctx mt <$> parseField r 20 numeric) -- dictRank
+        <*> (if length (recordFields r) <= 21
+             then pure Nothing
+             else mdForwardRefOrNull ctx mt <$> parseField r 21 numeric) -- dictAnnotations
       return $! updateMetadataTable
         (addDebugInfo isDistinct (DebugInfoCompositeType dict)) pm
 
@@ -790,6 +796,10 @@ parseMetadataEntry vt mt pm (fromEntry -> Just r) =
             | not hasSPFlags = recordSize >= 21
             | otherwise      = True
 
+          hasAnnotations
+            | not hasSPFlags = False
+            | otherwise      = recordSize >= 19
+
       -- Some additional sanity checking
       when (not hasSPFlags && hasUnit)
            (assertRecordSizeBetween 19 21)
@@ -828,6 +838,7 @@ parseMetadataEntry vt mt pm (fromEntry -> Just r) =
         <*> (mdForwardRefOrNull ctx mt <$> parseField r (14 + offsetB) numeric) -- dispDeclaration
         <*> (mdForwardRefOrNull ctx mt <$> parseField r (15 + offsetB) numeric) -- dispVariables
         <*> (optFwdRef hasThrownTypes (17 + offsetB))                           -- dispThrownTypes
+        <*> (optFwdRef hasAnnotations (18 + offsetB))                           -- dispAnnotations
 
       -- TODO: in the LLVM parser, it then goes into the metadata table
       -- and updates function entries to point to subprograms. Is that
@@ -916,7 +927,7 @@ parseMetadataEntry vt mt pm (fromEntry -> Just r) =
         (addDebugInfo isDistinct (DebugInfoTemplateValueParameter ditvp)) pm
 
     27 -> label "METADATA_GLOBAL_VAR" $ do
-      assertRecordSizeIn [11, 12]
+      assertRecordSizeBetween 11 13
       ctx        <- getContext
       field0     <- parseField r 0 numeric
       let isDistinct = testBit field0 0
@@ -933,9 +944,12 @@ parseMetadataEntry vt mt pm (fromEntry -> Just r) =
         <*> parseField r 8 nonzero                                  -- digvIsDefinition
         <*> (mdForwardRefOrNull ctx mt <$> parseField r 9 numeric)  -- digvVariable
         <*> (mdForwardRefOrNull ctx mt <$> parseField r 10 numeric) -- digvDeclaration
-        <*> if length (recordFields r) > 11
-            then Just                  <$> parseField r 11 numeric  -- digvAlignment
-            else pure Nothing
+        <*> (if length (recordFields r) > 11
+             then Just                  <$> parseField r 11 numeric  -- digvAlignment
+             else pure Nothing)
+        <*> (if length (recordFields r) > 12
+             then mdForwardRefOrNull ctx mt <$> parseField r 12 numeric -- digvAnnotations
+             else pure Nothing)
       return $! updateMetadataTable
         (addDebugInfo isDistinct (DebugInfoGlobalVariable digv)) pm
 
@@ -975,6 +989,9 @@ parseMetadataEntry vt mt pm (fromEntry -> Just r) =
         <*> parseField r (adj 6) numeric        -- dilvArg
         <*> parseField r (adj 7) numeric        -- dilvFlags
         <*> pure alignInBits                    -- dilvAlignment
+        <*> (if hasAlignment && length (recordFields r) > 9
+             then mdForwardRefOrNull ctx mt <$> parseField r 9 numeric -- dilvAnnotations
+             else pure Nothing)
       return $! updateMetadataTable
         (addDebugInfo isDistinct (DebugInfoLocalVariable dilv)) pm