[llvm] 3eacfdc - [BPF] Fix a BTF gen bug related to a pointer struct member
Yonghong Song via llvm-commits
llvm-commits at lists.llvm.org
Wed Jul 1 09:55:43 PDT 2020
Author: Yonghong Song
Date: 2020-07-01T09:55:01-07:00
New Revision: 3eacfdc72f1aa3ac53eb300116f194d560053ec7
URL: https://github.com/llvm/llvm-project/commit/3eacfdc72f1aa3ac53eb300116f194d560053ec7
DIFF: https://github.com/llvm/llvm-project/commit/3eacfdc72f1aa3ac53eb300116f194d560053ec7.diff
LOG: [BPF] Fix a BTF gen bug related to a pointer struct member
Currently, BTF generation stops at pointer struct members
if the pointee type is a struct. This is to avoid bloating
generated BTF size. The following is the process to
correctly record types for these pointee struct types.
- During type traversal stage, when a struct member, which
is a pointer to another struct, is encountered,
the pointee struct type, keyed with its name, is
remembered in a Fixup map.
- Later, when all type traversal is done, the Fixup map
is scanned, based on struct name matching, to either
resolve as pointing to a real already generated type
or as a forward declaration.
Andrii discovered a bug if the struct member pointee struct
is anonymous. In this case, a struct with empty name is
recorded in Fixup map, and later it happens another anonymous
struct with empty name is defined in BTF. So wrong type
resolution happens.
To fix the problem, if the struct member pointee struct
is anonymous, pointee struct type will be generated in
stead of being put in Fixup map.
Differential Revision: https://reviews.llvm.org/D82976
Added:
llvm/test/CodeGen/BPF/BTF/struct-anon-2.ll
Modified:
llvm/lib/Target/BPF/BTFDebug.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Target/BPF/BTFDebug.cpp b/llvm/lib/Target/BPF/BTFDebug.cpp
index f0996d637d36..6ada75adba96 100644
--- a/llvm/lib/Target/BPF/BTFDebug.cpp
+++ b/llvm/lib/Target/BPF/BTFDebug.cpp
@@ -568,7 +568,7 @@ void BTFDebug::visitDerivedType(const DIDerivedType *DTy, uint32_t &TypeId,
auto CTag = CTy->getTag();
if ((CTag == dwarf::DW_TAG_structure_type ||
CTag == dwarf::DW_TAG_union_type) &&
- !CTy->isForwardDecl()) {
+ !CTy->getName().empty() && !CTy->isForwardDecl()) {
/// Find a candidate, generate a fixup. Later on the struct/union
/// pointee type will be replaced with either a real type or
/// a forward declaration.
diff --git a/llvm/test/CodeGen/BPF/BTF/struct-anon-2.ll b/llvm/test/CodeGen/BPF/BTF/struct-anon-2.ll
new file mode 100644
index 000000000000..d8f4f2360eaf
--- /dev/null
+++ b/llvm/test/CodeGen/BPF/BTF/struct-anon-2.ll
@@ -0,0 +1,106 @@
+; RUN: llc -march=bpfel -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+; RUN: llc -march=bpfeb -filetype=asm -o - %s | FileCheck -check-prefixes=CHECK %s
+;
+; Source:
+; struct s1 {
+; struct { int A1; } a1;
+; struct { long B1; } *b1;
+; };
+; int f1(struct s1 *s1) { return 0; }
+; Compilation flag:
+; clang -target bpf -O2 -g -S -emit-llvm t.c
+
+%struct.s1 = type { %struct.anon, %struct.anon.0* }
+%struct.anon = type { i32 }
+%struct.anon.0 = type { i64 }
+
+; Function Attrs: norecurse nounwind readnone
+define dso_local i32 @f1(%struct.s1* nocapture readnone %s1) local_unnamed_addr #0 !dbg !7 {
+entry:
+ call void @llvm.dbg.value(metadata %struct.s1* %s1, metadata !25, metadata !DIExpression()), !dbg !26
+ ret i32 0, !dbg !27
+}
+
+; CHECK: .long 0 # BTF_KIND_PTR(id = 1)
+; CHECK-NEXT: .long 33554432 # 0x2000000
+; CHECK-NEXT: .long 2
+; CHECK-NEXT: .long 1 # BTF_KIND_STRUCT(id = 2)
+; CHECK-NEXT: .long 67108866 # 0x4000002
+; CHECK-NEXT: .long 16
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 3
+; CHECK-NEXT: .long 0 # 0x0
+; CHECK-NEXT: .long 7
+; CHECK-NEXT: .long 5
+; CHECK-NEXT: .long 64 # 0x40
+; CHECK-NEXT: .long 0 # BTF_KIND_STRUCT(id = 3)
+; CHECK-NEXT: .long 67108865 # 0x4000001
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 10
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 0 # 0x0
+; CHECK-NEXT: .long 13 # BTF_KIND_INT(id = 4)
+; CHECK-NEXT: .long 16777216 # 0x1000000
+; CHECK-NEXT: .long 4
+; CHECK-NEXT: .long 16777248 # 0x1000020
+; CHECK-NEXT: .long 0 # BTF_KIND_PTR(id = 5)
+; CHECK-NEXT: .long 33554432 # 0x2000000
+; CHECK-NEXT: .long 6
+; CHECK-NEXT: .long 0 # BTF_KIND_STRUCT(id = 6)
+; CHECK-NEXT: .long 67108865 # 0x4000001
+; CHECK-NEXT: .long 8
+; CHECK-NEXT: .long 17
+; CHECK-NEXT: .long 7
+; CHECK-NEXT: .long 0 # 0x0
+; CHECK-NEXT: .long 20 # BTF_KIND_INT(id = 7)
+; CHECK-NEXT: .long 16777216 # 0x1000000
+; CHECK-NEXT: .long 8
+; CHECK-NEXT: .long 16777280 # 0x1000040
+
+; CHECK: .ascii "s1" # string offset=1
+; CHECK: .ascii "a1" # string offset=4
+; CHECK: .ascii "b1" # string offset=7
+; CHECK: .ascii "A1" # string offset=10
+; CHECK: .ascii "int" # string offset=13
+; CHECK: .ascii "B1" # string offset=17
+; CHECK: .ascii "long int" # string offset=20
+
+
+; Function Attrs: nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+attributes #0 = { norecurse nounwind readnone "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "frame-pointer"="all" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nounwind readnone speculatable willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 11.0.0 (https://github.com/llvm/llvm-project.git ef36f5143d83897cc6f59ff918769d29ad5a0612)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "t.c", directory: "/tmp/home/yhs/btf/tmp")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 11.0.0 (https://github.com/llvm/llvm-project.git ef36f5143d83897cc6f59ff918769d29ad5a0612)"}
+!7 = distinct !DISubprogram(name: "f1", scope: !1, file: !1, line: 5, type: !8, scopeLine: 5, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !24)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !11}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !12, size: 64)
+!12 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "s1", file: !1, line: 1, size: 128, elements: !13)
+!13 = !{!14, !18}
+!14 = !DIDerivedType(tag: DW_TAG_member, name: "a1", scope: !12, file: !1, line: 2, baseType: !15, size: 32)
+!15 = distinct !DICompositeType(tag: DW_TAG_structure_type, scope: !12, file: !1, line: 2, size: 32, elements: !16)
+!16 = !{!17}
+!17 = !DIDerivedType(tag: DW_TAG_member, name: "A1", scope: !15, file: !1, line: 2, baseType: !10, size: 32)
+!18 = !DIDerivedType(tag: DW_TAG_member, name: "b1", scope: !12, file: !1, line: 3, baseType: !19, size: 64, offset: 64)
+!19 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !20, size: 64)
+!20 = distinct !DICompositeType(tag: DW_TAG_structure_type, scope: !12, file: !1, line: 3, size: 64, elements: !21)
+!21 = !{!22}
+!22 = !DIDerivedType(tag: DW_TAG_member, name: "B1", scope: !20, file: !1, line: 3, baseType: !23, size: 64)
+!23 = !DIBasicType(name: "long int", size: 64, encoding: DW_ATE_signed)
+!24 = !{!25}
+!25 = !DILocalVariable(name: "s1", arg: 1, scope: !7, file: !1, line: 5, type: !11)
+!26 = !DILocation(line: 0, scope: !7)
+!27 = !DILocation(line: 5, column: 25, scope: !7)
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