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3158f2e27c
Currently, BPF has XADD (locked add) insn support and the asm looks like: lock *(u32 *)(r1 + 0) += r2 lock *(u64 *)(r1 + 0) += r2 The instruction itself does not have a return value. At the source code level, users often use __sync_fetch_and_add() which eventually translates to XADD. The return value of __sync_fetch_and_add() is supposed to be the old value in the xadd memory location. Since BPF::XADD insn does not support such a return value, this patch added a PreEmit phase to check such a usage. If such an illegal usage pattern is detected, a fatal error will be reported like line 4: Invalid usage of the XADD return value if compiled with -g, or Invalid usage of the XADD return value if compiled without -g. Signed-off-by: Yonghong Song <yhs@fb.com> Acked-by: Alexei Starovoitov <ast@kernel.org> llvm-svn: 342692
60 lines
2.9 KiB
LLVM
60 lines
2.9 KiB
LLVM
; RUN: not llc -march=bpfel < %s 2>&1 | FileCheck %s
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; RUN: not llc -march=bpfeb < %s 2>&1 | FileCheck %s
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; This file is generated with the source command and source
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; $ clang -target bpf -O2 -g -S -emit-llvm t.c
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; $ cat t.c
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; int test(int *ptr) {
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; int r;
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; __sync_fetch_and_add(ptr, 4);
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; r = __sync_fetch_and_add(ptr, 6);
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; return r;
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; }
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; ModuleID = 't.c'
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source_filename = "t.c"
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target datalayout = "e-m:e-p:64:64-i64:64-n32:64-S128"
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target triple = "bpf"
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; Function Attrs: nounwind
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define dso_local i32 @test(i32* nocapture %ptr) local_unnamed_addr #0 !dbg !7 {
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entry:
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call void @llvm.dbg.value(metadata i32* %ptr, metadata !13, metadata !DIExpression()), !dbg !15
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%0 = atomicrmw add i32* %ptr, i32 4 seq_cst, !dbg !16
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%1 = atomicrmw add i32* %ptr, i32 6 seq_cst, !dbg !17
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; CHECK: line 4: Invalid usage of the XADD return value
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call void @llvm.dbg.value(metadata i32 %1, metadata !14, metadata !DIExpression()), !dbg !18
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ret i32 %1, !dbg !19
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}
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.value(metadata, metadata, metadata) #1
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attributes #0 = { nounwind "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #1 = { nounwind readnone speculatable }
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 8.0.0 (trunk 342605) (llvm/trunk 342612)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
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!1 = !DIFile(filename: "t.c", directory: "/home/yhs/work/tests/llvm/sync/test1")
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!2 = !{}
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!3 = !{i32 2, !"Dwarf Version", i32 4}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!5 = !{i32 1, !"wchar_size", i32 4}
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!6 = !{!"clang version 8.0.0 (trunk 342605) (llvm/trunk 342612)"}
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!7 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !12)
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!8 = !DISubroutineType(types: !9)
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!9 = !{!10, !11}
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!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!11 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 64)
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!12 = !{!13, !14}
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!13 = !DILocalVariable(name: "ptr", arg: 1, scope: !7, file: !1, line: 1, type: !11)
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!14 = !DILocalVariable(name: "r", scope: !7, file: !1, line: 2, type: !10)
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!15 = !DILocation(line: 1, column: 15, scope: !7)
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!16 = !DILocation(line: 3, column: 4, scope: !7)
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!17 = !DILocation(line: 4, column: 8, scope: !7)
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!18 = !DILocation(line: 2, column: 8, scope: !7)
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!19 = !DILocation(line: 5, column: 4, scope: !7)
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