2020-09-22 23:27:46 +08:00
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; RUN: opt < %s -asan -asan-module -asan-use-after-return=0 -S -enable-new-pm=0 | \
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; RUN: llc -O0 -filetype=obj - -o - | \
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; RUN: llvm-dwarfdump - | FileCheck %s
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; RUN: opt < %s -passes=asan-pipeline -asan-use-after-return=0 -S | \
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[AddressSanitizer] Ensure only AllocaInst is passed to dbg.declare
Various parts of the LLVM code generator assume that the address
argument of a dbg.declare is not a `ptrtoint`-of-alloca. ASan breaks
this assumption, and this results in local variables sometimes being
unavailable at -O0.
GlobalISel, SelectionDAG, and FastISel all do not appear to expect
dbg.declares to have a `ptrtoint` as an operand. This means that they do
not place entry block allocas in the usual side table reserved for local
variables available in the whole function scope. This isn't always a
problem, as LLVM can try to lower the dbg.declare to a DBG_VALUE, but
those DBG_VALUEs can get dropped for all the usual reasons DBG_VALUEs
get dropped. In the ObjC test case I'm looking at, the cause happens to
be that `replaceDbgDeclare` has hoisted dbg.declares into the entry
block, causing LiveDebugValues to "kill" the DBG_VALUEs because the
lexical dominance check fails.
To address this, I propose:
1) Have ASan (always) pass an alloca to dbg.declares (this patch). This
is a narrow bugfix for -O0 debugging.
2) Make replaceDbgDeclare not move dbg.declares around. This should be a
generic improvement for optimized debug info, as it would prevent the
lexical dominance check in LiveDebugValues from killing as many
variables.
This means reverting llvm/r227544, which fixed an assertion failure
(llvm.org/PR22386) but no longer seems to be necessary. I was able to
complete a stage2 build with the revert in place.
rdar://54688991
Differential Revision: https://reviews.llvm.org/D74369
2020-02-11 08:22:27 +08:00
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; RUN: llc -O0 -filetype=obj - -o - | \
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; RUN: llvm-dwarfdump - | FileCheck %s
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; For this test case, ASan used to produce IR which resulted in the following
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; DWARF (at -O0):
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;
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; DW_TAG_subprogram
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; DW_AT_low_pc (0x0000000000000000)
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; DW_AT_high_pc (0x00000000000000f1)
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;
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; DW_TAG_variable
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; DW_AT_location (0x00000000
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; [0x0000000000000014, 0x000000000000006d): DW_OP_breg0 RAX+32
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; [0x000000000000006d, 0x00000000000000a4): DW_OP_breg7 RSP+16, DW_OP_deref, DW_OP_plus_uconst 0x20
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; [0x00000000000000a6, 0x00000000000000ef): DW_OP_breg7 RSP+16, DW_OP_deref, DW_OP_plus_uconst 0x20)
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;
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; The DWARF produced for the original ObjC code that motivated this test case
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; was actually not as nice! In that example, the location list ranges didn't
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; intersect with the ranges of the parent lexical scope. But recreating that
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; exactly requires playing tricks to get LiveDebugValue's lexical dominance
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; check to kill a variable range early, and it isn't strictly necessary to show
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; the problem here.
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;
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; The problem is that we shouldn't get a location list at all. The instruction
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; selector should recognize that we have an "alloca" in the entry block, and
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; just make the fixed location available in the whole function. We now produce
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; the correct DWARF, namely:
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; CHECK: DW_TAG_variable
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; CHECK-NEXT: DW_AT_location (DW_OP_breg7 RSP+32, DW_OP_plus_uconst 0x20)
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target triple = "x86_64-apple-macosx10.10.0"
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declare void @escape(i8**)
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; Function Attrs: sanitize_address
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define i8* @foo(i1 %cond) #0 !dbg !6 {
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entry:
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%a1 = alloca i8*, !dbg !12
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call void @escape(i8** %a1), !dbg !13
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br i1 %cond, label %l1, label %l2, !dbg !14
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l1: ; preds = %entry
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ret i8* null, !dbg !15
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l2: ; preds = %entry
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call void @llvm.dbg.declare(metadata i8** %a1, metadata !11, metadata !DIExpression()), !dbg !16
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%p = load i8*, i8** %a1, !dbg !16
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ret i8* %p, !dbg !17
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}
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declare void @llvm.dbg.declare(metadata, metadata, metadata)
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attributes #0 = { sanitize_address }
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!llvm.dbg.cu = !{!0}
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!llvm.debugify = !{!3, !4}
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!llvm.module.flags = !{!5}
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!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
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!1 = !DIFile(filename: "redu.ll", directory: "/")
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!2 = !{}
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!3 = !{i32 6}
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!4 = !{i32 2}
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!5 = !{i32 2, !"Debug Info Version", i32 3}
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!6 = distinct !DISubprogram(name: "foo", linkageName: "foo", scope: null, file: !1, line: 1, type: !7, scopeLine: 1, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
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!7 = !DISubroutineType(types: !2)
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!8 = !{!11}
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!10 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
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!11 = !DILocalVariable(name: "2", scope: !6, file: !1, line: 5, type: !10)
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!12 = !DILocation(line: 1, column: 1, scope: !6)
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!13 = !DILocation(line: 2, column: 1, scope: !6)
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!14 = !DILocation(line: 3, column: 1, scope: !6)
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!15 = !DILocation(line: 4, column: 1, scope: !6)
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!16 = !DILocation(line: 5, column: 1, scope: !6)
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!17 = !DILocation(line: 6, column: 1, scope: !6)
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