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llvm-mirror/test/DebugInfo/X86/dw_op_constu.mir
Bjorn Pettersson 7157a84082 [DwarfExpression] Disallow some rewrites to avoid undefined behavior 
Summary:
The value operand in DW_OP_plus_uconst/DW_OP_constu value can be
large (it uses uint64_t as representation internally in LLVM).
This means that in the uint64_t to int conversions, previously done
by DwarfExpression::addMachineRegExpression, could lose information.
Also, the negation done in "-Offset" was undefined behavior in case
Offset was exactly INT_MIN.

To avoid the above problems, we now avoid transformation like
 [Reg, DW_OP_plus_uconst, Offset] --> [DW_OP_breg, Offset]
and
 [Reg, DW_OP_constu, Offset, DW_OP_plus]  --> [DW_OP_breg, Offset]
when Offset > INT_MAX.

And we avoid to transform
 [Reg, DW_OP_constu, Offset, DW_OP_minus] --> [DW_OP_breg,-Offset]
when Offset > INT_MAX+1.

The patch also adjusts DwarfCompileUnit::constructVariableDIEImpl
to make sure that "DW_OP_constu, Offset, DW_OP_minus" is used
instead of "DW_OP_plus_uconst, Offset" when creating DIExpressions
with negative frame index offsets.

Notice that this might just be the tip of the iceberg. There
are lots of fishy handling related to these constants. I think both
DIExpression::appendOffset and DIExpression::extractIfOffset may
trigger undefined behavior for certain values.

Reviewers: sdesmalen, rnk, JDevlieghere

Reviewed By: JDevlieghere

Subscribers: jholewinski, aprantl, hiraditya, ychen, uabelho, llvm-commits

Tags: #debug-info, #llvm

Differential Revision: https://reviews.llvm.org/D67263

llvm-svn: 371304
2019-09-07 11:40:10 +00:00

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# RUN: llc -o - %s -start-after=patchable-function -O0 -mtriple=x86_64-unknown-linux-gnu | FileCheck %s
# Test dwarf codegen of:
# - DW_OP_constu, X, DW_OP_minus
# - DW_OP_constu, X, DW_OP_plus
# - DW_OP_plus_uconst, X
# when feeding a DW_OP_breg.
#
# Internally in LLVM the value X is saved as an "uint64_t". But when
# DwarfExpression::addMachineRegExpression is trying to simplify the DWARF by
# folding such expressions into a DW_OP_breg (or DW_OP_fbreg) the offset is
# converted to an "int". We must be careful when doing those folds, checking
# that X is in the range for "int".
--- |
define void @test() !dbg !5 {
entry:
ret void, !dbg !14
}
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
!1 = !DIFile(filename: "1.cc", directory: "/tmp")
!2 = !{}
!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = distinct !DISubprogram(name: "test", scope: !1, file: !1, line: 4, type: !6, scopeLine: 4, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !8)
!6 = !DISubroutineType(types: !7)
!7 = !{null}
!8 = !{!9}
!9 = !DILocalVariable(name: "buf", scope: !5, file: !1, line: 5, type: !10)
!10 = !DICompositeType(tag: DW_TAG_array_type, baseType: !11, size: 3200, align: 32, elements: !12)
!11 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
!12 = !{!13}
!13 = !DISubrange(count: 100)
!14 = !DILocation(line: 7, column: 1, scope: !5)
...
---
name: test
tracksRegLiveness: true
body: |
bb.0: ;-------------------------- DW_OP_plus -------------------------------
; UINT_MAX
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 4294967295, DW_OP_minus), debug-location !14
; UINT_MAX+1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 4294967296, DW_OP_minus), debug-location !14
; INT_MAX
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 2147483647, DW_OP_minus), debug-location !14
; INT_MAX+1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 2147483648, DW_OP_minus), debug-location !14
; 0
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 0, DW_OP_minus), debug-location !14
; -1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 18446744073709551615, DW_OP_minus), debug-location !14
; -2
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 18446744073709551614, DW_OP_minus), debug-location !14
RETQ debug-location !14
bb.1: ;-------------------------- DW_OP_plus -------------------------------
; UINT_MAX
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 4294967295, DW_OP_plus), debug-location !14
; UINT_MAX+1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 4294967296, DW_OP_plus), debug-location !14
; INT_MAX
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 2147483647, DW_OP_plus), debug-location !14
; INT_MAX+1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 2147483648, DW_OP_plus), debug-location !14
; 0
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 0, DW_OP_plus), debug-location !14
; -1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 18446744073709551615, DW_OP_plus), debug-location !14
; -2
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_constu, 18446744073709551614, DW_OP_plus), debug-location !14
RETQ debug-location !14
bb.2: ;-------------------------- DW_OP_plus_uconst -------------------------------
; UINT_MAX
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_plus_uconst, 4294967295), debug-location !14
; UINT_MAX+1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_plus_uconst, 4294967296), debug-location !14
; INT_MAX
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_plus_uconst, 2147483647), debug-location !14
; INT_MAX+1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_plus_uconst, 2147483648), debug-location !14
; 0
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_plus_uconst, 0), debug-location !14
; -1
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_plus_uconst, 18446744073709551615), debug-location !14
; -2
renamable $rcx = MOV64rm renamable $noreg, 1, $noreg, 0, $fs
DBG_VALUE renamable $rcx, 0, !9, !DIExpression(DW_OP_plus_uconst, 18446744073709551614), debug-location !14
RETQ debug-location !14
...
# CHECK-LABEL: .Ldebug_loc0:
# CHECK-NEXT: .quad .Ltmp0-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp1-.Lfunc_begin0
# CHECK-NEXT: .short 9 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 16 # DW_OP_constu
# CHECK-NEXT: .byte 255 # 4294967295
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 15 #
# CHECK-NEXT: .byte 28 # DW_OP_minus
# CHECK-NEXT: .quad .Ltmp1-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp2-.Lfunc_begin0
# CHECK-NEXT: .short 9 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 16 # DW_OP_constu
# CHECK-NEXT: .byte 128 # 4294967296
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 16 #
# CHECK-NEXT: .byte 28 # DW_OP_minus
# CHECK-NEXT: .quad .Ltmp2-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp3-.Lfunc_begin0
# CHECK-NEXT: .short 6 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 129 # -2147483647
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 120 #
# CHECK-NEXT: .quad .Ltmp3-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp4-.Lfunc_begin0
# CHECK-NEXT: .short 6 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 128 # -2147483648
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 120 #
# CHECK-NEXT: .quad .Ltmp4-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp5-.Lfunc_begin0
# CHECK-NEXT: .short 2 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .quad .Ltmp5-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp6-.Lfunc_begin0
# CHECK-NEXT: .short 5 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 48 # DW_OP_lit0
# CHECK-NEXT: .byte 32 # DW_OP_not
# CHECK-NEXT: .byte 28 # DW_OP_minus
# CHECK-NEXT: .quad .Ltmp6-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp7-.Lfunc_begin0
# CHECK-NEXT: .short 14 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 16 # DW_OP_constu
# CHECK-NEXT: .byte 254 # 18446744073709551614
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 1 #
# CHECK-NEXT: .byte 28 # DW_OP_minus
#-----------------------------------------------------------------------
# CHECK-NEXT: .quad .Ltmp8-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp9-.Lfunc_begin0
# CHECK-NEXT: .short 9 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 16 # DW_OP_constu
# CHECK-NEXT: .byte 255 # 4294967295
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 15 #
# CHECK-NEXT: .byte 34 # DW_OP_plus
# CHECK-NEXT: .quad .Ltmp9-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp10-.Lfunc_begin0
# CHECK-NEXT: .short 9 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 16 # DW_OP_constu
# CHECK-NEXT: .byte 128 # 4294967296
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 16 #
# CHECK-NEXT: .byte 34 # DW_OP_plus
# CHECK-NEXT: .quad .Ltmp10-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp11-.Lfunc_begin0
# CHECK-NEXT: .short 6 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 255 # 2147483647
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 7 #
# CHECK-NEXT: .quad .Ltmp11-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp12-.Lfunc_begin0
# CHECK-NEXT: .short 9 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 16 # DW_OP_constu
# CHECK-NEXT: .byte 128 # 2147483648
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 8 #
# CHECK-NEXT: .byte 34 # DW_OP_plus
# CHECK-NEXT: .quad .Ltmp12-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp13-.Lfunc_begin0
# CHECK-NEXT: .short 2 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .quad .Ltmp13-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp14-.Lfunc_begin0
# CHECK-NEXT: .short 5 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 48 # DW_OP_lit0
# CHECK-NEXT: .byte 32 # DW_OP_not
# CHECK-NEXT: .byte 34 # DW_OP_plus
# CHECK-NEXT: .quad .Ltmp14-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp15-.Lfunc_begin0
# CHECK-NEXT: .short 14 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 16 # DW_OP_constu
# CHECK-NEXT: .byte 254 # 18446744073709551614
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 1 #
# CHECK-NEXT: .byte 34 # DW_OP_plus
#-----------------------------------------------------------------------
# CHECK-NEXT: .quad .Ltmp16-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp17-.Lfunc_begin0
# CHECK-NEXT: .short 8 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 35 # DW_OP_plus_uconst
# CHECK-NEXT: .byte 255 # 4294967295
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 15 #
# CHECK-NEXT: .quad .Ltmp17-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp18-.Lfunc_begin0
# CHECK-NEXT: .short 8 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 35 # DW_OP_plus_uconst
# CHECK-NEXT: .byte 128 # 4294967296
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 16 #
# CHECK-NEXT: .quad .Ltmp18-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp19-.Lfunc_begin0
# CHECK-NEXT: .short 6 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 255 # 2147483647
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 7 #
# CHECK-NEXT: .quad .Ltmp19-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp20-.Lfunc_begin0
# CHECK-NEXT: .short 8 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 35 # DW_OP_plus_uconst
# CHECK-NEXT: .byte 128 # 2147483648
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 128 #
# CHECK-NEXT: .byte 8 #
# CHECK-NEXT: .quad .Ltmp20-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp21-.Lfunc_begin0
# CHECK-NEXT: .short 2 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .quad .Ltmp21-.Lfunc_begin0
# CHECK-NEXT: .quad .Ltmp22-.Lfunc_begin0
# CHECK-NEXT: .short 13 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 35 # DW_OP_plus_uconst
# CHECK-NEXT: .byte 255 # 18446744073709551615
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 1 #
# CHECK-NEXT: .quad .Ltmp22-.Lfunc_begin0
# CHECK-NEXT: .quad .Lfunc_end0-.Lfunc_begin0
# CHECK-NEXT: .short 13 # Loc expr size
# CHECK-NEXT: .byte 114 # DW_OP_breg2
# CHECK-NEXT: .byte 0 # 0
# CHECK-NEXT: .byte 35 # DW_OP_plus_uconst
# CHECK-NEXT: .byte 254 # 18446744073709551614
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 255 #
# CHECK-NEXT: .byte 1 #
# CHECK-NEXT: .quad 0
# CHECK-NEXT: .quad 0
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