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llvm-project/llvm/test/CodeGen/X86/dbg-value-superreg-copy.mir

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[LiveDebugVariables] Avoid faulty addDefsFromCopies in computeIntervals Summary: When computeIntervals is looking through COPY instruction to extend the location mapping for a debug variable it did not handle subregisters correctly. For example DBG_VALUE debug-use %0.sub_8bit_hi, ... %1:gr16 = COPY %0 was transformed into DBG_VALUE debug-use %0.sub_8bit_hi, ... %1:gr16 = COPY %0 DBG_VALUE debug-use %1, ... So the subregister index was missing in the added DBG_VALUE. As long as the subreg refered to the least significant bits of the superreg, then I guess we could get the correct result in a debugger even when referring to the superreg. But as in the example above when the subreg refers to other parts of the superreg, then debuginfo would be incorrect. I'm not sure exactly how to fix this properly, so this patch just avoids looking through the COPY when there is a subreg involved (for more info, see the FIXME added in the code). Reviewers: rnk, aprantl Reviewed By: aprantl Subscribers: JDevlieghere, llvm-commits Tags: #debug-info Differential Revision: https://reviews.llvm.org/D50788 llvm-svn: 340679
2018-08-25 18:02:03 +08:00
# RUN: llc -O1 -start-after simple-register-coalescing -o - %s | FileCheck %s
--- |
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-pc-linux-gnu"
define i16 @foo(i8 %zzz) !dbg !4 {
entry:
ret i16 1
}
; Function Attrs: nounwind readnone speculatable
declare void @llvm.dbg.value(metadata, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !2)
!1 = !DIFile(filename: "test.c", directory: "")
!2 = !{}
!3 = !{i32 1, !"Debug Info Version", i32 3}
!4 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 3, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0)
!5 = !DISubroutineType(types: !6)
!6 = !{null}
!7 = !DILocalVariable(name: "zzz", arg: 1, scope: !4, file: !1, line: 3, type: !8)
!8 = !DIBasicType(name: "char", size: 8, align: 8, encoding: DW_ATE_signed)
!9 = !DILocation(line: 0, scope: !4)
!10 = !DILocation(line: 4, column: 22, scope: !11)
!11 = distinct !DILexicalBlock(scope: !4, file: !1, line: 3, column: 19)
...
---
name: foo
tracksRegLiveness: true
body: |
bb.0:
%0:gr16_abcd = MOV16ri 1
bb.1:
MachineOperand/MIParser: Do not print debug-use flag, infer it The debug-use flag must be set exactly for uses on DBG_VALUEs. This is so obvious that it can be trivially inferred while parsing. This will reduce noise when printing while omitting an information that has little value to the user. The parser will keep recognizing the flag for compatibility with old `.mir` files. Differential Revision: https://reviews.llvm.org/D53903 llvm-svn: 345671
2018-10-31 07:28:27 +08:00
DBG_VALUE %0.sub_8bit_hi, $noreg, !7, !DIExpression(), debug-location !9
[LiveDebugVariables] Avoid faulty addDefsFromCopies in computeIntervals Summary: When computeIntervals is looking through COPY instruction to extend the location mapping for a debug variable it did not handle subregisters correctly. For example DBG_VALUE debug-use %0.sub_8bit_hi, ... %1:gr16 = COPY %0 was transformed into DBG_VALUE debug-use %0.sub_8bit_hi, ... %1:gr16 = COPY %0 DBG_VALUE debug-use %1, ... So the subregister index was missing in the added DBG_VALUE. As long as the subreg refered to the least significant bits of the superreg, then I guess we could get the correct result in a debugger even when referring to the superreg. But as in the example above when the subreg refers to other parts of the superreg, then debuginfo would be incorrect. I'm not sure exactly how to fix this properly, so this patch just avoids looking through the COPY when there is a subreg involved (for more info, see the FIXME added in the code). Reviewers: rnk, aprantl Reviewed By: aprantl Subscribers: JDevlieghere, llvm-commits Tags: #debug-info Differential Revision: https://reviews.llvm.org/D50788 llvm-svn: 340679
2018-08-25 18:02:03 +08:00
%1:gr16 = COPY %0
%2:gr16 = COPY %0
bb.2:
$ax = COPY %1
$dx = COPY %2
RETQ killed $ax, killed $dx
...
# This test case was created as a reproducer for a bug when we got incorrect
# DBG_VALUE instructions after regalloc like this:
#
# movw $1, %cx
# #DEBUG_VALUE: foo:zzz <- $ch
# movl %ecx, %eax
# #DEBUG_VALUE: foo:zzz <- $ax
#
# The above is incorrect since the DBG_VALUE in the input is refering to the
# hi subreg, so after the COPY/movl the value is in $ah and not $ax (nor $al).
#
# We currently only get one DEBUG_VALUE here. In the future we could allow a
# second DEBUG_VALUE, as long as it is mapped to the hi subreg of the movl
# dst.
#
# CHECK-NOT: #DEBUG_VALUE:
# CHECK: #DEBUG_VALUE: foo:zzz <- ${{[abcd]+}}h
# CHECK-NOT: #DEBUG_VALUE: