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llvm-mirror/test/DebugInfo/X86/dbg-val-list-undef.ll
Jeremy Morse 409363cd51 [DebugInfo][InstrRef][3/4] Produce DBG_INSTR_REFs for all variable locations
This patch emits DBG_INSTR_REFs for two remaining flavours of variable
locations that weren't supported: copies, and inter-block VRegs. There are
still some locations that must be represented by DBG_VALUE such as
constants, but they're mostly independent of optimisations.

For variable locations that refer to values defined in different blocks,
vregs are allocated before isel begins, but the defining instruction
might not exist until late in isel. To get around this, emit
DBG_INSTR_REFs in a "half done" state, where the first operand refers to a
VReg. Then at the end of isel, patch these back up to refer to
instructions, using the finalizeDebugInstrRefs method.

Copies are something that I complained about the original RFC, and I
really don't want to have to put instruction numbers on copies. They don't
define a value: they move them. To address this isel, salvageCopySSA
interprets:
 * COPYs,
 * SUBREG_TO_REG,
 * Anything that isCopyInstr thinks is a copy.
And follows chains of copies back to the defining instruction that they
read from. This relies on any physical registers that COPYs read being
defined in the same block, or being entry-block arguments. For the former
we can put an instruction number on the defining instruction; for the
latter we can drop a DBG_PHI that reads the incoming value.

Differential Revision: https://reviews.llvm.org/D88896
2021-07-06 18:31:38 +01:00

42 lines
2.1 KiB
LLVM

; RUN: llc %s -start-after=codegenprepare -stop-before=finalize-isel -o - | FileCheck %s
;; %y is unused and cannot (FIXME: currently) be salvaged. Ensure that the
;; variadic dbg_value using %y becomes undef.
; CHECK: ![[C:[0-9]+]] = !DILocalVariable(name: "c",
; CHECK: DBG_VALUE $noreg, $noreg, ![[C]], !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_stack_value), debug-location
target triple = "x86_64-pc-windows-msvc19.16.27034"
define dso_local i32 @"?foo@@YAHHH@Z"(i32 %a, i32 %b) local_unnamed_addr !dbg !8 {
entry:
%x = add i32 %a, %b
%y = mul i32 %x, %b
call void @llvm.dbg.value(metadata !DIArgList(i32 %x, i32 %y), metadata !16, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_stack_value)), !dbg !17
ret i32 %x
}
declare void @llvm.dbg.value(metadata, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5, !6}
!llvm.ident = !{!7}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 11.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
!1 = !DIFile(filename: "test.cpp", directory: "/")
!2 = !{}
!3 = !{i32 2, !"CodeView", i32 1}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 2}
!6 = !{i32 7, !"PIC Level", i32 2}
!7 = !{!"clang version 11.0.0"}
!8 = distinct !DISubprogram(name: "foo", linkageName: "?foo@@YAHHH@Z", scope: !9, file: !9, line: 1, type: !10, scopeLine: 1, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
!9 = !DIFile(filename: "test.cpp", directory: "/")
!10 = !DISubroutineType(types: !11)
!11 = !{!12, !12, !12}
!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!13 = !{!14, !15, !16}
!14 = !DILocalVariable(name: "a", arg: 1, scope: !8, file: !9, line: 1, type: !12)
!15 = !DILocalVariable(name: "b", arg: 2, scope: !8, file: !9, line: 1, type: !12)
!16 = !DILocalVariable(name: "c", scope: !8, file: !9, line: 2, type: !12)
!17 = !DILocation(line: 0, scope: !8)