caio/clang-p2996
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity
Files
ef2cdfe393d01cd4935c806387ac912b5a2c8ced
clang-p2996/llvm/test/CodeGen/AMDGPU/ptr-arg-dbg-value.ll
Djordje Todorovic df686842bc [RemoveRedundantDebugValues] Add a Pass that removes redundant DBG_VALUEs 
This new MIR pass removes redundant DBG_VALUEs.

After the register allocator is done, more precisely, after
the Virtual Register Rewriter, we end up having duplicated
DBG_VALUEs, since some virtual registers are being rewritten
into the same physical register as some of existing DBG_VALUEs.
Each DBG_VALUE should indicate (at least before the LiveDebugValues)
variables assignment, but it is being clobbered for function
parameters during the SelectionDAG since it generates new DBG_VALUEs
after COPY instructions, even though the parameter has no assignment.
For example, if we had a DBG_VALUE $regX as an entry debug value
representing the parameter, and a COPY and after the COPY,
DBG_VALUE $virt_reg, and after the virtregrewrite the $virt_reg gets
rewritten into $regX, we'd end up having redundant DBG_VALUE.

This breaks the definition of the DBG_VALUE since some analysis passes
might be built on top of that premise..., and this patch tries to fix
the MIR with the respect to that.

This first patch performs bacward scan, by trying to detect a sequence of
consecutive DBG_VALUEs, and to remove all DBG_VALUEs describing one
variable but the last one:

For example:

(1) DBG_VALUE $edi, !"var1", ...
(2) DBG_VALUE $esi, !"var2", ...
(3) DBG_VALUE $edi, !"var1", ...
 ...

in this case, we can remove (1).

By combining the forward scan that will be introduced in the next patch
(from this stack), by inspecting the statistics, the RemoveRedundantDebugValues
removes 15032 instructions by using gdb-7.11 as a testbed.

Differential Revision: https://reviews.llvm.org/D105279
2021-07-14 04:29:42 -07:00

139 lines
7.1 KiB
LLVM
Raw Blame History

; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=amdgcn-amd-amdhsa -mcpu=gfx908 < %s | FileCheck %s
%struct.A = type { [100 x i32] }
; The 64-bit pointer argument %arg1 will be split into two registers
; and for its llvm.dbg.declare, DAG should emit two DBG_VALUE instructions
; with the fragment expressions.
define hidden void @ptr_arg_split_subregs(%struct.A* %arg1) #0 !dbg !9 {
; CHECK-LABEL: ptr_arg_split_subregs:
; CHECK: .Lfunc_begin0:
; CHECK: .loc 1 5 0 ; example.cpp:5:0
; CHECK-NEXT: .cfi_sections .debug_frame
; CHECK-NEXT: .cfi_startproc
; CHECK-NEXT: ; %bb.0:
; CHECK-NEXT: ;DEBUG_VALUE: ptr_arg_split_subregs:a <- [DW_OP_LLVM_fragment 32 32] [$vgpr1+0]
; CHECK-NEXT: ;DEBUG_VALUE: ptr_arg_split_subregs:a <- [DW_OP_LLVM_fragment 0 32] [$vgpr0+0]
; CHECK-NEXT: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
; CHECK-NEXT: v_mov_b32_e32 v2, 1
; CHECK-NEXT: .Ltmp0:
; CHECK-NEXT: .loc 1 7 13 prologue_end ; example.cpp:7:13
; CHECK-NEXT: flat_store_dword v[0:1], v2 offset:396
; CHECK-NEXT: .loc 1 8 5 ; example.cpp:8:5
; CHECK-NEXT: s_waitcnt vmcnt(0) lgkmcnt(0)
; CHECK-NEXT: s_setpc_b64 s[30:31]
; CHECK-NEXT: .Ltmp1:
; CHECK: .cfi_endproc
call void @llvm.dbg.declare(metadata %struct.A* %arg1, metadata !20, metadata !DIExpression()), !dbg !21
%gep1 = getelementptr inbounds %struct.A, %struct.A* %arg1, i32 0, i32 0, i32 99, !dbg !22
store i32 1, i32* %gep1, align 4, !dbg !23
ret void, !dbg !24
}
; FIXME: The 64-bit pointer argument %arg2 will be split between a register and
; the stack memory. The SelectionDAG though failed to emit the DBG_VALUE for the
; split part in memory. The two DBG_VALUE instructions emitted in the output pattern
; are totally misleading. The former represent part of the incoming argument in register
; while the latter was emitted for the parameter copy to a virtual register inserted
; at the function entry by DAGBuilder.
define hidden void @ptr_arg_split_reg_mem(<31 x i32>, %struct.A* %arg2) #0 !dbg !25 {
; CHECK-LABEL: ptr_arg_split_reg_mem:
; CHECK: .Lfunc_begin1:
; CHECK-NEXT: .loc 1 10 0 ; example.cpp:10:0
; CHECK-NEXT: .cfi_startproc
; CHECK-NEXT: ; %bb.0:
;; NOTE: One dbg_value (DEBUG_VALUE: ptr_arg_split_reg_mem:b <- [$vgpr31+0]) will be considered as
;; redundant after the virtregrewrite, so it will be removed.
; CHECK-NEXT: ;DEBUG_VALUE: ptr_arg_split_reg_mem:b <- [$vgpr31+0]
; CHECK-NEXT: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
; CHECK-NEXT: buffer_load_dword v32, off, s[0:3], s32
; CHECK-NEXT: v_mov_b32_e32 v0, 1
; CHECK-NEXT: .Ltmp2:
; CHECK-NEXT: .loc 1 12 13 prologue_end ; example.cpp:12:13
; CHECK-NEXT: s_waitcnt vmcnt(0)
; CHECK-NEXT: flat_store_dword v[31:32], v0 offset:396
; CHECK-NEXT: .loc 1 13 5 ; example.cpp:13:5
; CHECK-NEXT: s_waitcnt vmcnt(0) lgkmcnt(0)
; CHECK-NEXT: s_setpc_b64 s[30:31]
; CHECK-NEXT: .Ltmp3:
; CHECK: .cfi_endproc
call void @llvm.dbg.declare(metadata %struct.A* %arg2, metadata !26, metadata !DIExpression()), !dbg !27
%gep2 = getelementptr inbounds %struct.A, %struct.A* %arg2, i32 0, i32 0, i32 99, !dbg !28
store i32 1, i32* %gep2, align 4, !dbg !29
ret void, !dbg !30
}
; FIXME: The 64-bit pointer argument %arg3 will be entirely in the stack memory.
; No DBG_VALUE emitted for the incoming argument in this case and it should be fixed.
define hidden void @ptr_arg_in_memory(<32 x i32>, %struct.A* %arg3) #0 !dbg !31 {
; CHECK-LABEL: ptr_arg_in_memory:
; CHECK: .Lfunc_begin2:
; CHECK-NEXT: .loc 1 15 0 ; example.cpp:15:0
; CHECK-NEXT: .cfi_startproc
; CHECK-NEXT: ; %bb.0:
; CHECK-NEXT: s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
; CHECK-NEXT: buffer_load_dword v1, off, s[0:3], s32 offset:4
; CHECK-NEXT: buffer_load_dword v0, off, s[0:3], s32
; CHECK-NEXT: v_mov_b32_e32 v2, 1
; CHECK-NEXT: .Ltmp4:
; CHECK-NEXT: .loc 1 17 13 prologue_end ; example.cpp:17:13
; CHECK-NEXT: s_waitcnt vmcnt(0)
; CHECK-NEXT: flat_store_dword v[0:1], v2 offset:396
; CHECK-NEXT: .loc 1 18 5 ; example.cpp:18:5
; CHECK-NEXT: s_waitcnt vmcnt(0) lgkmcnt(0)
; CHECK-NEXT: s_setpc_b64 s[30:31]
; CHECK-NEXT: .Ltmp5:
; CHECK: .cfi_endproc
call void @llvm.dbg.declare(metadata %struct.A* %arg3, metadata !32, metadata !DIExpression()), !dbg !33
%gep3 = getelementptr inbounds %struct.A, %struct.A* %arg3, i32 0, i32 0, i32 99, !dbg !34
store i32 1, i32* %gep3, align 4, !dbg !35
ret void, !dbg !36
}
declare void @llvm.dbg.declare(metadata, metadata, metadata) #0
attributes #0 = { nounwind }
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!3, !4, !5, !6, !7}
!llvm.ident = !{!8}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 13.0.0", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, splitDebugInlining: false, nameTableKind: None)
!1 = !DIFile(filename: "example.cpp", directory: "temp")
!2 = !{}
!3 = !{i32 7, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{i32 1, !"wchar_size", i32 4}
!6 = !{i32 7, !"uwtable", i32 1}
!7 = !{i32 7, !"frame-pointer", i32 2}
!8 = !{!"clang version 13.0.0"}
!9 = distinct !DISubprogram(name: "ptr_arg_split_subregs", scope: !10, file: !10, line: 5, type: !11, scopeLine: 5, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
!10 = !DIFile(filename: "example.cpp", directory: "temp")
!11 = !DISubroutineType(types: !12)
!12 = !{!13}
!13 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "A", file: !10, line: 1, size: 3200, flags: DIFlagTypePassByValue, elements: !14, identifier: "_ZTS1A")
!14 = !{!15}
!15 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !13, file: !10, line: 2, baseType: !16, size: 3200)
!16 = !DICompositeType(tag: DW_TAG_array_type, baseType: !17, size: 3200, elements: !18)
!17 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!18 = !{!19}
!19 = !DISubrange(count: 100)
!20 = !DILocalVariable(name: "a", scope: !9, file: !10, line: 6, type: !13)
!21 = !DILocation(line: 6, column: 7, scope: !9)
!22 = !DILocation(line: 7, column: 7, scope: !9)
!23 = !DILocation(line: 7, column: 13, scope: !9)
!24 = !DILocation(line: 8, column: 5, scope: !9)
!25 = distinct !DISubprogram(name: "ptr_arg_split_reg_mem", scope: !10, file: !10, line: 10, type: !11, scopeLine: 10, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
!26 = !DILocalVariable(name: "b", scope: !25, file: !10, line: 11, type: !13)
!27 = !DILocation(line: 11, column: 7, scope: !25)
!28 = !DILocation(line: 12, column: 7, scope: !25)
!29 = !DILocation(line: 12, column: 13, scope: !25)
!30 = !DILocation(line: 13, column: 5, scope: !25)
!31 = distinct !DISubprogram(name: "ptr_arg_in_memory", scope: !10, file: !10, line: 15, type: !11, scopeLine: 15, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
!32 = !DILocalVariable(name: "c", scope: !31, file: !10, line: 16, type: !13)
!33 = !DILocation(line: 16, column: 7, scope: !31)
!34 = !DILocation(line: 17, column: 7, scope: !31)
!35 = !DILocation(line: 17, column: 13, scope: !31)
!36 = !DILocation(line: 18, column: 5, scope: !31)
Reference in New Issue View Git Blame Copy Permalink