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llvm-project/llvm/test/DebugInfo/WebAssembly/live-debug-values.mir
Heejin Ahn d198c75e5a [WebAssembly][LiveDebugValues] Handle target index defs 
This adds the missing handling for defs for target index operands, as is
already done for registers.

There are two kinds of target indices: local indices and stack operands.

- Locals are something similar to registers in Wasm-land. For local
  indices, we can check for local-defining instructions (`local.set` or
  `local.tee`).

- Wasm is a stack machine, so we have values in certain Wasm value stack
  location, which change when Wasm instructions produce or consume
  values. So basically any value-producing instrucion, i.e., instruction
  with defs, can change values in the Wasm stack. But I think we don't
  need to worry about this here, because `WebAssemblyDebugFixup`, which
  runs right before this analysis, makes sure to insert terminating
  `DBG_VALUE $noreg` instructions whenever a stack value gets popped.
  After `WebAssemblyDebugFixup`, there shouldn't be any `DBG_VALUE`s for
  stack operands that don't have a terminating `DBG_VALUE $noreg` within
  the same BB.

So this CL only works on `DBG_VALUE`s for locals. When we encounter a
`local.set` or `local.tee` instructions, we delete `DBG_VALUE`s for
those target index locations from the open range set, so they will not
be availble in `OutLocs`. For example,
```
bb.0:
  successors: %bb.1
  DBG_VALUE target-index(wasm-local) + 2, $noreg, "var", ...
  ...
  local.set 2 ...

bb.1:
; predecessors: %bb.0
  ; We shouldn't add `DBG_VALUE target (wasm-local) + 2 here because
  ; it was killed by 'local.set' in bb.0
```

After disabling register coalescing at -O1, the average PC ranges
covered for Emscripten core benchmarks is currently 20.6% in the LLVM
tot. After applying D138943 and this CL, the coverage goes up to 57%.
This also enables LiveDebugValues analysis in the Wasm pipeline by
default.

Reviewed By: dschuff, jmorse

Differential Revision: https://reviews.llvm.org/D140373
2023-01-10 09:56:25 -08:00

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# RUN: llc -run-pass livedebugvalues %s -o - | FileCheck %s
# Test if LiveDebugValue analysis works on Wasm.
--- |
target triple = "wasm32-unknown-unknown"
define void @test_consts() !dbg !5 {
call void @llvm.dbg.value(metadata i32 0, metadata !9, metadata !DIExpression()), !dbg !10
call void @llvm.dbg.value(metadata i32 0, metadata !11, metadata !DIExpression()), !dbg !10
call void @llvm.dbg.value(metadata i32 0, metadata !12, metadata !DIExpression()), !dbg !10
call void @llvm.dbg.value(metadata i32 0, metadata !13, metadata !DIExpression()), !dbg !10
ret void
}
define void @test_target_indices() !dbg !14 {
call void @llvm.dbg.value(metadata i32 0, metadata !15, metadata !DIExpression()), !dbg !16
call void @llvm.dbg.value(metadata i32 0, metadata !17, metadata !DIExpression()), !dbg !16
call void @llvm.dbg.value(metadata i32 0, metadata !18, metadata !DIExpression()), !dbg !16
call void @llvm.dbg.value(metadata i32 0, metadata !19, metadata !DIExpression()), !dbg !16
call void @llvm.dbg.value(metadata i32 0, metadata !20, metadata !DIExpression()), !dbg !16
ret void
}
define void @test_target_index_defs() !dbg !21 {
call void @llvm.dbg.value(metadata i32 0, metadata !22, metadata !DIExpression()), !dbg !23
call void @llvm.dbg.value(metadata i32 0, metadata !24, metadata !DIExpression()), !dbg !23
call void @llvm.dbg.value(metadata i32 0, metadata !25, metadata !DIExpression()), !dbg !23
ret void
}
declare void @llvm.dbg.value(metadata, metadata, metadata)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!2, !3, !4}
!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, emissionKind: FullDebug)
!1 = !DIFile(filename: "test.c", directory: "")
!2 = !{i32 7, !"Dwarf Version", i32 5}
!3 = !{i32 2, !"Debug Info Version", i32 3}
!4 = !{i32 1, !"wchar_size", i32 4}
!5 = distinct !DISubprogram(name: "test_consts", scope: !1, file: !1, line: 1, type: !6, scopeLine: 1, unit: !0)
; CHECK: ![[T0_SP:[0-9]+]] = distinct !DISubprogram(name: "test_consts"
!6 = !DISubroutineType(types: !7)
!7 = !{!8}
!8 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
!9 = !DILocalVariable(name: "var0", scope: !5, file: !1, line: 2, type: !8)
; CHECK: ![[T0_VAR0:[0-9]+]] = !DILocalVariable(name: "var0", scope: ![[T0_SP]]
!10 = !DILocation(line: 0, scope: !5)
!11 = !DILocalVariable(name: "var1", scope: !5, file: !1, line: 2, type: !8)
; CHECK: ![[T0_VAR1:[0-9]+]] = !DILocalVariable(name: "var1", scope: ![[T0_SP]]
!12 = !DILocalVariable(name: "var2", scope: !5, file: !1, line: 2, type: !8)
; CHECK: ![[T0_VAR2:[0-9]+]] = !DILocalVariable(name: "var2", scope: ![[T0_SP]]
!13 = !DILocalVariable(name: "var3", scope: !5, file: !1, line: 2, type: !8)
; CHECK: ![[T0_VAR3:[0-9]+]] = !DILocalVariable(name: "var3", scope: ![[T0_SP]]
!14 = distinct !DISubprogram(name: "test_target_indices", scope: !1, file: !1, line: 10, type: !6, scopeLine: 1, unit: !0)
; CHECK: ![[T1_SP:[0-9]+]] = distinct !DISubprogram(name: "test_target_indices"
!15 = !DILocalVariable(name: "var0", scope: !14, file: !1, line: 11, type: !8)
; CHECK: ![[T1_VAR0:[0-9]+]] = !DILocalVariable(name: "var0", scope: ![[T1_SP]]
!16 = !DILocation(line: 10, scope: !14)
!17 = !DILocalVariable(name: "var1", scope: !14, file: !1, line: 11, type: !8)
; CHECK: ![[T1_VAR1:[0-9]+]] = !DILocalVariable(name: "var1", scope: ![[T1_SP]]
!18 = !DILocalVariable(name: "var2", scope: !14, file: !1, line: 11, type: !8)
; CHECK: ![[T1_VAR2:[0-9]+]] = !DILocalVariable(name: "var2", scope: ![[T1_SP]]
!19 = !DILocalVariable(name: "var3", scope: !14, file: !1, line: 11, type: !8)
; CHECK: ![[T1_VAR3:[0-9]+]] = !DILocalVariable(name: "var3", scope: ![[T1_SP]]
!20 = !DILocalVariable(name: "var4", scope: !14, file: !1, line: 11, type: !8)
; CHECK: ![[T1_VAR4:[0-9]+]] = !DILocalVariable(name: "var4", scope: ![[T1_SP]]
!21 = distinct !DISubprogram(name: "test_target_index_defs", scope: !1, file: !1, line: 10, type: !6, scopeLine: 1, unit: !0)
!22 = !DILocalVariable(name: "var0", scope: !21, file: !1, line: 20, type: !8)
!23 = !DILocation(line: 10, scope: !21)
!24 = !DILocalVariable(name: "var1", scope: !21, file: !1, line: 20, type: !8)
!25 = !DILocalVariable(name: "var2", scope: !21, file: !1, line: 20, type: !8)
...
---
# var0: Its debug value is set once in bb.0 and valid throughout the function.
# So a new DBG_VALUE will be added to the beginnings of all other BBs
# (bb.1, bb.2, and bb.3).
# var1: Its debug value is set in bb.0, but is reset to no info in bb.1. So a
# new DBG_VALUE will be added in the beginning of bb.1 and bb.2, but bb.3
# will not, because its two predecesors (bb.1 and bb.2) have different
# debug values.
# var2: Its debug value is set both in bb.1 and bb.2 with the same value. bb.3
# will have a new DBG_VALUE representing that value.
# var3: Its debug value is set both in bb.1 and bb.2 but with different values.
# bb.3 will NOT have a new DBG_VALUE instruction because its predecessors
# don't agree on a value.
# CHECK-LABEL: name: test_consts
name: test_consts
liveins:
- { reg: '$arguments' }
body: |
bb.0:
successors: %bb.1, %bb.2
liveins: $arguments
DBG_VALUE 10, $noreg, !9, !DIExpression(), debug-location !10
DBG_VALUE 20, $noreg, !11, !DIExpression(), debug-location !10
%0:i32 = CONST_I32 1, implicit-def $arguments
BR_IF %bb.2, %0:i32, implicit-def $arguments
; CHECK: bb.1:
; CHECK-DAG: DBG_VALUE 10, $noreg, ![[T0_VAR0]]
; CHECK-DAG: DBG_VALUE 20, $noreg, ![[T0_VAR1]]
bb.1:
; predecessors: %bb.0
successors: %bb.3
DBG_VALUE $noreg, $noreg, !11, !DIExpression(), debug-location !10
DBG_VALUE 30, $noreg, !12, !DIExpression(), debug-location !10
DBG_VALUE 30, $noreg, !13, !DIExpression(), debug-location !10
BR %bb.3, implicit-def $arguments
; CHECK: bb.2:
; CHECK-DAG: DBG_VALUE 10, $noreg, ![[T0_VAR0]]
; CHECK-DAG: DBG_VALUE 20, $noreg, ![[T0_VAR1]]
bb.2:
; predecessors: %bb.0
successors: %bb.3
DBG_VALUE 30, $noreg, !12, !DIExpression(), debug-location !10
DBG_VALUE 40, $noreg, !13, !DIExpression(), debug-location !10
BR %bb.3, implicit-def $arguments
; CHECK: bb.3:
; CHECK-DAG: DBG_VALUE 10, $noreg, ![[T0_VAR0]]
; CHECK-DAG: DBG_VALUE 30, $noreg, ![[T0_VAR2]]
; CHECK-NOT: DBG_VALUE {{[0-9]+}}, $noreg, ![[T0_VAR1]]
; CHECK-NOT: DBG_VALUE {{[0-9]+}}, $noreg, ![[T0_VAR3]]
bb.3:
; predecessors: %bb.1, %bb.2
RETURN implicit-def dead $arguments
...
---
# var0: Its debug value is set once in bb.0 and valid throughout the function.
# So a new DBG_VALUE will be added to the beginnings of all other BBs
# (bb.1, bb.2, and bb.3).
# var1: Its debug value is set in bb.0, but is reset to no info back later in
# bb.0. So no DBG_VALUEs will be added in other BBs.
# var2: Its debug value is set both in bb.1 and bb.2 with the same value (The
# same kind (local) and same local index). bb.3 will have a new DBG_VALUE
# representing that value.
# var3: Its debug value is set both in bb.1 and bb.2 but with different values.
# Both are locals, but their indices are different. bb.3 will NOT have a
# new DBG_VALUE instruction because its predecessors don't agree on a
# value.
# var4: Its debug value is set both in bb.1 and bb.2 but with different values.
# They have different kinds; one is a local and the other is a stack
# operand. (Their index is the same, but it doesn't matter.) bb.3 will NOT
# have a new DBG_VALUE instruction because its predecessors don't agree on
# a value.
# CHECK-LABEL: name: test_target_indices
name: test_target_indices
liveins:
- { reg: '$arguments' }
body: |
bb.0:
successors: %bb.1, %bb.2
liveins: $arguments
DBG_VALUE target-index(wasm-local), $noreg, !15, !DIExpression(), debug-location !16
DBG_VALUE target-index(wasm-operand-stack) + 2, $noreg, !17, !DIExpression(), debug-location !16
%0:i32 = CONST_I32 1, implicit-def $arguments
DBG_VALUE $noreg, $noreg, !17, !DIExpression(), debug-location !16
BR_IF %bb.2, %0:i32, implicit-def $arguments
; CHECK: bb.1:
; CHECK: DBG_VALUE target-index(wasm-local), $noreg, ![[T1_VAR0]]
bb.1:
; predecessors: %bb.0
successors: %bb.3
DBG_VALUE target-index(wasm-local) + 2, $noreg, !18, !DIExpression(), debug-location !16
DBG_VALUE target-index(wasm-local) + 3, $noreg, !19, !DIExpression(), debug-location !16
DBG_VALUE target-index(wasm-operand-stack) + 3, $noreg, !20, !DIExpression(), debug-location !16
BR %bb.3, implicit-def $arguments
; CHECK: bb.2:
; CHECK: DBG_VALUE target-index(wasm-local), $noreg, ![[T1_VAR0]]
bb.2:
; predecessors: %bb.0
successors: %bb.3
DBG_VALUE target-index(wasm-local) + 2, $noreg, !18, !DIExpression(), debug-location !16
DBG_VALUE target-index(wasm-local) + 5, $noreg, !19, !DIExpression(), debug-location !16
DBG_VALUE target-index(wasm-local) + 3, $noreg, !20, !DIExpression(), debug-location !16
BR %bb.3, implicit-def $arguments
; CHECK: bb.3:
; CHECK-DAG: DBG_VALUE target-index(wasm-local), $noreg, ![[T1_VAR0]]
; CHECK-DAG: DBG_VALUE target-index(wasm-local) + 2, $noreg, ![[T1_VAR2]]
; CHECK-NOT: DBG_VALUE target-index(wasm-local){{.*}}, $noreg, ![[T1_VAR3]]
; CHECK-NOT: DBG_VALUE target-index(wasm-local){{.*}}, $noreg, ![[T1_VAR4]]
bb.3:
; predecessors: %bb.1, %bb.2
RETURN implicit-def dead $arguments
...
---
# bb.0 defines DBG_VALUEs for local index 2 and 3. The DBG_VALUE for local index
# 2 is killed in bb.1 due to 'local.tee 2' there, and DBG_VALUE for local
# index 3 is killed in bb.2 because there is 'local.set 3' there. As a result,
# bb.3 shoudln't have any additional DBG_VALUEs added for those locals.
# CHECK-LABEL: name: test_target_index_defs
name: test_target_index_defs
liveins:
- { reg: '$arguments' }
body: |
bb.0:
successors: %bb.1, %bb.2
liveins: $arguments
DBG_VALUE target-index(wasm-local) + 2, $noreg, !22, !DIExpression(), debug-location !23
DBG_VALUE target-index(wasm-local) + 3, $noreg, !24, !DIExpression(), debug-location !23
%0:i32 = CONST_I32 1, implicit-def $arguments
BR_IF %bb.2, %0:i32, implicit-def $arguments
bb.1:
; predecessors: %bb.0
successors: %bb.3
%0:i32 = CONST_I32 1, implicit-def $arguments
%1:i32 = LOCAL_TEE_I32 2, %0:i32, implicit-def $arguments
DROP_I32 killed %1:i32, implicit-def $arguments
BR %bb.3, implicit-def $arguments
bb.2:
; predecessors: %bb.0
successors: %bb.3
%0:i32 = CONST_I32 1, implicit-def $arguments
LOCAL_SET_I32 3, %0:i32, implicit-def $arguments
BR %bb.3, implicit-def $arguments
; CHECK: bb.3:
; CHECK-NOT: DBG_VALUE target-index(wasm-local){{.*}}
bb.3:
; predecessors: %bb.1, %bb.2
RETURN implicit-def dead $arguments
...
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