[LiveDebugVariables] Fix a DBG_VALUE reordering issue #111124
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@llvm/pr-subscribers-backend-amdgpu Author: David Stenberg (dstenb) ChangesLDV could reorder reinserted fragment and non-fragment debug values for For example, before: DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) After (without this patch): DBG_VALUE %stack.0, 0, !13, !DIExpression() It would also reorder DBG_VALUEs for different variables. Although that This should hopefully align so that instruction referencing and
Full diff: https://github.com/llvm/llvm-project/pull/111124.diff 6 Files Affected:
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index 822a1beb489592..13b33facb42086 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -1625,8 +1625,9 @@ findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx, LiveIntervals &LIS,
}
// Don't insert anything after the first terminator, though.
- return MI->isTerminator() ? MBB->getFirstTerminator() :
- std::next(MachineBasicBlock::iterator(MI));
+ auto It = MI->isTerminator() ? MBB->getFirstTerminator() :
+ std::next(MachineBasicBlock::iterator(MI));
+ return skipDebugInstructionsForward(It, MBB->end());
}
/// Find an iterator for inserting the next DBG_VALUE instruction
diff --git a/llvm/test/CodeGen/AMDGPU/debug-value2.ll b/llvm/test/CodeGen/AMDGPU/debug-value2.ll
index 1d4c11de4076cb..b09d540dd6d7b5 100644
--- a/llvm/test/CodeGen/AMDGPU/debug-value2.ll
+++ b/llvm/test/CodeGen/AMDGPU/debug-value2.ll
@@ -12,11 +12,11 @@ define <4 x float> @Scene_transformT(i32 %subshapeIdx, <4 x float> %v, float %ti
entry:
; CHECK: v_mov_b32_e32 v[[COPIED_ARG_PIECE:[0-9]+]], v9
- ; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr6
+ ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr[[COPIED_ARG_PIECE]]
+ ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr8
; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr7
+ ; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr6
call void @llvm.dbg.value(metadata ptr addrspace(1) %gScene, metadata !120, metadata !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef)), !dbg !154
- ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr8
- ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr[[COPIED_ARG_PIECE]]
call void @llvm.dbg.value(metadata ptr addrspace(1) %gSceneOffsets, metadata !121, metadata !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef)), !dbg !155
%call = tail call ptr addrspace(1) @Scene_getSubShapeData(i32 %subshapeIdx, ptr addrspace(1) %gScene, ptr addrspace(1) %gSceneOffsets)
%m_linearMotion = getelementptr inbounds %struct.ShapeData, ptr addrspace(1) %call, i64 0, i32 2
diff --git a/llvm/test/DebugInfo/MIR/Mips/livedebugvars-stop-trimming-loc.mir b/llvm/test/DebugInfo/MIR/Mips/livedebugvars-stop-trimming-loc.mir
index 5df70096e9305d..d6171ec30b1271 100644
--- a/llvm/test/DebugInfo/MIR/Mips/livedebugvars-stop-trimming-loc.mir
+++ b/llvm/test/DebugInfo/MIR/Mips/livedebugvars-stop-trimming-loc.mir
@@ -3,11 +3,13 @@
## This tests that LiveDebugVariables does not trim non-inlined variable
## location.
+# CHECK: ![[VARA:.*]] = !DILocalVariable(name: "a"
# CHECK: ![[VARB:.*]] = !DILocalVariable(name: "b"
# CHECK: ![[VARC:.*]] = !DILocalVariable(name: "c"
# CHECK: $at = COPY $a2
# CHECK-NEXT: DBG_VALUE $at, $noreg, ![[VARC]], !DIExpression(), debug-location
# CHECK: $s0 = COPY $a1
+# CHECK-NEXT: DBG_VALUE $a0, $noreg, ![[VARA]], !DIExpression(), debug-location
# CHECK-NEXT: DBG_VALUE $s0, $noreg, ![[VARB]], !DIExpression(), debug-location
--- |
diff --git a/llvm/test/DebugInfo/Mips/livedebugvariables-reorder.mir b/llvm/test/DebugInfo/Mips/livedebugvariables-reorder.mir
new file mode 100644
index 00000000000000..e9392586c2afb1
--- /dev/null
+++ b/llvm/test/DebugInfo/Mips/livedebugvariables-reorder.mir
@@ -0,0 +1,96 @@
+# RUN: llc -emit-call-site-info %s -mtriple=mips -start-before=register-coalescer -stop-after=virtregrewriter -o - | FileCheck %s
+
+# Verify that LiveDebugVariables does not reorder the stack location DBG_VALUE
+# and the fragmented DBG_VALUEs for aaa, as the latter may represent a stale
+# value. It should also not reorder the DBG_VALUEs for the different variables,
+# as that results in noise in pass before/after diffs.
+
+# CHECK-DAG: ![[aaa:[0-9]+]] = !DILocalVariable(name: "aaa"
+# CHECK-DAG: ![[bbb:[0-9]+]] = !DILocalVariable(name: "bbb"
+# CHECK-DAG: ![[ccc:[0-9]+]] = !DILocalVariable(name: "ccc"
+# CHECK-DAG: ![[ddd:[0-9]+]] = !DILocalVariable(name: "ddd"
+
+# CHECK: DBG_VALUE 1001, $noreg, ![[aaa]], !DIExpression(DW_OP_LLVM_fragment, 0, 16)
+# CHECK-NEXT: DBG_VALUE 1002, $noreg, ![[aaa]], !DIExpression(DW_OP_LLVM_fragment, 16, 16)
+# CHECK-NEXT: DBG_VALUE 222, $noreg, ![[bbb]], !DIExpression()
+# CHECK-NEXT: DBG_VALUE 333, $noreg, ![[ccc]], !DIExpression()
+# CHECK-NEXT: DBG_VALUE 444, $noreg, ![[ddd]], !DIExpression()
+# CHECK-NEXT: DBG_VALUE %stack.0, 0, ![[aaa]], !DIExpression()
+
+--- |
+ target datalayout = "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64"
+ target triple = "mips"
+
+ ; Function Attrs: nounwind
+ define dso_local i32 @main() local_unnamed_addr #0 !dbg !8 {
+ entry:
+ ret i32 0, !dbg !21
+ }
+
+ declare !dbg !22 dso_local i32 @foo() local_unnamed_addr
+
+ ; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
+ declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+ attributes #0 = { nounwind "frame-pointer"="all" }
+ attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
+
+ !llvm.dbg.cu = !{!0}
+ !llvm.module.flags = !{!2, !3, !4, !5, !6}
+ !llvm.ident = !{!7}
+
+ !0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 19.0.0git", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+ !1 = !DIFile(filename: "main.c", directory: "/", checksumkind: CSK_MD5, checksum: "9edfcd32ce51b21ab508a4a0755aa78b")
+ !2 = !{i32 7, !"Dwarf Version", i32 5}
+ !3 = !{i32 2, !"Debug Info Version", i32 3}
+ !4 = !{i32 1, !"wchar_size", i32 4}
+ !5 = !{i32 7, !"frame-pointer", i32 2}
+ !6 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+ !7 = !{!"clang version 19.0.0git"}
+ !8 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 12, type: !9, scopeLine: 12, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+ !9 = !DISubroutineType(types: !10)
+ !10 = !{!11}
+ !11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+ !12 = !{!13, !14, !15, !16}
+ !13 = !DILocalVariable(name: "aaa", scope: !8, file: !1, line: 13, type: !11)
+ !14 = !DILocalVariable(name: "bbb", scope: !8, file: !1, line: 14, type: !11)
+ !15 = !DILocalVariable(name: "ccc", scope: !8, file: !1, line: 15, type: !11)
+ !16 = !DILocalVariable(name: "ddd", scope: !8, file: !1, line: 16, type: !11)
+ !17 = !DILocation(line: 13, scope: !8)
+ !18 = !DILocation(line: 0, scope: !8)
+ !19 = !DILocation(line: 17, scope: !8)
+ !20 = !{i64 2147496201}
+ !21 = !DILocation(line: 18, scope: !8)
+ !22 = !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !9, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
+
+...
+---
+name: main
+alignment: 4
+tracksRegLiveness: true
+registers:
+ - { id: 0, class: gpr32 }
+frameInfo:
+ maxAlignment: 1
+ adjustsStack: true
+ hasCalls: true
+callSites:
+ - { bb: 0, offset: 1 }
+machineFunctionInfo: {}
+body: |
+ bb.0.entry:
+ ADJCALLSTACKDOWN 16, 0, implicit-def dead $sp, implicit $sp, debug-location !17
+ JAL @foo, csr_o32_fpxx, implicit-def dead $ra, implicit-def $sp, implicit-def $v0, debug-location !17
+ ADJCALLSTACKUP 16, 0, implicit-def dead $sp, implicit $sp, debug-location !17
+ %0:gpr32 = COPY killed $v0, debug-location !17
+ DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16), debug-location !18
+ DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16), debug-location !18
+ DBG_VALUE 222, $noreg, !14, !DIExpression(), debug-location !18
+ DBG_VALUE 333, $noreg, !15, !DIExpression(), debug-location !18
+ DBG_VALUE 444, $noreg, !16, !DIExpression(), debug-location !18
+ DBG_VALUE %0, $noreg, !13, !DIExpression(), debug-location !18
+ INLINEASM &"", 1 /* sideeffect attdialect */, 12 /* clobber */, implicit-def dead early-clobber $v0, 12 /* clobber */, implicit-def dead early-clobber $v1, 12 /* clobber */, implicit-def dead early-clobber $a0, 12 /* clobber */, implicit-def dead early-clobber $a1, 12 /* clobber */, implicit-def dead early-clobber $a2, 12 /* clobber */, implicit-def dead early-clobber $a3, 12 /* clobber */, implicit-def dead early-clobber $t0, 12 /* clobber */, implicit-def dead early-clobber $t1, 12 /* clobber */, implicit-def dead early-clobber $t2, 12 /* clobber */, implicit-def dead early-clobber $t3, 12 /* clobber */, implicit-def dead early-clobber $t4, 12 /* clobber */, implicit-def dead early-clobber $t5, 12 /* clobber */, implicit-def dead early-clobber $t6, 12 /* clobber */, implicit-def dead early-clobber $t7, 12 /* clobber */, implicit-def dead early-clobber $t8, 12 /* clobber */, implicit-def dead early-clobber $t9, 12 /* clobber */, implicit-def dead early-clobber $gp, 12 /* clobber */, implicit-def dead early-clobber $ra, 12 /* clobber */, implicit-def dead early-clobber $s0, 12 /* clobber */, implicit-def dead early-clobber $s1, 12 /* clobber */, implicit-def dead early-clobber $s2, 12 /* clobber */, implicit-def dead early-clobber $s3, 12 /* clobber */, implicit-def dead early-clobber $s4, 12 /* clobber */, implicit-def dead early-clobber $s5, 12 /* clobber */, implicit-def dead early-clobber $s6, 12 /* clobber */, implicit-def dead early-clobber $s7, 12 /* clobber */, implicit-def dead early-clobber $at, !20, debug-location !19
+ $v0 = COPY killed %0, debug-location !21
+ RetRA implicit killed $v0, debug-location !21
+
+...
diff --git a/llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir b/llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
index 08130b47b4c5c9..7c8aa966d3d643 100644
--- a/llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
+++ b/llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
@@ -118,15 +118,15 @@ body: |
# CHECK-LABEL: bb.3:
# CHECK: dead renamable $rcx = IMPLICIT_DEF
-# CHECK-NEXT: DBG_VALUE 0, $noreg, !23, !DIExpression()
# CHECK-NEXT: DBG_VALUE $rcx, $noreg, !18, !DIExpression()
+# CHECK-NEXT: DBG_VALUE 0, $noreg, !23, !DIExpression()
# CHECK-LABEL: bb.4:
# CHECK: liveins: $rax
# CHECK: DBG_VALUE $rax, $noreg, !18, !DIExpression()
# CHECK-NEXT: renamable $rax = BTS64ri8 killed renamable $rax, 0, implicit-def $eflags
-# CHECK-NEXT: DBG_VALUE 0, $noreg, !23, !DIExpression()
# CHECK-NEXT: DBG_VALUE $rax, $noreg, !18, !DIExpression()
+# CHECK-NEXT: DBG_VALUE 0, $noreg, !23, !DIExpression()
# CHECK-NEXT: renamable $rax = BTS64ri8 killed renamable $rax, 0, implicit-def $eflags
# CHECK-NEXT: DBG_VALUE $rax, $noreg, !18, !DIExpression()
# CHECK-NEXT: dead renamable $rax = BTS64ri8 killed renamable $rax, 0, implicit-def $eflags
diff --git a/llvm/test/DebugInfo/X86/sdag-salvage-add.ll b/llvm/test/DebugInfo/X86/sdag-salvage-add.ll
index 5a77b9504206cb..bd3ff01f9a8266 100644
--- a/llvm/test/DebugInfo/X86/sdag-salvage-add.ll
+++ b/llvm/test/DebugInfo/X86/sdag-salvage-add.ll
@@ -27,21 +27,18 @@
; instruction selection as it is folded into the load. As a result, we should
; refer to s4 and myVar with complex expressions.
;
-; NB: instruction referencing and DBG_VALUE modes produce debug insts in a
-; different order.
-;
; CHECK: ![[S4:.*]] = !DILocalVariable(name: "s4",
; CHECK: ![[MYVAR:.*]] = !DILocalVariable(name: "myVar",
; CHECK: $rax = MOV64rm
; INSTRREF-SAME: debug-instr-number 2,
; INSTRREF-NEXT: DBG_INSTR_REF ![[S4]],
-; DBGVALUE-NEXT: DBG_VALUE $rax, $noreg, ![[MYVAR]],
+; DBGVALUE-NEXT: DBG_VALUE $rax, $noreg, ![[S4]],
; DBGVALUE-SAME: !DIExpression(DW_OP_plus_uconst, 4096, DW_OP_stack_value)
; INSTRREF-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 4096, DW_OP_stack_value)
; INSTRREF-SAME: dbg-instr-ref(2, 0)
; INSTRREF: DBG_INSTR_REF ![[MYVAR]],
-; DBGVALUE: DBG_VALUE $rax, $noreg, ![[S4]],
+; DBGVALUE: DBG_VALUE $rax, $noreg, ![[MYVAR]],
; DBGVALUE-SAME: !DIExpression(DW_OP_plus_uconst, 4096, DW_OP_stack_value)
; INSTRREF-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 4096, DW_OP_stack_value)
; INSTRREF-SAME: dbg-instr-ref(2, 0)
|
|
@llvm/pr-subscribers-debuginfo Author: David Stenberg (dstenb) ChangesLDV could reorder reinserted fragment and non-fragment debug values for For example, before: DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) After (without this patch): DBG_VALUE %stack.0, 0, !13, !DIExpression() It would also reorder DBG_VALUEs for different variables. Although that This should hopefully align so that instruction referencing and
Full diff: https://github.com/llvm/llvm-project/pull/111124.diff 6 Files Affected:
diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index 822a1beb489592..13b33facb42086 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -1625,8 +1625,9 @@ findInsertLocation(MachineBasicBlock *MBB, SlotIndex Idx, LiveIntervals &LIS,
}
// Don't insert anything after the first terminator, though.
- return MI->isTerminator() ? MBB->getFirstTerminator() :
- std::next(MachineBasicBlock::iterator(MI));
+ auto It = MI->isTerminator() ? MBB->getFirstTerminator() :
+ std::next(MachineBasicBlock::iterator(MI));
+ return skipDebugInstructionsForward(It, MBB->end());
}
/// Find an iterator for inserting the next DBG_VALUE instruction
diff --git a/llvm/test/CodeGen/AMDGPU/debug-value2.ll b/llvm/test/CodeGen/AMDGPU/debug-value2.ll
index 1d4c11de4076cb..b09d540dd6d7b5 100644
--- a/llvm/test/CodeGen/AMDGPU/debug-value2.ll
+++ b/llvm/test/CodeGen/AMDGPU/debug-value2.ll
@@ -12,11 +12,11 @@ define <4 x float> @Scene_transformT(i32 %subshapeIdx, <4 x float> %v, float %ti
entry:
; CHECK: v_mov_b32_e32 v[[COPIED_ARG_PIECE:[0-9]+]], v9
- ; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr6
+ ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr[[COPIED_ARG_PIECE]]
+ ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr8
; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr7
+ ; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr6
call void @llvm.dbg.value(metadata ptr addrspace(1) %gScene, metadata !120, metadata !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef)), !dbg !154
- ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr8
- ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr[[COPIED_ARG_PIECE]]
call void @llvm.dbg.value(metadata ptr addrspace(1) %gSceneOffsets, metadata !121, metadata !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef)), !dbg !155
%call = tail call ptr addrspace(1) @Scene_getSubShapeData(i32 %subshapeIdx, ptr addrspace(1) %gScene, ptr addrspace(1) %gSceneOffsets)
%m_linearMotion = getelementptr inbounds %struct.ShapeData, ptr addrspace(1) %call, i64 0, i32 2
diff --git a/llvm/test/DebugInfo/MIR/Mips/livedebugvars-stop-trimming-loc.mir b/llvm/test/DebugInfo/MIR/Mips/livedebugvars-stop-trimming-loc.mir
index 5df70096e9305d..d6171ec30b1271 100644
--- a/llvm/test/DebugInfo/MIR/Mips/livedebugvars-stop-trimming-loc.mir
+++ b/llvm/test/DebugInfo/MIR/Mips/livedebugvars-stop-trimming-loc.mir
@@ -3,11 +3,13 @@
## This tests that LiveDebugVariables does not trim non-inlined variable
## location.
+# CHECK: ![[VARA:.*]] = !DILocalVariable(name: "a"
# CHECK: ![[VARB:.*]] = !DILocalVariable(name: "b"
# CHECK: ![[VARC:.*]] = !DILocalVariable(name: "c"
# CHECK: $at = COPY $a2
# CHECK-NEXT: DBG_VALUE $at, $noreg, ![[VARC]], !DIExpression(), debug-location
# CHECK: $s0 = COPY $a1
+# CHECK-NEXT: DBG_VALUE $a0, $noreg, ![[VARA]], !DIExpression(), debug-location
# CHECK-NEXT: DBG_VALUE $s0, $noreg, ![[VARB]], !DIExpression(), debug-location
--- |
diff --git a/llvm/test/DebugInfo/Mips/livedebugvariables-reorder.mir b/llvm/test/DebugInfo/Mips/livedebugvariables-reorder.mir
new file mode 100644
index 00000000000000..e9392586c2afb1
--- /dev/null
+++ b/llvm/test/DebugInfo/Mips/livedebugvariables-reorder.mir
@@ -0,0 +1,96 @@
+# RUN: llc -emit-call-site-info %s -mtriple=mips -start-before=register-coalescer -stop-after=virtregrewriter -o - | FileCheck %s
+
+# Verify that LiveDebugVariables does not reorder the stack location DBG_VALUE
+# and the fragmented DBG_VALUEs for aaa, as the latter may represent a stale
+# value. It should also not reorder the DBG_VALUEs for the different variables,
+# as that results in noise in pass before/after diffs.
+
+# CHECK-DAG: ![[aaa:[0-9]+]] = !DILocalVariable(name: "aaa"
+# CHECK-DAG: ![[bbb:[0-9]+]] = !DILocalVariable(name: "bbb"
+# CHECK-DAG: ![[ccc:[0-9]+]] = !DILocalVariable(name: "ccc"
+# CHECK-DAG: ![[ddd:[0-9]+]] = !DILocalVariable(name: "ddd"
+
+# CHECK: DBG_VALUE 1001, $noreg, ![[aaa]], !DIExpression(DW_OP_LLVM_fragment, 0, 16)
+# CHECK-NEXT: DBG_VALUE 1002, $noreg, ![[aaa]], !DIExpression(DW_OP_LLVM_fragment, 16, 16)
+# CHECK-NEXT: DBG_VALUE 222, $noreg, ![[bbb]], !DIExpression()
+# CHECK-NEXT: DBG_VALUE 333, $noreg, ![[ccc]], !DIExpression()
+# CHECK-NEXT: DBG_VALUE 444, $noreg, ![[ddd]], !DIExpression()
+# CHECK-NEXT: DBG_VALUE %stack.0, 0, ![[aaa]], !DIExpression()
+
+--- |
+ target datalayout = "E-m:m-p:32:32-i8:8:32-i16:16:32-i64:64-n32-S64"
+ target triple = "mips"
+
+ ; Function Attrs: nounwind
+ define dso_local i32 @main() local_unnamed_addr #0 !dbg !8 {
+ entry:
+ ret i32 0, !dbg !21
+ }
+
+ declare !dbg !22 dso_local i32 @foo() local_unnamed_addr
+
+ ; Function Attrs: nocallback nofree nosync nounwind speculatable willreturn memory(none)
+ declare void @llvm.dbg.value(metadata, metadata, metadata) #1
+
+ attributes #0 = { nounwind "frame-pointer"="all" }
+ attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
+
+ !llvm.dbg.cu = !{!0}
+ !llvm.module.flags = !{!2, !3, !4, !5, !6}
+ !llvm.ident = !{!7}
+
+ !0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 19.0.0git", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+ !1 = !DIFile(filename: "main.c", directory: "/", checksumkind: CSK_MD5, checksum: "9edfcd32ce51b21ab508a4a0755aa78b")
+ !2 = !{i32 7, !"Dwarf Version", i32 5}
+ !3 = !{i32 2, !"Debug Info Version", i32 3}
+ !4 = !{i32 1, !"wchar_size", i32 4}
+ !5 = !{i32 7, !"frame-pointer", i32 2}
+ !6 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+ !7 = !{!"clang version 19.0.0git"}
+ !8 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 12, type: !9, scopeLine: 12, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)
+ !9 = !DISubroutineType(types: !10)
+ !10 = !{!11}
+ !11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+ !12 = !{!13, !14, !15, !16}
+ !13 = !DILocalVariable(name: "aaa", scope: !8, file: !1, line: 13, type: !11)
+ !14 = !DILocalVariable(name: "bbb", scope: !8, file: !1, line: 14, type: !11)
+ !15 = !DILocalVariable(name: "ccc", scope: !8, file: !1, line: 15, type: !11)
+ !16 = !DILocalVariable(name: "ddd", scope: !8, file: !1, line: 16, type: !11)
+ !17 = !DILocation(line: 13, scope: !8)
+ !18 = !DILocation(line: 0, scope: !8)
+ !19 = !DILocation(line: 17, scope: !8)
+ !20 = !{i64 2147496201}
+ !21 = !DILocation(line: 18, scope: !8)
+ !22 = !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !9, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized)
+
+...
+---
+name: main
+alignment: 4
+tracksRegLiveness: true
+registers:
+ - { id: 0, class: gpr32 }
+frameInfo:
+ maxAlignment: 1
+ adjustsStack: true
+ hasCalls: true
+callSites:
+ - { bb: 0, offset: 1 }
+machineFunctionInfo: {}
+body: |
+ bb.0.entry:
+ ADJCALLSTACKDOWN 16, 0, implicit-def dead $sp, implicit $sp, debug-location !17
+ JAL @foo, csr_o32_fpxx, implicit-def dead $ra, implicit-def $sp, implicit-def $v0, debug-location !17
+ ADJCALLSTACKUP 16, 0, implicit-def dead $sp, implicit $sp, debug-location !17
+ %0:gpr32 = COPY killed $v0, debug-location !17
+ DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16), debug-location !18
+ DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16), debug-location !18
+ DBG_VALUE 222, $noreg, !14, !DIExpression(), debug-location !18
+ DBG_VALUE 333, $noreg, !15, !DIExpression(), debug-location !18
+ DBG_VALUE 444, $noreg, !16, !DIExpression(), debug-location !18
+ DBG_VALUE %0, $noreg, !13, !DIExpression(), debug-location !18
+ INLINEASM &"", 1 /* sideeffect attdialect */, 12 /* clobber */, implicit-def dead early-clobber $v0, 12 /* clobber */, implicit-def dead early-clobber $v1, 12 /* clobber */, implicit-def dead early-clobber $a0, 12 /* clobber */, implicit-def dead early-clobber $a1, 12 /* clobber */, implicit-def dead early-clobber $a2, 12 /* clobber */, implicit-def dead early-clobber $a3, 12 /* clobber */, implicit-def dead early-clobber $t0, 12 /* clobber */, implicit-def dead early-clobber $t1, 12 /* clobber */, implicit-def dead early-clobber $t2, 12 /* clobber */, implicit-def dead early-clobber $t3, 12 /* clobber */, implicit-def dead early-clobber $t4, 12 /* clobber */, implicit-def dead early-clobber $t5, 12 /* clobber */, implicit-def dead early-clobber $t6, 12 /* clobber */, implicit-def dead early-clobber $t7, 12 /* clobber */, implicit-def dead early-clobber $t8, 12 /* clobber */, implicit-def dead early-clobber $t9, 12 /* clobber */, implicit-def dead early-clobber $gp, 12 /* clobber */, implicit-def dead early-clobber $ra, 12 /* clobber */, implicit-def dead early-clobber $s0, 12 /* clobber */, implicit-def dead early-clobber $s1, 12 /* clobber */, implicit-def dead early-clobber $s2, 12 /* clobber */, implicit-def dead early-clobber $s3, 12 /* clobber */, implicit-def dead early-clobber $s4, 12 /* clobber */, implicit-def dead early-clobber $s5, 12 /* clobber */, implicit-def dead early-clobber $s6, 12 /* clobber */, implicit-def dead early-clobber $s7, 12 /* clobber */, implicit-def dead early-clobber $at, !20, debug-location !19
+ $v0 = COPY killed %0, debug-location !21
+ RetRA implicit killed $v0, debug-location !21
+
+...
diff --git a/llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir b/llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
index 08130b47b4c5c9..7c8aa966d3d643 100644
--- a/llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
+++ b/llvm/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
@@ -118,15 +118,15 @@ body: |
# CHECK-LABEL: bb.3:
# CHECK: dead renamable $rcx = IMPLICIT_DEF
-# CHECK-NEXT: DBG_VALUE 0, $noreg, !23, !DIExpression()
# CHECK-NEXT: DBG_VALUE $rcx, $noreg, !18, !DIExpression()
+# CHECK-NEXT: DBG_VALUE 0, $noreg, !23, !DIExpression()
# CHECK-LABEL: bb.4:
# CHECK: liveins: $rax
# CHECK: DBG_VALUE $rax, $noreg, !18, !DIExpression()
# CHECK-NEXT: renamable $rax = BTS64ri8 killed renamable $rax, 0, implicit-def $eflags
-# CHECK-NEXT: DBG_VALUE 0, $noreg, !23, !DIExpression()
# CHECK-NEXT: DBG_VALUE $rax, $noreg, !18, !DIExpression()
+# CHECK-NEXT: DBG_VALUE 0, $noreg, !23, !DIExpression()
# CHECK-NEXT: renamable $rax = BTS64ri8 killed renamable $rax, 0, implicit-def $eflags
# CHECK-NEXT: DBG_VALUE $rax, $noreg, !18, !DIExpression()
# CHECK-NEXT: dead renamable $rax = BTS64ri8 killed renamable $rax, 0, implicit-def $eflags
diff --git a/llvm/test/DebugInfo/X86/sdag-salvage-add.ll b/llvm/test/DebugInfo/X86/sdag-salvage-add.ll
index 5a77b9504206cb..bd3ff01f9a8266 100644
--- a/llvm/test/DebugInfo/X86/sdag-salvage-add.ll
+++ b/llvm/test/DebugInfo/X86/sdag-salvage-add.ll
@@ -27,21 +27,18 @@
; instruction selection as it is folded into the load. As a result, we should
; refer to s4 and myVar with complex expressions.
;
-; NB: instruction referencing and DBG_VALUE modes produce debug insts in a
-; different order.
-;
; CHECK: ![[S4:.*]] = !DILocalVariable(name: "s4",
; CHECK: ![[MYVAR:.*]] = !DILocalVariable(name: "myVar",
; CHECK: $rax = MOV64rm
; INSTRREF-SAME: debug-instr-number 2,
; INSTRREF-NEXT: DBG_INSTR_REF ![[S4]],
-; DBGVALUE-NEXT: DBG_VALUE $rax, $noreg, ![[MYVAR]],
+; DBGVALUE-NEXT: DBG_VALUE $rax, $noreg, ![[S4]],
; DBGVALUE-SAME: !DIExpression(DW_OP_plus_uconst, 4096, DW_OP_stack_value)
; INSTRREF-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 4096, DW_OP_stack_value)
; INSTRREF-SAME: dbg-instr-ref(2, 0)
; INSTRREF: DBG_INSTR_REF ![[MYVAR]],
-; DBGVALUE: DBG_VALUE $rax, $noreg, ![[S4]],
+; DBGVALUE: DBG_VALUE $rax, $noreg, ![[MYVAR]],
; DBGVALUE-SAME: !DIExpression(DW_OP_plus_uconst, 4096, DW_OP_stack_value)
; INSTRREF-SAME: !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_plus_uconst, 4096, DW_OP_stack_value)
; INSTRREF-SAME: dbg-instr-ref(2, 0)
|
|
✅ With the latest revision this PR passed the C/C++ code formatter. |
jmorse
reviewed
Oct 4, 2024
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This looks good with a question inline and nit, thanks for finding!
Technically this patch can have some quadratic behaviour, because if there are multiple DBG_VALUEs being inserted in the same place, we'll repeatedly skip over the ones we've already inserted. See the large comment above this hunk: I believe Facebook/Meta hit some serious compile-times because of that and installed a cache of insertion points at the start of blocks. I don't believe DBG_VALUEs cluster inside basic blocks to the same extent that they do at the start of blocks so this patch is /probably/ fine -- if you can see an obvious way to avoid skipping over previously-inserted DBG_VALUEs then that'd be great, but I don't think it should block the patch.
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| attributes #0 = { nounwind "frame-pointer"="all" } | ||
| attributes #1 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) } |
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If these aren't necessary attributes please remove, they add needless future maintenance otherwise
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I have removed unneeded attributes now.
I think that it might be possible to rewrite the test to not depend on "frame-pointer"="all" as well, but I did not do that now (but can do that if you prefer).
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|
|
||
| ; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr6 | ||
| ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr[[COPIED_ARG_PIECE]] | ||
| ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr8 | ||
| ; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr7 | ||
| ; CHECK: ;DEBUG_VALUE: Scene_transformT:gScene <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr6 | ||
| call void @llvm.dbg.value(metadata ptr addrspace(1) %gScene, metadata !120, metadata !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef)), !dbg !154 | ||
| ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 0 32] $vgpr8 | ||
| ; CHECK: ;DEBUG_VALUE: Scene_transformT:gSceneOffsets <- [DW_OP_constu 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment 32 32] $vgpr[[COPIED_ARG_PIECE]] | ||
| call void @llvm.dbg.value(metadata ptr addrspace(1) %gSceneOffsets, metadata !121, metadata !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef)), !dbg !155 | ||
| %call = tail call ptr addrspace(1) @Scene_getSubShapeData(i32 %subshapeIdx, ptr addrspace(1) %gScene, ptr addrspace(1) %gSceneOffsets) |
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Hard for me to analyse just from the github UI as this isn't a MIR test, but !120 = gScene, !121 = gSceneOffsets, which are ordered !120, !121 in the two pre-isel dbg.values. In the old check lines the DEBUG_VALUE lines come out in the right order, but now they're flipped?
Chances are I'm reading it wrong, or there's some other re-ordering happening somewhere in LLVM that LDVars was just accidentally undoing, seeing how the order in other test files changes is fixed.
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In this case the debug values get reordered at isel due to the order of the lowered parameters. I should perhaps have added an XXX note about that in the test. I can do that.
define <4 x float> @Scene_transformT(i32 %subshapeIdx, <4 x float> %v, float %time, ptr addrspace(1) %gScene, ptr addrspace(1) %gSceneOffsets) local_unnamed_addr !dbg !110 {
entry:
#dbg_value(ptr addrspace(1) %gScene, !120, !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef), !154)
#dbg_value(ptr addrspace(1) %gSceneOffsets, !121, !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef), !155)
# *** IR Dump After AMDGPU DAG->DAG Pattern Instruction Selection (amdgpu-isel) ***:
# Machine code for function Scene_transformT: IsSSA, TracksLiveness
Function Live Ins: $sgpr4_sgpr5 in %55, $sgpr8_sgpr9 in %56, $sgpr10_sgpr11 in %57, $sgpr12 in %58, $sgpr13 in %59, $sgpr14 in %60, $sgpr15 in %61, $vgpr0 in %62, $vgpr1 in %63, $vgpr2 in %64, $vgpr3 in %65, $vgpr4 in %66, $vgpr5 in %67, $vgpr6 in %68, $vgpr7 in %69, $vgpr8 in %70, $vgpr9 in %71, $sgpr6_sgpr7 in %73, $vgpr31 in %74
bb.0.entry:
successors: %bb.1(0x40000000), %bb.9(0x40000000); %bb.1(50.00%), %bb.9(50.00%)
liveins: $sgpr4_sgpr5, $sgpr8_sgpr9, $sgpr10_sgpr11, $sgpr12, $sgpr13, $sgpr14, $sgpr15, $vgpr0, $vgpr1, $vgpr2, $vgpr3, $vgpr4, $vgpr5, $vgpr6, $vgpr7, $vgpr8, $vgpr9, $sgpr6_sgpr7, $vgpr31
%74:vgpr_32 = COPY $vgpr31
%73:sgpr_64 = COPY $sgpr6_sgpr7
%71:vgpr_32 = COPY $vgpr9
DBG_VALUE %71:vgpr_32, $noreg, !"gSceneOffsets", !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment, 32, 32), debug-location !155; GraphMaterialSystemKernels1.cl:2182:102 line no:2182
%70:vgpr_32 = COPY $vgpr8
DBG_VALUE %70:vgpr_32, $noreg, !"gSceneOffsets", !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment, 0, 32), debug-location !155; GraphMaterialSystemKernels1.cl:2182:102 line no:2182
%69:vgpr_32 = COPY $vgpr7
DBG_VALUE %69:vgpr_32, $noreg, !"gScene", !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment, 32, 32), debug-location !154; GraphMaterialSystemKernels1.cl:2182:80 line no:2182
%68:vgpr_32 = COPY $vgpr6
DBG_VALUE %68:vgpr_32, $noreg, !"gScene", !DIExpression(DW_OP_constu, 1, DW_OP_swap, DW_OP_xderef, DW_OP_LLVM_fragment, 0, 32), debug-location !154; GraphMaterialSystemKernels1.cl:2182:80 line no:2182
arsenm
reviewed
Oct 4, 2024
|
|
||
| !llvm.dbg.cu = !{!0} | ||
| !llvm.module.flags = !{!2, !3, !4, !5, !6} | ||
| !llvm.ident = !{!7} |
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can lose ident and probably most of the module flags
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I've removed that, as well as some unneeded line number metadata.
I'll look further into that. I think I still have access to http://llvm-compile-time-tracker.com, so I should be hopefully able to run some performance measurements on this. |
The parent commit is a patch which disables instruction referencing mode (as the profiling is done on x86-64). I did not see any outliers there. However, I don't know how those builds compare to Facebook/Meta builds. |
jmorse
approved these changes
Oct 7, 2024
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Thanks for running the profile -- I think we've made the best effort of checking the performance implications so we should be clear to go.
(Fascinating how tramp3d-v4 is always a major outlier when it comes to debug-info performance, as far as we can tell it just spends 100% of its time processing DBG_VALUEs).
|
Thanks for the reviews, and sorry for the delay in landing this! Will land it shortly. |
dstenb
added a commit
to dstenb/llvm-project
that referenced
this pull request
Oct 15, 2024
LDV could reorder reinserted fragment and non-fragment debug values for the same variable (compared to the input order), potentially resulting in stale values being presented. For example, before: DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE %0, $noreg, !13, !DIExpression() After (without this patch): DBG_VALUE %stack.0, 0, !13, !DIExpression() DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) It would also reorder DBG_VALUEs for different variables. Although that does not matter for the debug information output, it resulted in some noise in before/after pass diffs. This should hopefully align so that instruction referencing and DBG_VALUE emit debug instructions in the same order (see the sdag-salvage-add.ll change).
LDV could reorder reinserted fragment and non-fragment debug values for the same variable (compared to the input order), potentially resulting in stale values being presented. For example, before: DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE %0, $noreg, !13, !DIExpression() After (without this patch): DBG_VALUE %stack.0, 0, !13, !DIExpression() DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) It would also reorder DBG_VALUEs for different variables. Although that does not matter for the debug information output, it resulted in some noise in before/after pass diffs. This should hopefully align so that instruction referencing and DBG_VALUE emit debug instructions in the same order (see the sdag-salvage-add.ll change).
DanielCChen
pushed a commit
to DanielCChen/llvm-project
that referenced
this pull request
Oct 16, 2024
LDV could reorder reinserted fragment and non-fragment debug values for the same variable (compared to the input order), potentially resulting in stale values being presented. For example, before: DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE %0, $noreg, !13, !DIExpression() After (without this patch): DBG_VALUE %stack.0, 0, !13, !DIExpression() DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) It would also reorder DBG_VALUEs for different variables. Although that does not matter for the debug information output, it resulted in some noise in before/after pass diffs. This should hopefully align so that instruction referencing and DBG_VALUE emit debug instructions in the same order (see the sdag-salvage-add.ll change).
bricknerb
pushed a commit
to bricknerb/llvm-project
that referenced
this pull request
Oct 17, 2024
LDV could reorder reinserted fragment and non-fragment debug values for the same variable (compared to the input order), potentially resulting in stale values being presented. For example, before: DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE %0, $noreg, !13, !DIExpression() After (without this patch): DBG_VALUE %stack.0, 0, !13, !DIExpression() DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) It would also reorder DBG_VALUEs for different variables. Although that does not matter for the debug information output, it resulted in some noise in before/after pass diffs. This should hopefully align so that instruction referencing and DBG_VALUE emit debug instructions in the same order (see the sdag-salvage-add.ll change).
EricWF
pushed a commit
to efcs/llvm-project
that referenced
this pull request
Oct 22, 2024
LDV could reorder reinserted fragment and non-fragment debug values for the same variable (compared to the input order), potentially resulting in stale values being presented. For example, before: DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE %0, $noreg, !13, !DIExpression() After (without this patch): DBG_VALUE %stack.0, 0, !13, !DIExpression() DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16) DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16) It would also reorder DBG_VALUEs for different variables. Although that does not matter for the debug information output, it resulted in some noise in before/after pass diffs. This should hopefully align so that instruction referencing and DBG_VALUE emit debug instructions in the same order (see the sdag-salvage-add.ll change).
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LDV could reorder reinserted fragment and non-fragment debug values for
the same variable (compared to the input order), potentially resulting
in stale values being presented.
For example, before:
DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16)
DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16)
DBG_VALUE %0, $noreg, !13, !DIExpression()
After (without this patch):
DBG_VALUE %stack.0, 0, !13, !DIExpression()
DBG_VALUE 1002, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 16, 16)
DBG_VALUE 1001, $noreg, !13, !DIExpression(DW_OP_LLVM_fragment, 0, 16)
It would also reorder DBG_VALUEs for different variables. Although that
does not matter for the debug information output, it resulted in some
noise in pass before/after diffs.
This should hopefully align so that instruction referencing and
DBG_VALUE emit debug instructions in the same order (see the
sdag-salvage-add.ll change).