[llvm] 53125e7 - [DebugInfo] Handle joins PHI+Def values in InstrRef LiveDebugValues
Stephen Tozer via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 22 06:57:58 PDT 2022
Author: Stephen Tozer
Date: 2022-08-22T14:51:27+01:00
New Revision: 53125e7d916306582bee0c828d38d1ef6d6061dc
URL: https://github.com/llvm/llvm-project/commit/53125e7d916306582bee0c828d38d1ef6d6061dc
DIFF: https://github.com/llvm/llvm-project/commit/53125e7d916306582bee0c828d38d1ef6d6061dc.diff
LOG: [DebugInfo] Handle joins PHI+Def values in InstrRef LiveDebugValues
In the InstrRefBasedImpl for LiveDebugValues, we attempt to propagate
debug values through basic blocks in part by checking to see whether all
a variable's incoming debug values to a BB "agree", i.e. whether their
properties match and they refer to the same underlying value.
Prior to this patch, the check for agreement between incoming values
relied on exact equality, which meant that a VPHI and a Def DbgValue
that referred to the same underlying value would be seen as disagreeing.
This patch changes this behaviour to treat them as referring to the same
value, allowing the shared value to propagate into the BB.
Differential Revision: https://reviews.llvm.org/D125953
Added:
llvm/test/DebugInfo/MIR/X86/instr-ref-join-def-vphi.mir
Modified:
llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
llvm/unittests/CodeGen/InstrRefLDVTest.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
index 23fde21a31e84..91d5ac2272538 100644
--- a/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues/InstrRefBasedImpl.cpp
@@ -2533,6 +2533,12 @@ bool InstrRefBasedLDV::vlocJoin(
if (*V.second == FirstVal)
continue; // No disagreement.
+ // If both values are not equal but have equal non-empty IDs then they refer
+ // to the same value from
diff erent sources (e.g. one is VPHI and the other
+ // is Def), which does not cause disagreement.
+ if (V.second->ID != ValueIDNum::EmptyValue && V.second->ID == FirstVal.ID)
+ continue;
+
// Eliminate if a backedge feeds a VPHI back into itself.
if (V.second->Kind == DbgValue::VPHI &&
V.second->BlockNo == MBB.getNumber() &&
diff --git a/llvm/test/DebugInfo/MIR/X86/instr-ref-join-def-vphi.mir b/llvm/test/DebugInfo/MIR/X86/instr-ref-join-def-vphi.mir
new file mode 100644
index 0000000000000..68be72dcd4ed9
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/X86/instr-ref-join-def-vphi.mir
@@ -0,0 +1,241 @@
+# RUN: llc -run-pass=livedebugvalues %s -o - -experimental-debug-variable-locations | FileCheck %s --check-prefixes=CHECK
+
+# Test that we do not drop debug values when joining a VPHI and a Def that use
+# the same value.
+# In this test case, the live out value for "a" from bb.4 is a VPHI with a
+# defined value, the value live-in register $esi at bb.3. In bb.5, we also have
+# a DBG_INSTR_REF that explicitly defines "a" as holding that same value. When
+# joining these values to determine the live-in value of "a" at bb.6, we should
+# recognize that these values are identical and produce a valid live-in debug
+# value.
+
+# CHECK: ![[VAR:[0-9]+]] = !DILocalVariable(name: "a"
+
+# CHECK-LABEL: bb.6
+# CHECK: DBG_VALUE $esi, $noreg, ![[VAR]], !DIExpression()
+
+--- |
+ target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+ target triple = "x86_64-unknown-linux-gnu"
+
+ ; Function Attrs: mustprogress uwtable
+ define dso_local noundef i32 @"?foo@@YAHH at Z"(i32 noundef %0) local_unnamed_addr #0 !dbg !8 {
+ call void @llvm.dbg.value(metadata i32 %0, metadata !14, metadata !DIExpression()), !dbg !16
+ %2 = tail call noundef i32 @"?bar@@YAHXZ"(), !dbg !17
+ br label %3, !dbg !18
+
+ 3: ; preds = %13, %1
+ %4 = phi i32 [ %0, %1 ], [ %14, %13 ]
+ %5 = phi i32 [ %2, %1 ], [ %7, %13 ], !dbg !16
+ call void @llvm.dbg.value(metadata i32 %4, metadata !14, metadata !DIExpression()), !dbg !16
+ %6 = tail call noundef i32 @"?bar@@YAHXZ"(), !dbg !19
+ %7 = sub nsw i32 %5, %6, !dbg !19
+ %8 = srem i32 %7, 3, !dbg !21
+ %9 = icmp eq i32 %8, 0, !dbg !21
+ br i1 %9, label %10, label %13, !dbg !21
+
+ 10: ; preds = %3
+ %11 = tail call noundef i32 @"?bar@@YAHXZ"(), !dbg !22
+ %12 = add nsw i32 %11, %4, !dbg !22
+ call void @llvm.dbg.value(metadata i32 %12, metadata !14, metadata !DIExpression()), !dbg !16
+ br label %13, !dbg !25
+
+ 13: ; preds = %10, %3
+ %14 = phi i32 [ %12, %10 ], [ %4, %3 ]
+ call void @llvm.dbg.value(metadata i32 %14, metadata !14, metadata !DIExpression()), !dbg !16
+ %15 = icmp sgt i32 %7, 0, !dbg !26
+ br i1 %15, label %3, label %16, !dbg !26, !llvm.loop !27
+
+ 16: ; preds = %13
+ %17 = and i32 %7, 1, !dbg !30
+ %18 = icmp eq i32 %17, 0, !dbg !30
+ br i1 %18, label %19, label %22, !dbg !30
+
+ 19: ; preds = %16
+ %20 = tail call noundef i32 @"?bar@@YAHXZ"(), !dbg !31
+ %21 = add nsw i32 %20, %14, !dbg !31
+ call void @llvm.dbg.value(metadata i32 %21, metadata !14, metadata !DIExpression()), !dbg !16
+ br label %22, !dbg !34
+
+ 22: ; preds = %19, %16
+ %23 = phi i32 [ %21, %19 ], [ %14, %16 ], !dbg !16
+ call void @llvm.dbg.value(metadata i32 %23, metadata !14, metadata !DIExpression()), !dbg !16
+ ret i32 %23, !dbg !35
+ }
+
+ declare dso_local noundef i32 @"?bar@@YAHXZ"() local_unnamed_addr #1
+
+ ; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+ declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+
+ attributes #0 = { mustprogress uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+ attributes #1 = { "frame-pointer"="none" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+ attributes #2 = { nocallback nofree nosync nounwind readnone speculatable willreturn }
+
+ !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 15.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+ !1 = !DIFile(filename: "test.cpp", directory: "\")
+ !3 = !{i32 2, !"Debug Info Version", i32 3}
+ !4 = !{i32 1, !"wchar_size", i32 2}
+ !5 = !{i32 7, !"PIC Level", i32 2}
+ !6 = !{i32 7, !"uwtable", i32 2}
+ !7 = !{!"clang version 15.0.0"}
+ !8 = distinct !DISubprogram(name: "foo", linkageName: "?foo@@YAHH at Z", scope: !9, file: !9, line: 3, type: !10, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !13)
+ !9 = !DIFile(filename: ".\\test.cpp", directory: "\")
+ !10 = !DISubroutineType(types: !11)
+ !11 = !{!12, !12}
+ !12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+ !13 = !{!14}
+ !14 = !DILocalVariable(name: "a", arg: 1, scope: !8, file: !9, line: 3, type: !12)
+ !16 = !DILocation(line: 0, scope: !8)
+ !17 = !DILocation(line: 4, scope: !8)
+ !18 = !DILocation(line: 5, scope: !8)
+ !19 = !DILocation(line: 6, scope: !20)
+ !20 = distinct !DILexicalBlock(scope: !8, file: !9, line: 5)
+ !21 = !DILocation(line: 7, scope: !20)
+ !22 = !DILocation(line: 8, scope: !23)
+ !23 = distinct !DILexicalBlock(scope: !24, file: !9, line: 7)
+ !24 = distinct !DILexicalBlock(scope: !20, file: !9, line: 7)
+ !25 = !DILocation(line: 9, scope: !23)
+ !26 = !DILocation(line: 10, scope: !20)
+ !27 = distinct !{!27, !18, !28, !29}
+ !28 = !DILocation(line: 10, scope: !8)
+ !29 = !{!"llvm.loop.mustprogress"}
+ !30 = !DILocation(line: 11, scope: !8)
+ !31 = !DILocation(line: 12, scope: !32)
+ !32 = distinct !DILexicalBlock(scope: !33, file: !9, line: 11)
+ !33 = distinct !DILexicalBlock(scope: !8, file: !9, line: 11)
+ !34 = !DILocation(line: 13, scope: !32)
+ !35 = !DILocation(line: 14, scope: !8)
+
+...
+---
+name: '?foo@@YAHH at Z'
+alignment: 16
+exposesReturnsTwice: false
+legalized: false
+regBankSelected: false
+selected: false
+failedISel: false
+tracksRegLiveness: true
+hasWinCFI: true
+callsEHReturn: false
+callsUnwindInit: false
+hasEHCatchret: false
+hasEHScopes: false
+hasEHFunclets: false
+failsVerification: false
+tracksDebugUserValues: true
+registers: []
+liveins:
+ - { reg: '$ecx', virtual-reg: '' }
+frameInfo:
+ isFrameAddressTaken: false
+ isReturnAddressTaken: false
+ hasStackMap: false
+ hasPatchPoint: false
+ stackSize: 56
+ offsetAdjustment: -56
+ maxAlignment: 8
+ adjustsStack: true
+ hasCalls: true
+ stackProtector: ''
+ functionContext: ''
+ maxCallFrameSize: 32
+ cvBytesOfCalleeSavedRegisters: 16
+ hasOpaqueSPAdjustment: false
+ hasVAStart: false
+ hasMustTailInVarArgFunc: false
+ hasTailCall: false
+ localFrameSize: 0
+ savePoint: ''
+ restorePoint: ''
+fixedStack:
+ - { id: 0, type: spill-slot, offset: -24, size: 8, alignment: 8, stack-id: default,
+ callee-saved-register: '$rdi', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+ - { id: 1, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default,
+ callee-saved-register: '$rsi', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+stack: []
+callSites: []
+debugValueSubstitutions: []
+constants: []
+machineFunctionInfo: {}
+body: |
+ bb.0 (%ir-block.1):
+ successors: %bb.1(0x80000000)
+ liveins: $ecx, $rsi, $rdi
+
+ DBG_VALUE $ecx, $noreg, !14, !DIExpression(), debug-location !16
+ frame-setup PUSH64r killed $rsi, implicit-def $rsp, implicit $rsp
+ frame-setup SEH_PushReg 57
+ frame-setup PUSH64r killed $rdi, implicit-def $rsp, implicit $rsp
+ frame-setup SEH_PushReg 53
+ $rsp = frame-setup SUB64ri8 $rsp, 40, implicit-def dead $eflags
+ frame-setup SEH_StackAlloc 40
+ frame-setup SEH_EndPrologue
+ $esi = MOV32rr $ecx
+ CALL64pcrel32 @"?bar@@YAHXZ", csr_win64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-instr-number 8, debug-location !17
+ $edi = MOV32rr $eax, debug-location !17
+ JMP_1 %bb.1
+
+ bb.3 (%ir-block.13, align 16):
+ successors: %bb.1(0x7c000000), %bb.4(0x04000000)
+ liveins: $edi, $esi
+
+ DBG_PHI $esi, 5
+ TEST32rr renamable $edi, renamable $edi, implicit-def $eflags, debug-location !26
+ JCC_1 %bb.4, 14, implicit $eflags, debug-location !26
+
+ bb.1 (%ir-block.3):
+ successors: %bb.2(0x30000000), %bb.3(0x50000000)
+ liveins: $edi, $esi
+
+ DBG_PHI $esi, 3
+ DBG_PHI $edi, 2
+ DBG_INSTR_REF 3, 0, !14, !DIExpression(), debug-location !16
+ CALL64pcrel32 @"?bar@@YAHXZ", csr_win64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !19
+ renamable $edi = nsw SUB32rr killed renamable $edi, killed renamable $eax, implicit-def dead $eflags, debug-instr-number 1, debug-location !19
+ renamable $eax = IMUL32rri renamable $edi, -1431655765, implicit-def dead $eflags, debug-location !21
+ renamable $eax = ADD32ri killed renamable $eax, 715827882, implicit-def dead $eflags, debug-location !21
+ CMP32ri killed renamable $eax, 1431655764, implicit-def $eflags, debug-location !21
+ JCC_1 %bb.3, 7, implicit $eflags, debug-location !21
+
+ bb.2 (%ir-block.10):
+ successors: %bb.3(0x80000000)
+ liveins: $edi, $esi
+
+ CALL64pcrel32 @"?bar@@YAHXZ", csr_win64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !22
+ renamable $esi = nsw ADD32rr killed renamable $esi, killed renamable $eax, implicit-def dead $eflags, debug-instr-number 4, debug-location !22
+ DBG_INSTR_REF 4, 0, !14, !DIExpression(), debug-location !16
+ JMP_1 %bb.3
+
+ bb.4 (%ir-block.16):
+ successors: %bb.5(0x40000000), %bb.6(0x40000000)
+ liveins: $edi, $esi
+
+ TEST8ri renamable $dil, 1, implicit-def $eflags, implicit killed $edi, debug-location !30
+ JCC_1 %bb.6, 5, implicit $eflags, debug-location !30
+
+ bb.5 (%ir-block.19):
+ successors: %bb.6(0x80000000)
+ liveins: $esi
+
+ CALL64pcrel32 @"?bar@@YAHXZ", csr_win64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp, implicit-def $eax, debug-location !31
+ DBG_INSTR_REF 5, 0, !14, !DIExpression(), debug-location !16
+
+ bb.6 (%ir-block.22):
+ liveins: $esi
+
+ $eax = MOV32rr killed $esi, debug-location !35
+ SEH_Epilogue debug-location !35
+ $rsp = frame-destroy ADD64ri8 $rsp, 40, implicit-def dead $eflags, debug-location !35
+ $rdi = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !35
+ $rsi = frame-destroy POP64r implicit-def $rsp, implicit $rsp, debug-location !35
+ RET64 $eax, debug-location !35
+
+...
diff --git a/llvm/unittests/CodeGen/InstrRefLDVTest.cpp b/llvm/unittests/CodeGen/InstrRefLDVTest.cpp
index f920737011502..7c2956364de0c 100644
--- a/llvm/unittests/CodeGen/InstrRefLDVTest.cpp
+++ b/llvm/unittests/CodeGen/InstrRefLDVTest.cpp
@@ -2238,6 +2238,17 @@ TEST_F(InstrRefLDVTest, vlocJoinDiamond) {
EXPECT_EQ(JoinedLoc.Kind, DbgValue::Def);
EXPECT_EQ(JoinedLoc.ID, LiveInRsp);
+ // Try the same PHI elimination but with one incoming value being a VPHI
+ // referring to the same value.
+ VLiveOuts[1] = DbgValue(LiveInRsp, EmptyProps, DbgValue::Def);
+ VLiveOuts[2] = DbgValue(2, EmptyProps, DbgValue::VPHI);
+ VLiveOuts[2].ID = LiveInRsp;
+ JoinedLoc = DbgValue(3, EmptyProps, DbgValue::VPHI);
+ Result = vlocJoin(*MBB3, VLiveOutIdx, AllBlocks, JoinedLoc);
+ EXPECT_TRUE(Result);
+ EXPECT_EQ(JoinedLoc.Kind, DbgValue::VPHI);
+ EXPECT_EQ(JoinedLoc.ID, LiveInRsp);
+
// If the "current" live-in is a VPHI, but not a VPHI generated in the current
// block, then it's the remains of an earlier value propagation. We should
// value propagate through this merge. Even if the current incoming values
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