[Assignment Tracking][24/*] Always RemoveRedundantDbgInstrs in instcombine in assignment tracking builds
The Assignment Tracking debug-info feature is outlined in this RFC: https://discourse.llvm.org/t/ rfc-assignment-tracking-a-better-way-of-specifying-variable-locations-in-ir This reduces peak memory overhead by 15% when building CTMark's tramp3d-v4 with -O2 -g with assignment tracking enabled. Reviewed By: jmorse Differential Revision: https://reviews.llvm.org/D133321
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OCHyams
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@ -99,6 +99,7 @@
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#include "llvm/Support/KnownBits.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/InstCombine/InstCombine.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include <algorithm>
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#include <cassert>
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@ -4593,6 +4594,13 @@ static bool combineInstructionsOverFunction(
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bool MadeIRChange = false;
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if (ShouldLowerDbgDeclare)
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MadeIRChange = LowerDbgDeclare(F);
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// LowerDbgDeclare calls RemoveRedundantDbgInstrs, but LowerDbgDeclare will
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// almost never return true when running an assignment tracking build. Take
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// this opportunity to do some clean up for assignment tracking builds too.
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if (!MadeIRChange && getEnableAssignmentTracking()) {
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for (auto &BB : F)
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RemoveRedundantDbgInstrs(&BB);
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}
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// Iterate while there is work to do.
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unsigned Iteration = 0;
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@ -0,0 +1,49 @@
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; RUN: opt -passes=instcombine -S %s -o - \
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; RUN: | FileCheck %s --implicit-check-not="call void @llvm.dbg"
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;; Based on the test remove-redundant-dbg.ll.
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;;
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;; Check that instcombine does not remove redundant debug intrinsics when
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;; assignment tracking is turned off. This test is here to check the existing
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;; behaviour is maintained. If it is discovered that it is profitable to remove
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;; these intrinsics in instcombine then it's okay to remove this test.
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; CHECK: @llvm.dbg.value(metadata i32 undef
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; CHECK: @llvm.dbg.value(metadata i32 0
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; CHECK: @llvm.dbg.value(metadata i32 1
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define dso_local void @_Z3funv() local_unnamed_addr !dbg !7 {
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entry:
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call void @llvm.dbg.value(metadata i32 undef, metadata !11, metadata !DIExpression()), !dbg !14
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call void @_Z3extv(), !dbg !15
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call void @llvm.dbg.value(metadata i32 0, metadata !11, metadata !DIExpression()), !dbg !14
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call void @llvm.dbg.value(metadata i32 1, metadata !11, metadata !DIExpression()), !dbg !14
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ret void, !dbg !16
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}
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declare !dbg !17 dso_local void @_Z3extv() local_unnamed_addr
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declare void @llvm.dbg.value(metadata, metadata, metadata)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2, !3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 14.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
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!1 = !DIFile(filename: "test.cpp", directory: "/")
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!2 = !{i32 7, !"Dwarf Version", i32 5}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = !{i32 1, !"wchar_size", i32 4}
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!5 = !{i32 7, !"uwtable", i32 1}
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!6 = !{!"clang version 14.0.0)"}
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!7 = distinct !DISubprogram(name: "fun", linkageName: "_Z3funv", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !10)
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!8 = !DISubroutineType(types: !9)
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!9 = !{null}
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!10 = !{!11}
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!11 = !DILocalVariable(name: "a", scope: !7, file: !1, line: 2, type: !12)
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!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!13 = distinct !DIAssignID()
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!14 = !DILocation(line: 0, scope: !7)
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!15 = !DILocation(line: 2, column: 25, scope: !7)
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!16 = !DILocation(line: 2, column: 32, scope: !7)
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!17 = !DISubprogram(name: "ext", linkageName: "_Z3extv", scope: !1, file: !1, line: 1, type: !8, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !18)
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!18 = !{}
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@ -0,0 +1,45 @@
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; RUN: opt -passes=instcombine -S %s -o - -experimental-assignment-tracking \
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; RUN: | FileCheck %s --implicit-check-not="call void @llvm.dbg"
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;; Check that instcombine removes redundant debug intrinsics. This has a
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;; significant positive impact on peak memory. CTMark's tramp3d-v4's peak
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;; memory with assignment tracking enabled is reduced by about 15% with this
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;; change.
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; CHECK: @llvm.dbg.assign(metadata i32 1
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define dso_local void @_Z3funv() local_unnamed_addr !dbg !7 {
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entry:
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call void @llvm.dbg.assign(metadata i32 undef, metadata !11, metadata !DIExpression(), metadata !13, metadata ptr undef, metadata !DIExpression()), !dbg !14
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call void @_Z3extv(), !dbg !15
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call void @llvm.dbg.assign(metadata i32 0, metadata !11, metadata !DIExpression(), metadata !13, metadata ptr undef, metadata !DIExpression()), !dbg !14
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call void @llvm.dbg.assign(metadata i32 1, metadata !11, metadata !DIExpression(), metadata !13, metadata ptr undef, metadata !DIExpression()), !dbg !14
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ret void, !dbg !16
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}
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declare !dbg !17 dso_local void @_Z3extv() local_unnamed_addr
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declare void @llvm.dbg.assign(metadata, metadata, metadata, metadata, metadata, metadata)
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!2, !3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 14.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
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!1 = !DIFile(filename: "test.cpp", directory: "/")
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!2 = !{i32 7, !"Dwarf Version", i32 5}
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!3 = !{i32 2, !"Debug Info Version", i32 3}
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!4 = !{i32 1, !"wchar_size", i32 4}
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!5 = !{i32 7, !"uwtable", i32 1}
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!6 = !{!"clang version 14.0.0)"}
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!7 = distinct !DISubprogram(name: "fun", linkageName: "_Z3funv", scope: !1, file: !1, line: 2, type: !8, scopeLine: 2, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !10)
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!8 = !DISubroutineType(types: !9)
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!9 = !{null}
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!10 = !{!11}
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!11 = !DILocalVariable(name: "a", scope: !7, file: !1, line: 2, type: !12)
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!12 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!13 = distinct !DIAssignID()
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!14 = !DILocation(line: 0, scope: !7)
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!15 = !DILocation(line: 2, column: 25, scope: !7)
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!16 = !DILocation(line: 2, column: 32, scope: !7)
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!17 = !DISubprogram(name: "ext", linkageName: "_Z3extv", scope: !1, file: !1, line: 1, type: !8, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !18)
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!18 = !{}
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@ -13,7 +13,7 @@ entry:
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; CHECK: call void @llvm.dbg.assign(metadata i32 %x,{{.+}}metadata !DIExpression(DW_OP_plus_uconst, 1, DW_OP_stack_value),{{.+}}, metadata ptr %p, metadata !DIExpression())
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%add1 = add nsw i32 %x, %y, !dbg !29
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call void @llvm.dbg.assign(metadata i32 %add1, metadata !14, metadata !DIExpression(), metadata !31, metadata ptr %p, metadata !DIExpression()), !dbg !16
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call void @llvm.dbg.assign(metadata i32 %add1, metadata !32, metadata !DIExpression(), metadata !31, metadata ptr %p, metadata !DIExpression()), !dbg !16
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;; %add1 is not salvaged as it requires two values and DIArgList is
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;; not (yet) supported for dbg.assigns.
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; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 undef,{{.+}}, metadata !DIExpression(),{{.+}}, metadata ptr %p, metadata !DIExpression())
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@ -24,12 +24,12 @@ entry:
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; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 %x,{{.+}}, metadata !DIExpression(),{{.+}}, metadata ptr %p, metadata !DIExpression())
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%arrayidx1 = getelementptr inbounds i32, ptr %p, i32 1
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call void @llvm.dbg.assign(metadata i32 %x, metadata !14, metadata !DIExpression(), metadata !18, metadata ptr %arrayidx1, metadata !DIExpression()), !dbg !16
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call void @llvm.dbg.assign(metadata i32 %x, metadata !33, metadata !DIExpression(), metadata !18, metadata ptr %arrayidx1, metadata !DIExpression()), !dbg !16
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;; %arrayidx1 is salvaged.
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; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 %x,{{.+}}, metadata !DIExpression(),{{.+}}, metadata ptr %p, metadata !DIExpression(DW_OP_plus_uconst, 4))
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%arrayidx2 = getelementptr inbounds i32, ptr %p, i32 %x
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call void @llvm.dbg.assign(metadata i32 %x, metadata !14, metadata !DIExpression(), metadata !19, metadata ptr %arrayidx2, metadata !DIExpression()), !dbg !16
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call void @llvm.dbg.assign(metadata i32 %x, metadata !34, metadata !DIExpression(), metadata !19, metadata ptr %arrayidx2, metadata !DIExpression()), !dbg !16
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;; Variadic DIExpressions for dbg.assign address component is not supported -
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;; set undef.
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; CHECK-NEXT: call void @llvm.dbg.assign(metadata i32 %x,{{.+}}, metadata !DIExpression(),{{.+}}, metadata ptr undef, metadata !DIExpression())
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@ -67,3 +67,7 @@ declare void @llvm.dbg.assign(metadata, metadata, metadata, metadata, metadata,
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!28 = distinct !DIAssignID()
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!29 = !DILocation(line: 4, column: 13, scope: !7)
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!31 = distinct !DIAssignID()
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!32 = !DILocalVariable(name: "Local1", scope: !7, file: !1, line: 3, type: !10)
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!33 = !DILocalVariable(name: "Local2", scope: !7, file: !1, line: 3, type: !10)
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!34 = !DILocalVariable(name: "Local3", scope: !7, file: !1, line: 3, type: !10)
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!35 = !DILocalVariable(name: "Local4", scope: !7, file: !1, line: 3, type: !10)
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