// What was the old variable value?
ValueIDNum OldValue = VarLocs[MLoc.asU64()];
+ clobberMloc(MLoc, OldValue, Pos, MakeUndef);
+ }
+ /// Overload that takes an explicit value \p OldValue for when the value in
+ /// \p MLoc has changed and the TransferTracker's locations have not been
+ /// updated yet.
+ void clobberMloc(LocIdx MLoc, ValueIDNum OldValue,
+ MachineBasicBlock::iterator Pos, bool MakeUndef = true) {
+ auto ActiveMLocIt = ActiveMLocs.find(MLoc);
+ if (ActiveMLocIt == ActiveMLocs.end())
+ return;
+
VarLocs[MLoc.asU64()] = ValueIDNum::EmptyValue;
// Examine the remaining variable locations: if we can find the same value
if (EmulateOldLDV && !SrcRegOp->isKill())
return false;
+ // Before we update MTracker, remember which values were present in each of
+ // the locations about to be overwritten, so that we can recover any
+ // potentially clobbered variables.
+ DenseMap<LocIdx, ValueIDNum> ClobberedLocs;
+ if (TTracker) {
+ for (MCRegAliasIterator RAI(DestReg, TRI, true); RAI.isValid(); ++RAI) {
+ LocIdx ClobberedLoc = MTracker->getRegMLoc(*RAI);
+ auto MLocIt = TTracker->ActiveMLocs.find(ClobberedLoc);
+ // If ActiveMLocs isn't tracking this location or there are no variables
+ // using it, don't bother remembering.
+ if (MLocIt == TTracker->ActiveMLocs.end() || MLocIt->second.empty())
+ continue;
+ ValueIDNum Value = MTracker->readReg(*RAI);
+ ClobberedLocs[ClobberedLoc] = Value;
+ }
+ }
+
// Copy MTracker info, including subregs if available.
InstrRefBasedLDV::performCopy(SrcReg, DestReg);
+ // The copy might have clobbered variables based on the destination register.
+ // Tell TTracker about it, passing the old ValueIDNum to search for
+ // alternative locations (or else terminating those variables).
+ if (TTracker) {
+ for (auto LocVal : ClobberedLocs) {
+ TTracker->clobberMloc(LocVal.first, LocVal.second, MI.getIterator(), false);
+ }
+ }
+
// Only produce a transfer of DBG_VALUE within a block where old LDV
// would have. We might make use of the additional value tracking in some
// other way, later.
if (EmulateOldLDV && SrcReg != DestReg)
MTracker->defReg(SrcReg, CurBB, CurInst);
- // Finally, the copy might have clobbered variables based on the destination
- // register. Tell TTracker about it, in case a backup location exists.
- if (TTracker) {
- for (MCRegAliasIterator RAI(DestReg, TRI, true); RAI.isValid(); ++RAI) {
- LocIdx ClobberedLoc = MTracker->getRegMLoc(*RAI);
- TTracker->clobberMloc(ClobberedLoc, MI.getIterator(), false);
- }
- }
-
return true;
}
--- /dev/null
+# RUN: llc --run-pass=livedebugvalues %s -o - -experimental-debug-variable-locations | FileCheck %s --check-prefixes=CHECK
+
+# Test that we accurately track variables through transfers and clobbers.
+
+# In this test case, the value of "b" is found in $rax. From there it is moved
+# to $r15, $rax is killed, the value is moved back from $r15 into $rax again,
+# and then $r15 is killed. Throughout this, we should track "b" and end up with
+# DBG_VALUEs pointing to $rax, then $r15, then $rax again.
+
+# CHECK-LABEL: bb.0.entry:
+# CHECK: DBG_VALUE $rax,
+# CHECK: $r15 = MOV64rr
+
+## Technically it's correct to insert the DBG_VALUE for $r15 either immediately
+## after the move to $r15 or immediately after $rax is clobbered, but no later.
+# CHECK: DBG_VALUE $r15,
+# CHECK: $rax = LEA64r
+# CHECK: $rax = MOV64rr
+
+## Again, the DBG_VALUE can come either after the copy to $rax or the kill of
+## $r15, but no later.
+# CHECK: $r15 = LEA64r
+# CHECK: DBG_VALUE $rax,
+# CHECK: RET64
+
+--- |
+ ; ModuleID = 'test.cpp'
+ source_filename = "test.cpp"
+ target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+ target triple = "x86_64-unknown-linux-gnu"
+
+ ; Function Attrs: mustprogress nofree norecurse nosync nounwind readnone willreturn uwtable
+ define dso_local noundef i64 @_Z3fooxx(i64 noundef %a, i64 noundef %b) local_unnamed_addr !dbg !7 {
+ entry:
+ call void @llvm.dbg.value(metadata i64 %a, metadata !12, metadata !DIExpression()), !dbg !16
+ call void @llvm.dbg.value(metadata i64 %b, metadata !13, metadata !DIExpression()), !dbg !16
+ %add = add nsw i64 %b, %a, !dbg !17
+ call void @llvm.dbg.value(metadata i64 %add, metadata !14, metadata !DIExpression()), !dbg !16
+ %mul17 = sub i64 %a, %b, !dbg !18
+ %sub = mul i64 %add, %mul17, !dbg !18
+ call void @llvm.dbg.value(metadata i64 %sub, metadata !15, metadata !DIExpression()), !dbg !16
+ %add2 = add nsw i64 %sub, %add, !dbg !19
+ ret i64 %add2, !dbg !20
+ }
+
+ ; Function Attrs: nocallback nofree nosync nounwind readnone speculatable willreturn
+ declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+ !llvm.dbg.cu = !{!0}
+ !llvm.module.flags = !{!2, !3, !4, !5}
+ !llvm.ident = !{!6}
+
+ !0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 15.0.0 (https://github.com/llvm/llvm-project.git 44673278e029d7a6f56c8a3177247026b831720f)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+ !1 = !DIFile(filename: "test.cpp", directory: "/home/stozer/dev/llvm-project-build", checksumkind: CSK_MD5, checksum: "1e1c19354b0e967af705e204e8740d56")
+ !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, !"uwtable", i32 2}
+ !6 = !{!"clang version 15.0.0 (https://github.com/llvm/llvm-project.git 44673278e029d7a6f56c8a3177247026b831720f)"}
+ !7 = distinct !DISubprogram(name: "foo", linkageName: "_Z3fooxx", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !11)
+ !8 = !DISubroutineType(types: !9)
+ !9 = !{!10, !10, !10}
+ !10 = !DIBasicType(name: "long long", size: 64, encoding: DW_ATE_signed)
+ !11 = !{!12, !13, !14, !15}
+ !12 = !DILocalVariable(name: "a", arg: 1, scope: !7, file: !1, line: 1, type: !10)
+ !13 = !DILocalVariable(name: "b", arg: 2, scope: !7, file: !1, line: 1, type: !10)
+ !14 = !DILocalVariable(name: "c", scope: !7, file: !1, line: 2, type: !10)
+ !15 = !DILocalVariable(name: "d", scope: !7, file: !1, line: 3, type: !10)
+ !16 = !DILocation(line: 0, scope: !7)
+ !17 = !DILocation(line: 2, column: 19, scope: !7)
+ !18 = !DILocation(line: 3, column: 23, scope: !7)
+ !19 = !DILocation(line: 4, column: 12, scope: !7)
+ !20 = !DILocation(line: 4, column: 3, scope: !7)
+
+...
+---
+name: _Z3fooxx
+alignment: 16
+exposesReturnsTwice: false
+legalized: false
+regBankSelected: false
+selected: false
+failedISel: false
+tracksRegLiveness: true
+hasWinCFI: false
+callsEHReturn: false
+callsUnwindInit: false
+hasEHCatchret: false
+hasEHScopes: false
+hasEHFunclets: false
+failsVerification: false
+tracksDebugUserValues: true
+registers: []
+liveins:
+ - { reg: '$rdi', virtual-reg: '' }
+ - { reg: '$rsi', virtual-reg: '' }
+frameInfo:
+ isFrameAddressTaken: false
+ isReturnAddressTaken: false
+ hasStackMap: false
+ hasPatchPoint: false
+ stackSize: 0
+ offsetAdjustment: 0
+ maxAlignment: 1
+ adjustsStack: false
+ hasCalls: false
+ stackProtector: ''
+ functionContext: ''
+ maxCallFrameSize: 0
+ cvBytesOfCalleeSavedRegisters: 0
+ hasOpaqueSPAdjustment: false
+ hasVAStart: false
+ hasMustTailInVarArgFunc: false
+ hasTailCall: false
+ localFrameSize: 0
+ savePoint: ''
+ restorePoint: ''
+fixedStack:
+- { id: 0, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default,
+ callee-saved-register: '$r15', callee-saved-restored: true, debug-info-variable: '',
+ debug-info-expression: '', debug-info-location: '' }
+stack: []
+callSites: []
+debugValueSubstitutions:
+ - { srcinst: 1, srcop: 0, dstinst: 3, dstop: 0, subreg: 0 }
+constants: []
+machineFunctionInfo: {}
+body: |
+ bb.0.entry:
+ liveins: $rdi, $rsi
+
+ renamable $rax = LEA64r renamable $rsi, 1, renamable $rdi, 0, $noreg, debug-instr-number 3, debug-location !17
+ DBG_VALUE $rax, $noreg, !13, !DIExpression(), debug-location !17
+ $r15 = MOV64rr killed $rax, debug-location !16
+ renamable $rax = LEA64r renamable $rdi, 1, $noreg, 12, $noreg, debug-location !16
+ $rax = MOV64rr killed $r15, debug-location !16
+ renamable $r15 = LEA64r renamable $rdi, 1, $noreg, 12, $noreg, debug-location !16
+ RET64 $r15, debug-location !20
+
+...