[llvm] r369092 - [DebugInfo] Handle complex expressions with spills in LiveDebugValues
Hans Wennborg via llvm-commits
llvm-commits at lists.llvm.org
Tue Aug 20 02:34:17 PDT 2019
Merged to release_90 in r369354. Thanks!
On Fri, Aug 16, 2019 at 12:03 PM Jeremy Morse via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
>
> Author: jmorse
> Date: Fri Aug 16 03:04:17 2019
> New Revision: 369092
>
> URL: http://llvm.org/viewvc/llvm-project?rev=369092&view=rev
> Log:
> [DebugInfo] Handle complex expressions with spills in LiveDebugValues
>
> In r369026 we disabled spill-recognition in LiveDebugValues for anything
> that has a complex expression. This is because it's hard to recover the
> complex expression once the spill location is baked into it.
>
> This patch re-enables spill-recognition and slightly adjusts the DBG_VALUE
> insts that LiveDebugValues tracks: instead of tracking the last DBG_VALUE
> for a variable, it tracks the last _unspilt_ DBG_VALUE. The spill-restore
> code is then able to access and copy the original complex expression; but
> the rest of LiveDebugValues has to be aware of the slight semantic shift,
> and produce a new spilt location if a spilt location is propagated between
> blocks.
>
> The test added produces an incorrect variable location (see FIXME), which
> will be the subject of future work.
>
> Differential Revision: https://reviews.llvm.org/D65368
>
> Modified:
> llvm/trunk/lib/CodeGen/LiveDebugValues.cpp
> llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir
>
> Modified: llvm/trunk/lib/CodeGen/LiveDebugValues.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveDebugValues.cpp?rev=369092&r1=369091&r2=369092&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/LiveDebugValues.cpp (original)
> +++ llvm/trunk/lib/CodeGen/LiveDebugValues.cpp Fri Aug 16 03:04:17 2019
> @@ -227,8 +227,8 @@ private:
>
> /// The constructor for spill locations.
> VarLoc(const MachineInstr &MI, unsigned SpillBase, int SpillOffset,
> - LexicalScopes &LS)
> - : Var(MI), MI(MI), UVS(MI.getDebugLoc(), LS) {
> + LexicalScopes &LS, const MachineInstr &OrigMI)
> + : Var(MI), MI(OrigMI), UVS(MI.getDebugLoc(), LS) {
> assert(MI.isDebugValue() && "not a DBG_VALUE");
> assert(MI.getNumOperands() == 4 && "malformed DBG_VALUE");
> Kind = SpillLocKind;
> @@ -567,11 +567,7 @@ void LiveDebugValues::transferDebugValue
> ID = VarLocIDs.insert(VL);
> OpenRanges.insert(ID, VL.Var);
> } else if (MI.hasOneMemOperand()) {
> - // It's a stack spill -- fetch spill base and offset.
> - VarLoc::SpillLoc SpillLocation = extractSpillBaseRegAndOffset(MI);
> - VarLoc VL(MI, SpillLocation.SpillBase, SpillLocation.SpillOffset, LS);
> - ID = VarLocIDs.insert(VL);
> - OpenRanges.insert(ID, VL.Var);
> + llvm_unreachable("DBG_VALUE with mem operand encountered after regalloc?");
> } else {
> // This must be an undefined location. We should leave OpenRanges closed.
> assert(MI.getOperand(0).isReg() && MI.getOperand(0).getReg() == 0 &&
> @@ -678,7 +674,7 @@ void LiveDebugValues::insertTransferDebu
> *MF, DebugInstr->getDebugLoc(), DebugInstr->getDesc(), true,
> SpillLocation.SpillBase, DebugInstr->getDebugVariable(), SpillExpr);
> VarLoc VL(*NewDebugInstr, SpillLocation.SpillBase,
> - SpillLocation.SpillOffset, LS);
> + SpillLocation.SpillOffset, LS, *DebugInstr);
> ProcessVarLoc(VL, NewDebugInstr);
> LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for spill: ";
> NewDebugInstr->print(dbgs(), /*IsStandalone*/false,
> @@ -691,17 +687,11 @@ void LiveDebugValues::insertTransferDebu
> "No register supplied when handling a restore of a debug value");
> MachineFunction *MF = MI.getMF();
> DIBuilder DIB(*const_cast<Function &>(MF->getFunction()).getParent());
> -
> - const DIExpression *NewExpr;
> - if (auto Fragment = DebugInstr->getDebugExpression()->getFragmentInfo())
> - NewExpr = *DIExpression::createFragmentExpression(DIB.createExpression(),
> - Fragment->OffsetInBits, Fragment->SizeInBits);
> - else
> - NewExpr = DIB.createExpression();
> -
> - NewDebugInstr =
> - BuildMI(*MF, DebugInstr->getDebugLoc(), DebugInstr->getDesc(), false,
> - NewReg, DebugInstr->getDebugVariable(), NewExpr);
> + // DebugInstr refers to the pre-spill location, therefore we can reuse
> + // its expression.
> + NewDebugInstr = BuildMI(
> + *MF, DebugInstr->getDebugLoc(), DebugInstr->getDesc(), false, NewReg,
> + DebugInstr->getDebugVariable(), DebugInstr->getDebugExpression());
> VarLoc VL(*NewDebugInstr, LS);
> ProcessVarLoc(VL, NewDebugInstr);
> LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for register restore: ";
> @@ -856,14 +846,9 @@ void LiveDebugValues::transferSpillOrRes
> << "\n");
> }
> // Check if the register or spill location is the location of a debug value.
> - // FIXME: Don't create a spill transfer if there is a complex expression,
> - // because we currently cannot recover the original expression on restore.
> for (unsigned ID : OpenRanges.getVarLocs()) {
> - const MachineInstr *DebugInstr = &VarLocIDs[ID].MI;
> -
> if (TKind == TransferKind::TransferSpill &&
> - VarLocIDs[ID].isDescribedByReg() == Reg &&
> - !DebugInstr->getDebugExpression()->isComplex()) {
> + VarLocIDs[ID].isDescribedByReg() == Reg) {
> LLVM_DEBUG(dbgs() << "Spilling Register " << printReg(Reg, TRI) << '('
> << VarLocIDs[ID].Var.getVar()->getName() << ")\n");
> } else if (TKind == TransferKind::TransferRestore &&
> @@ -1121,13 +1106,24 @@ bool LiveDebugValues::join(
> DebugInstr->getDebugVariable(),
> DebugInstr->getDebugExpression());
> } else {
> + auto *DebugExpr = DebugInstr->getDebugExpression();
> + Register Reg = DebugInstr->getOperand(0).getReg();
> + bool IsIndirect = DebugInstr->isIndirectDebugValue();
> +
> + if (DiffIt.Kind == VarLoc::SpillLocKind) {
> + // This is is a spilt location; DebugInstr refers to the unspilt
> + // location. We need to rebuild the spilt location expression and
> + // point the DBG_VALUE at the frame register.
> + DebugExpr = DIExpression::prepend(DebugInstr->getDebugExpression(),
> + DIExpression::ApplyOffset,
> + DiffIt.Loc.SpillLocation.SpillOffset);
> + Reg = TRI->getFrameRegister(*DebugInstr->getMF());
> + IsIndirect = true;
> + }
> +
> MI = BuildMI(MBB, MBB.instr_begin(), DebugInstr->getDebugLoc(),
> - DebugInstr->getDesc(), DebugInstr->isIndirectDebugValue(),
> - DebugInstr->getOperand(0).getReg(),
> - DebugInstr->getDebugVariable(),
> - DebugInstr->getDebugExpression());
> - if (DebugInstr->isIndirectDebugValue())
> - MI->getOperand(1).setImm(DebugInstr->getOperand(1).getImm());
> + DebugInstr->getDesc(), IsIndirect, Reg,
> + DebugInstr->getDebugVariable(), DebugExpr);
> }
> LLVM_DEBUG(dbgs() << "Inserted: "; MI->dump(););
> ILS.set(ID);
>
> Modified: llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir?rev=369092&r1=369091&r2=369092&view=diff
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir (original)
> +++ llvm/trunk/test/DebugInfo/MIR/X86/live-debug-values-restore.mir Fri Aug 16 03:04:17 2019
> @@ -2,6 +2,8 @@
>
> # Generated from the following source with:
> # clang -g -mllvm -stop-before=livedebugvalues -S -O2 test.c -o test.mir
> +# Then more functions added to test for extra behaviours with complex
> +# expressions.
>
> # #define FORCE_SPILL() \
> # __asm volatile("" : : : \
> @@ -14,9 +16,10 @@
> # return *(p + 1);
> # }
>
> -# Pick out DILocalVariable numbers for "p" and "q"
> +# Pick out DILocalVariable numbers for "p", "q" and "r"
> # CHECK: ![[PVAR:[0-9]+]] = !DILocalVariable(name: "p",
> # CHECK: ![[QVAR:[0-9]+]] = !DILocalVariable(name: "q",
> +# CHECK: ![[RVAR:[0-9]+]] = !DILocalVariable(name: "r",
>
> # Ascertain that the spill has been recognized and manifested in a DBG_VALUE.
> # CHECK: MOV64mr $rsp,{{.*-8.*}}killed{{.*}}$rdi :: (store 8 into %stack.0)
> @@ -59,6 +62,23 @@
> ret i32 %0, !dbg !128
> }
>
> + define dso_local i32 @h(i32* readonly %p) local_unnamed_addr !dbg !207 {
> + entry:
> + call void @llvm.dbg.value(metadata i32* %p, metadata !213, metadata !DIExpression()), !dbg !214
> + %tobool = icmp eq i32* %p, null, !dbg !215
> + br i1 %tobool, label %if.end, label %if.then, !dbg !217
> +
> + if.then: ; preds = %entry
> + tail call void asm sideeffect "", "~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"(), !dbg !218, !srcloc !220
> + br label %if.end, !dbg !221
> +
> + if.end: ; preds = %entry, %if.then
> + %add.ptr = getelementptr inbounds i32, i32* %p, i64 1, !dbg !222
> + %0 = load i32, i32* %add.ptr, align 4, !dbg !223, !tbaa !24
> + ret i32 %0, !dbg !228
> + }
> +
> +
> declare void @llvm.dbg.value(metadata, metadata, metadata)
>
> !llvm.dbg.cu = !{!0}
> @@ -95,7 +115,7 @@
> !27 = !{!"Simple C/C++ TBAA"}
> !28 = !DILocation(line: 9, column: 3, scope: !7)
> !101 = !DIBasicType(name: "looong int", size: 64, encoding: DW_ATE_signed)
> - !107 = distinct !DISubprogram(name: "g", scope: !1, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !112)
> + !107 = distinct !DISubprogram(name: "g", scope: !0, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !112)
> !112 = !{!113}
> !113 = !DILocalVariable(name: "q", arg: 1, scope: !107, file: !1, line: 105, type: !101)
> !114 = !DILocation(line: 105, column: 12, scope: !107)
> @@ -109,8 +129,21 @@
> !122 = !DILocation(line: 109, column: 14, scope: !107)
> !123 = !DILocation(line: 109, column: 10, scope: !107)
> !128 = !DILocation(line: 109, column: 3, scope: !107)
> -
> -
> + !201 = !DIBasicType(name: "looong int", size: 64, encoding: DW_ATE_signed)
> + !207 = distinct !DISubprogram(name: "g", scope: !0, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !212)
> + !212 = !{!213}
> + !213 = !DILocalVariable(name: "r", arg: 1, scope: !207, file: !1, line: 105, type: !201)
> + !214 = !DILocation(line: 105, column: 12, scope: !207)
> + !215 = !DILocation(line: 106, column: 7, scope: !216)
> + !216 = distinct !DILexicalBlock(scope: !207, file: !1, line: 106, column: 7)
> + !217 = !DILocation(line: 106, column: 7, scope: !207)
> + !218 = !DILocation(line: 107, column: 5, scope: !219)
> + !219 = distinct !DILexicalBlock(scope: !216, file: !1, line: 106, column: 10)
> + !220 = !{i32 -2147471544}
> + !221 = !DILocation(line: 108, column: 3, scope: !219)
> + !222 = !DILocation(line: 109, column: 14, scope: !207)
> + !223 = !DILocation(line: 109, column: 10, scope: !207)
> + !228 = !DILocation(line: 109, column: 3, scope: !207)
> ...
> ---
> name: f
> @@ -298,3 +331,111 @@ body: |
> RETQ $eax, debug-location !128
>
> ...
> +---
> +# This third function tests that complex expressions are spilt, and restored
> +# correctly within a basic block.
> +
> +# FIXME: the spilt location below is wrong, there should be a deref between
> +# the spill-offset and the DW_OP_plus_uconst.
> +
> +# CHECK-LABEL: name: h
> +# CHECK-LABEL: bb.0.entry:
> +# CHECK: DBG_VALUE $rdi, $noreg, ![[RVAR]], !DIExpression(DW_OP_plus_uconst, 1)
> +# CHECK-LABEL: bb.1.if.then:
> +# CHECK: DBG_VALUE $rdi, $noreg, ![[RVAR]], !DIExpression(DW_OP_plus_uconst, 1)
> +# CHECK: DBG_VALUE $rsp, 0, ![[RVAR]], !DIExpression(DW_OP_constu, 8, DW_OP_minus, DW_OP_plus_uconst, 1)
> +# CHECK: DBG_VALUE $rdi, $noreg, ![[RVAR]], !DIExpression(DW_OP_plus_uconst, 1)
> +# CHECK-LABEL: bb.2.if.end:
> +# CHECK: DBG_VALUE $rdi, $noreg, ![[RVAR]], !DIExpression(DW_OP_plus_uconst, 1)
> +
> +name: h
> +alignment: 4
> +tracksRegLiveness: true
> +liveins:
> + - { reg: '$rdi', virtual-reg: '' }
> +frameInfo:
> + stackSize: 48
> + offsetAdjustment: -48
> + maxAlignment: 8
> + cvBytesOfCalleeSavedRegisters: 48
> + localFrameSize: 0
> +fixedStack:
> + - { id: 0, type: spill-slot, offset: -56, size: 8, alignment: 8, stack-id: default,
> + callee-saved-register: '$rbx', callee-saved-restored: true, debug-info-variable: '',
> + debug-info-expression: '', debug-info-location: '' }
> + - { id: 1, type: spill-slot, offset: -48, size: 8, alignment: 16, stack-id: default,
> + callee-saved-register: '$r12', callee-saved-restored: true, debug-info-variable: '',
> + debug-info-expression: '', debug-info-location: '' }
> + - { id: 2, type: spill-slot, offset: -40, size: 8, alignment: 8, stack-id: default,
> + callee-saved-register: '$r13', callee-saved-restored: true, debug-info-variable: '',
> + debug-info-expression: '', debug-info-location: '' }
> + - { id: 3, type: spill-slot, offset: -32, size: 8, alignment: 16, stack-id: default,
> + callee-saved-register: '$r14', callee-saved-restored: true, debug-info-variable: '',
> + debug-info-expression: '', debug-info-location: '' }
> + - { id: 4, type: spill-slot, offset: -24, size: 8, alignment: 8, stack-id: default,
> + callee-saved-register: '$r15', callee-saved-restored: true, debug-info-variable: '',
> + debug-info-expression: '', debug-info-location: '' }
> + - { id: 5, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default,
> + callee-saved-register: '$rbp', callee-saved-restored: true, debug-info-variable: '',
> + debug-info-expression: '', debug-info-location: '' }
> +stack:
> + - { id: 0, name: '', type: spill-slot, offset: -64, size: 8, alignment: 8,
> + stack-id: default, callee-saved-register: '', callee-saved-restored: true,
> + debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
> +constants: []
> +body: |
> + bb.0.entry:
> + successors: %bb.2(0x30000000), %bb.1(0x50000000)
> + liveins: $rdi, $rbx, $r12, $r13, $r14, $r15, $rbp
> +
> + DBG_VALUE $rdi, $noreg, !213, !DIExpression(DW_OP_plus_uconst, 1), debug-location !214
> + TEST64rr renamable $rdi, renamable $rdi, implicit-def $eflags, debug-location !215
> + JCC_1 %bb.2, 4, implicit $eflags, debug-location !217
> +
> + bb.1.if.then:
> + successors: %bb.2(0x80000000)
> + liveins: $rdi, $rbp, $r15, $r14, $r13, $r12, $rbx
> +
> + frame-setup PUSH64r killed $rbp, implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 16
> + frame-setup PUSH64r killed $r15, implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 24
> + frame-setup PUSH64r killed $r14, implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 32
> + frame-setup PUSH64r killed $r13, implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 40
> + frame-setup PUSH64r killed $r12, implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 48
> + frame-setup PUSH64r killed $rbx, implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 56
> + CFI_INSTRUCTION offset $rbx, -56
> + CFI_INSTRUCTION offset $r12, -48
> + CFI_INSTRUCTION offset $r13, -40
> + CFI_INSTRUCTION offset $r14, -32
> + CFI_INSTRUCTION offset $r15, -24
> + CFI_INSTRUCTION offset $rbp, -16
> + MOV64mr $rsp, 1, $noreg, -8, $noreg, killed renamable $rdi :: (store 8 into %stack.0)
> + INLINEASM &"", 1, 12, implicit-def dead early-clobber $rax, 12, implicit-def dead early-clobber $rbx, 12, implicit-def dead early-clobber $rcx, 12, implicit-def dead early-clobber $rdx, 12, implicit-def dead early-clobber $rsi, 12, implicit-def dead early-clobber $rdi, 12, implicit-def dead early-clobber $rbp, 12, implicit-def dead early-clobber $r8, 12, implicit-def dead early-clobber $r9, 12, implicit-def dead early-clobber $r10, 12, implicit-def dead early-clobber $r11, 12, implicit-def dead early-clobber $r12, 12, implicit-def dead early-clobber $r13, 12, implicit-def dead early-clobber $r14, 12, implicit-def dead early-clobber $r15, 12, implicit-def dead early-clobber $eflags, !220, debug-location !218
> + renamable $rdi = MOV64rm $rsp, 1, $noreg, -8, $noreg :: (load 8 from %stack.0)
> + $rbx = frame-destroy POP64r implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 48
> + $r12 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 40
> + $r13 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 32
> + $r14 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 24
> + $r15 = frame-destroy POP64r implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 16
> + $rbp = frame-destroy POP64r implicit-def $rsp, implicit $rsp
> + CFI_INSTRUCTION def_cfa_offset 8
> +
> + bb.2.if.end:
> + liveins: $rdi, $rbx, $r12, $r13, $r14, $r15, $rbp
> +
> + renamable $eax = MOV32rm killed renamable $rdi, 1, $noreg, 4, $noreg, debug-location !223 :: (load 4 from %ir.add.ptr, !tbaa !24)
> + RETQ $eax, debug-location !228
> +
> +
> +
> +...
>
>
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