forked from OSchip/llvm-project
[DebugInfo] Avoid crash from dropped fragments in LiveDebugValues
This patch avoids a crash caused by DW_OP_LLVM_fragments being dropped from DIExpressions by LiveDebugValues spill-restore code. The appearance of a previously unseen fragment configuration confuses LDV, as documented in PR42773, and reproduced by the test function this patch adds (Crashes on a x86_64 debug build). To avoid this, on spill restore, we now use fragment information from the spilt-location-expression. In addition, when spilling, we now don't spill any DBG_VALUE with a complex expression, as it can't be safely restored and will definitely lead to an incorrect variable location. The discussion of this is in D65368. Differential Revision: https://reviews.llvm.org/D66284 llvm-svn: 369026
This commit is contained in:
Jeremy Morse
parent
626ed22fbe
commit
c476124bc8
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@ -691,9 +691,17 @@ void LiveDebugValues::insertTransferDebugPair(
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"No register supplied when handling a restore of a debug value");
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MachineFunction *MF = MI.getMF();
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DIBuilder DIB(*const_cast<Function &>(MF->getFunction()).getParent());
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const DIExpression *NewExpr;
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if (auto Fragment = DebugInstr->getDebugExpression()->getFragmentInfo())
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NewExpr = *DIExpression::createFragmentExpression(DIB.createExpression(),
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Fragment->OffsetInBits, Fragment->SizeInBits);
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else
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NewExpr = DIB.createExpression();
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NewDebugInstr =
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BuildMI(*MF, DebugInstr->getDebugLoc(), DebugInstr->getDesc(), false,
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NewReg, DebugInstr->getDebugVariable(), DIB.createExpression());
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NewReg, DebugInstr->getDebugVariable(), NewExpr);
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VarLoc VL(*NewDebugInstr, LS);
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ProcessVarLoc(VL, NewDebugInstr);
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LLVM_DEBUG(dbgs() << "Creating DBG_VALUE inst for register restore: ";
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@ -848,9 +856,14 @@ void LiveDebugValues::transferSpillOrRestoreInst(MachineInstr &MI,
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<< "\n");
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}
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// Check if the register or spill location is the location of a debug value.
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// FIXME: Don't create a spill transfer if there is a complex expression,
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// because we currently cannot recover the original expression on restore.
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for (unsigned ID : OpenRanges.getVarLocs()) {
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const MachineInstr *DebugInstr = &VarLocIDs[ID].MI;
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if (TKind == TransferKind::TransferSpill &&
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VarLocIDs[ID].isDescribedByReg() == Reg) {
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VarLocIDs[ID].isDescribedByReg() == Reg &&
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!DebugInstr->getDebugExpression()->isComplex()) {
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LLVM_DEBUG(dbgs() << "Spilling Register " << printReg(Reg, TRI) << '('
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<< VarLocIDs[ID].Var.getVar()->getName() << ")\n");
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} else if (TKind == TransferKind::TransferRestore &&
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@ -14,13 +14,17 @@
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# return *(p + 1);
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# }
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# Pick out DILocalVariable numbers for "p" and "q"
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# CHECK: ![[PVAR:[0-9]+]] = !DILocalVariable(name: "p",
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# CHECK: ![[QVAR:[0-9]+]] = !DILocalVariable(name: "q",
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# Ascertain that the spill has been recognized and manifested in a DBG_VALUE.
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# CHECK: MOV64mr $rsp,{{.*-8.*}}killed{{.*}}$rdi :: (store 8 into %stack.0)
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# CHECK-NEXT: DBG_VALUE $rsp,{{.*}}![[MDIX:[0-9]+]],{{.*}}!DIExpression(DW_OP_constu, 8, DW_OP_minus)
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# CHECK-NEXT: DBG_VALUE $rsp,{{.*}}![[PVAR]],{{.*}}!DIExpression(DW_OP_constu, 8, DW_OP_minus)
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# Check for the restore.
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# CHECK: $rdi = MOV64rm $rsp,{{.*-8.*}}:: (load 8 from %stack.0)
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# CHECK-NEXT: DBG_VALUE $rdi,{{.*}}![[MDIX]], !DIExpression()
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# CHECK-NEXT: DBG_VALUE $rdi,{{.*}}![[PVAR]], !DIExpression()
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--- |
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define dso_local i32 @f(i32* readonly %p) local_unnamed_addr !dbg !7 {
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@ -39,6 +43,22 @@
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ret i32 %0, !dbg !28
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}
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define dso_local i32 @g(i32* readonly %p) local_unnamed_addr !dbg !107 {
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entry:
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call void @llvm.dbg.value(metadata i32* %p, metadata !113, metadata !DIExpression()), !dbg !114
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%tobool = icmp eq i32* %p, null, !dbg !115
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br i1 %tobool, label %if.end, label %if.then, !dbg !117
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if.then: ; preds = %entry
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tail call void asm sideeffect "", "~{rax},~{rbx},~{rcx},~{rdx},~{rsi},~{rdi},~{rbp},~{r8},~{r9},~{r10},~{r11},~{r12},~{r13},~{r14},~{r15},~{dirflag},~{fpsr},~{flags}"(), !dbg !118, !srcloc !120
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br label %if.end, !dbg !121
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if.end: ; preds = %entry, %if.then
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%add.ptr = getelementptr inbounds i32, i32* %p, i64 1, !dbg !122
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%0 = load i32, i32* %add.ptr, align 4, !dbg !123, !tbaa !24
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ret i32 %0, !dbg !128
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}
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declare void @llvm.dbg.value(metadata, metadata, metadata)
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!llvm.dbg.cu = !{!0}
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@ -74,6 +94,22 @@
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!26 = !{!"omnipotent char", !27, i64 0}
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!27 = !{!"Simple C/C++ TBAA"}
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!28 = !DILocation(line: 9, column: 3, scope: !7)
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!101 = !DIBasicType(name: "looong int", size: 64, encoding: DW_ATE_signed)
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!107 = distinct !DISubprogram(name: "g", scope: !1, file: !1, line: 105, type: !8, scopeLine: 105, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !112)
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!112 = !{!113}
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!113 = !DILocalVariable(name: "q", arg: 1, scope: !107, file: !1, line: 105, type: !101)
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!114 = !DILocation(line: 105, column: 12, scope: !107)
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!115 = !DILocation(line: 106, column: 7, scope: !116)
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!116 = distinct !DILexicalBlock(scope: !107, file: !1, line: 106, column: 7)
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!117 = !DILocation(line: 106, column: 7, scope: !107)
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!118 = !DILocation(line: 107, column: 5, scope: !119)
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!119 = distinct !DILexicalBlock(scope: !116, file: !1, line: 106, column: 10)
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!120 = !{i32 -2147471544}
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!121 = !DILocation(line: 108, column: 3, scope: !119)
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!122 = !DILocation(line: 109, column: 14, scope: !107)
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!123 = !DILocation(line: 109, column: 10, scope: !107)
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!128 = !DILocation(line: 109, column: 3, scope: !107)
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...
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---
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@ -187,3 +223,78 @@ body: |
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RETQ $eax, debug-location !28
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...
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---
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# This second function has been appended as a regression test against a
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# crash, caused by expressions being created from spill restores that did
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# not preserve fragment information. Test that no empty expressions are
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# created at all, and the last block describes both variable fragments.
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# CHECK-LABEL: name: g
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# CHECK-NOT: !DIExpression()
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# CHECK-LABEL: bb.2.if.end:
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# CHECK: DBG_VALUE $rdi, $noreg, ![[QVAR]], !DIExpression(DW_OP_LLVM_fragment, 0, 32)
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# CHECK-NEXT: DBG_VALUE $rbx, $noreg, ![[QVAR]], !DIExpression(DW_OP_LLVM_fragment, 32, 32)
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name: g
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alignment: 4
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tracksRegLiveness: true
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liveins:
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- { reg: '$rdi', virtual-reg: '' }
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frameInfo:
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stackSize: 48
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offsetAdjustment: -48
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maxAlignment: 8
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cvBytesOfCalleeSavedRegisters: 48
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localFrameSize: 0
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fixedStack:
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- { id: 0, type: spill-slot, offset: -56, size: 8, alignment: 8, stack-id: default,
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callee-saved-register: '$rbx', callee-saved-restored: true, debug-info-variable: '',
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debug-info-expression: '', debug-info-location: '' }
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- { id: 1, type: spill-slot, offset: -48, size: 8, alignment: 16, stack-id: default,
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callee-saved-register: '$r12', callee-saved-restored: true, debug-info-variable: '',
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debug-info-expression: '', debug-info-location: '' }
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- { id: 2, type: spill-slot, offset: -40, size: 8, alignment: 8, stack-id: default,
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callee-saved-register: '$r13', callee-saved-restored: true, debug-info-variable: '',
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debug-info-expression: '', debug-info-location: '' }
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- { id: 3, type: spill-slot, offset: -32, size: 8, alignment: 16, stack-id: default,
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callee-saved-register: '$r14', callee-saved-restored: true, debug-info-variable: '',
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debug-info-expression: '', debug-info-location: '' }
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- { id: 4, type: spill-slot, offset: -24, size: 8, alignment: 8, stack-id: default,
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callee-saved-register: '$r15', callee-saved-restored: true, debug-info-variable: '',
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debug-info-expression: '', debug-info-location: '' }
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- { id: 5, type: spill-slot, offset: -16, size: 8, alignment: 16, stack-id: default,
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callee-saved-register: '$rbp', callee-saved-restored: true, debug-info-variable: '',
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debug-info-expression: '', debug-info-location: '' }
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stack:
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- { id: 0, name: '', type: spill-slot, offset: -64, size: 8, alignment: 8,
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stack-id: default, callee-saved-register: '', callee-saved-restored: true,
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debug-info-variable: '', debug-info-expression: '', debug-info-location: '' }
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constants: []
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body: |
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bb.0.entry:
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successors: %bb.1(0x50000000)
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liveins: $rdi, $rbx, $r12, $r13, $r14, $r15, $rbp
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DBG_VALUE $rdi, $noreg, !113, !DIExpression(DW_OP_LLVM_fragment, 0, 32), debug-location !114
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TEST64rr renamable $rdi, renamable $rdi, implicit-def $eflags, debug-location !115
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JMP_1 %bb.1, implicit $eflags, debug-location !117
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bb.1.if.then:
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successors: %bb.2(0x80000000)
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liveins: $rdi, $rbp, $r15, $r14, $r13, $r12, $rbx
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MOV64mr $rsp, 1, $noreg, -8, $noreg, killed renamable $rdi :: (store 8 into %stack.0)
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renamable $rdi = MOV64rm $rsp, 1, $noreg, -8, $noreg :: (load 8 from %stack.0)
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bb.2.if.end:
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liveins: $rdi, $rbx, $r12, $r13, $r14, $r15, $rbp
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DBG_VALUE $rbx, $noreg, !113, !DIExpression(DW_OP_LLVM_fragment, 32, 32), debug-location !114
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MOV64mr $rsp, 1, $noreg, -8, $noreg, killed renamable $rbx :: (store 8 into %stack.0)
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renamable $rsi = MOV64rm $rsp, 1, $noreg, -8, $noreg :: (load 8 from %stack.0)
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renamable $eax = MOV32rm killed renamable $rsi, 1, $noreg, 4, $noreg, debug-location !123 :: (load 4 from %ir.add.ptr, !tbaa !24)
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$rdi = MOV64ri 0
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RETQ $eax, debug-location !128
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...
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