| From 31e75512174e1bdaa242ee5c7f30fe56e68c3748 Mon Sep 17 00:00:00 2001 |
| From: Stephen Tozer <Stephen.Tozer@Sony.com> |
| Date: Mon, 26 Jul 2021 09:59:20 +0100 |
| Subject: [PATCH] [DebugInfo] Correctly update debug users of SSA values in |
| tail duplication |
| |
| During tail duplication, SSA values may be updated and have their uses |
| replaced with a virtual register, and any debug instructions that use |
| that value are deleted. This patch fixes the implementation of the debug |
| instruction deletion to work correctly for debug instructions that use |
| the SSA value multiple times, by batching deletions so that we don't |
| attempt to delete the same instruction twice. |
| |
| Differential Revision: https://reviews.llvm.org/D106557 |
| --- |
| llvm/lib/CodeGen/TailDuplicator.cpp | 7 +- |
| llvm/test/CodeGen/X86/tail-dup-debugvalue.mir | 127 ++++++++++++++++++ |
| 2 files changed, 133 insertions(+), 1 deletion(-) |
| create mode 100644 llvm/test/CodeGen/X86/tail-dup-debugvalue.mir |
| |
| diff --git a/llvm/lib/CodeGen/TailDuplicator.cpp b/llvm/lib/CodeGen/TailDuplicator.cpp |
| index 2b71490d67a8..af735f2a0216 100644 |
| --- a/llvm/lib/CodeGen/TailDuplicator.cpp |
| +++ b/llvm/lib/CodeGen/TailDuplicator.cpp |
| @@ -216,6 +216,9 @@ bool TailDuplicator::tailDuplicateAndUpdate( |
| |
| // Rewrite uses that are outside of the original def's block. |
| MachineRegisterInfo::use_iterator UI = MRI->use_begin(VReg); |
| + // Only remove instructions after loop, as DBG_VALUE_LISTs with multiple |
| + // uses of VReg may invalidate the use iterator when erased. |
| + SmallPtrSet<MachineInstr *, 4> InstrsToRemove; |
| while (UI != MRI->use_end()) { |
| MachineOperand &UseMO = *UI; |
| MachineInstr *UseMI = UseMO.getParent(); |
| @@ -225,13 +228,15 @@ bool TailDuplicator::tailDuplicateAndUpdate( |
| // a debug instruction that is a kill. |
| // FIXME: Should it SSAUpdate job to delete debug instructions |
| // instead of replacing the use with undef? |
| - UseMI->eraseFromParent(); |
| + InstrsToRemove.insert(UseMI); |
| continue; |
| } |
| if (UseMI->getParent() == DefBB && !UseMI->isPHI()) |
| continue; |
| SSAUpdate.RewriteUse(UseMO); |
| } |
| + for (auto *MI : InstrsToRemove) |
| + MI->eraseFromParent(); |
| } |
| |
| SSAUpdateVRs.clear(); |
| diff --git a/llvm/test/CodeGen/X86/tail-dup-debugvalue.mir b/llvm/test/CodeGen/X86/tail-dup-debugvalue.mir |
| new file mode 100644 |
| index 000000000000..835d276c9928 |
| --- /dev/null |
| +++ b/llvm/test/CodeGen/X86/tail-dup-debugvalue.mir |
| @@ -0,0 +1,127 @@ |
| +# RUN: llc -run-pass=early-tailduplication -mtriple=x86_64-unknown-linux-gnu %s -o - | FileCheck %s |
| + |
| +# Tail Duplication may update SSA values and invalidate any DBG_VALUEs that |
| +# use those values; those DBG_VALUEs should be deleted. This behaviour is tested |
| +# for DBG_VALUE users, and DBG_VALUE_LISTs that use the value multiple times. |
| + |
| +# CHECK-NOT: DBG_VALUE |
| +--- | |
| + 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" |
| + |
| + define dso_local void @main() local_unnamed_addr #0 !dbg !15 { |
| + entry: |
| + br label %L.outer |
| + |
| + L: ; preds = %L, %L.outer |
| + %tobool2.not = icmp eq i32 undef, 0 |
| + br i1 %tobool2.not, label %if.end4, label %L |
| + |
| + if.end4: ; preds = %L |
| + call void @llvm.dbg.value(metadata !DIArgList(i32 %f.0.ph, i32 1, i32 %f.0.ph), metadata !19, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_LLVM_arg, 2, DW_OP_and, DW_OP_or, DW_OP_stack_value)), !dbg !21 |
| + %cmp = icmp slt i32 %f.0.ph, undef |
| + br i1 %cmp, label %if.then5, label %if.end6 |
| + |
| + if.then5: ; preds = %if.end4 |
| + call void @h() #2 |
| + br label %L.outer |
| + |
| + L.outer: ; preds = %if.then5, %entry |
| + %f.0.ph = phi i32 [ 0, %if.then5 ], [ 1, %entry ] |
| + br label %L |
| + |
| + if.end6: ; preds = %if.end4 |
| + ret void |
| + } |
| + |
| + declare dso_local void @h() local_unnamed_addr |
| + |
| + declare void @llvm.dbg.value(metadata, metadata, metadata) |
| + |
| + !llvm.dbg.cu = !{!0} |
| + !llvm.module.flags = !{!13, !14} |
| + |
| + !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 13.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, globals: !3, splitDebugInlining: false, nameTableKind: None) |
| + !1 = !DIFile(filename: "tail-dup-debugvalue.c", directory: "/tmp") |
| + !2 = !{} |
| + !3 = !{!4, !7, !9, !11} |
| + !4 = !DIGlobalVariableExpression(var: !5, expr: !DIExpression()) |
| + !5 = distinct !DIGlobalVariable(name: "a", scope: !0, file: !1, line: 2, type: !6, isLocal: false, isDefinition: true) |
| + !6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) |
| + !7 = !DIGlobalVariableExpression(var: !8, expr: !DIExpression()) |
| + !8 = distinct !DIGlobalVariable(name: "b", scope: !0, file: !1, line: 2, type: !6, isLocal: false, isDefinition: true) |
| + !9 = !DIGlobalVariableExpression(var: !10, expr: !DIExpression()) |
| + !10 = distinct !DIGlobalVariable(name: "c", scope: !0, file: !1, line: 2, type: !6, isLocal: false, isDefinition: true) |
| + !11 = !DIGlobalVariableExpression(var: !12, expr: !DIExpression()) |
| + !12 = distinct !DIGlobalVariable(name: "d", scope: !0, file: !1, line: 2, type: !6, isLocal: false, isDefinition: true) |
| + !13 = !{i32 2, !"Debug Info Version", i32 3} |
| + !14 = !{i32 7, !"uwtable", i32 1} |
| + !15 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 3, type: !16, scopeLine: 3, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !18) |
| + !16 = !DISubroutineType(types: !17) |
| + !17 = !{!6} |
| + !18 = !{!19, !20} |
| + !19 = !DILocalVariable(name: "j", scope: !15, file: !1, line: 14, type: !6) |
| + !20 = !DILocalVariable(name: "k", scope: !15, file: !1, line: 14, type: !6) |
| + !21 = !DILocation(line: 0, scope: !15) |
| + |
| +... |
| +--- |
| +name: main |
| +alignment: 16 |
| +tracksRegLiveness: true |
| +registers: |
| + - { id: 0, class: gr32 } |
| + - { id: 1, class: gr32 } |
| + - { id: 2, class: gr32 } |
| + - { id: 3, class: gr8 } |
| + - { id: 4, class: gr32 } |
| + - { id: 5, class: gr32 } |
| + - { id: 6, class: gr32 } |
| +frameInfo: |
| + maxAlignment: 1 |
| + hasCalls: true |
| +machineFunctionInfo: {} |
| +body: | |
| + bb.0.entry: |
| + successors: %bb.4(0x80000000) |
| + |
| + %1:gr32 = MOV32ri 1 |
| + JMP_1 %bb.4 |
| + |
| + bb.1.L: |
| + successors: %bb.2(0x04000000), %bb.1(0x7c000000) |
| + |
| + %2:gr32 = MOV32r0 implicit-def dead $eflags |
| + %3:gr8 = COPY %2.sub_8bit |
| + TEST8rr %3, %3, implicit-def $eflags |
| + JCC_1 %bb.1, 5, implicit $eflags |
| + JMP_1 %bb.2 |
| + |
| + bb.2.if.end4: |
| + successors: %bb.3(0x783e0f0f), %bb.5(0x07c1f0f1) |
| + |
| + DBG_VALUE_LIST !19, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_LLVM_arg, 2, DW_OP_and, DW_OP_or, DW_OP_stack_value), %0, 1, %0, debug-location !21 |
| + DBG_VALUE %0, $noreg, !20, !DIExpression(), debug-location !21 |
| + %5:gr32 = IMPLICIT_DEF |
| + %4:gr32 = SUB32rr %0, killed %5, implicit-def $eflags |
| + JCC_1 %bb.5, 13, implicit $eflags |
| + JMP_1 %bb.3 |
| + |
| + bb.3.if.then5: |
| + successors: %bb.4(0x80000000) |
| + |
| + ADJCALLSTACKDOWN64 0, 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp |
| + CALL64pcrel32 @h, csr_64, implicit $rsp, implicit $ssp, implicit-def $rsp, implicit-def $ssp |
| + ADJCALLSTACKUP64 0, 0, implicit-def dead $rsp, implicit-def dead $eflags, implicit-def dead $ssp, implicit $rsp, implicit $ssp |
| + %6:gr32 = MOV32r0 implicit-def dead $eflags |
| + |
| + bb.4.L.outer: |
| + successors: %bb.1(0x80000000) |
| + |
| + %0:gr32 = PHI %1, %bb.0, %6, %bb.3 |
| + JMP_1 %bb.1 |
| + |
| + bb.5.if.end6: |
| + RET 0 |
| + |
| +... |
| -- |
| 2.33.0.800.g4c38ced690-goog |
| |
