[LiveDebugValues] Insert entry values after bundles

Summary:
Change LiveDebugValues so that it inserts entry values after the bundle
which contains the clobbering instruction. Previously it would insert
the debug value after the bundle head using insertAfter(), breaking the
bundle.

Reviewers: djtodoro, NikolaPrica, aprantl, vsk

Reviewed By: vsk

Subscribers: hiraditya, llvm-commits

Tags: #debug-info, #llvm

Differential Revision: https://reviews.llvm.org/D66888

llvm-svn: 370448

4 files changed, 154 insertions, 2 deletions

diff --git a/llvm/include/llvm/CodeGen/MachineBasicBlock.h b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
index 30131c23c33..7d6cd6657e5 100644
--- a/llvm/include/llvm/CodeGen/MachineBasicBlock.h
+++ b/llvm/include/llvm/CodeGen/MachineBasicBlock.h
@@ -636,6 +636,18 @@ public:
     return Insts.insertAfter(I.getInstrIterator(), MI);
   }
 
+  /// If I is bundled then insert MI into the instruction list after the end of
+  /// the bundle, otherwise insert MI immediately after I.
+  instr_iterator insertAfterBundle(instr_iterator I, MachineInstr *MI) {
+    assert((I == instr_end() || I->getParent() == this) &&
+           "iterator points outside of basic block");
+    assert(!MI->isBundledWithPred() && !MI->isBundledWithSucc() &&
+           "Cannot insert instruction with bundle flags");
+    while (I->isBundledWithSucc())
+      ++I;
+    return Insts.insertAfter(I, MI);
+  }
+
   /// Remove an instruction from the instruction list and delete it.
   ///
   /// If the instruction is part of a bundle, the other instructions in the
diff --git a/llvm/lib/CodeGen/LiveDebugValues.cpp b/llvm/lib/CodeGen/LiveDebugValues.cpp
index 29d307845cf..ea5512fc369 100644
--- a/llvm/lib/CodeGen/LiveDebugValues.cpp
+++ b/llvm/lib/CodeGen/LiveDebugValues.cpp
@@ -1311,8 +1311,7 @@ bool LiveDebugValues::ExtendRanges(MachineFunction &MF) {
 
         // Add any DBG_VALUE instructions necessitated by spills.
         for (auto &TR : Transfers)
-          MBB->insertAfter(MachineBasicBlock::iterator(*TR.TransferInst),
-                           TR.DebugInst);
+          MBB->insertAfterBundle(TR.TransferInst->getIterator(), TR.DebugInst);
         Transfers.clear();
 
         LLVM_DEBUG(printVarLocInMBB(MF, OutLocs, VarLocIDs,
diff --git a/llvm/test/DebugInfo/MIR/Hexagon/lit.local.cfg b/llvm/test/DebugInfo/MIR/Hexagon/lit.local.cfg
new file mode 100644
index 00000000000..cc6a7edf05f
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/Hexagon/lit.local.cfg
@@ -0,0 +1,2 @@
+if not 'Hexagon' in config.root.targets:
+    config.unsupported = True
diff --git a/llvm/test/DebugInfo/MIR/Hexagon/live-debug-values-bundled-entry-values.mir b/llvm/test/DebugInfo/MIR/Hexagon/live-debug-values-bundled-entry-values.mir
new file mode 100644
index 00000000000..b7881b42e29
--- /dev/null
+++ b/llvm/test/DebugInfo/MIR/Hexagon/live-debug-values-bundled-entry-values.mir
@@ -0,0 +1,139 @@
+# RUN: llc -debug-entry-values -run-pass=livedebugvalues -o - %s | FileCheck %s
+
+# Verify that the entry values for the input parameters are inserted after the
+# bundles which contains the registers' clobbering instructions (the calls to
+# @clobber). Previously the insertions would thrash the bundles, later on
+# triggering a crash in DebugHandlerBase.
+
+--- |
+  target datalayout = "e-m:e-p:32:32:32-a:0-n16:32-i64:64:64-i32:32:32-i16:16:16-i1:8:8-f32:32:32-f64:64:64-v32:32:32-v64:64:64-v512:512:512-v1024:1024:1024-v2048:2048:2048"
+  target triple = "hexagon"
+
+  ; Function Attrs: nounwind
+  define i32 @foo(i32 %arg) !dbg !12 {
+  entry:
+    call void @llvm.dbg.value(metadata i32 %arg, metadata !16, metadata !DIExpression()), !dbg !17
+    %call = tail call i32 @clobber(), !dbg !18
+    ret i32 1, !dbg !19
+  }
+
+  declare !dbg !4 i32 @clobber()
+
+  ; Function Attrs: nounwind
+  define i32 @bar(i32 %b) !dbg !20 {
+  entry:
+    call void @llvm.dbg.value(metadata i32 %b, metadata !22, metadata !DIExpression()), !dbg !23
+    %tobool = icmp eq i32 %b, 0, !dbg !24
+    br i1 %tobool, label %land.end, label %land.rhs, !dbg !24
+
+  land.rhs:                                         ; preds = %entry
+    %call = tail call i32 @clobber(), !dbg !25
+    br label %land.end
+
+  land.end:                                         ; preds = %entry, %land.rhs
+    ret i32 undef, !dbg !27
+  }
+
+  ; Function Attrs: nounwind readnone speculatable
+  declare void @llvm.dbg.value(metadata, metadata, metadata) #0
+
+  attributes #0 = { nounwind readnone speculatable }
+
+  !llvm.dbg.cu = !{!0}
+  !llvm.module.flags = !{!8, !9, !10}
+  !llvm.ident = !{!11}
+
+  !0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 10.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, nameTableKind: None)
+  !1 = !DIFile(filename: "foo.c", directory: "/")
+  !2 = !{}
+  !3 = !{!4}
+  !4 = !DISubprogram(name: "clobber", scope: !1, file: !1, line: 1, type: !5, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !2)
+  !5 = !DISubroutineType(types: !6)
+  !6 = !{!7}
+  !7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+  !8 = !{i32 2, !"Dwarf Version", i32 4}
+  !9 = !{i32 2, !"Debug Info Version", i32 3}
+  !10 = !{i32 1, !"wchar_size", i32 4}
+  !11 = !{!"clang version 10.0.0"}
+  !12 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 3, type: !13, scopeLine: 3, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !15)
+  !13 = !DISubroutineType(types: !14)
+  !14 = !{!7, !7}
+  !15 = !{!16}
+  !16 = !DILocalVariable(name: "arg", arg: 1, scope: !12, file: !1, line: 3, type: !7, flags: DIFlagArgumentNotModified)
+  !17 = !DILocation(line: 0, scope: !12)
+  !18 = !DILocation(line: 4, scope: !12)
+  !19 = !DILocation(line: 5, scope: !12)
+  !20 = distinct !DISubprogram(name: "bar", scope: !1, file: !1, line: 8, type: !13, scopeLine: 8, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !21)
+  !21 = !{!22}
+  !22 = !DILocalVariable(name: "arg", arg: 1, scope: !20, file: !1, line: 8, type: !7, flags: DIFlagArgumentNotModified)
+  !23 = !DILocation(line: 0, scope: !20)
+  !24 = !DILocation(line: 9, scope: !20)
+  !25 = !DILocation(line: 9, scope: !26)
+  !26 = distinct !DILexicalBlock(scope: !20, file: !1, line: 9)
+  !27 = !DILocation(line: 10, scope: !20)
+
+...
+---
+name:            foo
+tracksRegLiveness: true
+body:             |
+  bb.0.entry:
+    DBG_VALUE $r0, $noreg, !16, !DIExpression(), debug-location !17
+    CFI_INSTRUCTION def_cfa $r30, 8
+    CFI_INSTRUCTION offset $r31, -4
+    CFI_INSTRUCTION offset $r30, -8
+    BUNDLE implicit-def $r29, implicit-def $r30, implicit-def dead $pc, implicit-def dead $r31, implicit-def dead $r0, implicit $r29, implicit killed $framekey, implicit killed $framelimit, implicit killed $r30, implicit killed $r31, debug-location !18 {
+      $r29 = S2_allocframe $r29, 0, implicit-def $r30, implicit killed $framekey, implicit killed $framelimit, implicit killed $r30, implicit killed $r31, debug-location !18 :: (store 4 into stack)
+      J2_call @clobber, hexagoncsr, implicit-def dead $pc, implicit-def dead $r31, implicit internal killed $r29, implicit-def $r29, implicit-def dead $r0, debug-location !18
+    }
+    BUNDLE implicit-def dead $r0, implicit-def $d15, implicit-def $r30, implicit-def $r31, implicit-def $pc, implicit-def $r29, implicit killed $r30, implicit killed $framekey, debug-location !19 {
+      $r0 = A2_tfrsi 1, debug-location !19
+      $d15 = L4_return killed $r30, implicit-def $pc, implicit-def $r29, implicit killed $framekey, implicit-def dead $pc, implicit internal killed $r0, debug-location !19
+    }
+
+...
+
+# CHECK-LABEL: name: foo
+# CHECK: BUNDLE
+# CHECK-NEXT: $r29 = S2_allocframe $r29, 0
+# CHECK-NEXT: J2_call @clobber
+# CHECK-NEXT: }
+# CHECK-NEXT: DBG_VALUE $r0, $noreg, !16, !DIExpression(DW_OP_entry_value, 1)
+
+---
+name:            bar
+tracksRegLiveness: true
+liveins:
+  - { reg: '$r0' }
+body:             |
+  bb.0.entry:
+    successors: %bb.1
+    liveins: $r0
+
+    DBG_VALUE $r0, $noreg, !22, !DIExpression(), debug-location !23
+    DBG_VALUE $r0, $noreg, !22, !DIExpression(), debug-location !23
+    BUNDLE implicit-def dead $p0, implicit-def $pc, implicit killed $r0, implicit killed $r31, debug-location !24 {
+      renamable $p0 = C2_cmpeqi killed renamable $r0, 0, debug-location !24
+      PS_jmprettnew internal killed $p0, killed $r31, implicit-def $pc, implicit-def $pc, implicit killed undef $r0, debug-location !27
+    }
+
+  bb.1.land.rhs:
+    CFI_INSTRUCTION def_cfa $r30, 8
+    CFI_INSTRUCTION offset $r31, -4
+    CFI_INSTRUCTION offset $r30, -8
+    BUNDLE implicit-def $r29, implicit-def $r30, implicit-def $pc, implicit-def $r31, implicit-def dead $r0, implicit $r29, implicit killed $framekey, implicit killed $framelimit, implicit killed $r30, implicit killed $r31, debug-location !25 {
+      $r29 = S2_allocframe $r29, 0, implicit-def $r30, implicit killed $framekey, implicit killed $framelimit, implicit killed $r30, implicit killed $r31, debug-location !25 :: (store 4 into stack)
+      J2_call @clobber, hexagoncsr, implicit-def $pc, implicit-def $r31, implicit internal killed $r29, implicit-def $r29, implicit-def dead $r0, debug-location !25
+    }
+    $d15 = L2_deallocframe killed $r30, implicit-def $r29, implicit killed $framekey
+    PS_jmpret killed $r31, implicit-def $pc, implicit killed undef $r0, debug-location !27
+
+...
+
+# CHECK-LABEL: name: bar
+# CHECK: BUNDLE
+# CHECK: BUNDLE
+# CHECK-NEXT: $r29 = S2_allocframe $r29, 0
+# CHECK-NEXT: J2_call @clobber
+# CHECK-NEXT: }
+# CHECK-NEXT: DBG_VALUE $r0, $noreg, !22, !DIExpression(DW_OP_entry_value, 1)