From 783006ec19853403b8fe799e4c1b9496cb03504a Mon Sep 17 00:00:00 2001
From: Bjorn Pettersson <bjorn.a.pettersson@ericsson.com>
Date: Tue, 6 Mar 2018 08:47:07 +0000
Subject: [PATCH] [DebugInfo] Discard invalid DBG_VALUE instructions in
LiveDebugVariables
Summary:
This is a workaround for pr36417
https://bugs.llvm.org/show_bug.cgi?id=36417
LiveDebugVariables will now verify that the DBG_VALUE instructions
are sane (prior to register allocation) by asking LIS if a virtual
register used in the DBG_VALUE is live (or dead def) in the slot
index before the DBG_VALUE. If it isn't sane the DBG_VALUE is
discarded.
One pass that was identified as introducing non-sane DBG_VALUE
instructtons, when analysing pr36417, was the DAG->DAG Instruction
Selection. It sometimes inserts DBG_VALUE instructions referring to
a virtual register that is defined later in the same basic block.
So it is a use before def kind of problem. The DBG_VALUE is
typically inserted in the beginning of a basic block when this
happens. The problem can be seen in the test case
test/DebugInfo/X86/dbg-value-inlined-parameter.ll
Reviewers: aprantl, rnk, probinson
Reviewed By: aprantl
Subscribers: vsk, davide, alexcrichton, Ka-Ka, eraman, llvm-commits, JDevlieghere
Differential Revision: https://reviews.llvm.org/D43956
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326769 91177308-0d34-0410-b5e6-96231b3b80d8
---
lib/CodeGen/LiveDebugVariables.cpp | 38 +++++-
test/DebugInfo/X86/dbg-value-inlined-parameter.ll | 6 +-
.../X86/live-debug-vars-discard-invalid.mir | 141 +++++++++++++++++++++
3 files changed, 181 insertions(+), 4 deletions(-)
create mode 100644 test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
diff --git a/lib/CodeGen/LiveDebugVariables.cpp b/lib/CodeGen/LiveDebugVariables.cpp
index 09168b6..f3fcd00 100644
--- a/lib/CodeGen/LiveDebugVariables.cpp
+++ b/lib/CodeGen/LiveDebugVariables.cpp
@@ -514,6 +514,39 @@ bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) {
return false;
}
+ // Detect invalid DBG_VALUE instructions, with a debug-use of a virtual
+ // register that hasn't been defined yet. If we do not remove those here, then
+ // the re-insertion of the DBG_VALUE instruction after register allocation
+ // will be incorrect.
+ // TODO: If earlier passes are corrected to generate sane debug information
+ // (and if the machine verifier is improved to catch this), then these checks
+ // could be removed or replaced by asserts.
+ bool Discard = false;
+ if (MI.getOperand(0).isReg() &&
+ TargetRegisterInfo::isVirtualRegister(MI.getOperand(0).getReg())) {
+ const unsigned Reg = MI.getOperand(0).getReg();
+ if (!LIS->hasInterval(Reg)) {
+ // The DBG_VALUE is described by a virtual register that does not have a
+ // live interval. Discard the DBG_VALUE.
+ Discard = true;
+ DEBUG(dbgs() << "Discarding debug info (no LIS interval): "
+ << Idx << " " << MI);
+ } else {
+ // The DBG_VALUE is only valid if either Reg is live out from Idx, or Reg
+ // is defined dead at Idx (where Idx is the slot index for the instruction
+ // preceeding the DBG_VALUE).
+ const LiveInterval &LI = LIS->getInterval(Reg);
+ LiveQueryResult LRQ = LI.Query(Idx);
+ if (!LRQ.valueOutOrDead()) {
+ // We have found a DBG_VALUE with the value in a virtual register that
+ // is not live. Discard the DBG_VALUE.
+ Discard = true;
+ DEBUG(dbgs() << "Discarding debug info (reg not live): "
+ << Idx << " " << MI);
+ }
+ }
+ }
+
// Get or create the UserValue for (variable,offset) here.
bool IsIndirect = MI.getOperand(1).isImm();
if (IsIndirect)
@@ -522,7 +555,10 @@ bool LDVImpl::handleDebugValue(MachineInstr &MI, SlotIndex Idx) {
const DIExpression *Expr = MI.getDebugExpression();
UserValue *UV =
getUserValue(Var, Expr, MI.getDebugLoc());
- UV->addDef(Idx, MI.getOperand(0), IsIndirect);
+ if (!Discard)
+ UV->addDef(Idx, MI.getOperand(0), IsIndirect);
+ else
+ UV->addDef(Idx, MachineOperand::CreateReg(0U, RegState::Debug), false);
return true;
}
diff --git a/test/DebugInfo/X86/dbg-value-inlined-parameter.ll b/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
index 9954039..e83cf0a 100644
--- a/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
+++ b/test/DebugInfo/X86/dbg-value-inlined-parameter.ll
@@ -32,10 +32,10 @@
;CHECK-NEXT: DW_AT_call_line
;CHECK: DW_TAG_formal_parameter
-;FIXME: Linux shouldn't drop this parameter either...
;CHECK-NOT: DW_TAG
-;DARWIN: DW_AT_abstract_origin {{.*}} "sp"
-;DARWIN: DW_TAG_formal_parameter
+;FIXME: Shouldn't drop this parameter...
+;XCHECK: DW_AT_abstract_origin {{.*}} "sp"
+;XCHECK: DW_TAG_formal_parameter
;CHECK: DW_AT_abstract_origin {{.*}} "nums"
;CHECK-NOT: DW_TAG_formal_parameter
diff --git a/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir b/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
new file mode 100644
index 0000000..abc21bc
--- /dev/null
+++ b/test/DebugInfo/X86/live-debug-vars-discard-invalid.mir
@@ -0,0 +1,141 @@
+# RUN: llc -mtriple=x86_64-linux-gnu -start-before greedy -stop-after virtregrewriter -o - %s | FileCheck %s
+
+--- |
+ ; ModuleID = '<stdin>'
+ source_filename = "test/DebugInfo/X86/dbg-value-inlined-parameter.ll"
+ target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+ target triple = "x86_64-apple-darwin"
+
+ %struct.S1 = type { float*, i32 }
+
+ @p = common global %struct.S1 zeroinitializer, align 8, !dbg !0
+
+ ; Function Attrs: nounwind optsize ssp
+ define void @foobar() !dbg !15 {
+ entry:
+ tail call void @llvm.dbg.value(metadata %struct.S1* @p, metadata !18, metadata !DIExpression()) , !dbg !25
+ ret void, !dbg !32
+ }
+
+ ; Function Attrs: nounwind readnone speculatable
+ declare void @llvm.dbg.value(metadata, metadata, metadata) #2
+
+ !llvm.dbg.cu = !{!2}
+ !llvm.module.flags = !{!14}
+
+ !0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+ !1 = !DIGlobalVariable(name: "p", scope: !2, file: !3, line: 14, type: !6, isLocal: false, isDefinition: true)
+ !2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 2.9 (trunk 125693)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, retainedTypes: !4, globals: !5, imports: !4)
+ !3 = !DIFile(filename: "nm2.c", directory: "/private/tmp")
+ !4 = !{}
+ !5 = !{!0}
+ !6 = !DIDerivedType(tag: DW_TAG_typedef, name: "S1", scope: !2, file: !3, line: 4, baseType: !7)
+ !7 = !DICompositeType(tag: DW_TAG_structure_type, name: "S1", scope: !2, file: !3, line: 1, size: 128, align: 64, elements: !8)
+ !8 = !{!9, !12}
+ !9 = !DIDerivedType(tag: DW_TAG_member, name: "m", scope: !3, file: !3, line: 2, baseType: !10, size: 64, align: 64)
+ !10 = !DIDerivedType(tag: DW_TAG_pointer_type, scope: !2, baseType: !11, size: 64, align: 64)
+ !11 = !DIBasicType(name: "float", size: 32, align: 32, encoding: DW_ATE_float)
+ !12 = !DIDerivedType(tag: DW_TAG_member, name: "nums", scope: !3, file: !3, line: 3, baseType: !13, size: 32, align: 32, offset: 64)
+ !13 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+ !14 = !{i32 1, !"Debug Info Version", i32 3}
+ !15 = distinct !DISubprogram(name: "foobar", scope: !3, file: !3, line: 15, type: !16, isLocal: false, isDefinition: true, virtualIndex: 6, isOptimized: true, unit: !2)
+ !16 = !DISubroutineType(types: !17)
+ !17 = !{null}
+ !18 = !DILocalVariable(name: "sp", arg: 1, scope: !19, file: !3, line: 7, type: !24)
+ !19 = distinct !DISubprogram(name: "foo", scope: !3, file: !3, line: 8, type: !20, isLocal: false, isDefinition: true, scopeLine: 8, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !2, variables: !22)
+ !20 = !DISubroutineType(types: !21)
+ !21 = !{!13}
+ !22 = !{!18, !23}
+ !23 = !DILocalVariable(name: "nums", arg: 2, scope: !19, file: !3, line: 7, type: !13)
+ !24 = !DIDerivedType(tag: DW_TAG_pointer_type, scope: !2, baseType: !6, size: 64, align: 64)
+ !25 = !DILocation(line: 7, column: 13, scope: !19, inlinedAt: !26)
+ !26 = !DILocation(line: 16, column: 3, scope: !27)
+ !27 = distinct !DILexicalBlock(scope: !15, file: !3, line: 15, column: 15)
+ !32 = !DILocation(line: 17, column: 1, scope: !27)
+
+...
+---
+name: foobar
+tracksRegLiveness: true
+body: |
+ bb.0:
+ %1:gr64 = IMPLICIT_DEF
+ %2:gr64 = IMPLICIT_DEF
+
+ bb.1:
+ ; This DBG_VALUE will be discarded (use before def of %0).
+ DBG_VALUE debug-use %0, debug-use $noreg, !18, !DIExpression(), debug-location !25
+ %0:gr64 = IMPLICIT_DEF
+ %0:gr64 = IMPLICIT_DEF
+ %0:gr64 = IMPLICIT_DEF
+ %0:gr64 = IMPLICIT_DEF
+
+ bb.2:
+ ; This DBG_VALUE will be discarded (%1 is defined earlier, but it is not live in, so we do not know where %1 is stored).
+ DBG_VALUE debug-use %1, debug-use $noreg, !18, !DIExpression(), debug-location !25
+ %1:gr64 = IMPLICIT_DEF
+ %1:gr64 = IMPLICIT_DEF
+ %1:gr64 = IMPLICIT_DEF
+ %1:gr64 = IMPLICIT_DEF
+ ; This DBG_VALUE is kept, even if %1 is dead, it was defined in the prev instruction,
+ ; so the value should be available for as long as the register allocated to %1 is live.
+ DBG_VALUE debug-use %1, debug-use $noreg, !18, !DIExpression(), debug-location !25
+
+ bb.3:
+ %1:gr64 = IMPLICIT_DEF
+ DBG_VALUE 0, debug-use $noreg, !23, !DIExpression(), debug-location !25
+ ; This DBG_VALUE is kept, even if %1 is dead, it was defined in the prev non-dbg instruction,
+ ; so the value should be available for as long as the register allocated to %1 is live.
+ DBG_VALUE debug-use %1, debug-use $noreg, !18, !DIExpression(), debug-location !25
+
+ bb.4:
+ ; All DBG_VALUEs here should survive. %2 is livein as it was defined in bb.0, and it has use/def in the BTS64rr instruction.
+ DBG_VALUE debug-use %2, debug-use $noreg, !18, !DIExpression(), debug-location !25
+ %2:gr64 = BTS64rr %2, 0, implicit-def $eflags
+ DBG_VALUE 0, debug-use $noreg, !23, !DIExpression(), debug-location !25
+ DBG_VALUE debug-use %2, debug-use $noreg, !18, !DIExpression(), debug-location !25
+ %2:gr64 = BTS64rr %2, 0, implicit-def $eflags
+ DBG_VALUE debug-use %2, debug-use $noreg, !18, !DIExpression(), debug-location !25
+ %2:gr64 = BTS64rr %2, 0, implicit-def $eflags
+ DBG_VALUE debug-use %2, debug-use $noreg, !18, !DIExpression(), debug-location !25
+
+ bb.5:
+ RET 0, debug-location !32
+...
+
+# CHECK-LABEL: name: foobar
+
+# CHECK-LABEL: bb.1:
+## After solving https://bugs.llvm.org/show_bug.cgi?id=36579 we expect to get a
+## DBG_VALUE debug-use $noreg
+## here.
+# CHECK-NOT: DBG_VALUE
+
+# CHECK-LABEL: bb.2:
+## After solving https://bugs.llvm.org/show_bug.cgi?id=36579 we expect to get a
+## DBG_VALUE debug-use $noreg
+## here.
+# CHECK-NOT: DBG_VALUE
+# CHECK: dead renamable $rcx = IMPLICIT_DEF
+# CHECK-NEXT: dead renamable $rcx = IMPLICIT_DEF
+# CHECK-NEXT: dead renamable $rcx = IMPLICIT_DEF
+# CHECK-NEXT: dead renamable $rcx = IMPLICIT_DEF
+# CHECK-NEXT: DBG_VALUE debug-use $rcx, debug-use $noreg, !18, !DIExpression()
+
+# CHECK-LABEL: bb.3:
+# CHECK: dead renamable $rcx = IMPLICIT_DEF
+# CHECK-NEXT: DBG_VALUE 0, debug-use $noreg, !23, !DIExpression()
+# CHECK-NEXT: DBG_VALUE debug-use $rcx, debug-use $noreg, !18, !DIExpression()
+
+# CHECK-LABEL: bb.4:
+# CHECK: liveins: $rax
+# CHECK: DBG_VALUE debug-use $rax, debug-use $noreg, !18, !DIExpression()
+# CHECK-NEXT: renamable $rax = BTS64rr killed renamable $rax, 0, implicit-def $eflags
+# CHECK-NEXT: DBG_VALUE 0, debug-use $noreg, !23, !DIExpression()
+# CHECK-NEXT: DBG_VALUE debug-use $rax, debug-use $noreg, !18, !DIExpression()
+# CHECK-NEXT: renamable $rax = BTS64rr killed renamable $rax, 0, implicit-def $eflags
+# CHECK-NEXT: DBG_VALUE debug-use $rax, debug-use $noreg, !18, !DIExpression()
+# CHECK-NEXT: dead renamable $rax = BTS64rr killed renamable $rax, 0, implicit-def $eflags
+
+# CHECK-LABEL: bb.5:
+# CHECK-NEXT: RET 0
--
1.8.3.1