[llvm] 93c194f - [Assignment Tracking] Ignore zero-sized fragments
via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 5 01:31:47 PDT 2023
Author: OCHyams
Date: 2023-04-05T09:31:23+01:00
New Revision: 93c194fc9f40636d99b2d66a22abb1442c720451
URL: https://github.com/llvm/llvm-project/commit/93c194fc9f40636d99b2d66a22abb1442c720451
DIFF: https://github.com/llvm/llvm-project/commit/93c194fc9f40636d99b2d66a22abb1442c720451.diff
LOG: [Assignment Tracking] Ignore zero-sized fragments
Such dbg.assigns will occur if you write zero-sized memcpys (see
https://reviews.llvm.org/D146987#4240016).
Handle this in AssignmentTrackingAnalysis (back end) rather than
AssignmentTrackingPass (declare-to-assign) in case it is possible to reproduce
this as a result of optimisations.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D147435
Added:
llvm/test/DebugInfo/assignment-tracking/X86/frag-size-zero.ll
Modified:
llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp b/llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp
index a3b498335d3a6..cd094d6d89c50 100644
--- a/llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp
+++ b/llvm/lib/CodeGen/AssignmentTrackingAnalysis.cpp
@@ -1272,7 +1272,7 @@ class AssignmentTrackingLowering {
/// location information).
///@{
void processNonDbgInstruction(Instruction &I, BlockInfo *LiveSet);
- void processDbgInstruction(Instruction &I, BlockInfo *LiveSet);
+ void processDbgInstruction(DbgInfoIntrinsic &I, BlockInfo *LiveSet);
/// Update \p LiveSet after encountering an instruction with a DIAssignID
/// attachment, \p I.
void processTaggedInstruction(Instruction &I, BlockInfo *LiveSet);
@@ -1702,8 +1702,22 @@ void AssignmentTrackingLowering::processDbgValue(DbgValueInst &DVI,
emitDbgValue(LocKind::Val, &DVI, &DVI);
}
+static bool hasZeroSizedFragment(DbgVariableIntrinsic &DVI) {
+ if (auto F = DVI.getExpression()->getFragmentInfo())
+ return F->SizeInBits == 0;
+ return false;
+}
+
void AssignmentTrackingLowering::processDbgInstruction(
- Instruction &I, AssignmentTrackingLowering::BlockInfo *LiveSet) {
+ DbgInfoIntrinsic &I, AssignmentTrackingLowering::BlockInfo *LiveSet) {
+ auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I);
+ if (!DVI)
+ return;
+
+ // Ignore assignments to zero bits of the variable.
+ if (hasZeroSizedFragment(*DVI))
+ return;
+
if (auto *DAI = dyn_cast<DbgAssignIntrinsic>(&I))
processDbgAssign(*DAI, LiveSet);
else if (auto *DVI = dyn_cast<DbgValueInst>(&I))
@@ -1733,10 +1747,11 @@ void AssignmentTrackingLowering::process(BasicBlock &BB, BlockInfo *LiveSet) {
++II;
}
while (II != EI) {
- if (!isa<DbgInfoIntrinsic>(&*II))
+ auto *Dbg = dyn_cast<DbgInfoIntrinsic>(&*II);
+ if (!Dbg)
break;
resetInsertionPoint(*II);
- processDbgInstruction(*II, LiveSet);
+ processDbgInstruction(*Dbg, LiveSet);
assert(LiveSet->isValid());
++II;
}
diff --git a/llvm/test/DebugInfo/assignment-tracking/X86/frag-size-zero.ll b/llvm/test/DebugInfo/assignment-tracking/X86/frag-size-zero.ll
new file mode 100644
index 0000000000000..3a3865d0511b9
--- /dev/null
+++ b/llvm/test/DebugInfo/assignment-tracking/X86/frag-size-zero.ll
@@ -0,0 +1,67 @@
+; RUN: llc %s -stop-after=finalize-isel -o - | FileCheck %s
+
+;; Check that a zero-sized fragment (the final dbg.assign) is ignored by
+;; AssignmentTrackingAnalysis.
+
+; CHECK: stack:
+; CHECK-NEXT: - { id: 0, name: m4, type: default, offset: 0, size: 32, alignment: 8,
+; CHECK-NEXT: stack-id: default, callee-saved-register: '', callee-saved-restored: true,
+; CHECK-NEXT: debug-info-variable: '![[#]]', debug-info-expression: '!DIExpression()',
+; CHECK-NEXT: debug-info-location: '![[#]]' }
+
+target triple = "x86_64-unknown-unknown"
+
+%struct.mm = type { [8 x i32] }
+
+ at m1 = local_unnamed_addr global %struct.mm zeroinitializer, align 4, !dbg !0
+
+define dso_local i32 @main() local_unnamed_addr #0 !dbg !23 {
+entry:
+ %m4 = alloca %struct.mm, align 8, !DIAssignID !28
+ call void @llvm.dbg.assign(metadata i1 undef, metadata !27, metadata !DIExpression(), metadata !28, metadata ptr %m4, metadata !DIExpression()), !dbg !29
+ call void @llvm.memcpy.p0.p0.i64(ptr noundef nonnull align 8 dereferenceable(32) %m4, ptr noundef nonnull align 4 dereferenceable(32) @m1, i64 32, i1 false), !dbg !31, !DIAssignID !36
+ call void @llvm.dbg.assign(metadata i1 undef, metadata !27, metadata !DIExpression(), metadata !36, metadata ptr %m4, metadata !DIExpression()), !dbg !29
+ call void @llvm.dbg.assign(metadata i1 undef, metadata !27, metadata !DIExpression(DW_OP_LLVM_fragment, 64, 0), metadata !43, metadata ptr %m4, metadata !DIExpression(DW_OP_plus_uconst, 8)), !dbg !29
+ ret i32 0, !dbg !45
+}
+
+
+declare void @llvm.memcpy.p0.p0.i64(ptr noalias nocapture writeonly, ptr noalias nocapture readonly, i64, i1 immarg) #2
+declare void @foo(i32 noundef) local_unnamed_addr #3
+declare i32 @bar(ptr noundef byval(%struct.mm) align 8, ptr noundef byval(%struct.mm) align 8) local_unnamed_addr #3
+declare void @llvm.dbg.assign(metadata, metadata, metadata, metadata, metadata, metadata) #4
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!19, !20, !21}
+!llvm.ident = !{!22}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "m1", scope: !2, file: !9, line: 1, type: !10, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C11, file: !3, producer: "clang version 17.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, retainedTypes: !4, globals: !6, splitDebugInlining: false, nameTableKind: None)
+!3 = !DIFile(filename: "<stdin>", directory: "/")
+!4 = !{!5}
+!5 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
+!6 = !{!0}
+!9 = !DIFile(filename: "repro.c", directory: "/")
+!10 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "mm", file: !9, line: 1, size: 256, elements: !11)
+!11 = !{!12}
+!12 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !10, file: !9, line: 1, baseType: !13, size: 256)
+!13 = !DICompositeType(tag: DW_TAG_array_type, baseType: !14, size: 256, elements: !15)
+!14 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!15 = !{!16}
+!16 = !DISubrange(count: 8)
+!19 = !{i32 2, !"Debug Info Version", i32 3}
+!20 = !{i32 1, !"wchar_size", i32 4}
+!21 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+!22 = !{!"clang version 17.0.0"}
+!23 = distinct !DISubprogram(name: "main", scope: !9, file: !9, line: 7, type: !24, scopeLine: 8, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !26)
+!24 = !DISubroutineType(types: !25)
+!25 = !{!14}
+!26 = !{!27}
+!27 = !DILocalVariable(name: "m4", scope: !23, file: !9, line: 9, type: !10)
+!28 = distinct !DIAssignID()
+!29 = !DILocation(line: 0, scope: !23)
+!31 = !DILocation(line: 11, column: 8, scope: !23)
+!36 = distinct !DIAssignID()
+!43 = distinct !DIAssignID()
+!45 = !DILocation(line: 19, column: 3, scope: !23)
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