[llvm] d05b570 - [Assignment Tracking] Trunc fragments for stores to vars smaller than the alloca
via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 11 10:18:32 PDT 2023
Author: OCHyams
Date: 2023-04-11T18:18:11+01:00
New Revision: d05b5709881f15973aab6b1d463d919cd152f770
URL: https://github.com/llvm/llvm-project/commit/d05b5709881f15973aab6b1d463d919cd152f770
DIFF: https://github.com/llvm/llvm-project/commit/d05b5709881f15973aab6b1d463d919cd152f770.diff
LOG: [Assignment Tracking] Trunc fragments for stores to vars smaller than the alloca
In D147777 emitDbgAssign was fixed to discard assignments which touched any
bits outside the bounds of a variable. This patch changes emitDbgAssign to
discard assignments which touch bits only outside the variable bounds, and
creates a truncated fragment expression for stores partially overlapping the
variable. This is necessary because the alloca is interpreted as a store (of
undef), meaning without this patch emitDbgAssign would discard the inital
dbg.assign for a variable that is smaller than the alloca.
Reviewed By: jmorse
Differential Revision: https://reviews.llvm.org/D148018
Added:
llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/structured-bindings.ll
llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/var-not-alloca-sized.ll
Modified:
llvm/lib/IR/DebugInfo.cpp
Removed:
################################################################################
diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index 46a310ccf7962..9073e59723233 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -1843,26 +1843,35 @@ static CallInst *emitDbgAssign(AssignmentInfo Info, Value *Val, Value *Dest,
assert(ID && "Store instruction must have DIAssignID metadata");
(void)ID;
+ const uint64_t StoreStartBit = Info.OffsetInBits;
+ const uint64_t StoreEndBit = Info.OffsetInBits + Info.SizeInBits;
+
+ uint64_t FragStartBit = StoreStartBit;
+ uint64_t FragEndBit = StoreEndBit;
+
bool StoreToWholeVariable = Info.StoreToWholeAlloca;
if (auto Size = VarRec.Var->getSizeInBits()) {
- // Discard stores to bits outside this variable. NOTE: trackAssignments
- // doesn't understand base expressions yet, so all variables that reach
- // here are guaranteed to start at offset 0 in the alloca.
- // TODO: Could we truncate the fragment expression instead of discarding
- // the assignment?
- if (Info.OffsetInBits + Info.SizeInBits > *Size)
+ // NOTE: trackAssignments doesn't understand base expressions yet, so all
+ // variables that reach here are guaranteed to start at offset 0 in the
+ // alloca.
+ const uint64_t VarStartBit = 0;
+ const uint64_t VarEndBit = *Size;
+
+ // FIXME: trim FragStartBit when nonzero VarStartBit is supported.
+ FragEndBit = std::min(FragEndBit, VarEndBit);
+
+ // Discard stores to bits outside this variable.
+ if (FragStartBit >= FragEndBit)
return nullptr;
- // FIXME: As noted above - only variables at offset 0 are handled
- // currently.
- StoreToWholeVariable = Info.OffsetInBits == /*VarOffsetInAlloca*/ 0 &&
- Info.SizeInBits == *Size;
+
+ StoreToWholeVariable = FragStartBit <= VarStartBit && FragEndBit >= *Size;
}
DIExpression *Expr =
DIExpression::get(StoreLikeInst.getContext(), std::nullopt);
if (!StoreToWholeVariable) {
- auto R = DIExpression::createFragmentExpression(Expr, Info.OffsetInBits,
- Info.SizeInBits);
+ auto R = DIExpression::createFragmentExpression(Expr, FragStartBit,
+ FragEndBit - FragStartBit);
assert(R.has_value() && "failed to create fragment expression");
Expr = *R;
}
diff --git a/llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/structured-bindings.ll b/llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/structured-bindings.ll
new file mode 100644
index 0000000000000..776026fcbc013
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/structured-bindings.ll
@@ -0,0 +1,81 @@
+; RUN: opt -passes=declare-to-assign -S %s -o - | FileCheck %s
+
+;; Check assignment tracking debug info for structured bindings. FIXME only
+;; variables at offset 0 in the backing alloca are currently tracked with the
+;; feature.
+
+;; struct two { int a, b; };
+;; two get();
+;; int fun() {
+;; auto [a,b] = get();
+;; return a * b;
+;; }
+
+; CHECK: %0 = alloca %struct.two, align 4, !DIAssignID ![[ID1:[0-9]+]]
+; CHECK-NEXT: llvm.dbg.assign(metadata i1 undef, metadata ![[AGGR:[0-9]+]], metadata !DIExpression(), metadata ![[ID1]], metadata ptr %0, metadata !DIExpression())
+; CHECK-NEXT: llvm.dbg.assign(metadata i1 undef, metadata ![[A:[0-9]+]], metadata !DIExpression(), metadata ![[ID1]], metadata ptr %0, metadata !DIExpression())
+; CHECK-NEXT: llvm.dbg.declare(metadata ptr %0, metadata ![[B:[0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, 4))
+
+; CHECK: store i64 %call, ptr %0, align 4,{{.*}}, !DIAssignID ![[ID2:[0-9]+]]
+; CHECK-NEXT: llvm.dbg.assign(metadata i64 %call, metadata ![[AGGR]], metadata !DIExpression(), metadata ![[ID2]], metadata ptr %0, metadata !DIExpression())
+; CHECK-NEXT: llvm.dbg.assign(metadata i64 %call, metadata ![[A]], metadata !DIExpression(), metadata ![[ID2]], metadata ptr %0, metadata !DIExpression())
+
+; CHECK: ![[AGGR]] = !DILocalVariable(scope:
+; CHECK: ![[A]] = !DILocalVariable(name: "a", scope:
+; CHECK: ![[B]] = !DILocalVariable(name: "b", scope:
+
+%struct.two = type { i32, i32 }
+
+define dso_local noundef i32 @_Z3funv() #0 !dbg !10 {
+entry:
+ %0 = alloca %struct.two, align 4
+ call void @llvm.dbg.declare(metadata ptr %0, metadata !15, metadata !DIExpression()), !dbg !16
+ call void @llvm.dbg.declare(metadata ptr %0, metadata !17, metadata !DIExpression(DW_OP_plus_uconst, 4)), !dbg !18
+ call void @llvm.dbg.declare(metadata ptr %0, metadata !19, metadata !DIExpression()), !dbg !24
+ %call = call i64 @_Z3getv(), !dbg !25
+ store i64 %call, ptr %0, align 4, !dbg !25
+ %a = getelementptr inbounds %struct.two, ptr %0, i32 0, i32 0, !dbg !16
+ %1 = load i32, ptr %a, align 4, !dbg !26
+ %b = getelementptr inbounds %struct.two, ptr %0, i32 0, i32 1, !dbg !18
+ %2 = load i32, ptr %b, align 4, !dbg !27
+ %mul = mul nsw i32 %1, %2, !dbg !28
+ ret i32 %mul, !dbg !29
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+declare i64 @_Z3getv()
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 17.0.0)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"frame-pointer", i32 2}
+!9 = !{!"clang version 17.0.0)"}
+!10 = distinct !DISubprogram(name: "fun", linkageName: "_Z3funv", scope: !1, file: !1, line: 3, type: !11, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !14)
+!11 = !DISubroutineType(types: !12)
+!12 = !{!13}
+!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!14 = !{}
+!15 = !DILocalVariable(name: "a", scope: !10, file: !1, line: 4, type: !13)
+!16 = !DILocation(line: 4, column: 9, scope: !10)
+!17 = !DILocalVariable(name: "b", scope: !10, file: !1, line: 4, type: !13)
+!18 = !DILocation(line: 4, column: 11, scope: !10)
+!19 = !DILocalVariable(scope: !10, file: !1, line: 4, type: !20)
+!20 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "two", file: !1, line: 1, size: 64, flags: DIFlagTypePassByValue, elements: !21, identifier: "_ZTS3two")
+!21 = !{!22, !23}
+!22 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !20, file: !1, line: 1, baseType: !13, size: 32)
+!23 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !20, file: !1, line: 1, baseType: !13, size: 32, offset: 32)
+!24 = !DILocation(line: 4, column: 8, scope: !10)
+!25 = !DILocation(line: 4, column: 16, scope: !10)
+!26 = !DILocation(line: 5, column: 10, scope: !10)
+!27 = !DILocation(line: 5, column: 14, scope: !10)
+!28 = !DILocation(line: 5, column: 12, scope: !10)
+!29 = !DILocation(line: 5, column: 3, scope: !10)
diff --git a/llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/var-not-alloca-sized.ll b/llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/var-not-alloca-sized.ll
new file mode 100644
index 0000000000000..56b631a59200d
--- /dev/null
+++ b/llvm/test/DebugInfo/Generic/assignment-tracking/declare-to-assign/var-not-alloca-sized.ll
@@ -0,0 +1,71 @@
+; RUN: opt -passes=declare-to-assign -S %s -o - | FileCheck %s
+
+;; The variable doesn't fill the whole alloca which has a range of
diff erent
+;; sized stores to it, overlapping (or not) the variable in various ways. Check
+;; the fragment is truncated to represent the intersect between the store and
+;; the variable. If that intersect has exactly the same offset and size as the
+;; variable then a fragment should not be produced (the whole variable is
+;; covered by the store).
+;;
+;; Check directives written inline.
+
+%struct.two = type { i32, i32 }
+
+define dso_local noundef i32 @_Z3funv() #0 !dbg !10 {
+entry:
+ %0 = alloca [4 x i16], align 4
+ call void @llvm.dbg.declare(metadata ptr %0, metadata !15, metadata !DIExpression()), !dbg !16
+; CHECK: %0 = alloca [4 x i16], align 4, !DIAssignID ![[ID1:[0-9]+]]
+; CHECK-NEXT: llvm.dbg.assign(metadata i1 undef, metadata ![[#]], metadata !DIExpression(), metadata ![[ID1]], metadata ptr %0, metadata !DIExpression())
+ %a = getelementptr inbounds [4 x i16], ptr %0, i32 0, i32 0
+ %a.5 = getelementptr inbounds [4 x i16], ptr %0, i32 0, i32 1
+ %b = getelementptr inbounds [4 x i16], ptr %0, i32 0, i32 2
+ store i64 1, ptr %a, align 4
+; CHECK: store i64 1, ptr %a, align 4, !DIAssignID ![[ID2:[0-9]+]]
+; CHECK-NEXT: llvm.dbg.assign(metadata i64 1, metadata ![[#]], metadata !DIExpression(), metadata ![[ID2]], metadata ptr %a, metadata !DIExpression())
+ store i64 2, ptr %b, align 4
+;; %b is outside the variable bounds, no debug intrinsic needed.
+ store i16 3, ptr %a.5, align 4
+; CHECK: store i16 3, ptr %a.5, align 4, !DIAssignID ![[ID3:[0-9]+]]
+; CHECK-NEXT: llvm.dbg.assign(metadata i16 3, metadata ![[#]], metadata !DIExpression(DW_OP_LLVM_fragment, 16, 16), metadata ![[ID3]], metadata ptr %a.5, metadata !DIExpression())
+ store i32 4, ptr %a.5, align 4
+; CHECK: store i32 4, ptr %a.5, align 4, !DIAssignID ![[ID4:[0-9]+]]
+; CHECK-NEXT: llvm.dbg.assign(metadata i32 4, metadata ![[#]], metadata !DIExpression(DW_OP_LLVM_fragment, 16, 16), metadata ![[ID4]], metadata ptr %a.5, metadata !DIExpression())
+ store i32 5, ptr %a, align 4
+; CHECK: store i32 5, ptr %a, align 4, !DIAssignID ![[ID5:[0-9]+]]
+; CHECK-NEXT: llvm.dbg.assign(metadata i32 5, metadata ![[#]], metadata !DIExpression(), metadata ![[ID5]], metadata ptr %a, metadata !DIExpression())
+ ret i32 0
+}
+
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+declare i64 @_Z3getv()
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3, !4, !5, !6, !7, !8}
+!llvm.ident = !{!9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 17.0.0)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cpp", directory: "/")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = !{i32 8, !"PIC Level", i32 2}
+!6 = !{i32 7, !"PIE Level", i32 2}
+!7 = !{i32 7, !"uwtable", i32 2}
+!8 = !{i32 7, !"frame-pointer", i32 2}
+!9 = !{!"clang version 17.0.0)"}
+!10 = distinct !DISubprogram(name: "fun", linkageName: "_Z3funv", scope: !1, file: !1, line: 3, type: !11, scopeLine: 3, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !14)
+!11 = !DISubroutineType(types: !12)
+!12 = !{!13}
+!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!14 = !{}
+!15 = !DILocalVariable(name: "a", scope: !10, file: !1, line: 4, type: !13)
+!16 = !DILocation(line: 4, column: 9, scope: !10)
+!17 = !DILocalVariable(name: "b", scope: !10, file: !1, line: 4, type: !13)
+!18 = !DILocation(line: 4, column: 11, scope: !10)
+!19 = !DILocalVariable(scope: !10, file: !1, line: 4, type: !20)
+!20 = distinct !DICompositeType(tag: DW_TAG_structure_type, name: "two", file: !1, line: 1, size: 64, flags: DIFlagTypePassByValue, elements: !21, identifier: "_ZTS3two")
+!21 = !{!22, !23}
+!22 = !DIDerivedType(tag: DW_TAG_member, name: "a", scope: !20, file: !1, line: 1, baseType: !13, size: 32)
+!23 = !DIDerivedType(tag: DW_TAG_member, name: "b", scope: !20, file: !1, line: 1, baseType: !13, size: 32, offset: 32)
+!25 = !DILocation(line: 4, column: 16, scope: !10)
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