[LoopDeletion] Update debug values after loop deletion.
When loops are deleted, we don't keep track of variables modified inside
the loops, so the DI will contain the wrong value for these.
e.g.
int b() {
int i;
for (i = 0; i < 2; i++)
;
patatino();
return a;
-> 6 patatino();
7 return a;
8 }
9 int main() { b(); }
(lldb) frame var i
(int) i = 0
We mark instead these values as unavailable inserting a
@llvm.dbg.value(undef to make sure we don't end up printing an incorrect
value in the debugger. We could consider doing something fancier,
for, e.g. constants, in the future.
PR39868.
rdar://problem/46418795)
Differential Revision: https://reviews.llvm.org/D55299
llvm-svn: 348988
diff --git a/llvm/test/Transforms/LoopDeletion/diundef.ll b/llvm/test/Transforms/LoopDeletion/diundef.ll
new file mode 100644
index 0000000..c9074de
--- /dev/null
+++ b/llvm/test/Transforms/LoopDeletion/diundef.ll
@@ -0,0 +1,75 @@
+; RUN: opt %s -loop-deletion -S | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-apple-macosx10.14.0"
+
+@a = common local_unnamed_addr global i32 0, align 4, !dbg !0
+
+define i32 @b() local_unnamed_addr !dbg !12 {
+entry:
+ call void @llvm.dbg.value(metadata i32 0, metadata !16, metadata !DIExpression()), !dbg !17
+ br label %for.cond, !dbg !18
+
+for.cond: ; preds = %for.cond, %entry
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %for.cond ], !dbg !20
+ call void @llvm.dbg.value(metadata i32 %i.0, metadata !16, metadata !DIExpression()), !dbg !17
+ %inc = add nuw nsw i32 %i.0, 1, !dbg !21
+ call void @llvm.dbg.value(metadata i32 %inc, metadata !16, metadata !DIExpression()), !dbg !17
+ %exitcond = icmp ne i32 %inc, 3, !dbg !23
+ br i1 %exitcond, label %for.cond, label %for.end, !dbg !24, !llvm.loop !25
+
+; CHECK: call void @llvm.dbg.value(metadata void undef, metadata !16, metadata !DIExpression()), !dbg !17
+; CHECK-NEXT: %call = tail call i32 {{.*}} @patatino()
+for.end: ; preds = %for.cond
+ %call = tail call i32 (...) @patatino() #3, !dbg !27
+ %0 = load i32, i32* @a, align 4, !dbg !28
+ ret i32 %0, !dbg !33
+}
+
+declare i32 @patatino(...) local_unnamed_addr
+
+define i32 @main() local_unnamed_addr !dbg !34 {
+entry:
+ %call = call i32 @b(), !dbg !35
+ ret i32 0, !dbg !36
+}
+
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!7, !8, !9, !10}
+!llvm.ident = !{!11}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "a", scope: !2, file: !3, line: 1, type: !6, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang version 8.0.0 ", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5, nameTableKind: GNU)
+!3 = !DIFile(filename: "a.c", directory: "/Users/davide/work/llvm-project-20170507/build-debug/bin")
+!4 = !{}
+!5 = !{!0}
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = !{i32 2, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{i32 7, !"PIC Level", i32 2}
+!11 = !{!"clang version 8.0.0 "}
+!12 = distinct !DISubprogram(name: "b", scope: !3, file: !3, line: 2, type: !13, scopeLine: 2, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !15)
+!13 = !DISubroutineType(types: !14)
+!14 = !{!6}
+!15 = !{!16}
+!16 = !DILocalVariable(name: "i", scope: !12, file: !3, line: 3, type: !6)
+!17 = !DILocation(line: 3, column: 7, scope: !12)
+!18 = !DILocation(line: 4, column: 8, scope: !19)
+!19 = distinct !DILexicalBlock(scope: !12, file: !3, line: 4, column: 3)
+!20 = !DILocation(line: 0, scope: !19)
+!21 = !DILocation(line: 4, column: 23, scope: !22)
+!22 = distinct !DILexicalBlock(scope: !19, file: !3, line: 4, column: 3)
+!23 = !DILocation(line: 4, column: 17, scope: !22)
+!24 = !DILocation(line: 4, column: 3, scope: !19)
+!25 = distinct !{!25, !24, !26}
+!26 = !DILocation(line: 5, column: 5, scope: !19)
+!27 = !DILocation(line: 6, column: 3, scope: !12)
+!28 = !DILocation(line: 7, column: 10, scope: !12)
+!33 = !DILocation(line: 7, column: 3, scope: !12)
+!34 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 9, type: !13, scopeLine: 9, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !4)
+!35 = !DILocation(line: 9, column: 14, scope: !34)
+!36 = !DILocation(line: 9, column: 19, scope: !34)