102 lines
4.1 KiB
LLVM
102 lines
4.1 KiB
LLVM
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; RUN: opt < %s -S -simplifycfg | FileCheck %s
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; When SimplifyCFG changes the PHI node into a select instruction, the debug
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; information becomes ambiguous. It causes the debugger to display wrong
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; variable value.
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;
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; When in the debugger, on the line "if (read == 4)", the value of "result"
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; is reported as '2', where it should be zero.
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; IR generated with:
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; clang -S -g -O2 -emit-llvm pr38763.cpp -o pr38763.ll -mllvm -opt-bisect-limit=10
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; // pr38763.cpp
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; int main() {
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; volatile int foo = 4;
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; int read = foo;
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; int read1 = foo;
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;
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; int result = 0;
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; if (read == 4) {
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; result = read1 + 2;
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; } else {
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; result = read1 - 2;
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; }
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;
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; return result;
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; }
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; Remove the '@llvm.dbg.value' associated with 'result' for the true/false
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; branches, as they becomes ambiguous.
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; CHECK-LABEL: entry
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; CHECK: %cmp = icmp eq i32 %foo.0., 4, !dbg !14
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; CHECK: %add = add nsw i32 %foo.0.4, 2, !dbg !16
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; CHECK-NOT: @llvm.dbg.value(metadata i32 %add
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; CHECK: %sub = add nsw i32 %foo.0.4, -2, !dbg !16
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; CHECK-NOT: @llvm.dbg.value(metadata i32 %sub
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; CHECK: %result.0 = select i1 %cmp, i32 %add, i32 %sub
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; CHECK: call void @llvm.dbg.value(metadata i32 %result.0, metadata !12, metadata !DIExpression()), !dbg !13
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; ModuleID = 'pr38763.cpp'
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source_filename = "pr38763.cpp"
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target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
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target triple = "x86_64-pc-linux-gnu"
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; Function Attrs: norecurse nounwind uwtable
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define dso_local i32 @main() local_unnamed_addr #0 !dbg !7 {
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entry:
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%foo = alloca i32, align 4
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%foo.0..sroa_cast = bitcast i32* %foo to i8*
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store volatile i32 4, i32* %foo, align 4
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%foo.0. = load volatile i32, i32* %foo, align 4
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%foo.0.4 = load volatile i32, i32* %foo, align 4
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call void @llvm.dbg.value(metadata i32 0, metadata !16, metadata !DIExpression()), !dbg !27
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%cmp = icmp eq i32 %foo.0., 4, !dbg !28
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br i1 %cmp, label %if.then, label %if.else, !dbg !30
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if.then: ; preds = %entry
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%add = add nsw i32 %foo.0.4, 2, !dbg !31
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call void @llvm.dbg.value(metadata i32 %add, metadata !16, metadata !DIExpression()), !dbg !27
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br label %if.end
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if.else: ; preds = %entry
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%sub = add nsw i32 %foo.0.4, -2, !dbg !34
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call void @llvm.dbg.value(metadata i32 %sub, metadata !16, metadata !DIExpression()), !dbg !27
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br label %if.end
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if.end: ; preds = %if.else, %if.then
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%result.0 = phi i32 [ %add, %if.then ], [ %sub, %if.else ]
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call void @llvm.dbg.value(metadata i32 %result.0, metadata !16, metadata !DIExpression()), !dbg !27
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ret i32 %result.0
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}
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.value(metadata, metadata, metadata) #2
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!llvm.dbg.cu = !{!0}
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!llvm.module.flags = !{!3, !4, !5}
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!llvm.ident = !{!6}
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!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 8.0.0 (trunk 342209)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
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!1 = !DIFile(filename: "pr38763.cpp", directory: ".")
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!2 = !{}
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!3 = !{i32 2, !"Dwarf Version", i32 4}
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!4 = !{i32 2, !"Debug Info Version", i32 3}
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!5 = !{i32 1, !"wchar_size", i32 4}
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!6 = !{!"clang version 8.0.0 (trunk 342209)"}
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!7 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: true, unit: !0, retainedNodes: !11)
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!8 = !DISubroutineType(types: !9)
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!9 = !{!10}
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!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
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!11 = !{!16}
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!16 = !DILocalVariable(name: "result", scope: !7, file: !1, line: 6, type: !10)
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!27 = !DILocation(line: 6, column: 7, scope: !7)
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!28 = !DILocation(line: 7, column: 12, scope: !29)
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!29 = distinct !DILexicalBlock(scope: !7, file: !1, line: 7, column: 7)
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!30 = !DILocation(line: 7, column: 7, scope: !7)
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!31 = !DILocation(line: 8, column: 20, scope: !32)
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!32 = distinct !DILexicalBlock(scope: !29, file: !1, line: 7, column: 18)
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!34 = !DILocation(line: 10, column: 20, scope: !35)
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!35 = distinct !DILexicalBlock(scope: !29, file: !1, line: 9, column: 10)
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