PR27938: Don't remove valid DebugLoc in Scalarizer

[Ka-Ka]

Summary

Added checks to make sure the Scalarizer::transferMetadata() don't
remove valid debug location's from instructions. This is important as
the verifier pass require that e.g. inlinable callsites have a valid
debug location.

https://llvm.org/bugs/show_bug.cgi?id=27938

[Ka-Ka]

Inverted diff. Abandon.

lib/Transforms/Scalar/Scalarizer.cpp

void Scalarizer::transferMetadata(Instruction *Op, const ValueVector &CV) {
   for (unsigned I = 0, E = CV.size(); I != E; ++I) {
     if (Instruction *New = dyn_cast<Instruction>(CV[I])) {
       for (SmallVectorImpl<std::pair<unsigned, MDNode *>>::iterator
                MI = MDs.begin(),
                ME = MDs.end();
            MI != ME; ++MI)
         if (canTransferMetadata(MI->first))
           New->setMetadata(MI->first, MI->second);
-      if (Op->getDebugLoc() && !New->getDebugLoc())
-        New->setDebugLoc(Op->getDebugLoc());
     }
   }
 }
 
 // Try to fill in Layout from Ty, returning true on success.  Alignment is
 // the alignment of the vector, or 0 if the ABI default should be used.
 bool Scalarizer::getVectorLayout(Type *Ty, unsigned Alignment,
                                  VectorLayout &Layout, const DataLayout &DL) {

test/Transforms/Scalarizer/dbgloc-bug.ll

-; RUN: opt -S -march=x86 -scalarizer -o /dev/null %s
-
-; Reproducer for pr27938
-; https://llvm.org/bugs/show_bug.cgi?id=27938
-
-@d = internal unnamed_addr global i1 false
-@e = internal unnamed_addr global i16 0
-@a = global i16 0
-@b = global i16 0
-
-; Function Attrs: noinline norecurse nounwind readonly
-define i16 @f1() #0 !dbg !6 {
-  %_tmp1 = load i16, i16* @a, align 1, !dbg !10
-  ret i16 %_tmp1, !dbg !10
-}
-
-; Function Attrs: noinline norecurse nounwind
-define void @f2() #1 !dbg !11 {
-bb1:
-  %.old = load i16, i16* @b, align 1, !dbg !14
-  %_tmp3.old = icmp eq i16 %.old, 0, !dbg !14
-  br i1 %_tmp3.old, label %bb3.preheader, label %bb1.bb8_crit_edge, !dbg !14
-
-bb1.bb8_crit_edge:                                ; preds = %bb1
-  %_tmp19.b.pre = load i1, i1* @d, align 1
-  br label %bb8, !dbg !14
-
-bb3.preheader:                                    ; preds = %bb1
-  %e.promoted = load i16, i16* @e, align 1, !dbg !16
-  %_tmp7 = tail call i16 @f1(), !dbg !16
-  %0 = insertelement <4 x i16> <i16 undef, i16 0, i16 0, i16 0>, i16 %e.promoted, i32 0
-  %broadcast.splatinsert5 = insertelement <4 x i16> undef, i16 %_tmp7, i32 0
-  %broadcast.splat6 = shufflevector <4 x i16> %broadcast.splatinsert5, <4 x i16> undef, <4 x i32> zeroinitializer
-  br label %vector.body
-
-vector.body:                                      ; preds = %vector.body, %bb3.preheader
-  %index = phi i16 [ 0, %bb3.preheader ], [ %index.next, %vector.body ]
-  %vec.phi = phi <4 x i16> [ %0, %bb3.preheader ], [ %1, %vector.body ]
-  %1 = xor <4 x i16> %vec.phi, %broadcast.splat6, !dbg !16
-  %index.next = add i16 %index, 4
-  %2 = icmp eq i16 %index.next, -4
-  br i1 %2, label %middle.block, label %vector.body
-
-middle.block:                                     ; preds = %vector.body
-  %.lcssa = phi <4 x i16> [ %1, %vector.body ]
-  %rdx.shuf = shufflevector <4 x i16> %.lcssa, <4 x i16> undef, <4 x i32> <i32 2, i32 3, i32 undef, i32 undef>, !dbg !16
-  %bin.rdx = xor <4 x i16> %.lcssa, %rdx.shuf, !dbg !16
-  br label %bb3
-
-bb3:                                              ; preds = %middle.block
-  %rdx.shuf7 = shufflevector <4 x i16> %bin.rdx, <4 x i16> undef, <4 x i32> <i32 1, i32 undef, i32 undef, i32 undef>, !dbg !16
-  %bin.rdx8 = xor <4 x i16> %bin.rdx, %rdx.shuf7, !dbg !16
-  %3 = extractelement <4 x i16> %bin.rdx8, i32 0, !dbg !16
-  %_tmp10.2 = xor i16 %3, %_tmp7, !dbg !16
-  store i1 true, i1* @d, align 1
-  store i16 %_tmp10.2, i16* @e, align 1, !dbg !16
-  br label %bb8
-
-bb8:                                              ; preds = %bb1.bb8_crit_edge, %bb3
-  %_tmp19.b = phi i1 [ %_tmp19.b.pre, %bb1.bb8_crit_edge ], [ true, %bb3 ]
-  %_tmp19 = zext i1 %_tmp19.b to i16
-  store i16 %_tmp19, i16* @b, align 1, !dbg !22
-  ret void, !dbg !23
-}
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!3, !4}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, enums: !2, retainedTypes: !2)
-!1 = !DIFile(filename: "dbgloc-bug.c", directory: ".")
-!2 = !{}
-!3 = !{i32 2, !"Dwarf Version", i32 4}
-!4 = !{i32 2, !"Debug Info Version", i32 3}
-!6 = distinct !DISubprogram(name: "f1", scope: !1, file: !1, line: 9, type: !7, isLocal: false, isDefinition: true, scopeLine: 10, isOptimized: true, unit: !0, variables: !2)
-!7 = !DISubroutineType(types: !8)
-!8 = !{!9}
-!9 = !DIBasicType(name: "short", size: 16, align: 16, encoding: DW_ATE_signed)
-!10 = !DILocation(line: 11, column: 5, scope: !6)
-!11 = distinct !DISubprogram(name: "f2", scope: !1, file: !1, line: 14, type: !12, isLocal: false, isDefinition: true, scopeLine: 15, isOptimized: true, unit: !0, variables: !2)
-!12 = !DISubroutineType(types: !13)
-!13 = !{null}
-!14 = !DILocation(line: 19, column: 9, scope: !15)
-!15 = !DILexicalBlock(scope: !11, file: !1, line: 17, column: 5)
-!16 = !DILocation(line: 24, column: 9, scope: !15)
-!22 = !DILocation(line: 27, column: 5, scope: !11)
-!23 = !DILocation(line: 28, column: 1, scope: !11)