[CallSiteSplitting] Add debug location to created PHI nodes.

There are 2 cases when we create PHI nodes:
 * For the result of the call that was duplicated in the split blocks.
   Those PHI nodes should have the debug location of the call.

 * For values produced before the call. Those instructions need to be
   duplicated in the split blocks and the PHI nodes should have the
   debug locations of those instructions.

Fixes PR37962.

Reviewers: junbuml, gbedwell, vsk

Reviewed By: junbuml

Tags: #debug-info

Differential Revision: https://reviews.llvm.org/D51919

llvm-svn: 341970

llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp

@@ -312,8 +312,10 @@ static void splitCallSite(
   // `musttail` calls must be followed by optional `bitcast`, and `ret`. The
   // split blocks will be terminated right after that so there're no users for
   // this phi in a `TailBB`.
-  if (!IsMustTailCall && !Instr->use_empty())
+  if (!IsMustTailCall && !Instr->use_empty()) {
     CallPN = PHINode::Create(Instr->getType(), Preds.size(), "phi.call");
+    CallPN->setDebugLoc(Instr->getDebugLoc());
+  }
 
   LLVM_DEBUG(dbgs() << "split call-site : " << *Instr << " into \n");
 
@@ -394,6 +396,7 @@ static void splitCallSite(
       if (isa<PHINode>(CurrentI))
         continue;
       PHINode *NewPN = PHINode::Create(CurrentI->getType(), Preds.size());
+      NewPN->setDebugLoc(CurrentI->getDebugLoc());
       for (auto &Mapping : ValueToValueMaps)
         NewPN->addIncoming(Mapping[CurrentI],
                            cast<Instruction>(Mapping[CurrentI])->getParent());

llvm/test/Transforms/CallSiteSplitting/callsite-split-preserve-debug.ll

@@ -0,0 +1,85 @@
+; RUN: opt -callsite-splitting -S < %s | FileCheck %s
+
+; CHECK-LABEL: @test1
+; CHECK:         [[R1:%.+]] = call i32 @callee(i32 0, i32 %dd), !dbg [[DBG1:!.*]]
+; CHECK:         [[R2:%.+]] = call i32 @callee(i32 1, i32 %dd), !dbg [[DBG1]]
+; CHECK-LABEL: CallSite:
+; CHECK-NEXT:    phi i32 [ [[R2]], %land.rhs.split ], [ [[R1]], %entry.split ], !dbg [[DBG1]]
+
+define i32 @test1(i32* dereferenceable(4) %cc, i32 %dd) !dbg !6 {
+entry:
+  br i1 undef, label %CallSite, label %land.rhs
+
+land.rhs:                                         ; preds = %entry
+  br label %CallSite
+
+CallSite:                                         ; preds = %land.rhs, %entry
+  %pv = phi i32 [ 0, %entry ], [ 1, %land.rhs ]
+  %call = call i32 @callee(i32 %pv, i32 %dd), !dbg !18
+  ret i32 %call
+}
+
+; CHECK-LABEL: @test2
+; CHECK:         [[LV1:%.*]] = load i32, i32* %ptr, align 4, !dbg [[DBG_LV:!.*]]
+; CHECK-NEXT:    [[R1:%.+]] = call i32 @callee(i32 0, i32 10), !dbg [[DBG_CALL:!.*]]
+; CHECK:         [[LV2:%.*]] = load i32, i32* %ptr, align 4, !dbg [[DBG_LV]]
+; CHECK-NEXT:    [[R2:%.+]] = call i32 @callee(i32 0, i32 %i), !dbg [[DBG_CALL]]
+; CHECK-LABEL: CallSite:
+; CHECK-NEXT:    phi i32 [ [[LV1]], %Header.split ], [ [[LV2]], %TBB.split ], !dbg [[DBG_LV]]
+; CHECK-NEXT:    phi i32 [ [[R1]], %Header.split ], [ [[R2]], %TBB.split ], !dbg [[DBG_CALL]]
+
+define void @test2(i32* %ptr, i32 %i) !dbg !19 {
+Header:
+  %tobool = icmp ne i32 %i, 10
+  br i1 %tobool, label %TBB, label %CallSite
+
+TBB:                                              ; preds = %Header
+  br i1 undef, label %CallSite, label %End
+
+CallSite:                                         ; preds = %TBB, %Header
+  %lv = load i32, i32* %ptr, align 4, !dbg !25
+  %cv = call i32 @callee(i32 0, i32 %i), !dbg !26
+  %sub = sub nsw i32 %lv, %cv
+  br label %End
+
+End:                                              ; preds = %CallSite, %TBB
+  ret void
+}
+
+define i32 @callee(i32 %aa, i32 %bb) {
+entry:
+  %add = add nsw i32 %aa, %bb
+  ret i32 %add
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.debugify = !{!3, !4}
+!llvm.module.flags = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C, file: !1, producer: "debugify", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "<stdin>", directory: "/")
+!2 = !{}
+!3 = !{i32 23}
+!4 = !{i32 11}
+!5 = !{i32 2, !"Debug Info Version", i32 3}
+!6 = distinct !DISubprogram(name: "test", linkageName: "test", scope: null, file: !1, line: 3, type: !7, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: true, unit: !0, retainedNodes: !8)
+!7 = !DISubroutineType(types: !2)
+!8 = !{!9, !11, !13, !15, !16, !17}
+!9 = !DILocalVariable(name: "2", scope: !6, file: !1, line: 3, type: !10)
+!10 = !DIBasicType(name: "ty64", size: 64, encoding: DW_ATE_unsigned)
+!11 = !DILocalVariable(name: "3", scope: !6, file: !1, line: 5, type: !12)
+!12 = !DIBasicType(name: "ty32", size: 32, encoding: DW_ATE_unsigned)
+!13 = !DILocalVariable(name: "4", scope: !6, file: !1, line: 6, type: !14)
+!14 = !DIBasicType(name: "ty8", size: 8, encoding: DW_ATE_unsigned)
+!15 = !DILocalVariable(name: "5", scope: !6, file: !1, line: 9, type: !12)
+!16 = !DILocalVariable(name: "6", scope: !6, file: !1, line: 10, type: !12)
+!17 = !DILocalVariable(name: "7", scope: !6, file: !1, line: 11, type: !10)
+!18 = !DILocation(line: 10, column: 1, scope: !6)
+!19 = distinct !DISubprogram(name: "test_add_new_phi", linkageName: "test_add_new_phi", scope: null, file: !1, line: 14, type: !7, isLocal: false, isDefinition: true, scopeLine: 14, isOptimized: true, unit: !0, retainedNodes: !20)
+!20 = !{!21, !22, !23, !24}
+!21 = !DILocalVariable(name: "8", scope: !19, file: !1, line: 14, type: !14)
+!22 = !DILocalVariable(name: "9", scope: !19, file: !1, line: 17, type: !10)
+!23 = !DILocalVariable(name: "10", scope: !19, file: !1, line: 18, type: !12)
+!24 = !DILocalVariable(name: "11", scope: !19, file: !1, line: 20, type: !12)
+!25 = !DILocation(line: 18, column: 1, scope: !19)
+!26 = !DILocation(line: 19, column: 1, scope: !19)