Handle #dbg_values in SROA.

This patch properly handles #dbg_values in SROA by making sure that
any #dbg_values get moved to before a store just like
the right alloca after an aggregate alloca is broken up.

Author: rastogishubham

llvm/lib/Transforms/Scalar/SROA.cpp

@@ -5002,10 +5002,20 @@ static void insertNewDbgInst(DIBuilder &DIB, DbgVariableRecord *Orig,
                                                    BeforeInst->getIterator());
     return;
   }
+
+  if (Orig->isDbgValue()) {
+    DbgVariableRecord *DVR = DbgVariableRecord::createDbgVariableRecord(
+        NewAddr, Orig->getVariable(), NewFragmentExpr, Orig->getDebugLoc());
+    BeforeInst->getParent()->insertDbgRecordBefore(DVR,
+                                                   BeforeInst->getIterator());
+    return;
+  }
+
   if (!NewAddr->hasMetadata(LLVMContext::MD_DIAssignID)) {
     NewAddr->setMetadata(LLVMContext::MD_DIAssignID,
                          DIAssignID::getDistinct(NewAddr->getContext()));
   }
+
   DbgVariableRecord *NewAssign = DbgVariableRecord::createLinkedDVRAssign(
       NewAddr, Orig->getValue(), Orig->getVariable(), NewFragmentExpr, NewAddr,
       Orig->getAddressExpression(), Orig->getDebugLoc());
@@ -5178,6 +5188,7 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
       };
       for_each(findDbgDeclares(Fragment.Alloca), RemoveOne);
       for_each(findDVRDeclares(Fragment.Alloca), RemoveOne);
+      for_each(findDVRValues(Fragment.Alloca), RemoveOne);
 
       insertNewDbgInst(DIB, DbgVariable, Fragment.Alloca, FragmentExpr, &AI);
     }
@@ -5187,6 +5198,7 @@ bool SROA::splitAlloca(AllocaInst &AI, AllocaSlices &AS) {
   // and the individual partitions.
   for_each(findDbgDeclares(&AI), MigrateOne);
   for_each(findDVRDeclares(&AI), MigrateOne);
+  for_each(findDVRValues(&AI), MigrateOne);
   for_each(at::getAssignmentMarkers(&AI), MigrateOne);
   for_each(at::getDVRAssignmentMarkers(&AI), MigrateOne);
 
@@ -5314,6 +5326,8 @@ bool SROA::deleteDeadInstructions(
         OldDII->eraseFromParent();
       for (DbgVariableRecord *OldDII : findDVRDeclares(AI))
         OldDII->eraseFromParent();
+      for (DbgVariableRecord *OldDII : findDVRValues(AI))
+        OldDII->eraseFromParent();
     }
 
     at::deleteAssignmentMarkers(I);

llvm/lib/Transforms/Utils/PromoteMemoryToRegister.cpp

@@ -582,6 +582,9 @@ rewriteSingleStoreAlloca(AllocaInst *AI, AllocaInfo &Info, LargeBlockInfo &LBI,
         DbgItem->eraseFromParent();
       } else if (DbgItem->getExpression()->startsWithDeref()) {
         DbgItem->eraseFromParent();
+      } else if (DbgItem->isValueOfVariable()) {
+        InsertDebugValueAtStoreLoc(DbgItem, Info.OnlyStore, DIB);
+        DbgItem->eraseFromParent();
       }
     }
   };

llvm/test/DebugInfo/X86/sroa-after-inlining.ll

@@ -35,9 +35,11 @@
 ; CHECK: _Z3barv
 ; CHECK: %[[RESULT:.*]] = call i32 @_Z3foov
 ; CHECK: llvm.dbg.value(metadata i32 %[[RESULT]], metadata [[METADATA_IDX1:![0-9]+]]
+; CHECK: llvm.dbg.value(metadata i32 %[[RESULT]], metadata [[METADATA_IDX2:![0-9]+]]
 ; CHECK: ret
 ; CHECK: DICompileUnit
-; CHECK: [[METADATA_IDX1]] = !DILocalVariable(name: "result"
+; CHECK: [[METADATA_IDX2]] = !DILocalVariable(name: "result"
+; CHECK: [[METADATA_IDX1]] = !DILocalVariable(name: "this"
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"

llvm/test/DebugInfo/sroa-handle-dbg-value.ll

@@ -0,0 +1,56 @@
+; This test was obtained from swift source code and then automatically reducing it via Delta.
+; The swift source code was from the test test/DebugInfo/debug_scope_distinct.swift.
+
+; RUN: opt %s -S -p=sroa -o - | FileCheck %s
+
+; CHECK: [[SROA_5_SROA_21:%.*]] = alloca [7 x i8], align 8
+; CHECK-NEXT: tail call void @llvm.dbg.value(metadata ptr [[SROA_5_SROA_21]], metadata [[META59:![0-9]+]], metadata !DIExpression(DW_OP_LLVM_fragment, 72, 56)), !dbg [[DBG72:![0-9]+]]
+
+; CHECK: tail call void @llvm.dbg.value(metadata ptr [[REG2:%[0-9]+]], metadata [[META54:![0-9]+]], metadata !DIExpression(DW_OP_deref)), !dbg [[DBG78:![0-9]+]]
+; CHECK-NEXT: tail call void @llvm.dbg.value(metadata ptr [[REG2:%[0-9]+]], metadata [[META56:![0-9]+]], metadata !DIExpression(DW_OP_deref)), !dbg [[DBG78]]
+; CHECK-NEXT: tail call void @llvm.dbg.value(metadata i64 0, metadata [[META57:![0-9]+]], metadata !DIExpression()), !dbg [[DBG78]]
+
+; CHECK: [[SROA_418_SROA_COPYLOAD:%.*]] = load i8, ptr [[SROA_418_0_U1_IDX:%.*]], align 8, !dbg [[DBG78]]
+; CHECK-NEXT: tail call void @llvm.dbg.value(metadata i8 [[SROA_418_SROA_COPYLOAD]], metadata [[META59]], metadata !DIExpression(DW_OP_LLVM_fragment, 64, 8)), !dbg [[DBG72]]
+
+%T4main1TV13TangentVectorV = type <{ %T4main1UV13TangentVectorV, [7 x i8], %T4main1UV13TangentVectorV }>
+%T4main1UV13TangentVectorV = type <{ %T1M1SVySfG, [7 x i8], %T4main1VV13TangentVectorV }>
+%T1M1SVySfG = type <{ ptr, %Ts4Int8V }>
+%Ts4Int8V = type <{ i8 }>
+%T4main1VV13TangentVectorV = type <{ %T1M1SVySfG }>
+define hidden swiftcc void @"$s4main1TV13TangentVectorV1poiyA2E_AEtFZ"(ptr noalias nocapture sret(%T4main1TV13TangentVectorV) %0, ptr noalias nocapture dereferenceable(57) %1, ptr noalias nocapture dereferenceable(57) %2) #0 !dbg !44 {
+  %7 = alloca %T4main1VV13TangentVectorV
+  %8 = alloca %T4main1UV13TangentVectorV
+  tail call void @llvm.dbg.value(metadata ptr %8, metadata !82, metadata !DIExpression()), !dbg !92
+  tail call void @llvm.dbg.value(metadata ptr %1, metadata !54, metadata !DIExpression(DW_OP_deref)), !dbg !95
+  tail call void @llvm.dbg.value(metadata ptr %2, metadata !56, metadata !DIExpression(DW_OP_deref)), !dbg !95
+  tail call void @llvm.dbg.value(metadata i64 0, metadata !57, metadata !DIExpression()), !dbg !95
+  %.u2 = getelementptr inbounds %T4main1TV13TangentVectorV, ptr %1, i32 0, i32 2
+  call void @llvm.memcpy.p0.p0.i64(ptr align 8 %8, ptr align 8 %.u2, i64 25, i1 false), !dbg !95
+  %.s7 = getelementptr inbounds %T4main1UV13TangentVectorV, ptr %8, i32 0, i32 0
+  %.s7.b = getelementptr inbounds %T1M1SVySfG, ptr %.s7, i32 0, i32 1
+  %.s7.b._value = getelementptr inbounds %Ts4Int8V, ptr %.s7.b, i32 0, i32 0
+  %26 = load i8, ptr %.s7.b._value
+  %.v9 = getelementptr inbounds %T4main1UV13TangentVectorV, ptr %8, i32 0, i32 2
+  call void @llvm.memcpy.p0.p0.i64(ptr align 8 %7, ptr align 8 %.v9, i64 9, i1 false)
+  %.s11 = getelementptr inbounds %T4main1VV13TangentVectorV, ptr %7, i32 0, i32 0
+  %.s11.c = getelementptr inbounds %T1M1SVySfG, ptr %.s11, i32 0, i32 0
+  %32 = load ptr, ptr %.s11.c
+  ret void
+}
+!llvm.module.flags = !{ !7, !15}
+!7 = !{i32 2, !"Debug Info Version", i32 3}
+!15 = !{i32 1, !"Swift Minor Version", i8 0}
+!16 = distinct !DICompileUnit(language: DW_LANG_Swift, file: !17, sdk: "MacOSX14.2.sdk")
+!17 = !DIFile(filename: "/Users/shubham/Development/apple/swift/test/IRGen/debug_scope_distinct.swift", directory: "/Users/shubham/Development/apple/build/Ninja-RelWithDebInfoAssert/swift-macosx-arm64/test")
+!44 = distinct !DISubprogram( unit: !16, retainedNodes: !53)
+!53 = !{}
+!54 = !DILocalVariable( scope: !44, flags: DIFlagArtificial)
+!56 = !DILocalVariable( scope: !44, flags: DIFlagArtificial)
+!57 = !DILocalVariable( scope: !44, flags: DIFlagArtificial)
+!74 = distinct !DISubprogram( unit: !16, retainedNodes: !81)
+!81 = !{}
+!82 = !DILocalVariable( scope: !74, flags: DIFlagArtificial)
+!91 = distinct !DILocation( scope: !44)
+!92 = !DILocation( scope: !74, inlinedAt: !91)
+!95 = !DILocation( scope: !44)