Try to not lose variable's debug info during instcombine.

This is done by lowering dbg.declare intrinsic into dbg.value intrinsic.
Radar 9143931.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@127834 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Transforms/Utils/Local.h b/include/llvm/Transforms/Utils/Local.h
index 8f97428649be10e5708dbe08354ec9a8654a2ba5..16bcc545033fcf03f443e1cf92d1bfc0c4d7903f 100644 (file)
--- a/include/llvm/Transforms/Utils/Local.h
+++ b/include/llvm/Transforms/Utils/Local.h
@@ -19,6 +19,7 @@ namespace llvm {
 
 class User;
 class BasicBlock;
+class Function;
 class BranchInst;
 class Instruction;
 class DbgDeclareInst;
@@ -169,6 +170,10 @@ static inline unsigned getKnownAlignment(Value *V, const TargetData *TD = 0) {
 bool ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
                                      StoreInst *SI, DIBuilder &Builder);
 
+/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
+/// of llvm.dbg.value intrinsics.
+bool LowerDbgDeclare(Function &F);
+
 } // End llvm namespace
 
 #endif

diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index 37123d0621ebc306139a1954b152d66a6dd331ec..d88162a703f8bee26c8cb7098391af3238b50d6f 100644 (file)
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1648,6 +1648,10 @@ bool InstCombiner::runOnFunction(Function &F) {
   
   bool EverMadeChange = false;
 
+  // Lower dbg.declare intrinsics otherwise their value may be clobbered
+  // by instcombiner.
+  EverMadeChange = LowerDbgDeclare(F);
+
   // Iterate while there is work to do.
   unsigned Iteration = 0;
   while (DoOneIteration(F, Iteration++))

diff --git a/lib/Transforms/Utils/Local.cpp b/lib/Transforms/Utils/Local.cpp
index ddab6e0e9ef36626fe065162b1d666c7ef9bad8a..e54dfb3dc73f862a9a686d1ee7bbdde668895f8e 100644 (file)
--- a/lib/Transforms/Utils/Local.cpp
+++ b/lib/Transforms/Utils/Local.cpp
@@ -783,3 +783,29 @@ bool llvm::ConvertDebugDeclareToDebugValue(DbgDeclareInst *DDI,
   return true;
 }
 
+/// LowerDbgDeclare - Lowers llvm.dbg.declare intrinsics into appropriate set
+/// of llvm.dbg.value intrinsics.
+bool llvm::LowerDbgDeclare(Function &F) {
+  DIBuilder DIB(*F.getParent());
+  SmallVector<DbgDeclareInst *, 4> Dbgs;
+  for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
+    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end(); BI != BE; ++BI) {
+      if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(BI))
+        Dbgs.push_back(DDI);
+    }
+  if (Dbgs.empty())
+    return false;
+
+  for (SmallVector<DbgDeclareInst *, 4>::iterator I = Dbgs.begin(),
+         E = Dbgs.end(); I != E; ++I) {
+    DbgDeclareInst *DDI = *I;
+    if (AllocaInst *AI = dyn_cast_or_null<AllocaInst>(DDI->getAddress())) {
+      for (Value::use_iterator UI = AI->use_begin(), E = AI->use_end();
+           UI != E; ++UI)
+        if (StoreInst *SI = dyn_cast<StoreInst>(*UI))
+          ConvertDebugDeclareToDebugValue(DDI, SI, DIB);
+    }
+    DDI->eraseFromParent();
+  }
+  return true;
+}

diff --git a/test/Transforms/InstCombine/debuginfo.ll b/test/Transforms/InstCombine/debuginfo.ll
new file mode 100644 (file)
index 0000000..f6892fc
--- /dev/null
+++ b/test/Transforms/InstCombine/debuginfo.ll
@@ -0,0 +1,57 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
+
+declare i64 @llvm.objectsize.i64(i8*, i1) nounwind readnone
+
+declare i8* @foo(i8*, i32, i64, i64) nounwind
+
+define hidden i8* @foobar(i8* %__dest, i32 %__val, i64 %__len) nounwind inlinehint ssp {
+entry:
+  %__dest.addr = alloca i8*, align 8
+  %__val.addr = alloca i32, align 4
+  %__len.addr = alloca i64, align 8
+  store i8* %__dest, i8** %__dest.addr, align 8, !tbaa !1
+; CHECK-NOT: call void @llvm.dbg.declare
+; CHECK: call void @llvm.dbg.value
+  call void @llvm.dbg.declare(metadata !{i8** %__dest.addr}, metadata !0), !dbg !16
+  store i32 %__val, i32* %__val.addr, align 4, !tbaa !17
+  call void @llvm.dbg.declare(metadata !{i32* %__val.addr}, metadata !7), !dbg !18
+  store i64 %__len, i64* %__len.addr, align 8, !tbaa !19
+  call void @llvm.dbg.declare(metadata !{i64* %__len.addr}, metadata !9), !dbg !20
+  %tmp = load i8** %__dest.addr, align 8, !dbg !21, !tbaa !13
+  %tmp1 = load i32* %__val.addr, align 4, !dbg !21, !tbaa !17
+  %tmp2 = load i64* %__len.addr, align 8, !dbg !21, !tbaa !19
+  %tmp3 = load i8** %__dest.addr, align 8, !dbg !21, !tbaa !13
+  %0 = call i64 @llvm.objectsize.i64(i8* %tmp3, i1 false), !dbg !21
+  %call = call i8* @foo(i8* %tmp, i32 %tmp1, i64 %tmp2, i64 %0), !dbg !21
+  ret i8* %call, !dbg !21
+}
+
+!llvm.dbg.lv.foobar = !{!0, !7, !9}
+!llvm.dbg.sp = !{!1}
+
+!0 = metadata !{i32 590081, metadata !1, metadata !"__dest", metadata !2, i32 16777294, metadata !6, i32 0} ; [ DW_TAG_arg_variable ]
+!1 = metadata !{i32 589870, i32 0, metadata !2, metadata !"foobar", metadata !"foobar", metadata !"", metadata !2, i32 79, metadata !4, i1 true, i1 true, i32 0, i32 0, i32 0, i32 256, i1 true, i8* (i8*, i32, i64)* @foobar} ; [ DW_TAG_subprogram ]
+!2 = metadata !{i32 589865, metadata !"string.h", metadata !"Game", metadata !3} ; [ DW_TAG_file_type ]
+!3 = metadata !{i32 589841, i32 0, i32 12, metadata !"bits.c", metadata !"Game", metadata !"clang version 3.0 (trunk 127710)", i1 true, i1 true, metadata !"", i32 0} ; [ DW_TAG_compile_unit ]
+!4 = metadata !{i32 589845, metadata !2, metadata !"", metadata !2, i32 0, i64 0, i64 0, i32 0, i32 0, i32 0, metadata !5, i32 0, i32 0} ; [ DW_TAG_subroutine_type ]
+!5 = metadata !{metadata !6}
+!6 = metadata !{i32 589839, metadata !3, metadata !"", null, i32 0, i64 64, i64 64, i64 0, i32 0, null} ; [ DW_TAG_pointer_type ]
+!7 = metadata !{i32 590081, metadata !1, metadata !"__val", metadata !2, i32 33554510, metadata !8, i32 0} ; [ DW_TAG_arg_variable ]
+!8 = metadata !{i32 589860, metadata !3, metadata !"int", null, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ]
+!9 = metadata !{i32 590081, metadata !1, metadata !"__len", metadata !2, i32 50331726, metadata !10, i32 0} ; [ DW_TAG_arg_variable ]
+!10 = metadata !{i32 589846, metadata !3, metadata !"size_t", metadata !2, i32 80, i64 0, i64 0, i64 0, i32 0, metadata !11} ; [ DW_TAG_typedef ]
+!11 = metadata !{i32 589846, metadata !3, metadata !"__darwin_size_t", metadata !2, i32 90, i64 0, i64 0, i64 0, i32 0, metadata !12} ; [ DW_TAG_typedef ]
+!12 = metadata !{i32 589860, metadata !3, metadata !"long unsigned int", null, i32 0, i64 64, i64 64, i64 0, i32 0, i32 7} ; [ DW_TAG_base_type ]
+!13 = metadata !{metadata !"any pointer", metadata !14}
+!14 = metadata !{metadata !"omnipotent char", metadata !15}
+!15 = metadata !{metadata !"Simple C/C++ TBAA", null}
+!16 = metadata !{i32 78, i32 28, metadata !1, null}
+!17 = metadata !{metadata !"int", metadata !14}
+!18 = metadata !{i32 78, i32 40, metadata !1, null}
+!19 = metadata !{metadata !"long", metadata !14}
+!20 = metadata !{i32 78, i32 54, metadata !1, null}
+!21 = metadata !{i32 80, i32 3, metadata !22, null}
+!22 = metadata !{i32 589835, metadata !23, i32 80, i32 3, metadata !2, i32 7} ; [ DW_TAG_lexical_block ]
+!23 = metadata !{i32 589835, metadata !1, i32 79, i32 1, metadata !2, i32 6} ; [ DW_TAG_lexical_block ]