From 898fa74bf23beff0a5e9155741cdc97ce48fb515 Mon Sep 17 00:00:00 2001
From: Reid Kleckner <rnk@google.com>
Date: Tue, 8 Dec 2015 21:50:52 +0000
Subject: [PATCH] [CGP] Check that we have an insert point before moving
 llvm.dbg.value around

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@255055 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CodeGenPrepare.cpp                     | 12 +++--
 .../Transforms/CodeGenPrepare/catchpad-phi-cast.ll | 57 ++++++++++++++++++++++
 2 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/lib/CodeGen/CodeGenPrepare.cpp b/lib/CodeGen/CodeGenPrepare.cpp
index d619044e86c..615bcf33767 100644
--- a/lib/CodeGen/CodeGenPrepare.cpp
+++ b/lib/CodeGen/CodeGenPrepare.cpp
@@ -5251,12 +5251,16 @@ bool CodeGenPrepare::placeDbgValues(Function &F) {
 
       Instruction *VI = dyn_cast_or_null<Instruction>(DVI->getValue());
       if (VI && VI != PrevNonDbgInst && !VI->isTerminator()) {
-        DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI);
-        DVI->removeFromParent();
+        BasicBlock::iterator IP;
         if (isa<PHINode>(VI))
-          DVI->insertBefore(&*VI->getParent()->getFirstInsertionPt());
+          IP = VI->getParent()->getFirstInsertionPt();
         else
-          DVI->insertAfter(VI);
+          IP = ++VI->getIterator();
+        if (IP == VI->getParent()->end())
+          continue;
+        DEBUG(dbgs() << "Moving Debug Value before :\n" << *DVI << ' ' << *VI);
+        DVI->removeFromParent();
+        VI->getParent()->getInstList().insert(IP, DVI);
         MadeChange = true;
         ++NumDbgValueMoved;
       }
diff --git a/test/Transforms/CodeGenPrepare/catchpad-phi-cast.ll b/test/Transforms/CodeGenPrepare/catchpad-phi-cast.ll
index 998ca7069c8..c0b63b7d6d9 100644
--- a/test/Transforms/CodeGenPrepare/catchpad-phi-cast.ll
+++ b/test/Transforms/CodeGenPrepare/catchpad-phi-cast.ll
@@ -10,6 +10,7 @@ declare i32 @__CxxFrameHandler3(...)
 declare void @f()
 
 declare void @g(i8*)
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) #2
 
 ; CodeGenPrepare will want to sink these bitcasts, but it selects the catchpad
 ; blocks as the place to which the bitcast should be sunk.  Since catchpads
@@ -57,3 +58,59 @@ catchend1:
 catchend2:
   catchendpad unwind to caller
 }
+
+; CodeGenPrepare will want to hoist these llvm.dbg.value calls to the phi, but
+; there is no insertion point in a catchpad block.
+
+; CHECK-LABEL: @test_dbg_value(
+define void @test_dbg_value() personality i32 (...)* @__CxxFrameHandler3 {
+entry:
+  %a = alloca i8
+  %b = alloca i8
+  invoke void @f() to label %next unwind label %catch.dispatch
+next:
+  invoke void @f() to label %ret unwind label %catch.dispatch
+ret:
+  ret void
+
+catch.dispatch:
+  %p = phi i8* [%a, %entry], [%b, %next]
+  %cp1 = catchpad [] to label %catch unwind label %catchend
+
+catch:
+  tail call void @llvm.dbg.value(metadata i8* %p, i64 0, metadata !11, metadata !13), !dbg !14
+  invoke void @g(i8* %p) to label %catchret unwind label %catchend
+catchret:
+  catchret %cp1 to label %ret
+
+; CHECK: catch.dispatch:
+; CHECK-NEXT: phi i8
+; CHECK-NEXT: catchpad
+; CHECK-NOT: llvm.dbg.value
+
+; CHECK: catch:
+; CHECK-NEXT: call void @llvm.dbg.value
+
+catchend:
+  catchendpad unwind to caller
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!7, !8, !9}
+!llvm.ident = !{!10}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 254906) (llvm/trunk 254917)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: null, subprograms: !3)
+!1 = !DIFile(filename: "t.c", directory: "D:\5Csrc\5Cllvm\5Cbuild")
+!3 = !{!4}
+!4 = distinct !DISubprogram(name: "test_dbg_value", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, isOptimized: false, variables: null)
+!5 = !DISubroutineType(types: !6)
+!6 = !{null}
+!7 = !{i32 2, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"PIC Level", i32 2}
+!10 = !{!"clang version 3.8.0 (trunk 254906) (llvm/trunk 254917)"}
+!11 = !DILocalVariable(name: "p", scope: !4, file: !1, line: 2, type: !12)
+!12 = !DIBasicType(name: "char", size: 8, align: 8, encoding: DW_ATE_signed_char)
+!13 = !DIExpression()
+!14 = !DILocation(line: 2, column: 8, scope: !4)
+!15 = !DILocation(line: 3, column: 1, scope: !4)
-- 
2.11.0