From 93dd711033a224fb54de157fd5270967627affe5 Mon Sep 17 00:00:00 2001
From: Alexey Samsonov <vonosmas@gmail.com>
Date: Mon, 29 Jun 2015 21:30:14 +0000
Subject: [PATCH] [LoopSimplify] Set proper debug location in loop backedge
 blocks.

Set debug location for terminator instruction in loop backedge block
(which is an unconditional jump to loop header). We can't copy debug
location from original backedges, as there can be several of them,
with different debug info locations. So, we follow the approach of
SplitBlockPredecessors, and copy the debug info from first non-PHI
instruction in the header (i.e. destination block).

This is yet another change for PR23837.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@240999 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Utils/LoopSimplify.cpp         |  3 +-
 .../LoopSimplify/single-backedge.ll           | 38 +++++++++++++------
 2 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/lib/Transforms/Utils/LoopSimplify.cpp b/lib/Transforms/Utils/LoopSimplify.cpp
index d8f7c9176f5..2e7d21cb171 100644
--- a/lib/Transforms/Utils/LoopSimplify.cpp
+++ b/lib/Transforms/Utils/LoopSimplify.cpp
@@ -386,8 +386,9 @@ static BasicBlock *insertUniqueBackedgeBlock(Loop *L, BasicBlock *Preheader,
 
   // Create and insert the new backedge block...
   BasicBlock *BEBlock = BasicBlock::Create(Header->getContext(),
-                                           Header->getName()+".backedge", F);
+                                           Header->getName() + ".backedge", F);
   BranchInst *BETerminator = BranchInst::Create(Header, BEBlock);
+  BETerminator->setDebugLoc(Header->getFirstNonPHI()->getDebugLoc());
 
   DEBUG(dbgs() << "LoopSimplify: Inserting unique backedge block "
                << BEBlock->getName() << "\n");
diff --git a/test/Transforms/LoopSimplify/single-backedge.ll b/test/Transforms/LoopSimplify/single-backedge.ll
index aedd6f23091..92fbdca8a6d 100644
--- a/test/Transforms/LoopSimplify/single-backedge.ll
+++ b/test/Transforms/LoopSimplify/single-backedge.ll
@@ -5,19 +5,35 @@
 ; RUN: opt < %s -indvars -S | FileCheck %s
 ; CHECK: Loop.backedge:
 ; CHECK-NOT: br
-; CHECK: br label %Loop
+; CHECK: br label %Loop, !dbg [[BACKEDGE_LOC:![0-9]+]]
+
+; CHECK: [[BACKEDGE_LOC]] = !DILocation(line: 101, column: 1, scope: !{{.*}})
 
 define i32 @test(i1 %C) {
 ; <label>:0
-	br label %Loop
-Loop:		; preds = %BE2, %BE1, %0
-	%IV = phi i32 [ 1, %0 ], [ %IV2, %BE1 ], [ %IV2, %BE2 ]		; <i32> [#uses=2]
-	store i32 %IV, i32* null
-	%IV2 = add i32 %IV, 2		; <i32> [#uses=2]
-	br i1 %C, label %BE1, label %BE2
-BE1:		; preds = %Loop
-	br label %Loop
-BE2:		; preds = %Loop
-	br label %Loop
+  br label %Loop, !dbg !6
+Loop: ; preds = %BE2, %BE1, %0
+  %IV = phi i32 [ 1, %0 ], [ %IV2, %BE1 ], [ %IV2, %BE2 ] ; <i32> [#uses=2]
+  store i32 %IV, i32* null, !dbg !7
+  %IV2 = add i32 %IV, 2, !dbg !8 ; <i32> [#uses=2]
+  br i1 %C, label %BE1, label %BE2, !dbg !9
+BE1:  ; preds = %Loop
+  br label %Loop, !dbg !10
+BE2:    ; preds = %n br label %Loop
+  br label %Loop, !dbg !11
 }
 
+!llvm.module.flags = !{!0, !1}
+!0 = !{i32 2, !"Dwarf Version", i32 4}
+!1 = !{i32 2, !"Debug Info Version", i32 3}
+
+!2 = !{}
+!3 = !DISubroutineType(types: !2)
+!4 = !DIFile(filename: "atomic.cpp", directory: "/tmp")
+!5 = !DISubprogram(name: "test", scope: !4, file: !4, line: 99, type: !3, isLocal: false, isDefinition: true, scopeLine: 100, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
+!6 = !DILocation(line: 100, column: 1, scope: !5)
+!7 = !DILocation(line: 101, column: 1, scope: !5)
+!8 = !DILocation(line: 102, column: 1, scope: !5)
+!9 = !DILocation(line: 103, column: 1, scope: !5)
+!10 = !DILocation(line: 104, column: 1, scope: !5)
+!11 = !DILocation(line: 105, column: 1, scope: !5)
-- 
2.34.1