Set proper debug location for branch added in BasicBlock::splitBasicBlock().

This improves debug locations in passes that do a lot of basic block
transformations. Important case is LoopUnroll pass, the test for correct
debug locations accompanies this change.

Test Plan: regression test suite

Reviewers: dblaikie, sanjoy

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D10367

llvm-svn: 239551

2 files changed, 37 insertions, 13 deletions

diff --git a/llvm/lib/IR/BasicBlock.cpp b/llvm/lib/IR/BasicBlock.cpp
index 70ae3c39842..77cb10d5b6b 100644
--- a/llvm/lib/IR/BasicBlock.cpp
+++ b/llvm/lib/IR/BasicBlock.cpp
@@ -362,12 +362,15 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const Twine &BBName) {
   BasicBlock *New = BasicBlock::Create(getContext(), BBName,
                                        getParent(), InsertBefore);
 
+  // Save DebugLoc of split point before invalidating iterator.
+  DebugLoc Loc = I->getDebugLoc();
   // Move all of the specified instructions from the original basic block into
   // the new basic block.
   New->getInstList().splice(New->end(), this->getInstList(), I, end());
 
   // Add a branch instruction to the newly formed basic block.
-  BranchInst::Create(New, this);
+  BranchInst *BI = BranchInst::Create(New, this);
+  BI->setDebugLoc(Loc);
 
   // Now we must loop through all of the successors of the New block (which
   // _were_ the successors of the 'this' block), and update any PHI nodes in
diff --git a/llvm/test/Transforms/LoopUnroll/runtime-loop1.ll b/llvm/test/Transforms/LoopUnroll/runtime-loop1.ll
index 7684e394290..de61e847a5a 100644
--- a/llvm/test/Transforms/LoopUnroll/runtime-loop1.ll
+++ b/llvm/test/Transforms/LoopUnroll/runtime-loop1.ll
@@ -2,29 +2,50 @@
 
 ; This tests that setting the unroll count works
 
+; CHECK: for.body.preheader:
+; CHECK:   br {{.*}} label %for.body.prol, label %for.body.preheader.split, !dbg [[PH_LOC:![0-9]+]]
 ; CHECK: for.body.prol:
-; CHECK: br label %for.body.preheader.split
+; CHECK:   br label %for.body.preheader.split, !dbg [[BODY_LOC:![0-9]+]]
+; CHECK: for.body.preheader.split:
+; CHECK:   br {{.*}} label %for.end.loopexit, label %for.body.preheader.split.split, !dbg [[PH_LOC]]
 ; CHECK: for.body:
-; CHECK: br i1 %exitcond.1, label %for.end.loopexit.unr-lcssa, label %for.body
+; CHECK:   br i1 %exitcond.1, label %for.end.loopexit.unr-lcssa, label %for.body, !dbg [[BODY_LOC]]
 ; CHECK-NOT: br i1 %exitcond.4, label %for.end.loopexit{{.*}}, label %for.body
 
+; CHECK-DAG: [[PH_LOC]] = !DILocation(line: 101, column: 1, scope: !{{.*}})
+; CHECK-DAG: [[BODY_LOC]] = !DILocation(line: 102, column: 1, scope: !{{.*}})
+
 define i32 @test(i32* nocapture %a, i32 %n) nounwind uwtable readonly {
 entry:
-  %cmp1 = icmp eq i32 %n, 0
-  br i1 %cmp1, label %for.end, label %for.body
+  %cmp1 = icmp eq i32 %n, 0, !dbg !7
+  br i1 %cmp1, label %for.end, label %for.body, !dbg !7
 
 for.body:                                         ; preds = %for.body, %entry
   %indvars.iv = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %entry ]
   %sum.02 = phi i32 [ %add, %for.body ], [ 0, %entry ]
-  %arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv
-  %0 = load i32, i32* %arrayidx, align 4
-  %add = add nsw i32 %0, %sum.02
-  %indvars.iv.next = add i64 %indvars.iv, 1
-  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
-  %exitcond = icmp eq i32 %lftr.wideiv, %n
-  br i1 %exitcond, label %for.end, label %for.body
+  %arrayidx = getelementptr inbounds i32, i32* %a, i64 %indvars.iv, !dbg !8
+  %0 = load i32, i32* %arrayidx, align 4, !dbg !8
+  %add = add nsw i32 %0, %sum.02, !dbg !8
+  %indvars.iv.next = add i64 %indvars.iv, 1, !dbg !9
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32, !dbg !9
+  %exitcond = icmp eq i32 %lftr.wideiv, %n, !dbg !9
+  br i1 %exitcond, label %for.end, label %for.body, !dbg !9
 
 for.end:                                          ; preds = %for.body, %entry
   %sum.0.lcssa = phi i32 [ 0, %entry ], [ %add, %for.body ]
-  ret i32 %sum.0.lcssa
+  ret i32 %sum.0.lcssa, !dbg !10
 }
+
+!llvm.module.flags = !{!0, !1, !2}
+!0 = !{i32 2, !"Dwarf Version", i32 4}
+!1 = !{i32 2, !"Debug Info Version", i32 3}
+!2 = !{i32 1, !"PIC Level", i32 2}
+
+!3 = !{}
+!4 = !DISubroutineType(types: !3)
+!5 = !DIFile(filename: "test.cpp", directory: "/tmp")
+!6 = !DISubprogram(name: "test", scope: !5, file: !5, line: 99, type: !4, isLocal: false, isDefinition: true, scopeLine: 100, flags: DIFlagPrototyped, isOptimized: false, function: i32 (i32*, i32)* @test, variables: !3)
+!7 = !DILocation(line: 100, column: 1, scope: !6)
+!8 = !DILocation(line: 101, column: 1, scope: !6)
+!9 = !DILocation(line: 102, column: 1, scope: !6)
+!10 = !DILocation(line: 103, column: 1, scope: !6)