[TailDuplicator] Maintain DebugLoc for branch instructions

Summary: Existing implementation of duplicateSimpleBB function drops DebugLoc metadata of branch instructions during the transformation. This patch addresses this issue by making newly created branch instructions to keep the metadata of replaced branch instructions.

Reviewers: qcolombet, craig.topper, aprantl, MatzeB, sanjoy, dblaikie

Reviewed By: dblaikie

Subscribers: dblaikie, llvm-commits

Differential Revision: https://reviews.llvm.org/D30026

llvm-svn: 296371

1 files changed, 56 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/X86/tail-dup-debugloc.ll b/llvm/test/CodeGen/X86/tail-dup-debugloc.ll
new file mode 100644
index 00000000000..c5ca6fc5750
--- /dev/null
+++ b/llvm/test/CodeGen/X86/tail-dup-debugloc.ll
@@ -0,0 +1,56 @@
+; RUN: llc -stop-after=tailduplication -march=x86-64 < %s | FileCheck %s
+;
+; Check that DebugLoc attached to the branch instruction of 
+; 'while.cond1.preheader.lr.ph' survives after tailduplication pass.
+;
+; CHECK: [[DLOC:![0-9]+]] = !DILocation(line: 9, column: 5, scope: !{{[0-9]+}})
+; CHECK: [[VREG:%[^ ]+]] = COPY %rdi
+; CHECK: TEST64rr [[VREG]], [[VREG]]
+; CHECK-NEXT: JE_1 {{.+}}, debug-location [[DLOC]]
+; CHECK-NEXT: JMP_1 {{.+}}, debug-location [[DLOC]]
+
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct.Node = type { %struct.Node* }
+
+define i32 @foo(%struct.Node* readonly %node, %struct.Node* readnone %root) !dbg !6 {
+entry:
+  %cmp = icmp eq %struct.Node* %node, %root, !dbg !8
+  br i1 %cmp, label %while.end4, label %while.cond1.preheader.lr.ph, !dbg !10
+
+while.cond1.preheader.lr.ph:                      ; preds = %entry
+  %tobool = icmp eq %struct.Node* %node, null
+  br i1 %tobool, label %while.cond1.preheader.us.preheader, label %while.body2.preheader, !dbg !11
+
+while.body2.preheader:                            ; preds = %while.cond1.preheader.lr.ph
+  br label %while.body2, !dbg !11
+
+while.cond1.preheader.us.preheader:               ; preds = %while.cond1.preheader.lr.ph
+  br label %while.cond1.preheader.us, !dbg !10
+
+while.cond1.preheader.us:                         ; preds = %while.cond1.preheader.us.preheader, %while.cond1.preheader.us
+  br label %while.cond1.preheader.us, !dbg !10
+
+while.body2:                                      ; preds = %while.body2.preheader, %while.body2
+  br label %while.body2, !dbg !11
+
+while.end4:                                       ; preds = %entry
+  ret i32 0, !dbg !12
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: true, emissionKind: LineTablesOnly)
+!1 = !DIFile(filename: "foo.c", directory: "b/")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{}
+!6 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 5, type: !7, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: true, unit: !0, variables: !2)
+!7 = !DISubroutineType(types: !2)
+!8 = !DILocation(line: 7, column: 15, scope: !9)
+!9 = !DILexicalBlockFile(scope: !6, file: !1, discriminator: 2)
+!10 = !DILocation(line: 7, column: 3, scope: !9)
+!11 = !DILocation(line: 9, column: 5, scope: !9)
+!12 = !DILocation(line: 14, column: 3, scope: !6)