From ccc809e2e60fbcf519b3945bc33e92b9093405f1 Mon Sep 17 00:00:00 2001
From: David Majnemer <david.majnemer@gmail.com>
Date: Tue, 2 Feb 2016 06:41:55 +0000
Subject: [PATCH] [RegisterCoalescer] Better DebugLoc for
 reMaterializeTrivialDef

When rematerializing a computation by replacing the copy, use the copy's
location.  The location of the copy is more representative of the
original program.

This partially fixes PR10003.

llvm-svn: 259469
---
 llvm/lib/CodeGen/RegisterCoalescer.cpp |  2 +
 llvm/test/CodeGen/X86/loc-remat.ll     | 56 ++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 llvm/test/CodeGen/X86/loc-remat.ll

diff --git a/llvm/lib/CodeGen/RegisterCoalescer.cpp b/llvm/lib/CodeGen/RegisterCoalescer.cpp
index c1ff13ec7ca0..95c772357c3c 100644
--- a/llvm/lib/CodeGen/RegisterCoalescer.cpp
+++ b/llvm/lib/CodeGen/RegisterCoalescer.cpp
@@ -939,11 +939,13 @@ bool RegisterCoalescer::reMaterializeTrivialDef(const CoalescerPair &CP,
     }
   }
 
+  DebugLoc DL = CopyMI->getDebugLoc();
   MachineBasicBlock *MBB = CopyMI->getParent();
   MachineBasicBlock::iterator MII =
     std::next(MachineBasicBlock::iterator(CopyMI));
   TII->reMaterialize(*MBB, MII, DstReg, SrcIdx, DefMI, *TRI);
   MachineInstr *NewMI = std::prev(MII);
+  NewMI->setDebugLoc(DL);
 
   // In a situation like the following:
   //     %vreg0:subreg = instr              ; DefMI, subreg = DstIdx
diff --git a/llvm/test/CodeGen/X86/loc-remat.ll b/llvm/test/CodeGen/X86/loc-remat.ll
new file mode 100644
index 000000000000..1536546146ad
--- /dev/null
+++ b/llvm/test/CodeGen/X86/loc-remat.ll
@@ -0,0 +1,56 @@
+; RUN: llc < %s | FileCheck %s
+target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@x = common global i32 0, align 4
+
+define i32 @main() !dbg !4 {
+entry:
+  %0 = load volatile i32, i32* @x, align 4, !dbg !9, !tbaa !10
+  %add = add nsw i32 %0, 24, !dbg !9
+  store volatile i32 %add, i32* @x, align 4, !dbg !9, !tbaa !10
+  %1 = load volatile i32, i32* @x, align 4, !dbg !14, !tbaa !10
+  %add1 = add nsw i32 %1, 2, !dbg !14
+  store volatile i32 %add1, i32* @x, align 4, !dbg !14, !tbaa !10
+  %2 = load volatile i32, i32* @x, align 4, !dbg !15, !tbaa !10
+  %add2 = add nsw i32 %2, 3, !dbg !15
+  store volatile i32 %add2, i32* @x, align 4, !dbg !15, !tbaa !10
+  %3 = load volatile i32, i32* @x, align 4, !dbg !16, !tbaa !10
+  %add3 = add nsw i32 %3, 4, !dbg !16
+  store volatile i32 %add3, i32* @x, align 4, !dbg !16, !tbaa !10
+  tail call void @exit(i32 24), !dbg !17
+  unreachable, !dbg !17
+}
+
+; CHECK-LABEL: main:
+; CHECK:      .loc 1 3
+; CHECK:      .loc 1 4
+; CHECK:      .loc 1 5
+; CHECK:      .loc 1 6
+; CHECK:      .loc 1 7
+; CHECK:      .loc 1 8
+; CHECK-NEXT: movl  $24, %edi
+; CHECK-NEXT: callq exit
+
+declare void @exit(i32)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!6, !7}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.9.0 (trunk 259383) (llvm/trunk 259385)", isOptimized: true, runtimeVersion: 0, emissionKind: 2, enums: !2, subprograms: !3)
+!1 = !DIFile(filename: "t.c", directory: "/home/majnemer/llvm/src")
+!2 = !{}
+!3 = !{!4}
+!4 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 3, type: !5, isLocal: false, isDefinition: true, scopeLine: 3, isOptimized: true, variables: !2)
+!5 = !DISubroutineType(types: !2)
+!6 = !{i32 2, !"Dwarf Version", i32 4}
+!7 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !DILocation(line: 4, column: 5, scope: !4)
+!10 = !{!11, !11, i64 0}
+!11 = !{!"int", !12, i64 0}
+!12 = !{!"omnipotent char", !13, i64 0}
+!13 = !{!"Simple C/C++ TBAA"}
+!14 = !DILocation(line: 5, column: 5, scope: !4)
+!15 = !DILocation(line: 6, column: 5, scope: !4)
+!16 = !DILocation(line: 7, column: 5, scope: !4)
+!17 = !DILocation(line: 8, column: 3, scope: !4)