<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/65667>65667</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            Incorrect line number in debuginfo when duplicate callsites are merged together at -O1
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            new issue
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          wesleywiser
      </td>
    </tr>
</table>

<pre>
    When the following IR is compiled with `llc -O1 -trap-unreachable`, an incorrect line number is generated in the debuginfo for the call to `panic_test2::do_panic`:

<details><summary>IR</summary>

```llvm
source_filename = "panic_test2.6f3b49f66efc8fc7-cgu.0"
target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

@alloc_14c43fe6be9850e9c6ac099b83b2e4e2 = private unnamed_addr constant <{ [7 x i8] }> <{ [7 x i8] c"unknown" }>, align 1
@alloc_1a2b9f3efbe1a8edd339fa75af2334ed = private unnamed_addr constant <{ [5 x i8] }> <{ [5 x i8] c"hello" }>, align 1

; Function Attrs: inlinehint noreturn nounwind nonlazybind
define fastcc void @bad_debug_info(ptr noalias nocapture noundef readonly align 8 dereferenceable(16) %_1) unnamed_addr #4 !dbg !85 {
start:
  %_11 = alloca { ptr, i64 }, align 8
  %_7 = alloca { ptr, i64 }, align 8
  %0 = getelementptr inbounds { ptr, i64 }, ptr %_1, i64 0, i32 1, !dbg !87
 %_13.1 = load i64, ptr %0, align 8, !dbg !87, !noundef !14
; call panic_test2::condition
  %1 = tail call fastcc ptr @_ZN11panic_test29condition17haa518b986e55a3c9E(i64 noundef %_13.1) #9, !dbg !89
  %.not = icmp eq ptr %1, null, !dbg !90
  br i1 %.not, label %bb3, label %bb2, !dbg !90

bb2: ; preds = %start
  call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %_7), !dbg !91
  store ptr %1, ptr %_7, align 8, !dbg !91
  %2 = getelementptr inbounds { ptr, i64 }, ptr %_7, i64 0, i32 1, !dbg !91
 store i64 5, ptr %2, align 8, !dbg !91
; call panic_test2::do_panic
 call fastcc void @_ZN11panic_test28do_panic17h2c0ead66774c0583E(ptr noalias noundef nonnull readonly align 8 dereferenceable(16) %_7) #10, !dbg !92
 unreachable, !dbg !92

bb3: ; preds = %start
  call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %_11), !dbg !93
  store ptr @alloc_14c43fe6be9850e9c6ac099b83b2e4e2, ptr %_11, align 8, !dbg !93
  %3 = getelementptr inbounds { ptr, i64 }, ptr %_11, i64 0, i32 1, !dbg !93
  store i64 7, ptr %3, align 8, !dbg !93
; call panic_test2::do_panic
  call fastcc void @_ZN11panic_test28do_panic17h2c0ead66774c0583E(ptr noalias noundef nonnull readonly align 8 dereferenceable(16) %_11) #10, !dbg !94
  unreachable, !dbg !94
}

; panic_test2::condition
; Function Attrs: mustprogress nofree noinline norecurse nosync nounwind nonlazybind willreturn memory(none)
define internal fastcc ptr @_ZN11panic_test29condition17haa518b986e55a3c9E(i64 noundef %s.1) unnamed_addr #6 {
start:
  %0 = icmp eq i64 %s.1, 0
 %alloc_1a2b9f3efbe1a8edd339fa75af2334ed. = select i1 %0, ptr @alloc_1a2b9f3efbe1a8edd339fa75af2334ed, ptr null
  ret ptr %alloc_1a2b9f3efbe1a8edd339fa75af2334ed.
}

; panic_test2::do_panic
; Function Attrs: noreturn nounwind nonlazybind
define internal fastcc void @_ZN11panic_test28do_panic17h2c0ead66774c0583E(ptr noalias noundef readonly align 8 dereferenceable(16) %h) unnamed_addr #5 {
start:
 unreachable
}

; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #8

attributes #1 = { nounwind nonlazybind "probe-stack"="inline-asm" "target-cpu"="x86-64" }
attributes #5 = { noreturn nounwind nonlazybind "probe-stack"="inline-asm" "target-cpu"="x86-64" }
attributes #6 = { mustprogress nofree noinline norecurse nosync nounwind nonlazybind willreturn memory(none) "probe-stack"="inline-asm" "target-cpu"="x86-64" }
attributes #8 = { mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
attributes #9 = { nounwind }
attributes #10 = { noreturn nounwind }

!llvm.module.flags = !{!3, !4}
!llvm.ident = !{!5}
!llvm.dbg.cu = !{!6}

!3 = !{i32 2, !"Dwarf Version", i32 4}
!4 = !{i32 2, !"Debug Info Version", i32 3}
!5 = !{!"rustc version 1.73.0-beta.4 (9f37cd4f7 2023-09-01)"}
!6 = distinct !DICompileUnit(language: DW_LANG_Rust, file: !7, producer: "clang LLVM (rustc version 1.73.0-beta.4 (9f37cd4f7 2023-09-01))", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false)
!7 = !DIFile(filename: "src/main.rs/@/panic_test2.6f3b49f66efc8fc7-cgu.0", directory: "/tmp/panic_test")
!13 = !DISubroutineType(types: !14)
!14 = !{}
!80 = !DIFile(filename: "src/main.rs", directory: "/tmp/panic_test", checksumkind: CSK_MD5, checksum: "7cd0751a66038391ee52be036e31f480")
!81 = !DINamespace(name: "panic_test2", scope: null)
!85 = distinct !DISubprogram(name: "bad_debug_info", linkageName: "bad_debug_info", scope: !86, file: !80, line: 14, type: !13, scopeLine: 14, flags: DIFlagPrototyped | DIFlagNoReturn, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !6, templateParams: !14)
!86 = !DINamespace(name: "never_returns", scope: !81)
!87 = !DILocation(line: 15, column: 36, scope: !88)
!88 = distinct !DILexicalBlock(scope: !85, file: !80, line: 15, column: 39)
!89 = !DILocation(line: 15, column: 26, scope: !88)
!90 = !DILocation(line: 15, column: 16, scope: !88)
!91 = !DILocation(line: 16, column: 23, scope: !88)
!92 = !DILocation(line: 16, column: 13, scope: !88)
!93 = !DILocation(line: 18, column: 23, scope: !85)
!94 = !DILocation(line: 18, column: 13, scope: !85)
```

</details>

[godbolt](https://llvm.godbolt.org/z/s55TrGYs7)

Notice that in the source IR, both calls to `do_panic` have the correct line numbers:

```llvm
...
bb2: ; preds = %start
...
; call panic_test2::do_panic
  call fastcc void @_ZN11panic_test28do_panic17h2c0ead66774c0583E(ptr noalias noundef nonnull readonly align 8 dereferenceable(16) %_7) #10, !dbg !92
...

bb3:                                              ; preds = %start
...
; call panic_test2::do_panic
  call fastcc void @_ZN11panic_test28do_panic17h2c0ead66774c0583E(ptr noalias noundef nonnull readonly align 8 dereferenceable(16) %_11) #10, !dbg !94
...
!85 = distinct !DISubprogram(name: "bad_debug_info", linkageName: "bad_debug_info", scope: !86, file: !80, line: 14, type: !13, scopeLine: 14, flags: DIFlagPrototyped | DIFlagNoReturn, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !6, templateParams: !14)
!88 = distinct !DILexicalBlock(scope: !85, file: !80, line: 15, column: 39)
!92 = !DILocation(line: 16, column: 13, scope: !88)
!94 = !DILocation(line: 18, column: 13, scope: !85)
```

However, when lowering to machine code, these line numbers are erased and replaced with line 0:

```asm
...
        .loc    1 0 23 is_stmt 0 # src/main.rs:0:23
        leaq    8(%rsp), %rdi
        callq panic_test2::do_panic::h2c0ead66774c0583
 ud2
...
```

Looking at the optimization passes in godbolt, it seems that the "Control Flow Optimizer (branch-folder)" pass is responsible for merging the calls together and removing the correct line numbers. 
</pre>
<img width="1px" height="1px" alt="" src="http://email.email.llvm.org/o/eJzsWl9v47aW_zTMC2FDIvX3IQ9JPO4GnU6LmW6L3ReDoo5s7lCkS1KTST_9gpRkS44TJ70zxb0XNwhkieL58ZzD84-kmLViqwCuUXqL0tUV69xOm-sHsBIeH4QFc1Xp-vH69x0o7HaAGy2lfhBqi-8_YmEx1-1eSKjxg3A7jLJISo4XP8d44QzbLzplgPEdqySgLELkDjOFheLaGOAOS6EAq66twHiwLSgwzEGNRT9aDVW3FarRuNEmtHAmJXbaj7RnSvCNA-sIojeI3tR6E9r8SPQGRSsUjVd6V4NjQlpE3yF6Z7u2ZeYR0Xf3HxG9Q2R9bJnRZVH_L-WXtm-yujMcNo2QoFgLGNEVRoRMmFlmDa2SsskyaHjR8HzBt90yQoT0CI6ZLThcM8cke9SdGzFg0SJ6A4s9yb0AlISLf4znj_4uS8JlIcabpvBEMSkWqvA32UiTJYtPMSlOx3dG7OWB_69FtsmSRac-K_2gFlKo7utiq7oD1XBNIial5ps44QltIKugLNIISp4xHpVlVdCKQAIk4O6N-MIc4E55VdUbVtcGc62sY8pLfYfyW4zS2xx_xaJA6QqjfIXou7OvOCJkYA8RMvQMFiXFVuH4lEFGqrKh0FQQswLqmtKyYXnKGkJpAvWbGEyfZzCdMbgDKfVL7A3meIvXneJOaIVvnDMW0RsslHeHnVAOK23AdUZhpTv1IFSNlVaS_flYCVX3GDU03nkaZh3n-IsWNUZJVLF6E5xm470GkWLvDFaaScEsVpqzvesMBNgaGmyA1VrJx4HJAtdgoAEDikPwWVLEGSIlRiTdxP5mpilEaIIRietq63-KFKP8dnATx4w7eCHuAeKg9DA_zHfFe2e8ikSWBIUdtFVMyfK_QhUFoi04kNCCcl4PQlVebvsMiO8yyNm3h3glKMGhZSJnPgwUetNlL5bUrPZkE6hoytspRP88zgQicZwcrSOEuScBjmtVC280E0H7wX1s64kGgwgcJNHmfz_E8QSnPEDE-Y6xNC6qssggTRnl5TtECi_3kadevN4AaHkiQjnhYql0H8YEb_cY_hg1EDSnOinntGU00lYGi3hE8J0kq0D6hqqiJ8_kPEh_9a_pDfbK2xvwkxwCW9ob4jBa0NDoKz6mL6VowIkWlqHfch8NOvBm38-j0soL0JsiIidaKOMR2zptYCb3aFD5s2ZwpEYkJX_dZPNLJnsYqOfSd00nAOQih88b5SHr9gNMjXDU9KkVFiNNnO8Ij4DVWZbnCY_SwsfMk6DVG-M4DW8KWflgunF0ItWQ1PC0PjnbYzQu-v2NK46fWhc9Y12vTcGzmBY_P8N0YoP0HwibF-PmqTS-bz6BoBd5fLUV_nOZYRw_Z4fJyO_zhjhmhXx1WkJcyg_ny4y2s25v9NaA9WI1Bnw90BcfofDgnbH-zj4qfrYAwQ9CyqFAaaHV5hGRQmkF3n6nxYlQDoxi3zop2eXZUiR7sfqIZukp2O-AdIejYz5_XfG4DGAWpF_E9PkrOhjyayvQQwzw6XFg1IAbveGVnLzeOuYuct44Xl94ns7tt3SytzjX7pwpPF-ITv3sOc1d9BkfXCrGPx_dZ-4r5_yDmW0Lfn0XpHswwk3dhUtm4HXJQ_iF6vaYQIaafogwxVQY5pwRVefAhuDTZ6389rxT-0Ws0RUsrGP8s1_30RUipA8MC2bbsKwhpF8-Lvi-O_T5WmQLX_j2y54zQ6eToV8wsO_KQ3bg4ftGwO8qRPGcEN_OJJ8bunxqPs_0jKMXpvvU30gcrL3VdSdh2Ui2Haur2PswiemQD5Mj5UAjalBu3jl90qmutkvezXtlT5mgkx6-dBnXGoiQ1QMzDf4NjPWZlZCxupkxlLxA79fj-F41-gwInYKkczYRIaazjuMvPRmOlzldRosKHFv6_FWUDc15nTQ5JhGhi6hcRH0RSaawveXXwjqhuPP4q_u7ft_uv5VwiBSSqW3HtuBtYfX75v3Nhx82HzsbFmSNkKEdkbgv1oyuOw6mbyPc0-L373_7yTP0V_ktR5XYn_dOtOJPqD2-M10oh0ynfCgc1Udv-hoTWmF9w48-OdEbvO6kDNr2L-1eChee7r3nCbX1XRom7THweplGna_u1yKklnFrbxDQGo7IumVCLY1FZI2SCJH16_b7yB2uhQHuvMP1cIisXbufIYTWI0dHW1zdf-oqozsnFPz6uPfMucc92GE64mRGNjXB6fQX0RtFfBPfd5jvgH-2Xft5mIW7Tz9uflql01cDRs7rKE9jlmURLWgZA6SkgohmQOMmKaITRRTxkfEPrAW7Z9xzP-F8WuT03Fiu9-Ftv-swQUvPuMGnrgpBlLVz3NN9tAAthfrMtvDhQrcDB37Q7MSFimhACg1x2C3yczpOKT0gvJ_1CYExuOf9WrLtL0Y77el8QL0bGj_ojyHY9ta_PlJ8-sU_vPdJ4lftXX4g6ttXvqAL5fes-eiI5A53Pk70LAaJHLR7yRz8wgxrz9tjkV2cPQVfwGz6DGHPaS-eAU5c1csSFjqkOOiytzgtuzZECJo9gStmcMUZe3gPXwVn8lZqn7mLGXX68lSeDl_OBivfxDu5wHsZvQkuvgQXvwyXnXBHL8CRN8HFl-Doy3DFRe7SGVzyJrgz3E3gxvOhk8MmRNaT86bpu_R2q-tKS4fSFSLFzrm9dx-fV8g6FCzD-6X2Rf76T0TWNk1_NT_8j82P44brB-0EB-x2zI0HZv3pFL7_6JmutNuFjRA7nJhNDsjwjn2B_kTt6VmcPT0-e3oMtlwuX73veuj7L7p9c2kX8SjfdLPwTX__zuq7uPt1FPA_Wfpvz9J_Zxb81onhe0fy_9IPvkLxZA87UFjqBzBCbX04bRnf-YjJdR2WKG4HFmZBFDMDGAyzUGOmamxgLxkfP5UIPZ98pzBywexpnB0jxVJq7n9jHGFCsbAb61qHI-9geF7I0xuPT-gcQAL7w_8WiBSIpMbuD8cOqanFvLMPJH-8EG_C05PwMe611U8C5Dktv9f6s1cqcyEf6d6iw2ziPbMWrM9uY9r0i0SHLUBr-8znaRAhd1o5oyVeS_2AR68wftFZGab4btFoWfu59EvNgIuFxQbsXisrKgnhE5MWzDZM8PCpic-cW3A7MMMUtvrL4f2ZxLnEV_U1rUtasiu4jrMyieMsL-jV7jrhNSt4nZU1i-PYG19CmzyLWFECryq4Etd-URyVUR6XaZnQJWF5XRcRYXlU0SxKUBJBy4RchjpBm-2VsLaD6yzNsvwqHJTa8CGPr6wfcHjpo126ujLXnmZRdVuLkkgK6-wRxQkn4fr-_Fc5avIRTnCCuttLwZkbFCQc9JbuVQf1RF8OL36Orzojr-dVzla4XVctuW6Hkmf4WeyN_j_gDpF1YN0vtoNo_x8AAP__61S56Q">