A problem with private/internal symbols about llvm-prepo

[MaggieYingYi]

There are three issues in the test.

1. The redundant tickets are show in the .repo.tickets metadata.
2. The function hash calculation is wrong.
3. The linkage type of global variable .str has been changed from private to external, which is wrong.

[MaggieYingYi]

Issue 1: trimming the test, compile the following llvm IR code.

target triple = "x86_64-pc-linux-gnu-repo"

@.str = private unnamed_addr constant [13 x i8] c"Hello World\0A\00", align 1, !repo_ticket !0

define i32 @main() !repo_ticket !1 {
entry:
  %call = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([13 x i8], [13 x i8]* @.str, i32 0, i32 0))
  ret i32 0
}

declare i32 @printf(i8*, ...)

!repo.tickets = !{!0, !1}

!0 = !TicketNode(name: ".str", digest: [16 x i8] c"\D9Wq;\E9\B1\8Dh\E7\19\10\EE\A3!\EB\B7", linkage: private)
!1 = !TicketNode(name: "main", digest: [16 x i8] c"Z+i~nP8[\01\EE\BC\03ol\FCB", linkage: external)

using

opt test.ll -S -o test1.ll

The output test1.ll is shown below.

; ModuleID = 'repo_redundant_tickets.ll'
source_filename = "repo_redundant_tickets.ll"
target triple = "x86_64-pc-linux-gnu-repo"

@.str = external unnamed_addr constant [13 x i8], align 1, !repo_ticket !0

declare !repo_ticket !1 i32 @main()

declare i32 @printf(i8*, ...)

!repo.tickets = !{!0, !1, !0, !1}

!0 = !TicketNode(name: ".str", digest: [16 x i8] c"\D9Wq;\E9\B1\8Dh\E7\19\10\EE\A3!\EB\B7", linkage: private)
!1 = !TicketNode(name: "main", digest: [16 x i8] c"Z+i~nP8[\01\EE\BC\03ol\FCB", linkage: external)

The redundant metadata !0 and !1 are in the !repo.tickets metadata.

[MaggieYingYi]

Fixed in my local branch.
Branch name: llvm-prepo-13
git commit: cc2ed542.

[MaggieYingYi]

The second issue: the 'insertvalue' instruction hash is calculated incorrectly,

Compile the following llvm IR code.

target triple = "x86_64-pc-linux-gnu-repo"

@.str = private unnamed_addr constant [9 x i8] c"test.cpp\00", align 1, !repo_ticket !0

define internal void @__cxx_global_var_init() section ".text.startup" personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) !repo_ticket !1 {
  %exn.slot = alloca i8*
  %ehselector.slot = alloca i32

  %exn = load i8*, i8** %exn.slot, align 8
  %sel = load i32, i32* %ehselector.slot, align 4
  %lpad.val = insertvalue { i8*, i32 } undef, i8* %exn, 0
  %lpad.val1 = insertvalue { i8*, i32 } %lpad.val, i32 %sel, 1
  resume { i8*, i32 } %lpad.val1
}

declare i32 @__gxx_personality_v0(...)

!0 = !TicketNode(name: ".str", digest: [16 x i8] c"8\8A\98\B1^\AA\F0\06\01F\8E\AE\8F\14\BDK", linkage: private)
!1 = !TicketNode(name: "__cxx_global_var_init", digest: [16 x i8] c"\C7\96\DE\14\8C\01\EB \0F<8h\11-\BC7", linkage: internal)

using

opt.exe test.ll -S -o test1.ll

when you run opt.exe command, the hash value of __cxx_global_var_init function is not stable (varies).

[MaggieYingYi]

Fixed in my local branch.
Branch name: llvm-prepo-13
git commit: 04c35a7820ad6

[MaggieYingYi]

During the repository pruning pass, we can not change the linkage type of global variable .str from private to external. If the linkage type is private, the symbol name will change from .str to .L.str. If we change the linkage type to external, the symbal name will keep the same that is '.str'. It is wrong.

Fixed in my local branch.
Branch name: llvm-prepo-13
git commit: 6d57163d1f87b

[MaggieYingYi]

Fixed in git commit: f759454 and 9665035.

[MaggieYingYi]

For clang project, the mangling component in the repo datalayout string need to change from '-m:e' to '-m:r'. We will put the clang project in the github.