LLVM 21: issue-114312.rs fails after llvm-project@36f0838a3dd1

[durin42]

Starting with llvm/llvm-project@36f0838 tests/codegen/issues/issue-114312.rs fails thus:

---- [codegen] tests/codegen/issues/issue-114312.rs stdout ----

error: verification with 'FileCheck' failed
status: exit status: 1
command: "/tmp/rust/build/x86_64-unknown-linux-gnu/llvm/build/bin/FileCheck" "--input-file" "/tmp/rust/build/x86_64-unknown-linux-gnu/test/codegen/issues/issue-114312/issue-114312.ll" "/tmp/rust/tests/codegen/issues/issue-114312.rs" "--check-prefix=CHECK" "--allow-unused-prefixes" "--dump-input-context" "100"
stdout: none
--- stderr -------------------------------
/tmp/rust/tests/codegen/issues/issue-114312.rs:18:16: error: CHECK-NOT: excluded string found in input
 // CHECK-NOT: readonly
               ^
/tmp/rust/build/x86_64-unknown-linux-gnu/test/codegen/issues/issue-114312/issue-114312.ll:7:47: note: found here
define void @issue_114312(ptr noalias noundef readonly byval([24 x i8]) align 8 captures(none) dereferenceable(24) %expr) unnamed_addr #0 {
                                              ^~~~~~~~

Input file: /tmp/rust/build/x86_64-unknown-linux-gnu/test/codegen/issues/issue-114312/issue-114312.ll
Check file: /tmp/rust/tests/codegen/issues/issue-114312.rs

-dump-input=help explains the following input dump.

Input was:
<<<<<<
        1: ; ModuleID = 'issue_114312.979b24920b4087eb-cgu.0'
        2: source_filename = "issue_114312.979b24920b4087eb-cgu.0"
        3: target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
        4: target triple = "x86_64-unknown-linux-gnu"
        5:
        6: ; Function Attrs: mustprogress nofree norecurse nosync nounwind nonlazybind willreturn memory(argmem: read) uwtable
        7: define void @issue_114312(ptr noalias noundef readonly byval([24 x i8]) align 8 captures(none) dereferenceable(24) %expr) unnamed_addr #0 {
not:18                                                   !~~~~~~~                                                                                       error: no match expected
        8: start:
        9:  ret void
       10: }
       11:
       12: attributes #0 = { mustprogress nofree norecurse nosync nounwind nonlazybind willreturn memory(argmem: read) uwtable "probe-stack"="inline-asm" "target-cpu"="x86-64" }
       13:
       14: !llvm.module.flags = !{!0, !1}
       15: !llvm.ident = !{!2}
       16:
       17: !0 = !{i32 8, !"PIC Level", i32 2}
       18: !1 = !{i32 2, !"RtLibUseGOT", i32 1}
       19: !2 = !{!"rustc version 1.87.0-dev"}
>>>>>>
------------------------------------------

Given that the test is explicitly looking for the lack of readonly it seems like this must be a bug in LLVM? But I'm filing this bug so we can keep track of this and make sure our CI stays green.

[durin42]

fyi @nikic

[nikic]

It's fine to drop the CHECK-NOT: readonly from this test, the remaining check lines are sufficient.

The readonly check was testing the internal reason why the original issue happened in the first place, but having the attribute is not actually incorrect. (It's an empty function after optimization.)

[durin42]

Oh, nice. I'll prepare a patch!