TheRock/compiler/amd-llvm/lld/test/ELF/lto/arm-rtlibcall.ll

; REQUIRES: arm
;; Test for LTO optimizing out references to symbols that are pulled in by
;; compiler-generated libcalls (post LTO).
;; Lazy files extracted post LTO compilation might reference other lazy files.
;; Referenced relocatable files are extracted and everything works as intended.
;; However, if the referenced lazy file is a bitcode file, no further LTO
;; compilation occurs. lld currently treats any symbols from that bitcode file
;; as absolute, which leads to a "refer to absolute symbol" error in PIC links
;; and leads to silently broken output. For example, lazy aeabi_ldivmod.o post
;; LTO extraction might call __divmoddi4 defined in an unextracted lazy bitcode
;; file (https://github.com/llvm/llvm-project/issues/127284).
; RUN: rm -rf %t && split-file %s %t && cd %t
; RUN: llvm-as divmoddi4.ll -o divmoddi4.bc
; RUN: llvm-mc -filetype=obj -triple=armv7-none-unknown-eabi aeabi_ldivmod.s -o aeabi_ldivmod.o
;; With an explicit __aebi_ldivmod call in the input IR this works as expected:
; RUN: llvm-as main-explicit.ll -o main-explicit-ldivmod.bc
; RUN: ld.lld main-explicit-ldivmod.bc --start-lib aeabi_ldivmod.o divmoddi4.bc --end-lib -o out.explicit
; RUN: llvm-objdump -d -r -t out.explicit | FileCheck %s --check-prefix=GOOD-DUMP
; GOOD-DUMP-LABEL: SYMBOL TABLE:
; GOOD-DUMP: [[#]] g     F .text	00000024 __aeabi_ldivmod
; GOOD-DUMP: [[#]] g     F .text	[[#]] __divmoddi4
; GOOD-DUMP-LABEL: <__aeabi_ldivmod>:
; GOOD-DUMP:       bl	0x20140 <__divmoddi4>   @ imm = #0x28

;; But if the call is generated by ISel, we end up with an invalid reference:
; RUN: llvm-as main-implicit.ll -o main-implicit-ldivmod.bc
; RUN: ld.lld main-implicit-ldivmod.bc --start-lib aeabi_ldivmod.o divmoddi4.bc --end-lib -o out.implicit
; RUN: llvm-objdump -d -r -t out.implicit | FileCheck %s --check-prefix=BAD-DUMP
;; We jump to address zero here and __divmoddi4 ends up being an absolute symbol:
; BAD-DUMP-LABEL: SYMBOL TABLE:
; BAD-DUMP: [[#]] g     F .text	00000024 __aeabi_ldivmod
; BAD-DUMP: [[#]] g       *ABS*	00000000 __divmoddi4
; BAD-DUMP-LABEL: <__aeabi_ldivmod>:
; BAD-DUMP:       bl	0x0 <__divmoddi4>
;; Linking with -pie complains about the invalid relocation (and even points back to the source files)
; RUN: not ld.lld main-implicit-ldivmod.bc --start-lib aeabi_ldivmod.o divmoddi4.bc --end-lib -o out.pie --no-undefined -pie --no-dynamic-linker 2>&1 | FileCheck %s --check-prefix=PIE-ERROR
PIE-ERROR: ld.lld: error: relocation R_ARM_CALL cannot refer to absolute symbol: __divmoddi4
PIE-ERROR-NEXT: >>> defined in divmoddi4.bc
PIE-ERROR-NEXT: >>> referenced by aeabi_ldivmod.o:(__aeabi_ldivmod)
;; Removing --start-lib/--end-lib also ensures that the reference is retained
; RUN: ld.lld main-implicit-ldivmod.bc aeabi_ldivmod.o divmoddi4.bc -o out.nolib
; RUN: llvm-objdump -d -r -t out.nolib | FileCheck %s --check-prefix=GOOD-DUMP

;; Interestingly, just declaring __aeabi_ldivmod is sufficient to not run into this issue.
; RUN: llvm-as main-declared.ll -o main-declared-ldivmod.bc
; RUN: ld.lld main-declared-ldivmod.bc --start-lib aeabi_ldivmod.o divmoddi4.bc --end-lib -o out.declared
; RUN: llvm-objdump -d -r -t out.declared | FileCheck %s --check-prefix=GOOD-DUMP

;--- divmoddi4.ll
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "armv7-none-unknown-eabi"

; Adding it to llvm.used does not appears to have any effect!
;; @llvm.used = appending global [1 x ptr] [ptr @__divmoddi4], section "llvm.metadata"

; Stub version of the real __divmoddi4
define i64 @__divmoddi4(i64 %a, i64 %b, ptr writeonly %rem) #0 align 32 {
entry:
  %sub = sub i64 %a, %b
  store i64 0, ptr %rem, align 8
  ret i64 %sub
}

attributes #0 = { mustprogress nofree noinline norecurse nosync nounwind willreturn memory(argmem: write) "frame-pointer"="non-leaf" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="cortex-a15" }

;--- aeabi_ldivmod.s
.syntax unified
.p2align 2
.arm
.globl __aeabi_ldivmod
.type __aeabi_ldivmod,%function
__aeabi_ldivmod:
        push {r6, lr}
        sub sp, sp, #16
        add r6, sp, #8
        str r6, [sp]
        bl __divmoddi4
        ldr r2, [sp, #8]
        ldr r3, [sp, #12]
        add sp, sp, #16
        pop {r6, pc}
.size __aeabi_ldivmod, . - __aeabi_ldivmod

;--- main-implicit.ll
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "armv7-none-unknown-eabi"

define dso_local i64 @_start(i64 %num, i64 %denom) local_unnamed_addr #0 {
entry:
  %div = sdiv i64 %num, %denom
  %ret = add i64 %div, 2
  ret i64 %ret
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(none) "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="cortex-a15" }

;--- main-explicit.ll
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "armv7-none-unknown-eabi"

declare { i64, i64 } @__aeabi_ldivmod(i64, i64)

define dso_local noundef i64 @_start(i64 noundef %num, i64 noundef %denom) local_unnamed_addr #0 {
entry:
  %quotrem = call { i64, i64 } @__aeabi_ldivmod(i64 %num, i64 %denom)
  %div = extractvalue { i64, i64 } %quotrem, 0
  %ret = add i64 %div, 2
  ret i64 %ret
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(none) "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="cortex-a15" }

;--- main-declared.ll
target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"
target triple = "armv7-none-unknown-eabi"

declare { i64, i64 } @__aeabi_ldivmod(i64, i64)

define dso_local i64 @_start(i64 %num, i64 %denom) local_unnamed_addr #0 {
entry:
  %div = sdiv i64 %num, %denom
  %ret = add i64 %div, 2
  ret i64 %ret
}

attributes #0 = { mustprogress nofree norecurse nosync nounwind willreturn memory(none) "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="cortex-a15" }