[llvm] r367753 - [Thumb] Fix invalid symbol redefinition due to duplicated jumptable (PR42760)

[Hans Wennborg via llvm-commits]

Merged to release_90 in r367808.

On Sat, Aug 3, 2019 at 8:46 AM Nikita Popov via llvm-commits
<llvm-commits at lists.llvm.org> wrote:
>
> Author: nikic
> Date: Fri Aug  2 23:47:23 2019
> New Revision: 367753
>
> URL: http://llvm.org/viewvc/llvm-project?rev=367753&view=rev
> Log:
> [Thumb] Fix invalid symbol redefinition due to duplicated jumptable (PR42760)
>
> Fix for https://bugs.llvm.org/show_bug.cgi?id=42760. A tBR_JTr
> instruction is duplicated by tail duplication, which results in
> the same jumptable with the same label being emitted twice.
>
> Fix this by marking tBR_JTr as not duplicable. The corresponding
> ARM/Thumb instructions are already marked as not duplicable.
> Additionally also mark tTBB_JT and tTBH_JT to be consistent with
> Thumb2, even though this shouldn't be strictly necessary.
>
> Differential Revision: https://reviews.llvm.org/D65606
>
> Added:
>     llvm/trunk/test/CodeGen/Thumb/pr42760.ll
> Modified:
>     llvm/trunk/lib/Target/ARM/ARMInstrThumb.td
>
> Modified: llvm/trunk/lib/Target/ARM/ARMInstrThumb.td
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMInstrThumb.td?rev=367753&r1=367752&r2=367753&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Target/ARM/ARMInstrThumb.td (original)
> +++ llvm/trunk/lib/Target/ARM/ARMInstrThumb.td Fri Aug  2 23:47:23 2019
> @@ -592,6 +592,7 @@ let isBranch = 1, isTerminator = 1, isBa
>                        [(ARMbrjt tGPR:$target, tjumptable:$jt)]>,
>                        Sched<[WriteBrTbl]> {
>      let Size = 2;
> +    let isNotDuplicable = 1;
>      list<Predicate> Predicates = [IsThumb, IsThumb1Only];
>    }
>  }
> @@ -1471,7 +1472,7 @@ def tLEApcrelJT : tPseudoInst<(outs tGPR
>  // Thumb-1 doesn't have the TBB or TBH instructions, but we can synthesize them
>  // and make use of the same compressed jump table format as Thumb-2.
>  let Size = 2, isBranch = 1, isTerminator = 1, isBarrier = 1,
> -    isIndirectBranch = 1 in {
> +    isIndirectBranch = 1, isNotDuplicable = 1 in {
>  def tTBB_JT : tPseudoInst<(outs),
>          (ins tGPRwithpc:$base, tGPR:$index, i32imm:$jt, i32imm:$pclbl), 0,
>           IIC_Br, []>, Sched<[WriteBr]>;
>
> Added: llvm/trunk/test/CodeGen/Thumb/pr42760.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Thumb/pr42760.ll?rev=367753&view=auto
> ==============================================================================
> --- llvm/trunk/test/CodeGen/Thumb/pr42760.ll (added)
> +++ llvm/trunk/test/CodeGen/Thumb/pr42760.ll Fri Aug  2 23:47:23 2019
> @@ -0,0 +1,56 @@
> +; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
> +; RUN: llc -mtriple=thumbv6m-none-unknown-eabi -tail-dup-placement-threshold=3 < %s | FileCheck %s
> +
> +define hidden void @test() {
> +; CHECK-LABEL: test:
> +; CHECK:       @ %bb.0: @ %entry
> +; CHECK-NEXT:    movs r0, #1
> +; CHECK-NEXT:    lsls r1, r0, #2
> +; CHECK-NEXT:    b .LBB0_2
> +; CHECK-NEXT:  .LBB0_1: @ %bb2
> +; CHECK-NEXT:    @ in Loop: Header=BB0_2 Depth=1
> +; CHECK-NEXT:    cmp r0, #0
> +; CHECK-NEXT:    bne .LBB0_6
> +; CHECK-NEXT:  .LBB0_2: @ %switch
> +; CHECK-NEXT:    @ =>This Inner Loop Header: Depth=1
> +; CHECK-NEXT:    adr r2, .LJTI0_0
> +; CHECK-NEXT:    ldr r2, [r2, r1]
> +; CHECK-NEXT:    mov pc, r2
> +; CHECK-NEXT:  @ %bb.3:
> +; CHECK-NEXT:    .p2align 2
> +; CHECK-NEXT:  .LJTI0_0:
> +; CHECK-NEXT:    .long .LBB0_6+1
> +; CHECK-NEXT:    .long .LBB0_4+1
> +; CHECK-NEXT:    .long .LBB0_6+1
> +; CHECK-NEXT:    .long .LBB0_5+1
> +; CHECK-NEXT:  .LBB0_4: @ %switch
> +; CHECK-NEXT:    @ in Loop: Header=BB0_2 Depth=1
> +; CHECK-NEXT:    b .LBB0_1
> +; CHECK-NEXT:  .LBB0_5: @ %bb
> +; CHECK-NEXT:    @ in Loop: Header=BB0_2 Depth=1
> +; CHECK-NEXT:    cmp r0, #0
> +; CHECK-NEXT:    beq .LBB0_1
> +; CHECK-NEXT:  .LBB0_6: @ %dead
> +entry:
> +  br label %switch
> +
> +switch:                                           ; preds = %bb2, %entry
> +  switch i32 undef, label %dead2 [
> +    i32 0, label %dead
> +    i32 1, label %bb2
> +    i32 2, label %dead
> +    i32 3, label %bb
> +  ]
> +
> +dead:                                             ; preds = %bb2, %bb, %switch, %switch
> +  unreachable
> +
> +dead2:                                            ; preds = %switch
> +  unreachable
> +
> +bb:                                               ; preds = %switch
> +  br i1 undef, label %dead, label %bb2
> +
> +bb2:                                              ; preds = %bb, %switch
> +  br i1 undef, label %dead, label %switch
> +}
>
>
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