[PATCH] D153607: [CSKY] Optimize conditional branch with BHZ32/BHSZ32/BLSZ32/BLZ32

[Ben Shi via Phabricator via llvm-commits]

benshi001 added a comment.

In D153607#4467599 <https://reviews.llvm.org/D153607#4467599>, @barannikov88 wrote:

> In D153607#4467588 <https://reviews.llvm.org/D153607#4467588>, @benshi001 wrote:
>
>> In D153607#4467587 <https://reviews.llvm.org/D153607#4467587>, @barannikov88 wrote:
>>
>>> In D153607#4462927 <https://reviews.llvm.org/D153607#4462927>, @benshi001 wrote:
>>>
>>>> In D153607#4462762 <https://reviews.llvm.org/D153607#4462762>, @zixuan-wu wrote:
>>>>
>>>>> need more case about bhz/bhsz?
>>>>
>>>> It is hard to add tests for
>>>>
>>>>   def : Pat<(brcond (i32 (setge GPR:$rs1, (i32 1))), bb:$imm16),
>>>>             (BHZ32 GPR:$rs1, bb:$imm16)>;
>>>>
>>>> Since the original IR pattern
>>>>
>>>>   %icmp = icmp sge i32 %x, 1
>>>>   br i1 %icmp, label %label1, label %label2
>>>>
>>>> is always transformed to an equivalent form by DAGCombiner
>>>>
>>>>   %icmp = icmp slt i32 %x, 1
>>>>   br i1 %icmp, label %label2, label %label1
>>>>
>>>> before reaching to the CSKY backend.
>>>>
>>>> And `BHSZ32` has the same issue.
>>>>
>>>> I add these two `Pat`s for `BHSZ32` and `BHZ32`, just in case there is future changes in the DAGCombiner.
>>>
>>> Try something like:
>>>
>>>   extern void on_false(void);
>>>   void test_ge_1(int x) {
>>>     if (!(x >= 1))
>>>       on_false();
>>>   }
>>
>> Unfortunately your program can not lead to `BHSZ` or `BHZ`, still `BLSZ` as follow,
>>
>>           .type   test_ge_1, at function
>>   test_ge_1:                              # @test_ge_1
>>   # %bb.0:
>>           subi16  sp, sp, 4
>>           st32.w  lr, (sp, 0)                     # 4-byte Folded Spill
>>           blsz32  a0, .LBB0_2
>>   # %bb.1:
>>           ld32.w  lr, (sp, 0)                     # 4-byte Folded Reload
>>           addi16  sp, sp, 4
>>           rts16
>>   .LBB0_2:
>>           jsri32  [.LCPI0_0]
>>           ld32.w  lr, (sp, 0)                     # 4-byte Folded Reload
>>           addi16  sp, sp, 4
>>           rts16
>>           .p2align        1
>>   # %bb.3:
>>           .p2align        2, 0x0
>>   .LCPI0_0:
>>           .long   on_false
>>   .Lfunc_end0:
>>           .size   test_ge_1, .Lfunc_end0-test_ge_1
>>                                           # -- End function
>
> It does test the pattern though. You can see BHZ32 if you pass -stop-after=finalize-isel.

I still can not get BHZ32/BHSZ32, could you please make another patch for that?


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