ABataev added a comment.
In D114171#3528088 <https://reviews.llvm.org/D114171#3528088>, @alexfh wrote:
> No reduced test case, but one observation is that most samples in the slow version are around this (preexisting code):
>
> // The reduction nodes (stored in UserIgnoreList) also should stay scalar.
> for (Value *V : VL) {
> if (is_contained(UserIgnoreList, V)) {
>
>
>
> 0.00 │ 7aa: testq %rdx, %rdx ▒
> │ leaq -536(%rbp), %r15 ▒
> │ ; llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:4296 ▒
> │ ; for (Value *V : VL) { ◆
> │ ↓ je 80a ▒
> │ movq -80(%rbp), %rax ▒
> │ movq 2088(%rax), %rbx ▒
> │ movq 2096(%rax), %rcx ▒
> │ leaq (%rbx,%rcx,8), %r10 ▒
> │ leaq (,%rcx,8), %r8 ▒
> │ ↓ jmp 7e8 ▒
> │ ; llvm-project/llvm/include/llvm/ADT/STLExtras.h:1671 ▒
> │ ; return std::find(adl_begin(Range), adl_end(Range), Element) != adl_end(Range); ▒
> │ 7d6: cmpq %r10, %rax ▒
> │ ; llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:4297 ▒
> │ ; if (is_contained(UserIgnoreList, V)) { ▒
> │ ↓ jne a98 ▒
> │ ; llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:4296 ▒
> │ ; for (Value *V : VL) { ▒
> 0.12 │ 7df: addq $8, %rsi ▒
> 0.01 │ cmpq %r9, %rsi ▒
> │ ↓ je 80a ▒
> │ 7e8: movq %rbx, %rax ▒
> │ testq %rcx, %rcx ▒
> │ ; include/c++/v1/__algorithm/find.h:24 ▒
> │ ; for (; __first != __last; ++__first) ▒
> │ ↑ je 7d6 ▒
> 0.10 │ movq (%rsi), %rdi ▒
> │ movq %r8, %rdx ▒
> │ movq %rbx, %rax ▒
> │ ; include/c++/v1/__algorithm/find.h:25 ▒
> │ ; if (*__first == __value_) ▒
> 99.02 │ 7f9: cmpq %rdi, (%rax) ▒
> │ ↑ je 7d6 ▒
> │ ; include/c++/v1/__algorithm/find.h:24 ▒
> │ ; for (; __first != __last; ++__first) ▒
> │ addq $8, %rax ▒
> │ addq $-8, %rdx ▒
> 0.03 │ ↑ jne 7f9 ▒
> 0.28 │ ↑ jmp 7df ▒
> │ ; llvm-project/llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp:4308 ▒
> │ ; auto *VL0 = cast<Instruction>(S.OpValue); ▒
> │ 80a: movq -136(%rbp), %r14 ▒
Aha, I committed 4e271fc49517362a9333371fb1ab7e865d4c1b0e <https://reviews.llvm.org/rG4e271fc49517362a9333371fb1ab7e865d4c1b0e> earlier today, which should improve it. Try to update the compiler.
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https://reviews.llvm.org/D114171/new/
https://reviews.llvm.org/D114171