[opt] strength reduce umod-by-shifted-bit #3673
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| Node* divisor = n->operand(1); | ||
| const int64_t bit_count = x->BitCountOrDie(); | ||
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| auto replace_with_select = [&](Node* b, int64_t k) -> absl::StatusOr<bool> { |
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This only ever returns true
| m::Concat(m::Literal(UBits(0, 32 - k)), narrowed_and); | ||
| auto concat_form_flipped = | ||
| m::Concat(m::Literal(UBits(0, 32 - k)), narrowed_and_flipped); | ||
| EXPECT_THAT(f->return_value(), |
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Is there any convenient way to restrict the pass pipeline such that we don't need to assert over all these possible forms?
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| } // namespace | ||
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| std::optional<ShiftedBitView> IsOneShiftedBit(Node* node) { |
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This strikes me as a specialized form of querying bit_provenance_analysis for the source of a node's bits and then asking if all bits are literal 0 except for 1 bit. Can you look into using that analysis instead of implementing pattern matchers for these two cases?
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Uses a "View" extractor similarly to what we did for BinarySelect in the recent PR to consolidate two forms for "one bit is set" (concat and bit shifted by constant literal).