Add bitwise_shift_left and bitwise_shift_right #990

Blury233 · 2025-09-28T09:06:09Z

PR Category

Operator

Type of Change

New Feature

Description

This PR adds:

bitwise_shift_left
bitwise_shift_right

Issue

Progress

Change is properly reviewed (1 reviewer required, 2 recommended).
Change is responded to an issue.
Change is fully covered by a UT.

Performance

Accuracy Test

Performance Test

gemini-code-assist · 2025-09-28T09:06:21Z

Summary of Changes

Hello @Blury233, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request enhances the flag_gems library by adding two new bitwise shift operators: bitwise_shift_left and bitwise_shift_right. These operators are designed for high performance through Triton kernel implementations and are thoroughly validated with new accuracy and performance tests, ensuring their correctness and efficiency across different scenarios.

Highlights

New Bitwise Operators: Introduced bitwise_shift_left and bitwise_shift_right operators to the flag_gems library, expanding its functional capabilities.
Triton Kernel Implementation: Both new bitwise shift operators are implemented using Triton kernels, leveraging pointwise_dynamic for efficient execution.
Comprehensive Testing: Added extensive accuracy tests for both bitwise_left_shift and bitwise_right_shift, covering various input shapes, integer data types, and their inplace versions. Performance benchmarks were also included.

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Code Review

This pull request introduces bitwise_shift_left and bitwise_shift_right operators, complete with Triton kernels, registration, and both accuracy and performance tests. The implementation leverages pointwise_dynamic for handling broadcasting, which is a good approach. The overall structure is clean and follows the existing patterns in the codebase. My review comments focus on improving the comprehensiveness of the tests by using a wider, more realistic range of shift values, and on maintaining consistency in logging across the new operator files.

gemini-code-assist · 2025-09-28T09:07:28Z

benchmark/test_unary_pointwise_perf.py

+            shift_amount = torch.randint(
+                0, 8, shape, dtype=cur_dtype, device=self.device
+            )


The range of shift amounts [0, 8) is a bit narrow for integer types larger than 8 bits. To ensure the performance benchmark covers a more realistic range of inputs, consider using a range for the shift amount that is dependent on the cur_dtype, up to the number of bits in the type.

Suggested change

shift_amount = torch.randint(

0, 8, shape, dtype=cur_dtype, device=self.device

)

shift_amount = torch.randint(

0, torch.iinfo(cur_dtype).bits, shape, dtype=cur_dtype, device=self.device

)

gemini-code-assist · 2025-09-28T09:07:28Z

src/flag_gems/ops/bitwise_right_shift.py

+def bitwise_right_shift(self, other, *, out=None):
+    return bitwise_right_shift_kernel(self, other, out=out)


For consistency with bitwise_left_shift and to aid in debugging, it would be good to add a debug log message here.

Suggested change

def bitwise_right_shift(self, other, *, out=None):

return bitwise_right_shift_kernel(self, other, out=out)

def bitwise_right_shift(self, other, *, out=None):

logger.debug("GEMS BITWISE_RIGHT_SHIFT")

return bitwise_right_shift_kernel(self, other, out=out)

gemini-code-assist · 2025-09-28T09:07:28Z

tests/test_unary_pointwise_ops.py

+def test_accuracy_bitwise_left_shift(shapes, dtype):
+    shape_a, shape_b = shapes
+    res_a = torch.randint(0, 100, shape_a, dtype=dtype, device=flag_gems.device)
+    res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)


The range of shift amounts [0, 8) is a bit narrow for integer types larger than 8 bits. To improve test coverage, consider using a range that is dependent on the dtype, up to the number of bits in the type. This will ensure that shifts by larger amounts are also tested.

Suggested change

res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)

res_b = torch.randint(0, torch.iinfo(dtype).bits, shape_b, dtype=dtype, device=flag_gems.device)

gemini-code-assist · 2025-09-28T09:07:28Z

tests/test_unary_pointwise_ops.py

+def test_accuracy_bitwise_right_shift(shapes, dtype):
+    shape_a, shape_b = shapes
+    res_a = torch.randint(0, 100, shape_a, dtype=dtype, device=flag_gems.device)
+    res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)


The range of shift amounts [0, 8) is a bit narrow for integer types larger than 8 bits. To improve test coverage, consider using a range that is dependent on the dtype, up to the number of bits in the type. This will ensure that shifts by larger amounts are also tested.

Suggested change

res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)

res_b = torch.randint(0, torch.iinfo(dtype).bits, shape_b, dtype=dtype, device=flag_gems.device)

gemini-code-assist · 2025-09-28T09:07:28Z

tests/test_unary_pointwise_ops.py

+def test_accuracy_bitwise_left_shift_(shapes, dtype):
+    shape_a, shape_b = shapes
+    res_a = torch.randint(0, 100, shape_a, dtype=dtype, device=flag_gems.device)
+    res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)


The range of shift amounts [0, 8) is a bit narrow for integer types larger than 8 bits. To improve test coverage, consider using a range that is dependent on the dtype, up to the number of bits in the type. This will ensure that shifts by larger amounts are also tested for the in-place operation.

Suggested change

res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)

res_b = torch.randint(0, torch.iinfo(dtype).bits, shape_b, dtype=dtype, device=flag_gems.device)

gemini-code-assist · 2025-09-28T09:07:28Z

tests/test_unary_pointwise_ops.py

+def test_accuracy_bitwise_right_shift_(shapes, dtype):
+    shape_a, shape_b = shapes
+    res_a = torch.randint(0, 100, shape_a, dtype=dtype, device=flag_gems.device)
+    res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)


The range of shift amounts [0, 8) is a bit narrow for integer types larger than 8 bits. To improve test coverage, consider using a range that is dependent on the dtype, up to the number of bits in the type. This will ensure that shifts by larger amounts are also tested for the in-place operation.

Suggested change

res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)

res_b = torch.randint(0, torch.iinfo(dtype).bits, shape_b, dtype=dtype, device=flag_gems.device)

add bitwise shift ops (left/right)

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Add bitwise_shift_left and bitwise_shift_right #990

Add bitwise_shift_left and bitwise_shift_right #990

Blury233 commented Sep 28, 2025

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		def bitwise_right_shift(self, other, *, out=None):
		return bitwise_right_shift_kernel(self, other, out=out)

	res_b = torch.randint(0, 8, shape_b, dtype=dtype, device=flag_gems.device)
	res_b = torch.randint(0, torch.iinfo(dtype).bits, shape_b, dtype=dtype, device=flag_gems.device)

Add bitwise_shift_left and bitwise_shift_right #990

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Blury233 commented Sep 28, 2025

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