[Codegen] Fix if_then_else codegen - #16242
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junrushao
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Dec 17, 2023
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isn't short circuiting the defined behavior for ternary expression? |
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When generating codes for |
jinhongyii
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Jan 4, 2024
junrushao
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Jan 7, 2024
* fix * lint * fix while loop * clean * clean --------- Co-authored-by: Junru Shao <junrushao1994@gmail.com>
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Hi, bohan, I recently am supporting Ternary Operator(like cond?true_branch:false_branch) in our device. I don't understand this modification. Can u explain this with a case? Thanks a lot! |
tlopex
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Sep 10, 2026
… code (#20285) ## Problem Since #16242, the `if_then_else` builtin call is expanded into an if/else statement. When printing the condition, the codegen wraps it in another pair of parentheses even though it is already parenthesized, producing `if ((i == 0))`. ## Impact The doubled parentheses trigger clang's `-Wparentheses-equality` warning under `-Wall`/`-Wparentheses`, which is noisy for downstream users who compile TVM-generated C sources with strict warning settings. Correctness is not affected — the issue is cosmetic. ## Solution Reuse the same leading/trailing parenthesis check as the existing `IfThenElseNode` handling in `CodeGenC`, so a condition that already starts and ends with parentheses is printed as-is. The generated code now reads `if (i == 0)`. Since `CodeGenC` is the shared base of all C-style backends (CUDA, Metal, ROCm, Vulkan, WebGPU, Hexagon), this fix covers them all at once. ## Testing - Added a regression test `test_if_then_else_avoids_extraneous_parentheses` in `tests/python/codegen/test_target_codegen_c_host.py`, which asserts the generated C source contains no `if ((` and validates the runtime result. - Ran the full `test_target_codegen_c_host.py` suite on aarch64 Linux with a local build: 10/10 passed. - `pre-commit` (clang-format, ruff-check, ruff-format) passed on the changed files. Co-authored-by: hejun <hejun72@outlook.com>
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Evaluating
op.if_then_elsewitha?b:cis potentially dangerous as it might evaluate expressions in branches without a guard of condition.While loop condition expression might require several var bindings generated, so we correct the while loop codegen from
while (cond)towhile (True)