What is the interger arithmetic overflow behavior with CUDA PTX?
What happens when you add two b-bit integer values in CUDA, with the add PTX instruction rather than add.cc, add.c or add.sat, but their sum requires b+1 bits? I'm interested in both the signed and unsigned cases.
Similarly, what happens when you subtract two unsigned values with the latter lower than the former? Or subtract two negative b-bit signed integers, with the result requiring b+1 bits?
The PTX reference doesn't say. Is it like "undefined behavior" in C++, and we're not allowed to make any assumptions about it? Does it follow some per-uarch rule? Some global rule?
Notes:
- A related question: How do I check for overflow of integer arithmetic in CUDA?
cuda language-lawyer integer-overflow integer-arithmetic ptx
asked Dec 27 '18 at 19:57
einpoklum
33.4k26120234
add a comment |
What happens when you add two b-bit integer values in CUDA, with the add PTX instruction rather than add.cc, add.c or add.sat, but their sum requires b+1 bits? I'm interested in both the signed and unsigned cases.
Similarly, what happens when you subtract two unsigned values with the latter lower than the former? Or subtract two negative b-bit signed integers, with the result requiring b+1 bits?
The PTX reference doesn't say. Is it like "undefined behavior" in C++, and we're not allowed to make any assumptions about it? Does it follow some per-uarch rule? Some global rule?
Notes:
- A related question: How do I check for overflow of integer arithmetic in CUDA?
cuda language-lawyer integer-overflow integer-arithmetic ptx
asked Dec 27 '18 at 19:57
einpoklum
33.4k26120234
add a comment |
What happens when you add two b-bit integer values in CUDA, with the add PTX instruction rather than add.cc, add.c or add.sat, but their sum requires b+1 bits? I'm interested in both the signed and unsigned cases.
Similarly, what happens when you subtract two unsigned values with the latter lower than the former? Or subtract two negative b-bit signed integers, with the result requiring b+1 bits?
The PTX reference doesn't say. Is it like "undefined behavior" in C++, and we're not allowed to make any assumptions about it? Does it follow some per-uarch rule? Some global rule?
Notes:
- A related question: How do I check for overflow of integer arithmetic in CUDA?
cuda language-lawyer integer-overflow integer-arithmetic ptx
asked Dec 27 '18 at 19:57
einpoklum
33.4k26120234
What happens when you add two b-bit integer values in CUDA, with the add PTX instruction rather than add.cc, add.c or add.sat, but their sum requires b+1 bits? I'm interested in both the signed and unsigned cases.
Similarly, what happens when you subtract two unsigned values with the latter lower than the former? Or subtract two negative b-bit signed integers, with the result requiring b+1 bits?
The PTX reference doesn't say. Is it like "undefined behavior" in C++, and we're not allowed to make any assumptions about it? Does it follow some per-uarch rule? Some global rule?
Notes:
- A related question: How do I check for overflow of integer arithmetic in CUDA?
cuda language-lawyer integer-overflow integer-arithmetic ptx
cuda language-lawyer integer-overflow integer-arithmetic ptx
asked Dec 27 '18 at 19:57
einpoklum
33.4k26120234
asked Dec 27 '18 at 19:57
einpoklum
33.4k26120234
asked Dec 27 '18 at 19:57
einpoklum
33.4k26120234
asked Dec 27 '18 at 19:57
einpoklum
33.4k26120234
asked Dec 27 '18 at 19:57
einpoklum
33.4k26120234
33.4k26120234
add a comment |
add a comment |
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