MIPS: Improve WARN for $0 constraint on MIPSR6 branches
Change is invalid due to file duplication and incorrect commit message, and requires test invocation.
Maciej W. Rozycki states that a proposed change to improve warnings for the $0 constraint on MIPS R6 branches is invalid. He points out that the source file was already added and renamed in previous commits, the commit heading is inaccurate, and the change is missing test invocation in mips.exp. The issues collectively render the patch unusable in its current form.
- reviewer
States the change is invalid due to file duplication, lack of test invocation, and an inaccurate commit heading, referencing previous commits.
“This change is invalid. It wouldn't be in its current form owing to the missing source and the lack of test invocation in mips.exp, but it's just that the file was already added with commit 6914869aa73d ("MIPS: Fix constraint issues with the R6 beqc and bnec instructions") and then renamed with commit cd4797ee0546 ("MIPS/gas: Reject $0 as source register for DAUI instruction"). Also the co…”
- contributor
Submitted a patch to validate warnings for $0 constraint on MIPS R6 branches, aiming to improve assembler reliability.
“Validation of warnings and error detection within branching instructions for the MIPS R6 architecture. The test ensures that the assembler generates accurate warnings when a user makes an error involving the use of the $0 register in branching instructions, thereby improving the reliability and correctness of binary outputs.”
Technical Tradeoffs
- Correctness of assembler warnings for MIPS R6 architecture.
- Avoids code duplication and ensures accurate commit history.
In Details
This pertains to gas/mips/r6-branch-constraints.l and gas/testsuite/gas-mips/mips.exp. The patch attempts to add new warnings for the R6 MIPS architecture related to the use of the $0 register in branch instructions. The reviewer identifies that the file already exists from prior commits with different names and that the commit message doesn't accurately reflect the changes or the associated test setup.
- MIPS R6
- The sixth revision of the MIPS Reduced Instruction Set Computer (RISC) architecture, featuring specific instruction set extensions and behaviors.
- $0 register
- In MIPS assembly, the register
$0(or$zero) is hardwired to the value zero. It's often used for specific operations or as a conventional way to indicate a null or zero value. - branch instructions
- Instructions that alter the sequential flow of program execution, such as jumps and conditional branches.
- assembler
- A program that translates assembly language code into machine code.
- gas
- The GNU Assembler, part of the GNU Binutils package.
- commit
- A saved state of changes in a version control system like Git, representing a specific point in the project's history.