WebSep 4, 2024 · 參考 When to use earlyclobber constraint in extended GCC inline assembly? ... When not using an asmSymbolicName, use the (zero-based) position of the operand in the list of operands in the assembler template. For example if there are three output operands, use ‘%0’ in the template to refer to the first, ‘%1’ for the second, and ‘%2 ... Webwhere in the last forms, asm-qualifiers contains goto (and in the first shape, not). The asm keyword is ampere GNU extension. When writing code that can be compiled on -ansi and the various -std options, use __asm__ instead of asm (see Alternate Catchwords).. Qualifiers volatile. The typical use of upgraded asm statements is go manipulate input …
Assembler Instructions with C Expression Operands
WebMar 29, 2024 · A operand which is read by the instruction can be tied to an earlyclobber operand if its only use as an input occurs before the early result is written. Adding alternatives of this form often allows GCC to produce better code when only some of the read operands can be affected by the earlyclobber. See, for example, the ‘mulsi3’ insn … WebA "=" or "+" modifier usually has to be added to the constraint of the output operand. The "earlyclobber" modifier can be added to output operands (e.g. "=&r") to make sure GCC uses different registers for input and output operands. GCC assumes that the output operands are not used before the code is done with all input operands and reuses the ... soldiers after the vietnam war
Modifiers - Using the GNU Compiler Collection (GCC)
http://web.mit.edu/rhel-doc/3/rhel-gcc-en-3/constraints.html Web"&" : Means that this operand is an earlyclobber operand, which is modified before the instruction is finished using the input operands. Therefore, this operand may not lie in a … WebAug 31, 2015 · A operand which is read by the instruction can be tied to an earlyclobber operand if its only use as an input occurs before the early result is written. Adding alternatives of this form often allows GCC to produce better code when only some of the read operands can be affected by the earlyclobber. See, for example, the mulsi3 insn of … sma america downloads