riscv/musl - musl - Gitea: Git with a cup of tea

78 Tags

7.6 MiB

Tree: b8b729bd22

Author	SHA1	Message	Date
Alexander Monakov	4554f155dd	setjmp: optimize longjmp prologues Use a branchless sequence that is one byte shorter on 64-bit, same size on 32-bit. Thanks to Pete Cawley for suggesting this variant.	6 years ago
Alexander Monakov	59b64ff686	setjmp: optimize x86 longjmp epilogues	6 years ago
Alexander Monakov	c6a6fe4ccd	setjmp: avoid useless REX-prefix on xor %eax, %eax	6 years ago
Alexander Monakov	21431a0e43	setjmp: fix x86-64 longjmp argument adjustment longjmp 'val' argument is an int, but the assembly is referencing 64-bit registers as if the argument was a long, or the caller was responsible for extending the argument. Though the psABI is not clear on this, the interpretation in GCC is that high bits may be arbitrary and the callee is responsible for sign/zero-extending the value as needed (likewise for return values: callers must anticipate that high bits may be garbage). Therefore testing %rax is a functional bug: setjmp would wrongly return zero if longjmp was called with val==0, but high bits of %rsi happened to be non-zero. Rewrite the prologue to refer to 32-bit registers. In passing, change 'test' to use %rsi, as there's no advantage to using %rax and the new form is cheaper on processors that do not perform move elimination.	6 years ago
rofl0r	323272db17	import vanilla x86_64 code as x32	13 years ago