X28
alias W28architectural number 28Callee-saved (platform register)
X2864-bit view
X only
shared with W28
W2832-bit view
bits 31:0 of X28
write
Writing W28 does not simply deposit 32 bits. Bits 63:32 of X28 are reset to zero as a side effect, so a W write always clears the upper half. This is the reason W28 and X28 can never hold unrelated values at the same time.
Notes
Last of the general callee-saved registers before FP and LR.