X1
alias W1architectural number 1Argument 1 / return value 1
X164-bit view
X only
shared with W1
W132-bit view
bits 31:0 of X1
write
Writing W1 does not simply deposit 32 bits. Bits 63:32 of X1 are reset to zero as a side effect, so a W write always clears the upper half. This is the reason W1 and X1 can never hold unrelated values at the same time.
Notes
Holds the high half of a small struct return value. Otherwise identical in status to X0.