X15
alias W15architectural number 15Temporary (platform register)
X1564-bit view
X only
shared with W15
W1532-bit view
bits 31:0 of X15
write
Writing W15 does not simply deposit 32 bits. Bits 63:32 of X15 are reset to zero as a side effect, so a W write always clears the upper half. This is the reason W15 and X15 can never hold unrelated values at the same time.
Notes
Last of the caller-saved temporaries before the IP registers.