BLR

Branch with link to register

This instruction calls a subroutine at an address in a register, setting register X30 to PC+4.

Encoding: Integer

31	30	29	28	27	26	25	24	23	22	21	20	19	18	17	16	15	14	13	12	11	10	9	8	7	6	5	4	3	2	1	0
1	1	0	1	0	1	1	0	0	0	1	1	1	1	1	1	0	0	0	0	0	0						0	0	0	0	0
							Z		op		op2									A	M	Rn					Rm

BLR <Xn>

Decoding algorithm

constant integer n = UInt(Rn);

Operation

constant bits(64) target = X[n, 64];
if IsFeatureImplemented(FEAT_GCS) && GCSPCREnabled(PSTATE.EL) then
    AddGCSRecord(PC64 + 4);

// Value in BTypeNext will be used to set PSTATE.BTYPE
BTypeNext = '10';

X[30, 64] = PC64 + 4;

constant boolean branch_conditional = FALSE;
BranchTo(target, BranchType_INDCALL, branch_conditional);

Explanations

<Xn>: Is the 64-bit name of the general-purpose register holding the address to be branched to, encoded in the "Rn" field.