BR

Branch to Register branches unconditionally to an address in a register, with a hint that this is not a subroutine return.

313029282726252423222120191817161514131211109876543210
1101011000011111000000Rn00000
ZopAMRm

Integer

BR <Xn>

integer n = UInt(Rn); BranchType branch_type; integer m = UInt(Rm); boolean pac = (A == '1'); boolean use_key_a = (M == '0'); boolean source_is_sp = ((Z == '1') && (m == 31)); if !pac && m != 0 then UnallocatedEncoding(); elsif pac && !HavePACExt() then UnallocatedEncoding(); case op of when '00' branch_type = BranchType_JMP; when '01' branch_type = BranchType_CALL; when '10' branch_type = BranchType_RET; otherwise UnallocatedEncoding(); if pac then if Z == '0' && m != 31 then UnallocatedEncoding(); if branch_type == BranchType_RET then if n !=31 then UnallocatedEncoding(); n = 30; source_is_sp = TRUE;

Assembler Symbols

<Xn>

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

Operation

bits(64) target = X[n]; if pac then bits(64) modifier = if source_is_sp then SP[] else X[m]; if use_key_a then target = AuthIA(target, modifier); else target = AuthIB(target, modifier); if branch_type == BranchType_CALL then X[30] = PC[] + 4; BranchTo(target, branch_type);


Internal version only: isa v27.02, AdvSIMD v26.0, pseudocode v34.2.2 ; Build timestamp: 2018-03-28T19:55

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