Hint instruction is for the instruction set space that is reserved for architectural hint instructions.
Some encodings described here are not allocated in this revision of the architecture, and behave as NOPs. These encodings might be allocated to other hint functionality in future revisions of the architecture and therefore must not be used by software.
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| 1 | 1 | 0 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 0 | 1 | 0 | CRm | op2 | 1 | 1 | 1 | 1 | 1 | |||||
HINT #<imm>
SystemHintOp op; case CRm:op2 of when '0000 000' op = SystemHintOp_NOP; when '0000 001' op = SystemHintOp_YIELD; when '0000 010' op = SystemHintOp_WFE; when '0000 011' op = SystemHintOp_WFI; when '0000 100' op = SystemHintOp_SEV; when '0000 101' op = SystemHintOp_SEVL; when '0000 110' if !IsFeatureImplemented(FEAT_DGH) then EndOfInstruction(); // Instruction executes as NOP op = SystemHintOp_DGH; when '0000 111' SEE "XPACLRI"; when '0001 xxx' case op2 of when '000' SEE "PACIA1716"; when '010' SEE "PACIB1716"; when '100' SEE "AUTIA1716"; when '110' SEE "AUTIB1716"; otherwise EndOfInstruction(); // Instruction executes as NOP when '0010 000' if !IsFeatureImplemented(FEAT_RAS) then EndOfInstruction(); // Instruction executes as NOP op = SystemHintOp_ESB; when '0010 001' if !IsFeatureImplemented(FEAT_SPE) then EndOfInstruction(); // Instruction executes as NOP op = SystemHintOp_PSB; when '0010 010' if !IsFeatureImplemented(FEAT_TRF) then EndOfInstruction(); // Instruction executes as NOP op = SystemHintOp_TSB; when '0010 011' if !IsFeatureImplemented(FEAT_GCS) then EndOfInstruction(); // Instruction executes as NOP op = SystemHintOp_GCSB; when '0010 100' op = SystemHintOp_CSDB; when '0010 110' // Instruction executes as NOP if !IsFeatureImplemented(FEAT_CLRBHB) then EndOfInstruction(); op = SystemHintOp_CLRBHB; when '0011 xxx' case op2 of when '000' SEE "PACIAZ"; when '001' SEE "PACIASP"; when '010' SEE "PACIBZ"; when '011' SEE "PACIBSP"; when '100' SEE "AUTIAZ"; when '101' SEE "AUTIASP"; when '110' SEE "AUTIBZ"; when '111' SEE "AUTIBSP"; when '0100 xx0' // Instruction executes as NOP if !IsFeatureImplemented(FEAT_BTI) then EndOfInstruction(); // Check branch target compatibility between BTI instruction and PSTATE.BTYPE SetBTypeCompatible(BTypeCompatible_BTI(op2<2:1>)); op = SystemHintOp_BTI; when '0100 111' SEE "PACM"; when '0101 000' if !IsFeatureImplemented(FEAT_CHK) then EndOfInstruction(); // Instruction executes as NOP op = SystemHintOp_CHKFEAT; otherwise EndOfInstruction(); // Instruction executes as NOP
case op of when SystemHintOp_YIELD Hint_Yield(); when SystemHintOp_DGH Hint_DGH(); when SystemHintOp_WFE integer localtimeout = 1 << 64; // No local timeout event is generated Hint_WFE(localtimeout, WFxType_WFE); when SystemHintOp_WFI integer localtimeout = 1 << 64; // No local timeout event is generated Hint_WFI(localtimeout, WFxType_WFI); when SystemHintOp_SEV SendEvent(); when SystemHintOp_SEVL SendEventLocal(); when SystemHintOp_ESB if IsFeatureImplemented(FEAT_TME) && TSTATE.depth > 0 then FailTransaction(TMFailure_ERR, FALSE); SynchronizeErrors(); AArch64.ESBOperation(); if PSTATE.EL IN {EL0, EL1} && EL2Enabled() then AArch64.vESBOperation(); TakeUnmaskedSErrorInterrupts(); when SystemHintOp_PSB ProfilingSynchronizationBarrier(); when SystemHintOp_TSB TraceSynchronizationBarrier(); when SystemHintOp_GCSB GCSSynchronizationBarrier(); when SystemHintOp_CHKFEAT X[16, 64] = AArch64.ChkFeat(X[16, 64]); when SystemHintOp_CSDB ConsumptionOfSpeculativeDataBarrier(); when SystemHintOp_CLRBHB Hint_CLRBHB(); when SystemHintOp_BTI SetBTypeNext('00'); when SystemHintOp_NOP return; // Do nothing otherwise Unreachable();
Internal version only: aarchmrs v2024-03_relA, pseudocode v2024-03_rel, sve v2024-03_rel ; Build timestamp: 2024-03-26T09:45
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