Some guest env are small enough to reach the tlb with only a 12-bit addition.
Signed-off-by: Richard Henderson <r...@twiddle.net> --- tcg/aarch64/tcg-target.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/tcg/aarch64/tcg-target.c b/tcg/aarch64/tcg-target.c index 5691cc3..1905271 100644 --- a/tcg/aarch64/tcg-target.c +++ b/tcg/aarch64/tcg-target.c @@ -1136,46 +1136,58 @@ static void add_qemu_ldst_label(TCGContext *s, int is_ld, int opc, slow path for the failure case, which will be patched later when finalizing the slow path. Generated code returns the host addend in X1, clobbers X0,X2,X3,TMP. */ -static void tcg_out_tlb_read(TCGContext *s, TCGReg addr_reg, - int s_bits, uint8_t **label_ptr, int mem_index, int is_read) +static void tcg_out_tlb_read(TCGContext *s, TCGReg addr_reg, int s_bits, + uint8_t **label_ptr, int mem_index, int is_read) { TCGReg base = TCG_AREG0; int tlb_offset = is_read ? offsetof(CPUArchState, tlb_table[mem_index][0].addr_read) : offsetof(CPUArchState, tlb_table[mem_index][0].addr_write); + /* Extract the TLB index from the address into X0. X0<CPU_TLB_BITS:0> = addr_reg<TARGET_PAGE_BITS+CPU_TLB_BITS:TARGET_PAGE_BITS> */ tcg_out_ubfm(s, (TARGET_LONG_BITS == 64), TCG_REG_X0, addr_reg, TARGET_PAGE_BITS, TARGET_PAGE_BITS + CPU_TLB_BITS); + /* Store the page mask part of the address and the low s_bits into X3. Later this allows checking for equality and alignment at the same time. X3 = addr_reg & (PAGE_MASK | ((1 << s_bits) - 1)) */ tcg_fmt_Rdn_limm(s, INSN_ANDI, TARGET_LONG_BITS == 64, TCG_REG_X3, addr_reg, TARGET_PAGE_MASK | ((1 << s_bits) - 1)); + /* Add any "high bits" from the tlb offset to the env address into X2, to take advantage of the LSL12 form of the ADDI instruction. X2 = env + (tlb_offset & 0xfff000) */ - tcg_fmt_Rdn_aimm(s, INSN_ADDI, 1, TCG_REG_X2, base, tlb_offset & 0xfff000); + if (tlb_offset & 0xfff000) { + tcg_fmt_Rdn_aimm(s, INSN_ADDI, 1, TCG_REG_X2, base, + tlb_offset & 0xfff000); + base = TCG_REG_X2; + } + /* Merge the tlb index contribution into X2. - X2 = X2 + (X0 << CPU_TLB_ENTRY_BITS) */ - tcg_fmt_Rdnm_lsl(s, INSN_ADD, 1, TCG_REG_X2, TCG_REG_X2, + X2 = base + (X0 << CPU_TLB_ENTRY_BITS) */ + tcg_fmt_Rdnm_lsl(s, INSN_ADD, 1, TCG_REG_X2, base, TCG_REG_X0, CPU_TLB_ENTRY_BITS); + /* Merge "low bits" from tlb offset, load the tlb comparator into X0. X0 = load [X2 + (tlb_offset & 0x000fff)] */ tcg_out_ldst(s, TARGET_LONG_BITS == 64 ? LDST_64 : LDST_32, LDST_LD, TCG_REG_X0, TCG_REG_X2, (tlb_offset & 0xfff)); + /* Load the tlb addend. Do that early to avoid stalling. X1 = load [X2 + (tlb_offset & 0xfff) + offsetof(addend)] */ tcg_out_ldst(s, LDST_64, LDST_LD, TCG_REG_X1, TCG_REG_X2, (tlb_offset & 0xfff) + (offsetof(CPUTLBEntry, addend)) - (is_read ? offsetof(CPUTLBEntry, addr_read) : offsetof(CPUTLBEntry, addr_write))); + /* Perform the address comparison. */ tcg_out_cmp(s, (TARGET_LONG_BITS == 64), TCG_REG_X0, TCG_REG_X3, 0); - *label_ptr = s->code_ptr; + /* If not equal, we jump to the slow path. */ + *label_ptr = s->code_ptr; tcg_out_goto_cond_noaddr(s, TCG_COND_NE); } -- 1.8.3.1