timing loop warning when synthesis

[hhhsiang]

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Is there an existing CVA6 bug for this?

• [X] I have searched the existing bug issues

Bug Description

When I synthesize cva6 with WB cache, there is timing loop warning occurred in cache system. It happened in tag_cmp and miss_hander. I think it is a significant warning. Is it normal or acceptable?

It seems to relate to https://github.com/openhwgroup/cva6/pull/1761, but the problem is still exist.

The following is the timing loop path：

Startpoint: gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u7/O (internal pin) Endpoint: gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u7/O (internal pin) Path Group: (none) Path Type: max

---

gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u7/O (INV6CK) 0.00 0.00 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/n1954 (net) 3 0.00 0.00 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u6/I (BUF1S) 0.00 0.00 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u6/O (BUF1S) 0.17 0.17 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/n4119 (net) 1 0.00 0.17 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u4/I (INV1S) 0.00 0.17 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u4/O (INV1S) 0.16 0.33 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/n1935 (net) 1 0.00 0.33 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u5/I (INV3) 0.00 0.33 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u5/O (INV3) 1.35 1.69 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/gnt_o[3] (net) 211 0.00 1.69 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u682/B1 (AOI22S) 0.00 1.69 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u682/O (AOI22S) 0.13 1.82 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/n660 (net) 1 0.00 1.82 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u1502/I1 (ND3) 0.00 1.82 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u1502/O (ND3) 0.33 2.15 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/req_o[2] (net) 4 0.00 2.15 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/req_o[2] (tag_cmp_00000005_0000000c_010242) 0.00 2.15 r gen_cache_wb_i_cache_subsystem/i_nbdcache/req_ram[2] (net) 0.00 2.15 r gen_cache_wb_i_cache_subsystem/i_nbdcache/u15/I1 (NR3) 0.00 2.15 r gen_cache_wb_i_cache_subsystem/i_nbdcache/u15/O (NR3) 0.29 2.44 f gen_cache_wb_i_cache_subsystem/i_nbdcache/n302 (net) 1 0.00 2.44 f gen_cache_wb_i_cache_subsystem/i_nbdcache/u18/I1 (ND3) 0.00 2.44 f gen_cache_wb_i_cache_subsystem/i_nbdcache/u18/O (ND3) 0.24 2.68 r gen_cache_wb_i_cache_subsystem/i_nbdcache/n_69_net_ (net) 2 0.00 2.68 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/req_i (dcache_valid_array_real_sram_00000040_1_00000100) 0.00 2.68 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/req_i (net) 0.00 2.68 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/u15/I (INV1S) 0.00 2.68 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/u15/O (INV1S) 0.18 2.85 f gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/n70 (net) 1 0.00 2.85 f gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/u11/I1 (NR2P) 0.00 2.85 f gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/u11/O (NR2P) 0.23 3.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/oe (net) 1 0.00 3.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/gen_cut_0__dcache_valid_array_wrapper/oe (dcache_valid_array_wrapper) 0.00 3.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/gen_cut_0__dcache_valid_array_wrapper/oe (net) 0.00 3.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/gen_cut_0__dcache_valid_array_wrapper/i_dcache_valid_array/OE (SUMA180_256X8X8BM1) 0.00 3.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/gen_cut_0__dcache_valid_array_wrapper/i_dcache_valid_array/DO49 (SUMA180_256X8X8BM1) 0.78 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/gen_cut_0__dcache_valid_array_wrapper/do[49] (net) 2 0.00 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/gen_cut_0__dcache_valid_array_wrapper/do[49] (dcache_valid_array_wrapper) 0.00 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/rdata_o[49] (net) 0.00 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/valid_dirty_sram/rdata_o[49] (dcache_valid_array_real_sram_00000040_1_00000100) 0.00 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/rdata_ram[1045] (net) 0.00 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/rdata_i[1045] (tag_cmp_00000005_0000000c_010242) 0.00 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/rdata_i[1045] (net) 0.00 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u29/I (BUF2) 0.00 3.86 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u29/O (BUF2) 0.23 4.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/rdata_o[1045] (net) 4 0.00 4.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/rdata_o[1045] (tag_cmp_00000005_0000000c_010242) 0.00 4.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/rdata[1045] (net) 0.00 4.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/data_i[1045] (miss_handler_00000004_244242) 0.00 4.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/data_i[1045] (net) 0.00 4.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u27/I1 (ND2S) 0.00 4.09 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u27/O (ND2S) 0.18 4.27 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/n4091 (net) 2 0.00 4.27 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u52/I1 (ND2S) 0.00 4.27 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u52/O (ND2S) 0.17 4.44 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/n3973 (net) 1 0.00 4.44 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u169/I1 (OR2P) 0.00 4.44 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u169/O (OR2P) 0.28 4.73 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/n4546 (net) 3 0.00 4.73 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u6/I2 (NR2F) 0.00 4.73 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u6/O (NR2F) 0.09 4.82 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/n4409 (net) 4 0.00 4.82 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u5/I2 (OR2T) 0.00 4.82 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u5/O (OR2T) 0.35 5.16 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/n5957 (net) 20 0.00 5.16 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u76/I2 (OR2) 0.00 5.16 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u76/O (OR2) 0.30 5.47 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/be_o[0] (net) 2 0.00 5.47 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u64/I (INV2) 0.00 5.47 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u64/O (INV2) 0.10 5.56 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/n4519 (net) 1 0.00 5.56 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u119/I1 (ND3P) 0.00 5.56 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/u119/O (ND3P) 0.14 5.70 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/req_o[0] (net) 2 0.00 5.70 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_miss_handler/req_o[0] (miss_handler_00000004_244242) 0.00 5.70 f gen_cache_wb_i_cache_subsystem/i_nbdcache/req[0] (net) 0.00 5.70 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/req_i[0] (tag_cmp_00000005_0000000c_010242) 0.00 5.70 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/req_i[0] (net) 0.00 5.70 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u65/I2 (NR2T) 0.00 5.70 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u65/O (NR2T) 0.35 6.05 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/n4125 (net) 10 0.00 6.05 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u1494/I1 (AN2T) 0.00 6.05 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u1494/O (AN2T) 0.57 6.63 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/gnt_o[2] (net) 20 0.00 6.63 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u9/I1 (ND3P) 0.00 6.63 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u9/O (ND3P) 0.56 7.18 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/n1953 (net) 20 0.00 7.18 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u7/I (INV6CK) 0.00 7.18 f gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/u7/O (INV6CK) 0.15 7.33 r gen_cache_wb_i_cache_subsystem/i_nbdcache/i_tag_cmp/n1954 (net) 3 0.00 7.33 r data arrival time 7.33