synth: Make "slang" the default frontend #3772

openroad-ci · 2026-01-08T14:09:10Z

Make slang the default frontend and add opt-outs for some designs. The opt-outs are for

all private designs except those which already use slang, this is done to save on private CI churn
the remaining opt-outs are on designs which don't go through with slang because slang is flagging a syntactical or semantical error in the input

CI Could not Update Rules

[ERROR] asap7/aes-block: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/aes-mbff: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/aes: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/aes_lvt: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/cva6: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/ethmac: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/ethmac_lvt: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/gcd-ccs: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/gcd: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/ibex: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/jpeg: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/jpeg_lvt: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/mock-alu: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/mock-cpu: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/riscv32i-mock-sram: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/riscv32i: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/swerv_wrapper: No metrics found, please check the latest CI build for issues.
[ERROR] asap7/uart: No metrics found, please check the latest CI build for issues.
[ERROR] gf180/aes-hybrid: No metrics found, please check the latest CI build for issues.
[ERROR] gf180/aes: No metrics found, please check the latest CI build for issues.
[ERROR] gf180/ibex: No metrics found, please check the latest CI build for issues.
[ERROR] gf180/jpeg: No metrics found, please check the latest CI build for issues.
[ERROR] gf180/riscv32i: No metrics found, please check the latest CI build for issues.
[ERROR] gf180/uart-blocks: No metrics found, please check the latest CI build for issues.
[ERROR] ihp-sg13g2/aes: No metrics found, please check the latest CI build for issues.
[ERROR] ihp-sg13g2/gcd: No metrics found, please check the latest CI build for issues.
[ERROR] ihp-sg13g2/i2c-gpio-expander: No metrics found, please check the latest CI build for issues.
[ERROR] ihp-sg13g2/ibex: No metrics found, please check the latest CI build for issues.
[ERROR] ihp-sg13g2/jpeg: No metrics found, please check the latest CI build for issues.
[ERROR] ihp-sg13g2/riscv32i: No metrics found, please check the latest CI build for issues.
[ERROR] ihp-sg13g2/spi: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/aes: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/ariane133: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/ariane136: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/black_parrot: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/bp_be_top: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/bp_fe_top: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/bp_multi_top: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/dynamic_node: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/gcd: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/ibex: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/jpeg: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/mempool_group: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/swerv: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/swerv_wrapper: No metrics found, please check the latest CI build for issues.
[ERROR] nangate45/tinyRocket: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hd/aes: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hd/chameleon: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hd/gcd: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hd/ibex: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hd/jpeg: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hd/microwatt: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hd/riscv32i: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hs/aes: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hs/gcd: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hs/ibex: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hs/jpeg: No metrics found, please check the latest CI build for issues.
[ERROR] sky130hs/riscv32i: No metrics found, please check the latest CI build for issues.

Updated Rules

designs/asap7/aes-block/rules-base.json updates:

Metric	Old	New	Type
placeopt__design__instance__count__stdcell	10573	19934	Failing
detailedroute__route__wirelength	52923	77305	Failing

designs/asap7/aes-mbff/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__ws	-38.2	-69.5	Failing
cts__timing__setup__tns	-687.0	-1500.0	Failing
globalroute__timing__setup__ws	-49.6	-72.6	Failing
globalroute__timing__setup__tns	-2160.0	-3090.0	Failing
finish__timing__setup__tns	-1130.0	-1500.0	Failing

[WARNING] Multiple clocks not supported. Will use first clock: mrx_clk_pad_i: 300.0000.
[WARNING] Multiple clocks not supported. Will use first clock: mrx_clk_pad_i: 300.0000.
designs/asap7/gcd/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-281.0	-422.0	Failing
globalroute__timing__setup__tns	-439.0	-513.0	Failing
finish__timing__setup__tns	-270.0	-361.0	Failing

designs/asap7/gcd-ccs/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-103.0	-207.0	Failing
globalroute__timing__setup__tns	-102.0	-187.0	Failing

[WARNING] Multiple clocks not supported. Will use first clock: clk: 333.0000.
designs/gf180/aes/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-107.0	-141.0	Failing
globalroute__timing__setup__tns	-124.0	-165.0	Failing
finish__timing__setup__tns	-119.0	-157.0	Failing

designs/gf180/aes-hybrid/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-144.0	-208.0	Failing
globalroute__timing__setup__tns	-158.0	-230.0	Failing
finish__timing__setup__tns	-154.0	-221.0	Failing

designs/gf180/uart-blocks/rules-base.json updates:

Metric	Old	New	Type
placeopt__design__instance__count__stdcell	726	1036	Failing
detailedroute__route__wirelength	18889	29243	Failing

designs/ihp-sg13g2/i2c-gpio-expander/rules-base.json updates:

Metric	Old	New	Type
placeopt__design__instance__count__stdcell	951	1448	Failing
detailedroute__route__wirelength	38152	46152	Failing

designs/nangate45/bp_be_top/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-12.8	-16.3	Failing
globalroute__timing__setup__tns	-18.6	-19.9	Failing
finish__timing__setup__tns	-17.1	-19.6	Failing

designs/nangate45/bp_fe_top/rules-base.json updates:

Metric	Old	New	Type
globalroute__timing__setup__tns	-0.36	-0.753	Failing
finish__timing__setup__tns	-0.795	-1.89	Failing

designs/nangate45/gcd/rules-base.json updates:

Metric	Old	New	Type
detailedroute__route__wirelength	4515	5793	Failing

designs/nangate45/jpeg/rules-base.json updates:

Metric	Old	New	Type
finish__timing__setup__tns	-41.1	-41.6	Failing

[WARNING] Multiple clocks not supported. Will use first clock: clk_i: 3.0000.
designs/nangate45/tinyRocket/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-23.6	-58.0	Failing
globalroute__timing__setup__tns	-39.6	-70.7	Failing
finish__timing__setup__tns	-33.7	-69.2	Failing

designs/sky130hd/gcd/rules-base.json updates:

Metric	Old	New	Type
detailedroute__route__wirelength	8444	10996	Failing

designs/sky130hd/jpeg/rules-base.json updates:

Metric	Old	New	Type
globalroute__timing__setup__tns	-8.68	-22.2	Failing

[WARNING] Multiple clocks not supported. Will use first clock: ext_clk: 15.0000.
designs/sky130hd/riscv32i/rules-base.json updates:

Metric	Old	New	Type
finish__timing__setup__tns	-8.38	-10.1	Failing

designs/sky130hs/aes/rules-base.json updates:

Metric	Old	New	Type
globalroute__timing__setup__ws	-0.244	-0.397	Failing
globalroute__timing__setup__tns	-2.47	-5.1	Failing
finish__timing__setup__tns	-0.632	-1.7	Failing

designs/sky130hs/gcd/rules-base.json updates:

Metric	Old	New	Type
cts__timing__setup__tns	-10.5	-11.2	Failing
globalroute__timing__setup__tns	-16.3	-16.7	Failing
finish__timing__setup__tns	-12.0	-12.7	Failing

Messages from CI

[INFO] asap7/minimal not included in CI.
[INFO] gf12 not included in the update.
[INFO] gf55 not included in the update.
[INFO] nangate45/bp_quad not included in CI.
[INFO] rapidus2hp not included in the update.

When using slang in synthesis, switch on Verilog compatibility if all source file names end in `.v` Signed-off-by: Martin Povišer <[email protected]>

Pass the extra flag to make slang ignore a class of synthesizable language features. Signed-off-by: Martin Povišer <[email protected]>

Make slang the default and apply a number of opt-outs across the design suite. The opt-outs are for designs which don't go through with slang today, usually because the input is not fully up to spec. Private designs which weren't using slang previously get an opt-out to save on private CI churn. Signed-off-by: Martin Povišer <[email protected]>

povik · 2026-01-08T14:23:28Z

@maliberty Now that slang has a Verilog compatibility mode most designs go through. Those that don't could be fixed by a slight modification of the input but I leave that for later. Let me know if you agree with the change of default.

povik · 2026-01-08T14:24:40Z

Those that don't could be fixed by a slight modification of the input

That is true at least of the ones I looked at.

maliberty · 2026-01-08T16:06:21Z

Is it possible to accept those without modification? Unless they are illegal we should support them.

povik · 2026-01-08T16:19:13Z

I'm sampling some of the ones which I think are illegal below.

designs/src/swerv/swerv_wrapper.sv2v.v:65987:55: error: redefinition of 'dec_tlu_debug_mode'
  N44,N45,N46,N47,N48,N49,N50,N51,N52,N53,N54,N55,N56,dec_tlu_debug_mode,
                                                      ^
designs/src/swerv/swerv_wrapper.sv2v.v:65971:68: note: previous definition here
  dec_tlu_mpc_halted_only,dec_tlu_dbg_halted,dec_tlu_pmu_fw_halted,dec_tlu_debug_mode,
                                                                   ^

designs/src/riscv32i/dmem.v:33:10: error: cannot assign to a net within a procedural context
         we_mem = 4'b0000;
         ^~~~~~

designs/src/bp_multi_top/pickled.v:54505:35: error: redefinition of 'exclusive_flag_o'
  exclusive_flag_o,N0,N1,N2,N3,N4,exclusive_flag_o,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,
                                  ^

designs/src/bp_multi_top/pickled.v:54505:3: note: previous definition here
  exclusive_flag_o,N0,N1,N2,N3,N4,exclusive_flag_o,N5,N6,N7,N8,N9,N10,N11,N12,N13,N14,N15,N16,
  ^

These next two I'm not sure of. It might be the case they are illegal per the standard but widely accepted.

designs/src/fifo/wptr_full.v:28:78: error: endianness of selection must match declared range (type is 'logic[1:0]')
  assign wfull_val = (wgraynext == {~wq2_rptr[ADDRSIZE:ADDRSIZE-1], wq2_rptr[ADDRSIZE-2:0]});
                                                                             ^~~~~~~~~~~~

designs/src/microwatt/IPs/RAM512.v:2:21: error: misplaced trailing ','
    parameter BITS=9,
                    ^

maliberty · 2026-01-08T16:32:47Z

Apparently yosys can read them. However if they are truly illegal we could diverge.

Signed-off-by: Martin Povišer <[email protected]>

Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

povik added 3 commits January 8, 2026 14:58

synth: Enable verilog compat if all files are .v

5d793b1

When using slang in synthesis, switch on Verilog compatibility if all source file names end in `.v` Signed-off-by: Martin Povišer <[email protected]>

synth: Pass --ignore-timing to slang

d7caef0

Pass the extra flag to make slang ignore a class of synthesizable language features. Signed-off-by: Martin Povišer <[email protected]>

openroad-ci assigned povik Jan 8, 2026

synth: Disable slang for nangate45/ariane133

56d4fd4

Signed-off-by: Martin Povišer <[email protected]>

povik added the UpdateRules Starts GHA to update rules label Jan 8, 2026

openroad-ci removed the UpdateRules Starts GHA to update rules label Jan 9, 2026

Merge remote-tracking branch 'origin/master' into synth-slang-verilog

b11ce93

povik added the UpdateRules Starts GHA to update rules label Jan 13, 2026

flow: update rules

c19d20c

Signed-off-by: github-actions[bot] <github-actions[bot]@users.noreply.github.com>

openroad-ci removed the UpdateRules Starts GHA to update rules label Jan 13, 2026

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synth: Make "slang" the default frontend #3772

synth: Make "slang" the default frontend #3772

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synth: Make "slang" the default frontend #3772

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openroad-ci commented Jan 8, 2026 •

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