synth_ice40: call wreduce before mul2dsp

diff --git a/techlibs/ice40/synth_ice40.cc b/techlibs/ice40/synth_ice40.cc
index 121bcff1fed8a225823e5032ab5303c25869e1bd..d92e407262e76c1eba194b78ee8d80ec697bf25e 100644 (file)
--- a/techlibs/ice40/synth_ice40.cc
+++ b/techlibs/ice40/synth_ice40.cc
@@ -273,7 +273,8 @@ struct SynthIce40Pass : public ScriptPass
                        run("opt_expr");
                        run("opt_clean");
                        if (help_mode || dsp) {
-                               run("memory_dff");
+                               run("memory_dff"); // ice40_dsp will merge registers, reserve memory port registers first
+                               run("wreduce t:$mul");
                                run("techmap -map +/mul2dsp.v -map +/ice40/dsp_map.v -D DSP_A_MAXWIDTH=16 -D DSP_B_MAXWIDTH=16 "
                                                "-D DSP_A_MINWIDTH=2 -D DSP_B_MINWIDTH=2 -D DSP_Y_MINWIDTH=11 "
                                                "-D DSP_NAME=$__MUL16X16", "(if -dsp)");