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Merge pull request #5663 from YosysHQ/emil/opt_expr-fix-pow-shift

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opt_expr: fix const lhs of $pow to $shl
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Emil J 2026-02-05 13:09:01 +01:00 • committed by GitHub
commit 1717fa0180
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2 changed files with 61 additions and 2 deletions
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7
passes/opt/opt_expr.cc
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@ -1667,7 +1667,11 @@ skip_identity:
int bit_idx;
const auto onehot = sig_a.is_onehot(&bit_idx);
if (onehot) {
// Power of two
// A is unsigned or positive
if (onehot && (!cell->parameters[ID::A_SIGNED].as_bool() || bit_idx < sig_a.size() - 1)) {
cell->parameters[ID::A_SIGNED] = 0;
// 2^B = 1<<B
if (bit_idx == 1) {
log_debug("Replacing pow cell `%s' in module `%s' with left-shift\n",
cell->name.c_str(), module->name.c_str());
@ -1679,7 +1683,6 @@ skip_identity:
log_debug("Replacing pow cell `%s' in module `%s' with multiply and left-shift\n",
cell->name.c_str(), module->name.c_str());
cell->type = ID($mul);
cell->parameters[ID::A_SIGNED] = 0;
cell->setPort(ID::A, Const(bit_idx, cell->parameters[ID::A_WIDTH].as_int()));
SigSpec y_wire = module->addWire(NEW_ID, y_size);