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Optimize comparisons with identical operands in Dfg

This commit is contained in:
Geza Lore 2026-03-25 16:33:35 +00:00
parent e0fc69a2f0
commit 2759f2ab16
3 changed files with 134 additions and 0 deletions
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114
src/V3DfgPeephole.cpp
View File

@ -327,6 +327,13 @@ class V3DfgPeephole final : public DfgVisitor {
return new DfgConst{m_dfg, flp, width, 0};
}
// Create a DfgConst vertex with the given width and value all ones
DfgConst* makeOnes(FileLine* flp, uint32_t width) {
DfgConst* const resp = makeZero(flp, width);
resp->num().setAllBits1();
return resp;
}
// Create a new vertex of the given type
template <typename Vertex, typename... Operands>
Vertex* make(FileLine* flp, const DfgDataType& dtype, Operands... operands) {
@ -1850,6 +1857,14 @@ class V3DfgPeephole final : public DfgVisitor {
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_EQ) {
replace(makeOnes(flp, 1));
return;
}
}
if (DfgConst* const lhsConstp = lhsp->cast<DfgConst>()) {
if (DfgConcat* const rhsConcatp = rhsp->cast<DfgConcat>()) {
@ -1860,18 +1875,62 @@ class V3DfgPeephole final : public DfgVisitor {
void visit(DfgGt* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_GT) {
replace(makeZero(flp, 1));
return;
}
}
}
void visit(DfgGtS* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_GTS) {
replace(makeZero(flp, 1));
return;
}
}
}
void visit(DfgGte* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_GTE) {
replace(makeOnes(flp, 1));
return;
}
}
}
void visit(DfgGteS* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_GTES) {
replace(makeOnes(flp, 1));
return;
}
}
}
void visit(DfgLogAnd* const vtxp) override {
@ -1912,18 +1971,62 @@ class V3DfgPeephole final : public DfgVisitor {
void visit(DfgLt* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_LT) {
replace(makeZero(flp, 1));
return;
}
}
}
void visit(DfgLtS* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_LTS) {
replace(makeZero(flp, 1));
return;
}
}
}
void visit(DfgLte* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_LTE) {
replace(makeOnes(flp, 1));
return;
}
}
}
void visit(DfgLteS* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_LTES) {
replace(makeOnes(flp, 1));
return;
}
}
}
void visit(DfgModDiv* const vtxp) override {
@ -1948,6 +2051,17 @@ class V3DfgPeephole final : public DfgVisitor {
void visit(DfgNeq* const vtxp) override {
if (foldBinary(vtxp)) return;
DfgVertex* const lhsp = vtxp->lhsp();
DfgVertex* const rhsp = vtxp->rhsp();
FileLine* const flp = vtxp->fileline();
if (isSame(lhsp, rhsp)) {
APPLYING(FOLD_SELF_NEQ) {
replace(makeZero(flp, 1));
return;
}
}
}
void visit(DfgPow* const vtxp) override {

10
src/V3DfgPeepholePatterns.h
View File

@ -32,6 +32,16 @@
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_ASSOC_BINARY_RHS_OF_LHS) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_BINARY) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SEL) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_EQ) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_GT) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_GTE) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_GTES) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_GTS) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_LT) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_LTE) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_LTES) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_LTS) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_SELF_NEQ) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, FOLD_UNARY) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, INLINE_ARRAYSEL_SPLICE) \
_FOR_EACH_DFG_PEEPHOLE_OPTIMIZATION_APPLY(macro, INLINE_ARRAYSEL_UNIT) \

10
test_regress/t/t_dfg_peephole.v
View File

@ -295,6 +295,16 @@ module t (
`signal(REPLACE_ADD_WITH_COUNT_ONES_B, 32'(rand_a[63]) + 32'(rand_a[62]) + 32'(rand_a[61]));
`signal(REPLACE_ADD_WITH_COUNT_ONES_C, 200'(rand_a[63]) + 200'(rand_a[62]) + 200'(rand_a[61]));
`signal(REPLACE_ADD_WITH_COUNT_ONES_D, 1'(rand_a[63]) + 1'(rand_a[62]) + 1'(rand_a[61]));
`signal(FOLD_SELF_EQ, rand_a == rand_a);
`signal(FOLD_SELF_NEQ, rand_a != rand_a);
`signal(FOLD_SELF_GT, rand_a > rand_a);
`signal(FOLD_SELF_GTS, srand_a > srand_a);
`signal(FOLD_SELF_GE, rand_a >= rand_a);
`signal(FOLD_SELF_GES, srand_a >= srand_a);
`signal(FOLD_SELF_LT, rand_a < rand_a);
`signal(FOLD_SELF_LTS, srand_a < srand_a);
`signal(FOLD_SELF_LE, rand_a <= rand_a);
`signal(FOLD_SELF_LES, srand_a <= srand_a);
// Operators that should work wiht mismatched widths
`signal(MISMATCHED_ShiftL,const_a << 4'd2);