From 86b7cfb05cc6b3df965c6ec3ac351c106fdcfabb Mon Sep 17 00:00:00 2001
From: Geza Lore <glore@tenstorrent.com>
Date: Tue, 18 Aug 2026 19:41:24 +0200
Subject: [PATCH] Optimize associative constant patterns to fixed point (#8147)

Re-associating constants can enable further simplification e.g. when
those constant become all zero/all ones. Run these patterns to fixed
point to capture the simplification, by revisiting the node.
---
 src/V3Const.cpp | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/src/V3Const.cpp b/src/V3Const.cpp
index 47c7bbd13..c6e5895f4 100644
--- a/src/V3Const.cpp
+++ b/src/V3Const.cpp
@@ -1709,8 +1709,7 @@ class ConstVisitor final : public VNVisitor {
         const V3Number num{constp, subsize, constp->num()};
         nodep->lhsp(new AstConst{constp->fileline(), num});
         VL_DO_DANGLING(pushDeletep(constp), constp);
-        UINFOTREE(9, nodep, "", "BI(EXTEND)-ou");
-        return true;
+        return false;  // input node is still valid, keep going
     }
     bool operandBiExtendConstOver(const AstNodeBiop* nodep) {
         // EQ(const{width32}, EXTEND(xx{width3})) -> constant
@@ -2070,7 +2069,7 @@ class ConstVisitor final : public VNVisitor {
         rp->rhsp(bp);
         rp->dtypeFrom(nodep);  // Upper widthMin more likely correct
         if (VN_IS(rp->lhsp(), Const) && VN_IS(rp->rhsp(), Const)) replaceConst(rp);
-        // UINFOTREE(1, nodep, "", "repAsvConst_new");
+        iterate(nodep);  // Proceed to fixed point
     }
     void replaceAsvLUp(AstNodeBiop* nodep) {
         // BIASV(BIASV(CONSTll,lr),r) -> BIASV(CONSTll,BIASV(lr,r))
@@ -2083,7 +2082,7 @@ class ConstVisitor final : public VNVisitor {
         lp->lhsp(lrp);
         lp->rhsp(rp);
         lp->dtypeFrom(nodep);  // Upper widthMin more likely correct
-        // UINFOTREE(1, nodep, "", "repAsvLUp_new");
+        iterate(nodep);  // Proceed to fixed point
     }
     void replaceAsvRUp(AstNodeBiop* nodep) {
         // BIASV(l,BIASV(CONSTrl,rr)) -> BIASV(CONSTrl,BIASV(l,rr))
@@ -2096,7 +2095,7 @@ class ConstVisitor final : public VNVisitor {
         rp->lhsp(lp);
         rp->rhsp(rrp);
         rp->dtypeFrom(nodep);  // Upper widthMin more likely correct
-        // UINFOTREE(1, nodep, "", "repAsvRUp_new");
+        iterate(nodep);  // Proceed to fixed point
     }
     void replaceAndOr(AstNodeBiop* nodep) {
         //  OR  (AND (CONSTll,lr), AND(CONSTrl==ll,rr))    -> AND (CONSTll, OR(lr,rr))