luke/verilator
1
0
Fork 0
mirror of https://github.com/verilator/verilator.git synced 2026-10-06 01:54:01 +02:00
Code Issues Packages Projects Releases Wiki Activity

Accelerate bit-selected inversions.

Browse Source
This commit is contained in:
Wilson Snyder
2011-02-23 21:36:38 -05:00
parent cfdb852843
commit 9a697dc5f5
3 changed files with 24 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/V3Const.cpp
+21 -2
View File
@@ -1078,6 +1078,20 @@ private:
fromp->widthSignedFrom(nodep);
nodep->replaceWith(fromp); nodep->deleteTree(); nodep=NULL;
}
void replaceSelIntoUniop(AstSel* nodep) {
// SEL(NOT(a),1,bit) => NOT(SEL(a,bit))
AstNodeUniop* fromp = nodep->fromp()->unlinkFrBack()->castNodeUniop();
if (!fromp) nodep->v3fatalSrc("Called on non biop");
AstNode* lsbp = nodep->lsbp()->unlinkFrBack();
AstNode* widthp = nodep->widthp()->unlinkFrBack();
//
AstNode* bilhsp = fromp->lhsp()->unlinkFrBack();
//
fromp->lhsp(new AstSel(nodep->fileline(),
bilhsp, lsbp->cloneTree(true), widthp->cloneTree(true)));
fromp->widthSignedFrom(nodep);
nodep->replaceWith(fromp); nodep->deleteTree(); nodep=NULL;
}
virtual void visit(AstVarRef* nodep, AstNUser*) {
nodep->iterateChildren(*this);
@@ -1786,9 +1800,14 @@ private:
TREEOPV("AstSel{$fromp.castConcat, $lsbp.castConst, $widthp.castConst, }", "replaceSelConcat(nodep)");
TREEOPV("AstSel{$fromp.castReplicate, $lsbp.castConst, $widthp.isOne, }", "replaceSelReplicate(nodep)");
// V3Tristate requires selects below BufIf1.
// We can probably extend this to additional logical operators, but only definite
// Also do additional operators that are bit-independent, but only definite
// win if bit select is a constant (otherwise we may need to compute bit index several times)
TREEOPV("AstSel{$fromp.castBufIf1}", "replaceSelIntoBiop(nodep)");
TREEOPV("AstSel{$fromp.castBufIf1}", "replaceSelIntoBiop(nodep)");
TREEOPV("AstSel{$fromp.castNot}", "replaceSelIntoUniop(nodep)");
TREEOPV("AstSel{$fromp.castAnd,$lhsp.castConst}", "replaceSelIntoUniop(nodep)");
TREEOPV("AstSel{$fromp.castOr,$lhsp.castConst}", "replaceSelIntoUniop(nodep)");
TREEOPV("AstSel{$fromp.castXor,$lhsp.castConst}", "replaceSelIntoUniop(nodep)");
TREEOPV("AstSel{$fromp.castXnor,$lhsp.castConst}", "replaceSelIntoUniop(nodep)");
// Conversions
TREEOPV("AstRedXnor{$lhsp}", "AstNot{AstRedXor{$lhsp}}"); // Just eliminate XNOR's
TREEOPV("AstLogIf {$lhsp, $rhsp}", "AstLogOr{AstLogNot{$lhsp},$rhsp}");