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DFG: Special case representation of AstSel

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AstSel is a ternary node, but the 'widthp' is always constant and is
hence redundant, and 'lsbp' is very often constant. As AstSel is fairly
common, we special case as a DfgSel for the constant 'lsbp', and as
'DfgMux` for the non-constant 'lsbp'.
This commit is contained in:
Geza Lore
2022-10-06 19:59:01 +01:00
parent 0570cb8d9f
commit 29a080dd9b
5 changed files with 309 additions and 284 deletions
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src/V3DfgDfgToAst.cpp
+16
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@@ -332,6 +332,22 @@ class DfgToAstVisitor final : DfgVisitor {
m_resultp = vtxp->constp()->cloneTree(false);
}
void visit(DfgSel* vtxp) override {
FileLine* const flp = vtxp->fileline();
AstNodeMath* const fromp = convertSource(vtxp->fromp());
AstConst* const lsbp = new AstConst{flp, vtxp->lsb()};
AstConst* const widthp = new AstConst{flp, vtxp->width()};
m_resultp = new AstSel{flp, fromp, lsbp, widthp};
}
void visit(DfgMux* vtxp) override {
FileLine* const flp = vtxp->fileline();
AstNodeMath* const fromp = convertSource(vtxp->fromp());
AstNodeMath* const lsbp = convertSource(vtxp->lsbp());
AstConst* const widthp = new AstConst{flp, vtxp->width()};
m_resultp = new AstSel{flp, fromp, lsbp, widthp};
}
// The rest of the 'visit' methods are generated by 'astgen'
#include "V3Dfg__gen_dfg_to_ast.h"