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Fix severe runtime performance bug in certain foreach loops.

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This commit is contained in:
John Coiner
2018-03-15 08:59:52 -04:00
parent 2d580e6939
commit f55040a38b
4 changed files with 36 additions and 13 deletions
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src/V3LinkParse.cpp
+21 -13
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@@ -340,6 +340,7 @@ private:
FileLine* fl = varsp->fileline();
AstNode* varp = new AstVar(fl, AstVarType::BLOCKTEMP,
varsp->name(), nodep->findSigned32DType());
// These will be the left and right dimensions of the array:
AstNode* leftp = new AstAttrOf(fl, AstAttrType::DIM_LEFT,
new AstVarRef(fl, arrayp->name(), false),
new AstConst(fl, dimension));
@@ -347,19 +348,26 @@ private:
new AstVarRef(fl, arrayp->name(), false),
new AstConst(fl, dimension));
AstNode* stmtsp = varp;
stmtsp->addNext(new AstAssign(fl, new AstVarRef(fl, varp->name(), true), leftp));
AstNode* comparep =
new AstCond(fl, new AstLte(fl, leftp->cloneTree(true), rightp->cloneTree(true)),
// left increments up to right
new AstLte(fl, new AstVarRef(fl, varp->name(), false), rightp->cloneTree(true)),
// left decrements down to right
new AstGte(fl, new AstVarRef(fl, varp->name(), false), rightp));
AstNode* incp =
new AstAssign(fl, new AstVarRef(fl, varp->name(), true),
new AstAdd(fl, new AstVarRef(fl, varp->name(), false),
new AstNegate(fl, new AstAttrOf(fl, AstAttrType::DIM_INCREMENT,
new AstVarRef(fl, arrayp->name(), false),
new AstConst(fl, dimension)))));
// Assign left-dimension into the loop var:
stmtsp->addNext(new AstAssign
(fl, new AstVarRef(fl, varp->name(), true), leftp));
// This will turn into a bool constant, indicating whether
// we count the loop variable up or down:
AstNode* countupp = new AstLte(fl, leftp->cloneTree(true),
rightp->cloneTree(true));
AstNode* comparep = new AstCond(
fl, countupp->cloneTree(true),
// Left increments up to right
new AstLte(fl, new AstVarRef(fl, varp->name(), false),
rightp->cloneTree(true)),
// Left decrements down to right
new AstGte(fl, new AstVarRef(fl, varp->name(), false), rightp));
AstNode* incp = new AstAssign(
fl, new AstVarRef(fl, varp->name(), true),
new AstAdd(fl, new AstVarRef(fl, varp->name(), false),
new AstCond(fl, countupp,
new AstConst(fl, 1),
new AstConst(fl, -1))));
stmtsp->addNext(new AstWhile(fl, comparep, newp, incp));
newp = new AstBegin(nodep->fileline(),"",stmtsp);
dimension--;