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Add simple cost model to perfect shuffle. Currently we're doing just greedy search for cost instead of (proper) dynamic programming approach.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79623 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Anton Korobeynikov 2009-08-21 12:41:03 +00:00
parent 62e84f177d
commit c9d44f0d9c
1 changed files with 9 additions and 6 deletions
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15
utils/PerfectShuffle/PerfectShuffle.cpp
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@ -104,9 +104,11 @@ struct Operator {
unsigned short ShuffleMask;
unsigned short OpNum;
const char *Name;
Operator(unsigned short shufflemask, const char *name, unsigned opnum)
: ShuffleMask(shufflemask), OpNum(opnum), Name(name) {
unsigned Cost;
Operator(unsigned short shufflemask, const char *name, unsigned opnum,
unsigned cost = 1)
: ShuffleMask(shufflemask), OpNum(opnum), Name(name), Cost(cost) {
TheOperators.push_back(this);
}
~Operator() {
@ -119,7 +121,8 @@ struct Operator {
}
const char *getName() const { return Name; }
unsigned getCost() const { return Cost; }
unsigned short getTransformedMask(unsigned short LHSMask, unsigned RHSMask) {
// Extract the elements from LHSMask and RHSMask, as appropriate.
unsigned Result = 0;
@ -302,7 +305,7 @@ int main() {
// Evaluate op(LHS,LHS)
unsigned ResultMask = Op->getTransformedMask(LHS, LHS);
unsigned Cost = ShufTab[LHS].Cost + 1;
unsigned Cost = ShufTab[LHS].Cost + Op->getCost();
if (Cost < ShufTab[ResultMask].Cost) {
ShufTab[ResultMask].Cost = Cost;
ShufTab[ResultMask].Op = Op;
@ -340,7 +343,7 @@ int main() {
EvaluateOps(LHS, Vals, NumVals);
EvaluateOps(RHS, Vals, NumVals);
unsigned Cost = NumVals + 1;
unsigned Cost = NumVals + Op->getCost();
if (Cost < ShufTab[ResultMask].Cost) {
ShufTab[ResultMask].Cost = Cost;
ShufTab[ResultMask].Op = Op;