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Add a very simple cost model to estimate runtime cost of running code.

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This is currently only used to decide whether it's worth doing an
"are all lanes running" check at the start of functions--for small
functions, it's not worth the overhead.

The cost is estimated relatively early in compilation (e.g. before
we know if an array access is a scatter/gather or not, before
constant folding, etc.), so there are many known shortcomings.
This commit is contained in:
Matt Pharr
2011-09-16 15:09:17 -07:00
parent 38fc13d1ab
commit ca87579f23
6 changed files with 263 additions and 9 deletions
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12
stmt.h
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@@ -75,6 +75,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
private:
Expr *expr;
@@ -92,8 +93,9 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
private:
private:
Declaration *declaration;
};
@@ -110,6 +112,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
// @todo these are only public for lHasVaryingBreakOrContinue(); would
// be nice to clean that up...
@@ -151,6 +154,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
private:
Expr *testExpr;
@@ -172,6 +176,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
private:
/** 'for' statment initializer; may be NULL, indicating no intitializer */
@@ -199,6 +204,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
private:
/** This indicates whether the generated code will check to see if no
@@ -220,6 +226,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
private:
/** This indicates whether the generated code will check to see if no
@@ -241,6 +248,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
private:
Expr *val;
@@ -263,6 +271,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
void Add(Stmt *s) { if (s) stmts.push_back(s); }
const std::vector<Stmt *> &GetStatements() { return stmts; }
@@ -290,6 +299,7 @@ public:
Stmt *Optimize();
Stmt *TypeCheck();
int EstimateCost() const;
private:
/** Format string for the print() statement. */