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#include "Halide.h"
#include <stdio.h>
// This file demonstrates two example custom lowering passes. The
// first just makes sure the IR passes some test, and doesn't modify
// it. The second actually changes the IR in some useful way.
using namespace Halide;
using namespace Halide::Internal;
// Verify that all floating point divisions by constants have been
// converted to float multiplication.
class CheckForFloatDivision : public IRMutator {
using IRMutator::visit;
Expr visit(const Div *op) override {
if (op->type.is_float() && is_const(op->b)) {
std::cerr << "Found floating-point division by constant: " << Expr(op) << "\n";
exit(1);
}
return op;
}
};
// A mutator that injects code that counts floating point multiplies,
// and an extern function that it calls out to for the accounting.
int multiply_count = 0;
extern "C" HALIDE_EXPORT_SYMBOL float record_float_mul(float arg) {
multiply_count++;
return arg;
}
HalideExtern_1(float, record_float_mul, float);
class CountMultiplies : public IRMutator {
using IRMutator::visit;
Expr visit(const Mul *op) override {
Expr expr = IRMutator::visit(op);
if (op->type.is_float()) {
expr = record_float_mul(expr);
}
return expr;
}
};
int main(int argc, char **argv) {
Func f;
Var x;
f(x) = x / 2.4f + x / sin(x) + x * sin(x);
f.add_custom_lowering_pass(new CheckForFloatDivision);
f.add_custom_lowering_pass(new CountMultiplies);
const int size = 10;
f.realize({size});
if (multiply_count != size * 2) {
printf("The multiplies weren't all counted. Got %d instead of %d\n",
multiply_count, size);
return 1;
}
printf("Success!\n");
return 0;
}
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