Duncan Temple Lang

University of California at Davis

Department of Statistics

In this example, we illustrate how to generate a routine via LLVM which calls a routine that exists in the R executable. This shows how we can make use of existing functions.

library(Rllvm)
InitializeNativeTarget()
mod = Module("dotC")

Now we create the routine.

fun = Function("tossCoin", Int32Type, module = mod)

b = Block(fun, "entry")
head = Block(fun)
tail = Block(fun)
ret = Block(fun)
ir = IRBuilder(b)

zero = createIntegerConstant( 0L)
one = createIntegerConstant( 1L)

ans = createLocalVariable(ir, Int32Type, "ans")
runif = Function("runif", DoubleType, module = mod)
setLinkage(runif, ExternalLinkage)
toss = ir$createCall(runif)
point5 = createDoubleConstant(0.5)
gt = ir$createFCmp(FCMP_ULT, toss, point5)

ir$createCondBr(gt, head, tail)

ir$setInsertPoint(head)
ir$createStore(one, ans)
ir$createBr(ret)

ir$setInsertPoint(tail)
ir$createStore(zero, ans)
ir$createBr(ret)


ir$setInsertPoint(ret)
ans = ir$createLoad(ans)
ir$createRet(ans)

llvmAddSymbol(runif = getNativeSymbolInfo("runif")$address)
print(run(fun))

llvmLoadDLL(system.file("libs", "Rllvm.so", package = "Rllvm"))
print(run(fun))