What is happening here is that the compiler makes a legitimate
optimization, but that runs into a long-standing issue, not related to
compilation, with certain assignment expressions in arguments. The
general issue will take some time to address; hopefully it will be
resolved in time for the next major release. In the interim, to avoid
the particular discrepancy reported here the compiler has been
adjusted to not optimize assignments within argument expressions.
This adjustment is in R-devel (r73161) and R-patched (r73162).
Best,
luke
On Thu, 24 Aug 2017, luke-tier...@uiowa.edu wrote:
Thanks.
Here is a simplified version:
library(compiler)
zero <- 0
one <- 1
expr <- quote((z <- zero + one) + (z <- z + 1))
eval(compiler::compile(expr))
Sill fix shortly.
Best,
luke
On Thu, 24 Aug 2017, Lukas Stadler wrote:
Hi!
We’ve seen a problem with the compiler in specific cases of matrix
updates:
{ m <- matrix(1:4, 2) ; z <- 0; for(i in 1) { m[z <- z + 1,z <- z + 1] <-
99; } ; m }
[,1] [,2]
[1,] 1 3
[2,] 2 99
Here, it modifies element [2,2], which is unexpected.
It behaves correct without the loop:
{ m <- matrix(1:4, 2) ; z <- 0; m[z <- z + 1,z <- z + 1] <- 99 ; m }
[,1] [,2]
[1,] 1 99
[2,] 2 4
… and without the jit:
enableJIT(0)
[1] 3
{ m <- matrix(1:4, 2) ; z <- 0; for(i in 1) { m[z <- z + 1,z <- z + 1] <-
99; } ; m }
[,1] [,2]
[1,] 1 99
[2,] 2 4
I checked with "R Under development (unstable) (2017-08-23 r73116)”, and
the problem is still there.
- Lukas
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--
Luke Tierney
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa Phone: 319-335-3386
Department of Statistics and Fax: 319-335-3017
Actuarial Science
241 Schaeffer Hall email: luke-tier...@uiowa.edu
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
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