loop compilation problem

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

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