cmd/compile: cannot slice 2³²-element array on amd64 #7397
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http://play.golang.org/p/U5-fzNJD0Z The problem comes from gc/walk.c // static checks if possible bv = 1LL<<50; if(isconst(bound, CTINT)) { if(!smallintconst(bound)) yyerror("array len too large"); else bv = mpgetfix(bound->val.u.xval); } smallintconst asserts that the constant can be expressed as a x86_64 immediate constant which is only 31 bits wide (32 bits maybe, certainly not larger). Labels changed: added release-go1.3maybe, repo-main, arch-x86-64. Status changed to Accepted. |
This doesn't seem important enough to fix now. Note that it only occurs for the
fixed-length array. If you use make I believe everything is fine. This works on my
64-bit system:
package main
import "fmt"
func main() {
// does not work in playground
r := make([]struct{}, 0x80000000)
rr := r[:1]
fmt.Println(rr)
}
Labels changed: added release-go1.4, removed release-go1.3. |
rsc
changed the title
|
Looks like this can be closed. The following: now works (tested on |
|
@ALTree, thanks. Closing. |
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by john.souvestre:
I’m having trouble slicing a large array. The slice is only 1 item. The problem happens when the array is 2**32 items or larger. This works. var r [int64(0x0fffffff)]struct{} rr := r[:1] This fails with “array len too large” on the second line. var r [int64(0x80000000)]struct{} rr := r[:1] I can go all the way to 2**64 before hitting the expected array bounds error on the first line. I’m running Go 1.3, 64-bit, on Windows 7. I'm told that the problem does not occur on the 32-bit version, including the Playground.The text was updated successfully, but these errors were encountered: