Original bug ID: 6006
Reporter: wime
Assigned to: meurer
Status: closed (set by @xavierleroy on 2015-12-11T18:18:52Z)
Resolution: fixed
Priority: normal
Severity: major
Version: 4.00.1
Fixed in version: 4.00.2+dev
Category: back end (clambda to assembly)
Duplicate of: #5910
Monitored by: @gasche

Bug description

When I tried to compile ocamlnet on a Pandaboard the compiler failed with the messages

...
/tmp/camlasm0de67d.s: Assembler messages:
/tmp/camlasm0de67d.s:9339: Error: shift expression is too large -- mov r0,r1,lsl#32' /tmp/camlasm0de67d.s:9431: Error: shift expression is too large -- mov r4,r5,lsl#32'
File "netmech_scram.ml", line 1:
Error: Assembler error, input left in file /tmp/camlasm0de67d.s
make[1]: *** [netmech_scram.cmx] Fehler 2
make: *** [opt] Fehler 2

Steps to reproduce

The following simplified code produces a similar error if you "ocamlopt" it. ocamlc works fine.

let x = (Random.int 255) in print_int (x mod 1);

Additional information

Currently "x mod 1" results in an left bit shift of 32 bits (lsl#32), which is not allowed on ARM. I was able to circumvent this problem by applying the attached patch, which limits the shift width to 31 bits and handles 32 bits in a separate case. It might need some refinement.

File attachments

• ocaml_arm_mod.patch