>Number:         9832
>Category:       target
>Synopsis:       ARM: Arithmetic and move could be combined using liveness information
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          pessimizes-code
>Submitter-Id:   net
>Arrival-Date:   Mon Feb 24 15:26:00 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     László Vidács
>Release:        gcc version 3.3 20030217 (prerelease)
>Organization:
>Environment:
BUILD & HOST: Linux 2.4.20 i686 unknown
TARGET: arm-unknown-elf
>Description:
Arithmetic and move instructions are replaced by a combined arithmetic in ARM target. The combine cannot be done if the destination of the arithmetic is also used. However, if based on liveness information this destination is never used the combine could be safely applied.

For example, in file ... if r4 is not used after the and instruction, the combine can be applied as in the modified file.
>How-To-Repeat:
gcc -S -Os 01.i

// 01.i

# 1 "01.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "01.c"
void func(char c, int t)
{
  ;
}
void foo(int u)
{
  func ( 8, (u >> 24) & 0xffL );
  func ( 8, (u >> 16) & 0xffL );
}
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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