target/9831: ARM: Peephole for multiple load/store could be more effective.

target/9831: ARM: Peephole for multiple load/store could be more effective.

[gertom]

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>Number:         9831
>Category:       target
>Synopsis:       ARM: Peephole for multiple load/store could be more effective.
>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:     Tamás Gergely
>Release:        gcc version 3.3 20030217 (prerelease)
>Organization:
>Environment:
BUILD & HOST: Linux 2.4.20 i686 unknown
TARGET: arm-unknown-elf
>Description:
In the case of subsequent loads from subsequent memory locations, if the base address is not loaded into a register (e.g. the loads use a label, that will be converted to pc relative loads), the corresponding peephole patterns will not optimize. The pattern will match, but multiple load instruction will not be generated. The same apply to stores.

In the attached modified assembly code the 4 load instructions are replaced by an address computation and a multiple load (note that no additional register is required).
>How-To-Repeat:
gcc -S -Os 01.i

// 01.i

# 1 "01.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "01.c"
int f(int, int, int, int);

void foo ()
{
  f(12345,238764,2345234, 83746556);
} 
>Fix:

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