optimization/9702: Constant pools are not shared among functions

optimization/9702: Constant pools are not shared among functions

[beszedes]

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>Number:         9702
>Category:       optimization
>Synopsis:       Constant pools are not shared among functions
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          pessimizes-code
>Submitter-Id:   net
>Arrival-Date:   Fri Feb 14 09:36:01 UTC 2003
>Closed-Date:
>Last-Modified:
>Originator:     Árpád Beszédes
>Release:        gcc version 3.3 20030210 (prerelease)
>Organization:
>Environment:
BUILD & HOST: Linux 2.4.20 i686 unknown
TARGET: arm-unknown-elf
>Description:
Currently all functions have their own constant pool even if they use the same constants. Gcc should merge appropriate constant pools and place this common pool to a location accessible from all appropriate functions.
>How-To-Repeat:
Use the command line below to compile the specified source code:
arm-elf-gcc -S -g0 -Os -o 02.s ./02.c

Attached is the original assembly output where constant pools labeled by .L2 and .L5 could be merged together as shown in the manually edited assembly file.

// 02.c:

# 1 "02.c"
# 1 "<built-in>"
# 1 "<command line>"
# 1 "02.c"
unsigned int a;
int f1()
{
  return a+2;
}
int f3()
{
  a=12;
}
int main ()
{
  f3();
  return f1();
}

>Fix:
If unit-at-a-time compilation is implemented in gcc, this issue could be solved within gcc more easily.
>Release-Note:
>Audit-Trail:
>Unformatted:
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