[Bug c/51622] New: GCC generates bad code that generate big executable sizes when using _Decimal*

["mingodad at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51622

             Bug #: 51622
           Summary: GCC generates bad code that generate big executable
                    sizes when using _Decimal*
    Classification: Unclassified
           Product: gcc
           Version: 4.6.1
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: mingodad@gmail.com


Created attachment 26140
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26140
Program and a batch file to show how strange is gcc code generation when using
_Decimal*

The main point here is to demonstrate that gcc is capable to generate good code
size when using _Decimal* but for some reason it get lost with some code
combinations and generates very big executables unnecessarily making a bad
balance between functionality/size.

Here is a program that demonstrate that gcc is generating bad code resulting in
big executables when using _Decimal*.

There is a main.c with several operations on _Decimal64, few on _Decimal128
with some combination of the code (with all operations) the final executable
file is 8KB but with a different combination (again with all operations) the
executable is 2.206KB or 2.2MB. This last one is very strange because the
diference betwen then is calling a printf to print several existing _Decimal64
variable (the biggest 2.2MB) and calling a printf to print only one existing
_Decimal64 variable ((double)discount_over_sales the smallest 8KB but if we try
to any other existing variables it goes to 2.2MB).

gcc -s -O2 -DWITH_TMP main.c -o smallest.exe -> 8KB
gcc -s -O2 -DWITH_ONE_BIG_PRINTF -DWITH_TMP main.c -o strange-big-size-jump.exe
-> 2.206KB or 2.2MB
gcc -s -O2 main.c -o good1.exe -> 8KB
gcc -s -O2 -DWITH_DEC128 -DWITH_ISNAN -DWITH_MPRINTF main.c printf.c -o
biggest.exe -> 2.444KB or 2.4MB
gcc -s -O2 -DWITH_MPRINTF main.c printf.c -o optimus.exe -> 154KB
gcc -s -O2 -DWITH_DEC128 -DWITH_MPRINTF main.c printf.c -o good2.exe -> 367KB