[
https://issues.apache.org/jira/browse/STDCXX-335?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Martin Sebor updated STDCXX-335:
--------------------------------
Severity: Inefficiency
Remaining Estimate: 4h
Original Estimate: 4h
Estimated effort to assess the issue by reviewing object code generated by
popular compilers and decide on a solution (if any).
> std::min() suboptimal
> ---------------------
>
> Key: STDCXX-335
> URL: https://issues.apache.org/jira/browse/STDCXX-335
> Project: C++ Standard Library
> Issue Type: Bug
> Components: 25. Algorithms
> Affects Versions: 4.1.3
> Environment: gcc 3.2.3, x86 Linux
> Reporter: Mark Brown
> Fix For: 4.3
>
> Original Estimate: 4h
> Remaining Estimate: 4h
>
> I don't know if it's the compiler that's generating worse code for the stdcxx
> version of min or if the function is not implemented as efficiently as it
> could be but the disassembly for the two functions below shows that my_min()
> is one instruction shorter than test_min():
> #include <algorithm>
> int test_min (int x, int y) { return std::min (x, y); }
> int my_min (int x, int y) { return x < y ? x : y; }
> _Z8test_minii:
> pushl %ebp
> movl %esp, %ebp
> movl 12(%ebp), %eax
> cmpl %eax, 8(%ebp)
> jg .L2
> leal 8(%ebp), %eax <<< extra load?
> .L4:
> movl (%eax), %eax
> leave
> ret
> _Z6my_minii:
> pushl %ebp
> movl %esp, %ebp
> movl 12(%ebp), %eax
> cmpl 8(%ebp), %eax
> jle .L6
> movl 8(%ebp), %eax
> .L6:
> leave
> ret
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
