[Bug c++/13044] Calls to stack object destructors should be merged for multiple return points

[bangerth at dealii dot org]

------- Additional Comments From bangerth at dealii dot org  2003-11-14 14:34 -------
Your solution has a penalty, namely one additional jump.

That being said, on the tree-ssa branch, this is what happens:
--------------------------------
_Z12earlyReturn1i:
	pushl	%ebp
	movl	%esp, %ebp
	subl	$56, %esp
	cmpl	$0, 8(%ebp)
	je	.L5
	movl	$0, -28(%ebp)
	jmp	.L6
.L5:
	leal	-24(%ebp), %eax
	movl	%eax, (%esp)
	call	_ZN1A6methodEv
	movl	%eax, -28(%ebp)
.L6:
	leal	-24(%ebp), %eax
	movl	%eax, (%esp)
	call	_ZN1AD1Ev
	movl	-28(%ebp), %eax
	leave
	ret

_Z12earlyReturn2i:
	pushl	%ebp
	movl	%esp, %ebp
	pushl	%ebx
	subl	$52, %esp
	cmpl	$0, 8(%ebp)
	je	.L11
	movl	$0, -28(%ebp)
	jmp	.L12
.L11:
	leal	-24(%ebp), %eax
	movl	%eax, (%esp)
	call	_ZN1A6methodEv
	movl	%eax, -28(%ebp)
.L12:
	movl	-28(%ebp), %ebx
	leal	-24(%ebp), %eax
	movl	%eax, (%esp)
	call	_ZN1AD1Ev
	movl	%ebx, %eax
	addl	$52, %esp
	popl	%ebx
	popl	%ebp
	ret
-------------------------

In other words, we do as you suggest. (This is with
  g/x> /home/bangerth/bin/gcc-3.4-pre/bin/c++ -S x.cc -fno-exceptions -v
Reading specs from
/home/bangerth/bin/gcc-3.4-pre/lib/gcc/i686-pc-linux-gnu/3.5-tree-ssa/specs
Configured with: ../gcc-tree-ssa/configure --enable-languages=c,c++
--prefix=/home/bangerth/bin/gcc-3.4-pre --enable-checking
Thread model: posix
gcc version 3.5-tree-ssa 20031111 (merged 20031026)
 /home/bangerth/bin/gcc-3.4-pre/libexec/gcc/i686-pc-linux-gnu/3.5-tree-ssa/cc1plus -quiet -v -D_GNU_SOURCE x.cc -quiet -dumpbase x.cc -mtune=pentiumpro -auxbase x -version -fno-exceptions -o x.s
ignoring nonexistent directory
"/home/bangerth/bin/gcc-3.4-pre/lib/gcc/i686-pc-linux-gnu/3.5-tree-ssa/../../../../i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/bangerth/bin/gcc-3.4-pre/lib/gcc/i686-pc-linux-gnu/3.5-tree-ssa/../../../../include/c++/3.5-tree-ssa
 /home/bangerth/bin/gcc-3.4-pre/lib/gcc/i686-pc-linux-gnu/3.5-tree-ssa/../../../../include/c++/3.5-tree-ssa/i686-pc-linux-gnu
 /home/bangerth/bin/gcc-3.4-pre/lib/gcc/i686-pc-linux-gnu/3.5-tree-ssa/../../../../include/c++/3.5-tree-ssa/backward
 /usr/local/include
 /home/bangerth/bin/gcc-3.4-pre/include
 /home/bangerth/bin/gcc-3.4-pre/lib/gcc/i686-pc-linux-gnu/3.5-tree-ssa/include
 /usr/include
End of search list.
GNU C++ version 3.5-tree-ssa 20031111 (merged 20031026) (i686-pc-linux-gnu)
        compiled by GNU C version 3.5-tree-ssa 20031111 (merged 20031026).
GGC heuristics: --param ggc-min-expand=30 --param ggc-min-heapsize=4096

W.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13044