🚀 go-pugleaf

Here is a question for the maintainers of the gcc optimizer for the
80386. consider this file:

// file test.cc used to  show the (non) optimizer problem.---------
class tree_element {
  int value;
  tree_element *larger;
  tree_element *smaller;
  tree_element *parent;
  int num_larger;
  int num_smaller;
public:
  int get() {return value;};
  int get_value() {return value;};
  tree_element(int i);
  ~tree_element();
  friend class binary_tree;
};

tree_element::tree_element(int i)
{
  value = i;
  num_larger = num_smaller = 0;
  parent = larger = smaller = 0;
}

tree_element::~tree_element()
{
  if(larger) delete larger;
  if(smaller) delete smaller;
}
//--------<end>---------------------------------------

Compiled thusly on Interactive 2.2.1 (SysV/386 R3.2):

> gcc -v -O2 -S test.cc
Reading specs from /usr/local/lib/gcc-lib/i386-isc/2.2.2/specs
gcc version 2.2.2
 /usr/local/lib/gcc-lib/i386-isc/2.2.2/cpp -lang-c++ -v -undef -D__GNUC__=2 -D__GNUG__=2 -D__cplusplus -Dunix -Di386 -D__unix__ -D__i386__ -D__unix -D__i386 -D__OPTIMIZE__ test.cc /usr/tmp/cca01388.i
GNU CPP version 2.2.2 (80386, ATT syntax)
 /usr/local/lib/gcc-lib/i386-isc/2.2.2/cc1plus /usr/tmp/cca01388.i -quiet -dumpbase test.cc -O2 -version -o test.s
GNU C++ version 2.2.2 (80386, ATT syntax) compiled by GNU C version 2.2.2.
> cat test.s
	.file	"test.cc"
gcc2_compiled.:
.text
	.align 4
.globl __12tree_elementi
__12tree_elementi:
	pushl %ebp
	movl %esp,%ebp
	movl 8(%ebp),%eax
	movl 12(%ebp),%edx
	movl %edx,(%eax)
	movl $0,20(%eax)
	movl $0,16(%eax)
	movl $0,8(%eax)
	movl $0,4(%eax)
	movl $0,12(%eax)
	leave
	ret
	.align 4      <----------why two of these??
	.align 4
.globl _._12tree_element
_._12tree_element:
	pushl %ebp
	movl %esp,%ebp
	pushl %ebx
	movl 8(%ebp),%ebx
	cmpl $0,4(%ebx)
	je .L8       <----------why two of these??
	je .L8
	pushl $3
	pushl 4(%ebx)
	call _._12tree_element
	addl $8,%esp
.L8:
	cmpl $0,8(%ebx)
	je .L14      <----------why two of these??
	je .L14
	pushl $3
	pushl 8(%ebx)
	call _._12tree_element
	addl $8,%esp
.L14:
	movb 12(%ebp),%al
	andb $1,%al
	je .L16
	pushl %ebx
	call __builtin_delete
.L16:
	movl -4(%ebp),%ebx
	leave
	ret
> 

I hope they are not in there as two byte nop's for alignment, because they
don't cause any thing to become aligned (jump targets or instructions following
calls)

Dave Daney       daney@mermaid.micro.umn.edu