Re: if X in 1..35000 versus Boolean

[sk <noname@myob.com>]

Hi,

> I know only basics of Assembler, so this would be pointless in my case.

Pointless ?

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procedure xxx is
begin
    Loop_Name : for i in 1 .. 1000 loop
        null;
    end loop Loop_Name;
end xxx;

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gcc -S -c xxx.adb (Linux, Gnat 3.13p)

---------------------------------------------------
	.file	"xxx.adb"
	.version	"01.01"
gcc2_compiled.:
.text
	.align 4
.globl _ada_xxx
	.type	 _ada_xxx,@function
_ada_xxx:                          -- Set up
	pushl %ebp
	movl %esp,%ebp             <-- Set base to stack 
	subl $4,%esp               <-- Decrement stack 4 bytes for loop
variable
	movl $1,-4(%ebp)           <-- Set loop variable to 1
.L2:
	cmpl $1000,-4(%ebp)        <-- Is the loop variable = 1000 ?
	jle .L5                    <-- No, variable is less than 1000, jump
to .L5
	jmp .L3                    <-- Yes, jump to .L3
	.align 4
.L5:
	jmp .L4                    <-- Jump to .L4
	.align 4
	jmp .L3
	.align 4
.L6:
.L4:
	incl -4(%ebp)              <-- Increment the loop counter
	jmp .L2                    <-- Go to beginning of loop
	.align 4
.L3:
	jmp .L1                    <-- Ok, finished
	.align 4
.L1:                               -- Clean up
	movl %ebp,%esp
	popl %ebp
	ret
.Lfe1:
	.size	 _ada_xxx,.Lfe1-_ada_xxx
	.ident	"GCC: (GNU) 2.8.1"

---------------------------------------------------
Play with the Ada code by changing the "x in 1 .. 1000" to 
"x in 5 .. 57" for example, and look at the resultant 
assembly listing.

-- 
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-- Merge vertically for real address
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s n p @ t . o
 k i e k c c m
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