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* i386: Somewhat optimized fpc_mul_qword routine, got rid from variable 'r', registers esi and edi. Also ignore overflow checking when both operands have their high dwords equal to zero, because in such case multiplication cannot overflow.

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git-svn-id: trunk@26511 -
This commit is contained in:
sergei 2014-01-18 19:28:00 +00:00
parent e6a9f3b15b
commit 78e726b34f
1 changed files with 18 additions and 38 deletions
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56
rtl/i386/int64p.inc
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@ -170,7 +170,6 @@
}
function fpc_mul_qword(f1,f2 : qword;checkoverflow : longbool) : qword;[public,alias: 'FPC_MUL_QWORD']; compilerproc;
var
r : qword;
overflowed : boolean;
begin
overflowed:=false;
@ -179,77 +178,58 @@
asm
movl f1+4,%edx
movl f2+4,%ecx
cmpl $0,checkoverflow
jnz .Loverflowchecked
orl %ecx,%edx
movl f2,%edx
movl f1,%eax
jnz .Lqwordmultwomul
{ if both upper dwords are =0 then it cannot overflow }
mull %edx
jmp .Lqwordmulready
.Lqwordmultwomul:
cmpl $0,checkoverflow
jnz .Loverflowchecked
imul f1+4,%edx
imul %eax,%ecx
addl %edx,%ecx
mull f2
add %ecx,%edx
.Lqwordmulready:
movl %eax,r
movl %edx,r+4
movl %eax,__RESULT
movl %edx,__RESULT+4
jmp .Lend
.Loverflowchecked:
{ if both upper dwords are <>0 then it overflows always }
or %ecx,%ecx
jz .Loverok1
or %edx,%edx
cmpl $0,f1+4
jnz .Loverflowed
.Loverok1:
{ overflow checked code }
orl %ecx,%edx
movl f2,%edi
movl f1,%esi
jnz .Lqwordmultwomul2
movl %edi,%eax
mull %esi
movl %eax,%esi
movl %edx,%edi
jmp .Lqwordmulready2
.Lqwordmultwomul2:
movl f1+4,%eax
mull %edi
movl %eax,%edi
jc .Loverflowed
movl %esi,%eax
mull %ecx
mull f2
movl %eax,%ecx
jc .Loverflowed
addl %edi,%ecx
movl f1,%eax
mull f2+4
jc .Loverflowed
addl %eax,%ecx
jc .Loverflowed
movl f2,%eax
mull %esi
movl %eax,%esi
movl %edx,%edi
addl %ecx,%edi
jc .Loverflowed
.Lqwordmulready2:
movl %esi,r
movl %edi,r+4
jmp .Lend
mull f1
addl %ecx,%edx
movl %eax,__RESULT
movl %edx,__RESULT+4
jnc .Lend
.Loverflowed:
movb $1,overflowed
.Lend:
end [ 'eax','edx','ecx','edi','esi' ];
fpc_mul_qword:=r;
end [ 'eax','edx','ecx'];
if overflowed then
HandleErrorFrame(215,get_frame);