Re: [patch,avr] Adjust insn length of forward branches.

[Denis Chertykov]

2016-08-01 10:56 GMT+03:00 Georg-Johann Lay :
> The length computation of "branch" flavour insn length attribute computed a
> length one instruction too short, e.g. in the following test case:
>
> #define N0(N) if (X++ < N) __builtin_avr_nop()
>
> #define N1(N) N0(N);N0(N);N0(N);N0(N);N0(N);N0(N);N0(N);N0(N);N0(N);N0(N)
> #define N2(N) N1(N);N1(N);N1(N);N1(N);N1(N);N1(N);N1(N);N1(N);N1(N);N1(N)
> #define N3(N) N2(N);N2(N);N2(N);N2(N);N2(N);N2(N);N2(N);N2(N);N2(N);N2(N)
> #define N4(N) N3(N);N3(N);N3(N);N3(N);N3(N);N3(N);N3(N);N3(N);N3(N);N3(N)
>
> void bra_63 (unsigned char x)
> {
> if (x > 0)
> {
> unsigned X = 0;
> N4 (63);
> }
> }
>
> void bra_2045 (unsigned char x)
> {
> if (x > 0)
> {
> unsigned X = 0;
> N4 (2045);
> }
> }
>
> when compiled for MCU with JMP instruction like -mmcu=atmega168
>
> Ok to apply?
>
> Johann
>
>
> * config/avr/avr.md (length) [branch]: Correct insn length
> attribute for forward branches.

Please apply.

[patch,avr] Adjust insn length of forward branches.

[Georg-Johann Lay]

The length computation of "branch" flavour insn length attribute computed a 
length one instruction too short, e.g. in the following test case:


#define N0(N) if (X++ < N) __builtin_avr_nop()

#define N1(N) N0(N);N0(N);N0(N);N0(N);N0(N);N0(N);N0(N);N0(N);N0(N);N0(N)
#define N2(N) N1(N);N1(N);N1(N);N1(N);N1(N);N1(N);N1(N);N1(N);N1(N);N1(N)
#define N3(N) N2(N);N2(N);N2(N);N2(N);N2(N);N2(N);N2(N);N2(N);N2(N);N2(N)
#define N4(N) N3(N);N3(N);N3(N);N3(N);N3(N);N3(N);N3(N);N3(N);N3(N);N3(N)

void bra_63 (unsigned char x)
{
if (x > 0)
{
unsigned X = 0;
N4 (63);
}
}

void bra_2045 (unsigned char x)
{
if (x > 0)
{
unsigned X = 0;
N4 (2045);
}
}

when compiled for MCU with JMP instruction like -mmcu=atmega168

Ok to apply?

Johann


* config/avr/avr.md (length) [branch]: Correct insn length
attribute for forward branches.
Index: config/avr/avr.md
===
--- config/avr/avr.md	(revision 238871)
+++ config/avr/avr.md	(working copy)
@@ -112,12 +112,12 @@ (define_attr "type" "branch,branch1,arit
 (define_attr "length" ""
   (cond [(eq_attr "type" "branch")
  (if_then_else (and (ge (minus (pc) (match_dup 0))
-(const_int -63))
+(const_int -62))
 (le (minus (pc) (match_dup 0))
 (const_int 62)))
(const_int 1)
(if_then_else (and (ge (minus (pc) (match_dup 0))
-  (const_int -2045))
+  (const_int -2044))
   (le (minus (pc) (match_dup 0))
   (const_int 2045)))
  (const_int 2)