epiphany-gcc-pr-fix-fp-r11-r15-regression

epiphany-gcc-pr-fix-fp-r11-r15-regression

Ignore me (fix Github's gist name)

gcc-command

e-gcc -o zigzag768 -DROWS=32 -DCOLS=24 -DFIRST_CORE=0x808 -g -O0 -Wall -Wno-unused -Werror -ffast-math zigzag.c -le-lib -Wl,-T/opt/adapteva/esdk/bsps/current/fast.ldf

objdump.diff

--- zigzag768.fail.dump	2014-10-29 11:21:59.249960826 +0100
+++ zigzag768.fix.dump	2014-10-29 11:23:15.934927885 +0100
@@ -14690,7 +14690,7 @@
      a9a:	0ccc 0500 	ldr r0,[fp,-0x1]
      a9e:	23bb 0003 	sub r1,r0,31
      aa2:	a090      	blte 9e2 <_print_route+0xe6>
-     aa4:	bcef 2402 	mov sp,r15
+     aa4:	acef 2402 	mov sp,fp
      aa8:	74cc 2400 	ldr fp,[sp,+0x1]
      aac:	d44c 2600 	ldr lr,[sp],+0x0
      ab0:	194f 0402 	rts

zigzag.c

#include <stdio.h>
#include <stdint.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>

#include <e_lib.h>

#ifndef ROWS
#  define ROWS 4
#endif
#ifndef COLS
#  define COLS 4
#endif


#define E_ROW(x) ((x) >> 6)
#define E_COL(x) ((x) & ((1<<6)-1))
#define E_CORE(r, c) (((r) << 6) | (c))

#ifndef FIRST_CORE
#  define FIRST_CORE 0x808  // Coreid of first core in group
#endif

#define FIRST_ROW E_ROW(FIRST_CORE)    // First row in group
#define FIRST_COL E_COL(FIRST_CORE)    // First col in group

#if FIRST_CORE
#define LEADER FIRST_CORE
#else
#define LEADER 0x1
#endif

/* Make linker allocate memory for message box. Same binary, so same address
 * on all cores. */
uint16_t _msg_box[ROWS*COLS+1];
#define MSG_BOX _msg_box

/* Can't hook up to sync since e-server traps it */
void interrupt_handler() __attribute__ ((interrupt ("message")));
void pass_message();
void print_route();

void __attribute__ ((aligned(8))) __attribute__ ((noinline)) e_idle()
{
  // but these two instructions is what we really need to align 
  // so the attribute won't help
  asm("gie");
  asm("idle");
}

int main()
{
  int i;

  e_irq_global_mask(E_TRUE);
  e_irq_mask(E_MESSAGE_INT, E_FALSE);
  e_irq_attach(E_MESSAGE_INT, interrupt_handler);

  if (e_get_coreid() == LEADER)
    {
      /* Give other processes time to go to idle */
      for (i=0; i < 1000000; ++i) ;
      pass_message();
    }

  e_irq_global_mask(E_FALSE);
  asm("idle");
  //e_idle();
  return 0;

}

void interrupt_handler()
{
  if (e_get_coreid() == LEADER)
    {
      /* Print route message took */
      print_route();
      exit(3);
    }
  else
    {
      /* Pass message to next core in path */
      pass_message();
      _exit(2); // Normal exit seems to close other processes stdout ???
    }
}

e_coreid_t next_hop()
{
  enum direction_t { LEFT, RIGHT } direction;

  e_coreid_t coreid;
  unsigned row, col, rel_row, rel_col;

  coreid = e_get_coreid();
  row = E_ROW(coreid);
  col = E_COL(coreid);
  rel_row = row - FIRST_ROW;
  rel_col = col - FIRST_COL;

  /* Go left on odd rel row, right on even */
  direction = (rel_row & 1) ? LEFT : RIGHT;

  if (coreid == LEADER)
    {
      if (rel_col < COLS-1)
	return E_CORE(row, col+1);
      else
	return E_CORE(row+1, col);
    }

  if (!rel_col)
    {
      if (rel_row == 1)
	return LEADER;
      else
	return E_CORE(row-1, col);
    }

  //if (rel_row == ROWS-1)
  //  return E_CORE(row, col-1);

  switch (direction)
    {
    case LEFT:
      if (rel_col == 1 && rel_row != ROWS-1)
	return E_CORE(row+1, col);
      else
	return E_CORE(row, col-1);

    case RIGHT:
      if (rel_row == ROWS-1 && rel_col == COLS-1)
	return E_CORE(row, FIRST_COL);
      else if (rel_col == COLS-1)
	return E_CORE(row+1, col);
      else
	return E_CORE(row, col+1);
    }

  return FIRST_CORE;

}

void pass_message()
{
  e_coreid_t next;
  uint16_t n;
  uint16_t *next_msgbox;
  uint16_t *msgbox = (uint16_t *) MSG_BOX;

  if (e_get_coreid() == LEADER)
    {
      *msgbox = 0;
    }

  msgbox[0]++;
  n = msgbox[0];
  msgbox[n] = (uint16_t) (((unsigned) e_get_coreid()) & 0xffff);

  next = next_hop();
  next_msgbox = (uint16_t *)
    e_get_global_address(E_ROW(next), E_COL(next), (void *) MSG_BOX);
  memcpy((void *) next_msgbox, (void *) msgbox, (n+1)*sizeof(msgbox[0]));

  printf("Passing message to 0x%x (%p)\n", next, next_msgbox);
  e_irq_set(E_ROW(next), E_COL(next), E_MESSAGE_INT);
}

inline void print_path(uint16_t path[ROWS][COLS], uint16_t row, uint16_t col)
{
  signed north, east, south, west;
  uint16_t next, prev;

  north = row == 0      ? -2 : path[row-1][col  ];
  west  = col == 0      ? -2 : path[row  ][col-1];
  south = row == ROWS-1 ? -2 : path[row+1][col  ];
  east  = col == COLS-1 ? -2 : path[row  ][col+1];

  next = path[row][col] + 1;
  prev = path[row][col] - 1;

  if (!prev)
    fputs("○", stdout);
  else if (north == next)
    if (south == prev) fputs("|", stdout); else fputs("▲", stdout);
  else if (south == next)
    if (north == prev) fputs("|", stdout); else fputs("▼", stdout);
  else if (west == next)
    if (east == prev)  fputs("—", stdout); else fputs("◀", stdout);
  else if (east == next)
    if (west == prev)  fputs("—", stdout); else fputs("▶", stdout);
  else
    fputs("⚫", stdout);
}

void print_route()
{
  int i,j;
  e_coreid_t core;
  unsigned row, col;
  uint16_t path[ROWS][COLS];
  uint16_t *msgbox = (uint16_t *) MSG_BOX;

  printf("Got %d messages\n", msgbox[0]);
  printf("Message path:\n");
  for (i=0; i < msgbox[0]; i++)
    {
      core = msgbox[i+1];
      if (core)
	{
	  row = E_ROW(core) - FIRST_ROW;
	  col = E_COL(core) - FIRST_COL;
	  path[row][col] = i+1;
	}
    }
  for (i=0; i < ROWS; i++)
    {
      for (j=0; j < COLS; j++)
	{
	  if (path[i][j])
	    print_path(path, i, j);
	  else
	    fputs("⨯", stdout);
	}

      fputs("\n", stdout);
    }
}