Richard Henderson - fix pr 29558 (original) (raw)

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• From: Richard Henderson
• To: gcc-patches at gcc dot gnu dot org
• Date: Mon, 19 Feb 2007 08:19:49 -0800
• Subject: fix pr 29558

The pr highlights a big problem with the var tracking code on big-endian systems. Namely, the REG_OFFSET information can be wrong/useless after reload has got done flattening paradoxical subregs. Namely, what once was

(subreg:SI (reg:QI 101 temp+0) 0)

becomes (reg:SI 11 temp+-3)

First, a -3 offset into a data structure is pointless. But second, even if we took big-endian things into account to try and resolve that, we've lost information: namely, the amount of data actually present in that register. It does us no good to see (reg:SI 11 temp+12), and say that there are 4 bytes of temp in reg11, if in fact there is only one byte of temp present, and it's offset is actually +15.

None of which can be fixed for the 4.2 branch. But at least we can fix the crash. In this case we had a TImode array in memory, and the test for "structures and arrays" didn't trigger.

Fixed thus, tested ppc64.

r~

    PR debug/29558
    * var-tracking.c (track_expr_p): Disallow AGGREGATE_TYPE_P
    in memory.

--- gcc/testsuite/gcc.dg/debug/pr29558.c (revision 122139) +++ gcc/testsuite/gcc.dg/debug/pr29558.c (local) @@ -0,0 +1,30 @@ +/* { dg-do compile } */ + +void stpi_unpack_16_1(int length, unsigned char *out, unsigned char bit) +{

• unsigned char tempin;
• unsigned char temp[16];
• for (bit = 128; length > 0; length--) {
• if (tempin & 128)

•  temp[0] |= bit;

• else

•  {

•    *out++ = temp[1];

•    *out++ = temp[2];

•    *out++ = temp[3];

•    *out++ = temp[4];

•    *out++ = temp[5];

•    *out++ = temp[6];

•    *out++ = temp[7];

•    *out++ = temp[9];

•    *out++ = temp[10];

•    *out++ = temp[11];

•    *out++ = temp[12];

•    *out++ = temp[13];

•    *out++ = temp[14];

•    *out++ = temp[15];

•    __builtin_memset (temp, 0, 16);

• }

• } +}
• --- gcc/var-tracking.c (revision 122139) +++ gcc/var-tracking.c (local) @@ -1529,7 +1529,8 @@ track_expr_p (tree expr) if (MEM_P (decl_rtl)) { /* Do not track structures and arrays. */

•  if (GET_MODE (decl_rtl) == BLKmode)

•  if (GET_MODE (decl_rtl) == BLKmode

•  || AGGREGATE_TYPE_P (TREE_TYPE (realdecl)))
  return 0;
    if (MEM_SIZE (decl_rtl)
    && INTVAL (MEM_SIZE (decl_rtl)) > MAX_VAR_PARTS)