REG_DEAD/REG_EQUIV problem.

[Alan Modra]

Here's a testcase for a problem that shows up on hppa-linux, hppa64-linux,
hppa64-hpux11, hppa1.1-hpux11.

cat > losum.c <<EOF
extern void foo (char *);

inline char *
f1 (char *str, long A, long B, long C, long D, long E, long F, long G,
    long H, long I, long J, long K, long L, long M)
{
  long a,b,c,d,e,f,g,h,i,j,k,l,m,p = 0;

  for (a = 0; a < A; a++)
    for (b = 0; b < B; b++)
      for (c = 0; c < C; c++)
        for (d = 0; d < D; d++)
          for (e = 0; e < E; e++)
            for (f = 0; f < F; f++)
              for (g = 0; g < G; g++)
                for (h = 0; h < H; h++)
                  for (i = 0; i < I; i++)
                    for (j = 0; j < J; j++)
                      for (k = 0; k < K; k++)
                        for (l = 0; l < L; l++)
                          for (m = 0; m < M; m++)
                            {
                              foo ("");
                              p++;
                            }
  foo("");
  return str + p;
}

char *f2 (long x)
{
  return f1 ("zz", x, x, x, x, x, x, x, x, x, x, x, x, x);
}
EOF

hppa64-hpux11-gcc -O2 -fPIC -S losum.c -da --save-temps
gives me code like this near the end of f2:

        addil LT'L$C0000,%r27
        ldo -16(%r30),%r29
        ldd RT'L$C0000(%r1),%r1
        b,l foo,%r2
        copy %r1,%r26
        copy %r14,%r27
        ldd RT'L$C0001(%r1),%r19	; Oops, where's the addil for r1?
	ldd -272(%r30),%r2
	add,l %r19,%r16,%r28

Extract from losum.c.18.lreg:
===
(insn 15 6 17 (set (reg:DI 70)
        (plus:DI (reg:DI 27 %r27)
            (high:DI (symbol_ref/v/f:DI ("*L$C0001"))))) 81 {*pa.md:2337} (nil)
    (nil))

(insn 17 15 21 (set (reg/v:DI 69)
        (mem/u:DI (lo_sum:DI (reg:DI 70)
                (unspec:DI[ 
                        (symbol_ref/v/f:DI ("*L$C0001"))
                    ]  0)) 0)) 83 {*pa.md:2368} (insn_list 15 (nil))
    (expr_list:REG_EQUIV (mem/u:DI (lo_sum:DI (reg:DI 70)
                (unspec:DI[ 
                        (symbol_ref/v/f:DI ("*L$C0001"))
                    ]  0)) 0)
        (expr_list:REG_DEAD (reg:DI 70)
            (nil))))

[snip]

(insn/i 258 257 267 (set (reg:DI 88)
        (plus:DI (reg/v:DI 69)
            (reg/v:DI 84))) 166 {*pa.md:3738} (insn_list:REG_DEP_ANTI 257 (nil))
    (expr_list:REG_DEAD (reg/v:DI 69)
        (expr_list:REG_DEAD (reg/v:DI 84)
            (nil))))

===
Now from losum.c.19.greg:

(insn 492 257 258 (set (reg:DI 19 %r19)
        (mem/u:DI (lo_sum:DI (reg:DI 1 %r1 [70])
                (unspec:DI[ 
                        (symbol_ref/v/f:DI ("*L$C0001"))
                    ]  0)) 0)) 83 {*pa.md:2368} (nil)
    (nil))

(insn/i 258 492 267 (set (reg:DI 28 %r28 [88])
        (plus:DI (reg:DI 19 %r19)
            (reg/v:DI 16 %r16 [84]))) 166 {*pa.md:3738} (insn_list:REG_DEP_ANTI 257 (nil))
    (nil))

===

Notice how insn 492 uses the equivalence for reg 69, but reg 70 is
dead.  If I'm more than halfway right about what is causing this problem,
then it's probably not specific to PA.

Alan Modra
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