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(synth_mult): Delay allocation of algorithm structures until they are needed. 

(synth_mult): Delay allocation of algorithm structures until they are
needed.  Reorder early-exit tests to avoid comparing value that is not
yet set.

From-SVN: r6464
This commit is contained in:
Richard Kenner 1994-02-02 13:24:14 -05:00
parent 09e3dd7232
commit 52786026fa
1 changed files with 12 additions and 10 deletions
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22
gcc/expmed.c
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@ -1,6 +1,6 @@
/* Medium-level subroutines: convert bit-field store and extract
and shifts, multiplies and divides to rtl instructions.
Copyright (C) 1987, 1988, 1989, 1992, 1993 Free Software Foundation, Inc.
Copyright (C) 1987, 88, 89, 92, 93, 1994 Free Software Foundation, Inc.
This file is part of GNU CC.
@ -1851,10 +1851,7 @@ synth_mult (alg_out, t, cost_limit)
int cost_limit;
{
int m;
struct algorithm *best_alg
= (struct algorithm *)alloca (sizeof (struct algorithm));
struct algorithm *alg_in
= (struct algorithm *)alloca (sizeof (struct algorithm));
struct algorithm *alg_in, *best_alg;
unsigned int cost;
unsigned HOST_WIDE_INT q;
@ -1889,6 +1886,11 @@ synth_mult (alg_out, t, cost_limit)
}
}
/* We'll be needing a couple extra algorithm structures now. */
alg_in = (struct algorithm *)alloca (sizeof (struct algorithm));
best_alg = (struct algorithm *)alloca (sizeof (struct algorithm));
/* If we have a group of zero bits at the low-order part of T, try
multiplying by the remaining bits and then doing a shift. */
@ -2051,16 +2053,16 @@ synth_mult (alg_out, t, cost_limit)
}
}
/* If we are getting a too long sequence for `struct algorithm'
to record, make this search fail. */
if (best_alg->ops == MAX_BITS_PER_WORD)
return;
/* If cost_limit has not decreased since we stored it in alg_out->cost,
we have not found any algorithm. */
if (cost_limit == alg_out->cost)
return;
/* If we are getting a too long sequence for `struct algorithm'
to record, make this search fail. */
if (best_alg->ops == MAX_BITS_PER_WORD)
return;
/* Copy the algorithm from temporary space to the space at alg_out.
We avoid using structure assignment because the majority of
best_alg is normally undefined, and this is a critical function. */