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gcse.c (is_too_expensive): New function.
* gcse.c (is_too_expensive): New function. (gcse_main, delete_null_pointer_checks, bypass_jumps): Use it. From-SVN: r70801
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Nathan Sidwell
Nathan Sidwell
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7e2055ec11
commit
d128effb32
@ -1,3 +1,8 @@
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2003-08-26 Nathan Sidwell <nathan@codesourcery.com>
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* gcse.c (is_too_expensive): New function.
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(gcse_main, delete_null_pointer_checks, bypass_jumps): Use it.
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2003-08-25 Zack Weinberg <zack@codesourcery.com>
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* config.gcc (hppa*-*-hpux11*, ia64*-*-hpux*): Remove
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131
gcc/gcse.c
131
gcc/gcse.c
@ -165,7 +165,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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#include "ggc.h"
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#include "params.h"
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#include "cselib.h"
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#include "intl.h"
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#include "obstack.h"
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/* Propagate flow information through back edges and thus enable PRE's
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@ -703,7 +703,9 @@ static void local_cprop_find_used_regs (rtx *, void *);
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static bool do_local_cprop (rtx, rtx, int, rtx*);
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static bool adjust_libcall_notes (rtx, rtx, rtx, rtx*);
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static void local_cprop_pass (int);
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static bool is_too_expensive (const char *);
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/* Entry point for global common subexpression elimination.
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F is the first instruction in the function. */
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@ -737,39 +739,10 @@ gcse_main (rtx f, FILE *file)
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if (file)
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dump_flow_info (file);
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/* Return if there's nothing to do. */
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if (n_basic_blocks <= 1)
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/* Return if there's nothing to do, or it is too expensive. */
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if (n_basic_blocks <= 1 || is_too_expensive (_("GCSE disabled")))
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return 0;
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/* Trying to perform global optimizations on flow graphs which have
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a high connectivity will take a long time and is unlikely to be
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particularly useful.
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In normal circumstances a cfg should have about twice as many edges
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as blocks. But we do not want to punish small functions which have
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a couple switch statements. So we require a relatively large number
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of basic blocks and the ratio of edges to blocks to be high. */
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if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
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{
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if (warn_disabled_optimization)
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warning ("GCSE disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
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n_basic_blocks, n_edges / n_basic_blocks);
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return 0;
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}
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/* If allocating memory for the cprop bitmap would take up too much
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storage it's better just to disable the optimization. */
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if ((n_basic_blocks
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* SBITMAP_SET_SIZE (max_gcse_regno)
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* sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
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{
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if (warn_disabled_optimization)
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warning ("GCSE disabled: %d basic blocks and %d registers",
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n_basic_blocks, max_gcse_regno);
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return 0;
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}
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gcc_obstack_init (&gcse_obstack);
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bytes_used = 0;
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@ -5945,28 +5918,17 @@ delete_null_pointer_checks (rtx f ATTRIBUTE_UNUSED)
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basic_block bb;
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int reg;
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int regs_per_pass;
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int max_reg;
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int max_reg = max_reg_num ();
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struct null_pointer_info npi;
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int something_changed = 0;
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/* If we have only a single block, then there's nothing to do. */
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if (n_basic_blocks <= 1)
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return 0;
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/* Trying to perform global optimizations on flow graphs which have
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a high connectivity will take a long time and is unlikely to be
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particularly useful.
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In normal circumstances a cfg should have about twice as many edges
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as blocks. But we do not want to punish small functions which have
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a couple switch statements. So we require a relatively large number
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of basic blocks and the ratio of edges to blocks to be high. */
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if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
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/* If we have only a single block, or it is too expensive, give up. */
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if (n_basic_blocks <= 1
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|| is_too_expensive (_ ("NULL pointer checks disabled")))
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return 0;
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/* We need four bitmaps, each with a bit for each register in each
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basic block. */
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max_reg = max_reg_num ();
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regs_per_pass = get_bitmap_width (4, last_basic_block, max_reg);
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/* Allocate bitmaps to hold local and global properties. */
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@ -7704,39 +7666,10 @@ bypass_jumps (FILE *file)
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if (file)
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dump_flow_info (file);
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/* Return if there's nothing to do. */
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if (n_basic_blocks <= 1)
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/* Return if there's nothing to do, or it is too expensive */
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if (n_basic_blocks <= 1 || is_too_expensive (_ ("jump bypassing disabled")))
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return 0;
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/* Trying to perform global optimizations on flow graphs which have
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a high connectivity will take a long time and is unlikely to be
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particularly useful.
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In normal circumstances a cfg should have about twice as many edges
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as blocks. But we do not want to punish small functions which have
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a couple switch statements. So we require a relatively large number
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of basic blocks and the ratio of edges to blocks to be high. */
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if (n_basic_blocks > 1000 && n_edges / n_basic_blocks >= 20)
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{
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if (warn_disabled_optimization)
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warning ("BYPASS disabled: %d > 1000 basic blocks and %d >= 20 edges/basic block",
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n_basic_blocks, n_edges / n_basic_blocks);
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return 0;
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}
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/* If allocating memory for the cprop bitmap would take up too much
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storage it's better just to disable the optimization. */
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if ((n_basic_blocks
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* SBITMAP_SET_SIZE (max_gcse_regno)
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* sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
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{
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if (warn_disabled_optimization)
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warning ("GCSE disabled: %d basic blocks and %d registers",
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n_basic_blocks, max_gcse_regno);
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return 0;
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}
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gcc_obstack_init (&gcse_obstack);
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bytes_used = 0;
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@ -7777,4 +7710,44 @@ bypass_jumps (FILE *file)
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return changed;
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}
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/* Return true if the graph is too expensive to optimize. PASS is the
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optimization about to be performed. */
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static bool
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is_too_expensive (const char *pass)
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{
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/* Trying to perform global optimizations on flow graphs which have
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a high connectivity will take a long time and is unlikely to be
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particularly useful.
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In normal circumstances a cfg should have about twice as many
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edges as blocks. But we do not want to punish small functions
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which have a couple switch statements. Rather than simply
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threshold the number of blocks, uses something with a more
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graceful degradation. */
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if (n_edges > 20000 + n_basic_blocks * 4)
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{
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if (warn_disabled_optimization)
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warning ("%s: %d basic blocks and %d edges/basic block",
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pass, n_basic_blocks, n_edges / n_basic_blocks);
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return true;
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}
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/* If allocating memory for the cprop bitmap would take up too much
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storage it's better just to disable the optimization. */
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if ((n_basic_blocks
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* SBITMAP_SET_SIZE (max_reg_num ())
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* sizeof (SBITMAP_ELT_TYPE)) > MAX_GCSE_MEMORY)
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{
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if (warn_disabled_optimization)
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warning ("%s: %d basic blocks and %d registers",
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pass, n_basic_blocks, max_reg_num ());
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return true;
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}
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return false;
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}
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#include "gt-gcse.h"
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