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Fix performance degradation introduced by the second expansion feature.

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I did this by adding intelligence into the algorithm such that the
second expansion was only actually performed when the prerequisite list
contained at least one "$", so we knew it is actually needed.

Without this we were using up a LOT more memory, since every single
target (even ones never used by make) had their file variables
initialized.  This also used a lot more CPU, since we needed to create
and populate a new variable hash table for every target.

There is one issue remaining with this feature: it leaks memory.  In
pattern_search() we now initialize the file variables for every pattern
target, which allocates a hash table, etc.  However, sometimes we
recursively invoke pattern_search() (for intermediate files) with an
automatic variable (alloca() I believe) as the file.  When that function
returns, obviously, the file variable hash memory is lost.
This commit is contained in:
Paul Smith 2005-04-13 03:16:33 +00:00
parent 3daf8df6ee
commit 49ee105c68
7 changed files with 117 additions and 58 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
ChangeLog
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@ -1,3 +1,30 @@
2005-04-12 Paul D. Smith <psmith@gnu.org>
The second expansion feature causes significant slowdown. Timing
a complex makefile (GCC 4.1) shows a slowdown from .25s to just
read the makefile before the feature, to 11+s to do the same
operations after the feature. Additionally, memory usage
increased drastically. To fix this I added some intelligence that
avoids the overhead of the second expansion unless it's required.
* dep.h: Add a new boolean field, need_2nd_expansion.
* read.c (eval): When creating the struct dep for the target,
check if the name contains a "$"; if so set need_2nd_expansion to 1.
(record_files): If there's a "%" in a static pattern rule, it gets
converted to "$*" so set need_2nd_expansion to 1.
* file.c (expand_deps): Rework to be more efficient. Only perform
initialize_file_variables(), set_file_variables(), and
variable_expand_for_file() if the need_2nd_expansion is set.
* implicit.c (pattern_search): Default need_2nd_expansion to 0.
(pattern_search): Ditto.
* main.c (handle_non_switch_argument): Ditto.
(main): Ditto.
* read.c (read_all_makefiles): Ditto.
(eval_makefile): Ditto.
2005-04-07 Paul D. Smith <psmith@gnu.org>
* main.c (main) [WINDOWS32]: Export PATH to sub-shells, not Path.

1
dep.h
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@ -40,6 +40,7 @@ struct dep
struct file *file;
unsigned int changed : 8;
unsigned int ignore_mtime : 1;
unsigned int need_2nd_expansion : 1;
};

47
file.c
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@ -418,28 +418,40 @@ set_intermediate (const void *item)
static void
expand_deps (struct file *f)
{
register struct dep *d, *d1;
struct dep *d, *d1;
struct dep *new = 0;
struct dep *old = f->deps;
unsigned int last_dep_has_cmds = f->updating;
int initialized = 0;
f->updating = 0;
f->deps = 0;
/* We are going to do second expansion so initialize file
variables for the file. */
initialize_file_variables (f, 0);
for (d = old; d != 0; d = d->next)
{
if (d->name != 0)
{
char *p;
struct dep **d_ptr;
/* If we need a second expansion on these, set up the file
variables, etc. It takes a lot of extra memory and processing
to do this, so only do it if it's needed. */
if (! d->need_2nd_expansion)
p = d->name;
else
{
/* We are going to do second expansion so initialize file
variables for the file. */
if (!initialized)
{
initialize_file_variables (f, 0);
initialized = 1;
}
set_file_variables (f);
p = variable_expand_for_file (d->name, f);
}
/* Parse the dependencies. */
new = (struct dep *)
@ -452,8 +464,8 @@ expand_deps (struct file *f)
/* Files that follow '|' are special prerequisites that
need only exist in order to satisfy the dependency.
Their modification times are irrelevant. */
struct dep **d_ptr;
struct dep *d;
for (d_ptr = &new; *d_ptr; d_ptr = &(*d_ptr)->next)
;
++p;
@ -463,8 +475,8 @@ expand_deps (struct file *f)
parse_file_seq (&p, '\0', sizeof (struct dep), 1),
sizeof (struct dep));
for (d = *d_ptr; d != 0; d = d->next)
d->ignore_mtime = 1;
for (d1 = *d_ptr; d1 != 0; d1 = d1->next)
d1->ignore_mtime = 1;
}
/* Enter them as files. */
@ -476,6 +488,7 @@ expand_deps (struct file *f)
else
free (d1->name);
d1->name = 0;
d1->need_2nd_expansion = 0;
}
/* Add newly parsed deps to f->deps. If this is the last
@ -492,6 +505,7 @@ expand_deps (struct file *f)
{
if (d->next == 0 && last_dep_has_cmds)
{
struct dep **d_ptr;
for (d_ptr = &new; *d_ptr; d_ptr = &(*d_ptr)->next)
;
@ -500,7 +514,8 @@ expand_deps (struct file *f)
}
else
{
for (d_ptr = &(f->deps); *d_ptr; d_ptr = &(*d_ptr)->next)
struct dep **d_ptr;
for (d_ptr = &f->deps; *d_ptr; d_ptr = &(*d_ptr)->next)
;
*d_ptr = new;
@ -521,12 +536,12 @@ expand_deps (struct file *f)
void
snap_deps (void)
{
register struct file *f;
register struct file *f2;
register struct dep *d;
register struct file **file_slot_0;
register struct file **file_slot;
register struct file **file_end;
struct file *f;
struct file *f2;
struct dep *d;
struct file **file_slot_0;
struct file **file_slot;
struct file **file_end;
/* Perform second expansion and enter each dependency
name as a file. */

24
implicit.c
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@ -509,19 +509,19 @@ pattern_search (struct file *file, int archive,
break; /* No more words */
/* If the dependency name has %, substitute the stem.
Watch out, we are going to do something very smart
here. If we just replace % with the stem value,
later, when we do the second expansion, we will
re-expand this stem value once again. This is not
good especially if you have certain characters in
your setm (like $).
Watch out, we are going to do something tricky here. If
we just replace % with the stem value, later, when we do
the second expansion, we will re-expand this stem value
once again. This is not good especially if you have
certain characters in your setm (like $).
Instead, we will replace % with $* and allow the
second expansion to take care of it for us. This
way (since $* is a simple variable) there won't
be additional re-expansion of the stem.*/
Instead, we will replace % with $* and allow the second
expansion to take care of it for us. This way (since $*
is a simple variable) there won't be additional
re-expansion of the stem. */
for (p2 = p; p2 < p + len && *p2 != '%'; ++p2);
for (p2 = p; p2 < p + len && *p2 != '%'; ++p2)
;
if (p2 < p + len)
{
@ -836,6 +836,7 @@ pattern_search (struct file *file, int archive,
dep = (struct dep *) xmalloc (sizeof (struct dep));
dep->ignore_mtime = d->ignore_mtime;
dep->need_2nd_expansion = 0;
s = d->name; /* Hijacking the name. */
d->name = 0;
if (recursions == 0)
@ -908,6 +909,7 @@ pattern_search (struct file *file, int archive,
struct dep *new = (struct dep *) xmalloc (sizeof (struct dep));
/* GKM FIMXE: handle '|' here too */
new->ignore_mtime = 0;
new->need_2nd_expansion = 0;
new->name = p = (char *) xmalloc (rule->lens[i] + fullstemlen + 1);
bcopy (rule->targets[i], p,
rule->suffixes[i] - rule->targets[i] - 1);

2
main.c
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@ -2125,6 +2125,7 @@ main (int argc, char **argv, char **envp)
goals->next = 0;
goals->name = 0;
goals->ignore_mtime = 0;
goals->need_2nd_expansion = 0;
goals->file = default_goal_file;
}
}
@ -2290,6 +2291,7 @@ handle_non_switch_argument (char *arg, int env)
lastgoal->name = 0;
lastgoal->file = f;
lastgoal->ignore_mtime = 0;
lastgoal->need_2nd_expansion = 0;
{
/* Add this target name to the MAKECMDGOALS variable. */

47
read.c
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@ -253,6 +253,7 @@ read_all_makefiles (char **makefiles)
d->file = enter_file (*p);
d->file->dontcare = 1;
d->ignore_mtime = 0;
d->need_2nd_expansion = 0;
/* Tell update_goal_chain to bail out as soon as this file is
made, and main not to die if we can't make this file. */
d->changed = RM_DONTCARE;
@ -372,6 +373,7 @@ eval_makefile (char *filename, int flags)
filename = deps->file->name;
deps->changed = flags;
deps->ignore_mtime = 0;
deps->need_2nd_expansion = 0;
if (flags & RM_DONTCARE)
deps->file->dontcare = 1;
@ -1167,9 +1169,21 @@ eval (struct ebuffer *ebuf, int set_default)
if (beg <= end && *beg != '\0')
{
char *top;
const char *fromp = beg;
/* Make a copy of the dependency string. Note if we find '$'. */
deps = (struct dep*) xmalloc (sizeof (struct dep));
deps->next = 0;
deps->name = savestring (beg, end - beg + 1);
deps->name = top = (char *) xmalloc (end - beg + 2);
deps->need_2nd_expansion = 0;
while (fromp <= end)
{
if (*fromp == '$')
deps->need_2nd_expansion = 1;
*(top++) = *(fromp++);
}
*top = '\0';
deps->file = 0;
}
else
@ -1194,11 +1208,10 @@ eval (struct ebuffer *ebuf, int set_default)
commands[commands_idx++] = '\n';
}
/* Determine if this target should be made default. We used
to do this in record_files() but because of the delayed
target recording and because preprocessor directives are
legal in target's commands it is too late. Consider this
fragment for example:
/* Determine if this target should be made default. We used to do
this in record_files() but because of the delayed target recording
and because preprocessor directives are legal in target's commands
it is too late. Consider this fragment for example:
foo:
@ -1206,10 +1219,10 @@ eval (struct ebuffer *ebuf, int set_default)
...
endif
Because the target is not recorded until after ifeq
directive is evaluated the .DEFAULT_TARGET does not
contain foo yet as one would expect. Because of this
we have to move some of the logic here. */
Because the target is not recorded until after ifeq directive is
evaluated the .DEFAULT_TARGET does not contain foo yet as one
would expect. Because of this we have to move some of the logic
here. */
if (**default_target_name == '\0' && set_default)
{
@ -1912,21 +1925,19 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
this = 0;
}
else
{
/* We use subst_expand to do the work of translating
% to $* in the dependency line. */
/* We use subst_expand to do the work of translating % to $* in
the dependency line. */
if (this != 0 && find_percent (this->name) != 0)
{
char *o;
char *buffer = variable_expand ("");
o = subst_expand (buffer, this->name, "%", "$*",
1, 2, 0);
o = subst_expand (buffer, this->name, "%", "$*", 1, 2, 0);
free (this->name);
this->name = savestring (buffer, o - buffer);
}
this->need_2nd_expansion = 1;
}
}
@ -2009,7 +2020,7 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
/* This is the rule without commands. Put its
dependencies at the end but before dependencies
from the rule with commands (if any). This way
everyhting appears in makefile order. */
everything appears in makefile order. */
if (f->cmds != 0)
{
@ -2026,7 +2037,7 @@ record_files (struct nameseq *filenames, char *pattern, char *pattern_percent,
/* This is a hack. I need a way to communicate to snap_deps()
that the last dependency line in this file came with commands
(so that logic in snap_deps() can put it in front and all
this $< -logic works). I cannot's simply rely oon file->cmds
this $< -logic works). I cannot simply rely on file->cmds
being not 0 because of the cases like the following:
foo: bar

1
rule.c
View File

@ -206,6 +206,7 @@ convert_suffix_rule (char *target, char *source, struct commands *cmds)
deps->next = 0;
deps->name = depname;
deps->ignore_mtime = 0;
deps->need_2nd_expansion = 0;
}
create_pattern_rule (names, percents, 0, deps, cmds, 0);