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Fix code suppression during nocode_wanted

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we activate code (CODE_ON) only when the target labels are used,
which doesn't happen during nocode_wanted regions.  So, we cannot
just switch off code either during nocode_wanted regions, nothing
would switch it on again (except in the happy coincidences when we
outright save/restore nocode_wanted).  See the testcase for one
example, reduced from code generated by yarpgen: in
  ext = (xxx || 1)           // #1
        || ((xxx && 1) || 1) // #2
code is first suppressed in #1 normally, then (before this commit)
was suppressed via CODE_OFF during #2 (via indirect gjmp),
then the suppression from #1 was undone, but nothing undoes the
suppression from #2 anymore as everything therein was generated
while nocode_wanted was active.

So, we would either need to save/restore nocode_wanted around
some more expressions, activate CODE_ON also with unused labels (breaks
some optimizations we want), or deactivate CODE_OFF only when not
already in nocode_wanted state.  This does the latter.
This commit is contained in:
Michael Matz 2023-03-07 18:10:02 +01:00
parent ccc1651075
commit c771cb52fa
3 changed files with 13 additions and 1 deletions
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2
tccgen.c
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@ -56,7 +56,7 @@ ST_DATA int nocode_wanted; /* no code generation wanted */
#define unevalmask 0xffff /* unevaluated subexpression */
#define NODATA_WANTED (nocode_wanted > 0) /* no static data output wanted either */
#define DATA_ONLY_WANTED 0x80000000 /* ON outside of functions and for static initializers */
#define CODE_OFF() (nocode_wanted |= 0x20000000)
#define CODE_OFF() if(!nocode_wanted)(nocode_wanted |= 0x20000000)
#define CODE_ON() (nocode_wanted &= ~0x20000000)
ST_DATA int global_expr; /* true if compound literals must be allocated globally (used during initializers parsing */

11
tests/tests2/88_codeopt.c
View File

@ -44,6 +44,16 @@ void bla(void)
get_args(!!__ret, sizeof(__ret));
}
int ext;
void broken_jumpopt (int xxx)
{
/* This was broken in 8227db3a2 by code suppression during suppressed
code :) */
ext = (xxx || 1) || ((xxx && 1) || 1);
printf("okay: %d %d\n", xxx, ext);
}
_Bool chk(unsigned long addr, unsigned long limit, unsigned long size)
{
_Bool ret;
@ -65,5 +75,6 @@ int main()
else
printf("okay\n");
bla();
broken_jumpopt(42);
return 0;
}

1
tests/tests2/88_codeopt.expect
View File

@ -1,2 +1,3 @@
okay
okay
okay: 42 1