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error: unknown constraint 'x' (x86_64) #1

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absop opened this issue Oct 14, 2019 · 0 comments
Open

error: unknown constraint 'x' (x86_64) #1

absop opened this issue Oct 14, 2019 · 0 comments

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@absop
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absop commented Oct 14, 2019

I tried to use tcc run the following code on x86_64, it threw the following error.
gcc done it well.

double glibc_sqrt(double x)
{
    double res;

    asm("sqrtsd %1, %0" : "=x" (res) : "xm" (x));

    return res;
}

error: unknown constraint 'x'
MXEBot pushed a commit that referenced this issue Mar 7, 2023
@susematz
Fix code suppression during nocode_wanted
c771cb5 
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.
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@absop