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new hlt block terminator

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It is handy to express when
the end of a block cannot be
reached. If a hlt terminator
is executed, it traps the
program.

We don't go the llvm way and
specify execution semantics as
undefined behavior.
This commit is contained in:
Quentin Carbonneaux 2022-11-24 11:08:33 +01:00
parent b5da3f3d64
commit 9126afa2da
9 changed files with 30 additions and 13 deletions
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3
amd64/emit.c
View file

@ -582,6 +582,9 @@ amd64_emitfn(Fn *fn, FILE *f)
emitins(*i, fn, f);
lbl = 1;
switch (b->jmp.type) {
case Jhlt:
fprintf(f, "\tud2\n");
break;
case Jret0:
if (fn->dynalloc)
fprintf(f,

4
amd64/isel.c
View file

@ -465,7 +465,9 @@ seljmp(Blk *b, Fn *fn)
Ins *fi;
Tmp *t;
if (b->jmp.type == Jret0 || b->jmp.type == Jjmp)
if (b->jmp.type == Jret0
|| b->jmp.type == Jjmp
|| b->jmp.type == Jhlt)
return;
assert(b->jmp.type == Jjnz);
r = b->jmp.arg;