"protected scope" is very unhelpful here and actively confuses users. Instead,
simply state the nature of the problem in the diagnostic: we cannot jump from
here to there. The notes explain nicely why not.
llvm-svn: 217293
in the scope checker. With that done, turn an indirect goto into a
protected scope into a hard error; otherwise IR generation has to start
worrying about declarations not dominating their scopes, as exemplified
in PR8473.
If this really affects anyone, I can probably adjust this to only hard-error
on possible indirect gotos into VLA scopes rather than arbitrary scopes.
But we'll see how people cope with the aggressive change on the marginal
feature.
llvm-svn: 117539
about the permitted scopes. Specifically:
1) Permit labels and gotos to appear after a prologue of variable initializations.
2) Permit indirect gotos to jump out of scopes that don't require cleanup.
3) Diagnose possible attempts to indirect-jump out of scopes that do require
cleanup.
This requires a substantial reinvention of the algorithm for checking indirect
goto. The current algorithm is Omega(M*N), with M = the number of unique
scopes being jumped from and N = the number of unique scopes being jumped to,
with an additional factor that is probably (worst-case) linear in the depth
of scopes. Thus the entire thing is likely cubic given some truly bizarre
ill-formed code; on well-formed code the additional factor collapses to
an amortized constant (when amortized over the entire function) and so
the algorithm is quadratic. Even this requires every label to appear in
its own scope, which would be very unusual for indirect-goto code (and
extremely unlikely for well-formed code); it is far more likely that
all labels will be in the same scope and so the algorithm becomes linear.
For such a marginal feature, I am fairly happy with this result.
(this is using JumpDiagnostic's definition of scope, where successive
variables in a block appear in their own scope)
llvm-svn: 103536
- This is designed to make it obvious that %clang_cc1 is a "test variable"
which is substituted. It is '%clang_cc1' instead of '%clang -cc1' because it
can be useful to redefine what gets run as 'clang -cc1' (for example, to set
a default target).
llvm-svn: 91446
statements don't end up in the LabelMap so we don't have a quick way
to filter them. We could add state to Sema (a "has vla" and "has
jump" bit) to try to filter this out, but that would be sort of gross
and I'm not convinced it is the best way. Thoughts welcome.
llvm-svn: 69476
specific bad case instead of on the switch. Putting it on the
switch means you don't know what case is the problem. For
example:
scope-check.c:54:3: error: illegal switch case into protected scope
case 2:
^
scope-check.c:53:9: note: jump bypasses initialization of variable length array
int a[x];
^
llvm-svn: 69462
produce better diagnostics, and be more correct in ObjC cases (fixing
rdar://6803963).
An example is that we now diagnose:
int test1(int x) {
goto L;
int a[x];
int b[x];
L:
return sizeof a;
}
with:
scope-check.c:15:3: error: illegal goto into protected scope
goto L;
^
scope-check.c:17:7: note: scope created by variable length array
int b[x];
^
scope-check.c:16:7: note: scope created by variable length array
int a[x];
^
instead of just saying "invalid jump". An ObjC example is:
void test1() {
goto L;
@try {
L: ;
} @finally {
}
}
t.m:6:3: error: illegal goto into protected scope
goto L;
^
t.m:7:3: note: scope created by @try block
@try {
^
There are a whole ton of fixme's for stuff to do, but I believe that this
is a monotonic improvement over what we had.
llvm-svn: 69437
As far as I know, this catches all cases of jumping into the scope of a
variable with a variably modified type (excluding statement
expressions) in C. This is missing some stuff we probably want to check
(other kinds of variably modified declarations, statement expressions,
indirect gotos/addresses of labels in a scope, ObjC @try/@finally, cleanup
attribute), the diagnostics aren't very good, and it's not particularly
efficient, but it's a decent start.
This patch is a slightly modified version of the patch I attached to
PR3259, and it fixes that bug. I was sort of planning on improving
it, but I think it's okay as-is, especially since it looks like CodeGen
doesn't have any use for this sort of data structure. The only
significant change I can think of from the version I attached to PR3259
is that this version skips running the checking code when a function
doesn't contain any labels.
This patch doesn't cover case statements, which also need similar
checking; I'm not sure how we should deal with that. Extending the goto
checking to also check case statements wouldn't be too hard; it's just a
matter of keeping track of the scope of the closest switch and checking that
the scope of every case is the same as the scope of the switch. That said,
it would likely be a performance hit to run this check on every
function (it's an extra pass over the entire function), so we probably want
some other solution.
llvm-svn: 65678
Richard Smith