jyu2 marked an inline comment as done.
jyu2 added inline comments.
================
Comment at: lib/Sema/SemaStmtAsm.cpp:470
+ if (NS->isGCCAsmGoto() &&
+ Exprs[ConstraintIdx]->getStmtClass() == Stmt::AddrLabelExprClass)
+ break;
----------------
efriedma wrote:
> jyu2 wrote:
> > jyu2 wrote:
> > > efriedma wrote:
> > > > jyu2 wrote:
> > > > > efriedma wrote:
> > > > > > jyu2 wrote:
> > > > > > > efriedma wrote:
> > > > > > > > This looks suspicious; an AddrLabelExpr could be an input or
> > > > > > > > output, e.g. `"r"(&&foo)`.
> > > > > > > Syntax for asm goto:
> > > > > > > Syntax:
> > > > > > > asm [volatile] goto ( AssemblerTemplate
> > > > > > > :
> > > > > > > : InputOperands
> > > > > > > : Clobbers
> > > > > > > : GotoLabels)
> > > > > > >
> > > > > > > Only input is allowed. Output is not allowed
> > > > > > >
> > > > > > That doesn't really address my point here... ignore the "or output"
> > > > > > part of the comment.
> > > > > Sorry did not realize that. Thank you so much for catching that.
> > > > > Need to add other condition "ConstraintIdx > NS->getNumInputs() - 1",
> > > > > change to :
> > > > >
> > > > > if (NS->isGCCAsmGoto() && ConstraintIdx > NS->getNumInputs() - 1 &&
> > > > > Exprs[ConstraintIdx]->getStmtClass() ==
> > > > > Stmt::AddrLabelExprClass)
> > > > > break;
> > > > >
> > > > > Is this ok with you? Thanks
> > > > That's the right idea. But I still see a few issues at that point:
> > > >
> > > > 1. The AddrLabelExprClass check is redundant.
> > > > 2. "NS->getNumInputs() - 1" can overflow; probably should use
> > > > "ConstraintIdx >= NS->getNumInputs()".
> > > > 3. "break" exits the loop completely (so it skips validating all
> > > > constraints written after the label).
> > > > 4. The code needs to verify that the user correctly specified the "l"
> > > > constraint modifier.
> > > Sorry not done yet.
> > For you comment 4:
> >
> > The code needs to verify that the user correctly specified the "l"
> > constraint modifier. We already emit error like following?
> >
> > Do you mean, we need more checking here? Thanks.
> >
> > n.c:4:35: error: unknown symbolic operand name in inline assembly string
> > asm goto ("frob %%r5, %1; jc %l[error]; mov (%2), %%r5"
> > ~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~
> > n.c:8:15: error: use of undeclared label 'error1'
> > : error1);
> >
> > Test is:
> > int frob(int x)
> > {
> > int y;
> > asm goto ("frob %%r5, %1; jc %l[error]; mov (%2), %%r5"
> > : /* No outputs. */
> > : "r"(x), "r"(&y)
> > : "memory"
> > : error1);
> > return y;
> > error:
> > return -1;
> > }
> >
> >
> I mean, there needs to be a diagnostic for the following:
>
> ```
> asm goto ("jne %h0"::::x);
> ```
>
> On a related note, there should also be a diagnostic for the following
> somewhere:
>
> ```
> asm ("jne %l0"::"r"(0));
> ```
Hi Eli,
Thanks for your review.
For case:
asm goto ("jne %h0"::::x);
Without define label x, both clang and my current implementation give error of
"use of undeclared label"
if x is defined: gcc give error
asm_goto>!gcc
gcc n.c
n.c: Assembler messages:
n.c:4: Error: operand type mismatch for `jne'
My current implementation don't emit error. I think this is need to be done in
LLVM. Am I right here?
For the case:
asm ("jne %l0"::"r"(0));
gcc don't allow any modifier 'l' with asm stmt but it allows with asm goto.
Is that something you are look for? Thanks.
So I add code in AST/Stmt.cpp to emit error.
.....
return diag::err_asm_invalid_escape;
} else if (!this->isGCCAsmGoto() && EscapedChar == 'l' &&
isDigit(*CurPtr)) {
DiagOffs = CurPtr-StrStart;
return diag::err_asm_invalid_operand_number;
}
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https://reviews.llvm.org/D56571/new/
https://reviews.llvm.org/D56571
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