[PATCH] Fix bug in Sema::ActOnGCCAsmStmt (PR21270)

[Reid Kleckner]

lgtm

+
+// No warnings expected.

Consider adding "// CHECK-NOT: warning:" to verify this.

On Tue, Feb 3, 2015 at 11:53 AM, Akira Hatanaka <ahatanak at gmail.com> wrote:

> ping
>
> On Mon, Nov 3, 2014 at 1:07 PM, Akira Hatanaka <ahatanak at gmail.com> wrote:
>
>> ping
>>
>> On Wed, Oct 15, 2014 at 9:27 AM, Akira Hatanaka <ahatanak at gmail.com>
>> wrote:
>>
>>> There were mistakes in my previous email. The correct mapping should be
>>> like this:
>>>
>>> %0 => "+r" (one) => ConstraintIdx = 0
>>> %1 => "+r" (two) => ConstraintIdx = 1
>>> %2 => "r" (three) => ConstraintIdx = 2
>>> %3 => "+r" (one) => ConstraintIdx = 0
>>> %4 => "+r" (two) => ConstraintIdx = 1
>>>
>>> On Wed, Oct 15, 2014 at 8:36 AM, Akira Hatanaka <ahatanak at gmail.com>
>>> wrote:
>>>
>>>> The attached patch fixes a bug in Sema::ActOnGCCAsmStmt where it wasn't
>>>> computing the corresponding ConstraintIdx from an operand number correctly
>>>> when there were constraints with the '+' modifier.
>>>>
>>>> For example, when the following inline-asm statement is compiled,
>>>>
>>>> void g2(int one, int two, int three) {
>>>>   asm volatile ("%0 %1 %2 %3 %4" : "+r" (one), "+r"(two) : "r"(three));
>>>> }
>>>>
>>>> the existing code maps the operand number in the assembly template to
>>>> ConstraintIdx in the following way:
>>>>
>>>> %0 => "+r" (one) => ConstraintIdx = 0
>>>> %1 => "+r" (one) => ConstraintIdx = 0
>>>> %2 => "+r" (two) => ConstraintIdx = 1
>>>> %3 => "+r" (two) => ConstraintIdx = 1
>>>> %4 => "+r" (three) => ConstraintIdx = 2
>>>>
>>>> The correct mapping should be like this:
>>>>
>>>> %0 => "+r" (one) => ConstraintIdx = 0
>>>> %1 => "+r" (two) => ConstraintIdx = 1
>>>> %3 => "+r" (three) => ConstraintIdx = 2
>>>> %4 => "+r" (one) => ConstraintIdx = 0
>>>> %5 => "+r" (two) => ConstraintIdx = 1
>>>>
>>>> I couldn't find the rule documented anywhere in the link below, but
>>>> judging from the code I see in CodeGenFunction::EmitAsmStmt and the IR
>>>> clang generates, I believe this is the correct way to find the
>>>> corresponding constraint.
>>>>
>>>> https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html
>>>>
>>>> This is the IR generated:
>>>>
>>>> %1 = tail call { i32, i32 } asm sideeffect "$0 $1 $2 $3 $4",
>>>> "=r,=r,r,0,1"(i32 %three, i32 %one, i32 %two)
>>>>
>>>
>>>
>>
>
> _______________________________________________
> cfe-commits mailing list
> cfe-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/cfe-commits/attachments/20150203/0fa435c2/attachment.html>