Hello,
I have a code (from example in docs):
%struct.ST = type { i32, double, %struct.RT }
%struct.RT = type { i8, [10 x [20 x i32]], i8 }
; Function Attrs: norecurse nounwind readnone uwtable
define i32* @foo(%struct.ST* readnone %s) #0 {
%1 = getelementptr inbounds %struct.ST, %struct.ST* %s, i64 1, i32 2, i32
1, i64 5, i64 13
ret i32* %1
}
I want to identify, that %s is pointer to struct, determine what this
struct is and determine the size of every component? With every component
is more or less ok, but the operand %s is not a struct but a pointer. Is
there a convenient way to track this structure usage in getelementptr?
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
<http://lists.llvm.org/pipermail/llvm-dev/attachments/20170831/41ad45a4/attachment.html>
On 8/31/2017 8:11 AM, Anastasiya Ruzhanskaya via llvm-dev wrote:> > I want to identify, that %s is pointer to struct, determine what this > struct is and determine the size of every component? With every > component is more or less ok, but the operand %s is not a struct but a > pointer. Is there a convenient way to track this structure usage in > getelementptr?If you have a Type* object that you know it a pointer, you can cast it to PointerType*, and then obtain the pointee type via getElementType member function. If you have a Type* object that is a structure, you can cast it to StructType*, which then has iterators that allow you to inspect every member type. Look in include/llvm/IR/DerivedTypes.h for more information. -Krzysztof -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
On Thu, Aug 31, 2017 at 7:55 AM Krzysztof Parzyszek via llvm-dev < llvm-dev at lists.llvm.org> wrote:> On 8/31/2017 8:11 AM, Anastasiya Ruzhanskaya via llvm-dev wrote: > > > > I want to identify, that %s is pointer to struct, determine what this > > struct is and determine the size of every component? With every > > component is more or less ok, but the operand %s is not a struct but a > > pointer. Is there a convenient way to track this structure usage in > > getelementptr? > > If you have a Type* object that you know it a pointer, you can cast it > to PointerType*, and then obtain the pointee type via getElementType > member function. >Note: Please don't rely on this, eventually pointer element types will go away. GEP does have a value type you can access directly. (GetElementPointer::getValueType, if I recall correctly)> > If you have a Type* object that is a structure, you can cast it to > StructType*, which then has iterators that allow you to inspect every > member type. > > Look in include/llvm/IR/DerivedTypes.h for more information. > > -Krzysztof > > > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > hosted by The Linux Foundation > _______________________________________________ > LLVM Developers mailing list > llvm-dev at lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev >-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20170831/f20dfdcc/attachment.html>