[coroutines] Get an IntegerType from the value instead of defaulting to 64 bit

[lanza]

Summary

This AliasPtr is being created always from an Int64 even for targets
where 32 bit is the proper type. e.g. “thumbv7-none-linux-android16”.
This causes the assert in the get func to fail as we're getting a 32
bit from the APInt.

Fix this by simply always just getting the type from the value instead.

[ChuanqiXu]

When post a revision, it would be better to contain more context of the diff page. Generally, this could be done by adding the argument -U9999 when you generates the diff.

[lanza]

update from repo

[lanza]

In D123272#3434918, @ChuanqiXu wrote:

When post a revision, it would be better to contain more context of the diff page. Generally, this could be done by adding the argument -U9999 when you generates the diff.

Sorry, don't typically use the raw diff submission, was just too lazy to fix my arcanist :P But good point!

[ChuanqiXu]

LGTM.

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

for (const auto &A : FrameData.Allocas) {
     }
     // For each alias to Alloca created before CoroBegin but used after
     // CoroBegin, we recreate them after CoroBegin by appplying the offset
     // to the pointer in the frame.
     for (const auto &Alias : A.Aliases) {
       auto *FramePtr = GetFramePointer(Alloca);
       auto *FramePtrRaw =
           Builder.CreateBitCast(FramePtr, Type::getInt8PtrTy(C));
-      auto *AliasPtr = Builder.CreateGEP(
-          Type::getInt8Ty(C), FramePtrRaw,
-          ConstantInt::get(Type::getInt64Ty(C), Alias.second.getValue()));
+      auto &Value = Alias.second.getValue();
+      auto ITy = IntegerType::get(C, Value.getBitWidth());
+      auto *AliasPtr = Builder.CreateGEP(Type::getInt8Ty(C), FramePtrRaw,
+                                         ConstantInt::get(ITy, Value));
       auto *AliasPtrTyped =
           Builder.CreateBitCast(AliasPtr, Alias.first->getType());
       Alias.first->replaceUsesWithIf(
           AliasPtrTyped, [&](Use &U) { return DT.dominates(CB, U); });
     }
   }
 }