LoopIdiomRecognize: strip bad TODO (NFC) (#92890)

There are several reasons why handling powi in LoopIdiomRecognize is a
bad idea:

- powi corresponds to a GCC builtin that is only defined for C int
(which is i32 for most targets).
- powi isn't always lowered by targets correctly for non-i32 parameters.
Several targets fail to compile llvm.powi.f32.i16, for example.
- Unlike memcpy and memset, which tend to be important enough internal
intrinsics that you have to handle them correctly even in freestanding
modes, powi isn't.

Strip this bad TODO to avoid misleading contributors.

Author: artagnon

llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp

@@ -22,8 +22,6 @@
 //
 // Future loop memory idioms to recognize:
 //   memcmp, strlen, etc.
-// Future floating point idioms to recognize in -ffast-math mode:
-//   fpowi
 //
 // This could recognize common matrix multiplies and dot product idioms and
 // replace them with calls to BLAS (if linked in??).
@@ -1107,7 +1105,7 @@ bool LoopIdiomRecognize::processLoopStridedStore(
     GV->setAlignment(Align(16));
     Value *PatternPtr = GV;
     NewCall = Builder.CreateCall(MSP, {BasePtr, PatternPtr, NumBytes});
-    
+
     // Set the TBAA info if present.
     if (AATags.TBAA)
       NewCall->setMetadata(LLVMContext::MD_tbaa, AATags.TBAA);
@@ -1117,7 +1115,7 @@ bool LoopIdiomRecognize::processLoopStridedStore(
 
     if (AATags.NoAlias)
       NewCall->setMetadata(LLVMContext::MD_noalias, AATags.NoAlias);
-  } 
+  }
 
   NewCall->setDebugLoc(TheStore->getDebugLoc());