[llvm] [TLI] replace-with-veclib works with FRem Instruction. (PR #76166)

[Maciej Gabka via llvm-commits]

================
@@ -69,52 +69,57 @@ Function *getTLIFunction(Module *M, FunctionType *VectorFTy,
   return TLIFunc;
 }
 
-/// Replace the call to the vector intrinsic ( \p CalltoReplace ) with a call to
-/// the corresponding function from the vector library ( \p TLIVecFunc ).
-static void replaceWithTLIFunction(CallInst &CalltoReplace, VFInfo &Info,
+/// Replace the Instruction \p I, that may be a vector intrinsic CallInst or
+/// the frem instruction,  with a call to the corresponding function from the
+/// vector library ( \p TLIVecFunc ).
+static void replaceWithTLIFunction(Instruction &I, VFInfo &Info,
                                    Function *TLIVecFunc) {
-  IRBuilder<> IRBuilder(&CalltoReplace);
-  SmallVector<Value *> Args(CalltoReplace.args());
+  IRBuilder<> IRBuilder(&I);
+  auto *CI = dyn_cast<CallInst>(&I);
+  SmallVector<Value *> Args(CI ? CI->args() : I.operands());
   if (auto OptMaskpos = Info.getParamIndexForOptionalMask()) {
-    auto *MaskTy = VectorType::get(Type::getInt1Ty(CalltoReplace.getContext()),
-                                   Info.Shape.VF);
+    auto *MaskTy =
+        VectorType::get(Type::getInt1Ty(I.getContext()), Info.Shape.VF);
     Args.insert(Args.begin() + OptMaskpos.value(),
                 Constant::getAllOnesValue(MaskTy));
   }
 
-  // Preserve the operand bundles.
+  // Preserve the operand bundles for CallInsts.
   SmallVector<OperandBundleDef, 1> OpBundles;
-  CalltoReplace.getOperandBundlesAsDefs(OpBundles);
+  if (CI)
+    CI->getOperandBundlesAsDefs(OpBundles);
+
   CallInst *Replacement = IRBuilder.CreateCall(TLIVecFunc, Args, OpBundles);
-  CalltoReplace.replaceAllUsesWith(Replacement);
+  I.replaceAllUsesWith(Replacement);
   // Preserve fast math flags for FP math.
   if (isa<FPMathOperator>(Replacement))
-    Replacement->copyFastMathFlags(&CalltoReplace);
+    Replacement->copyFastMathFlags(&I);
 }
 
-/// Returns true when successfully replaced \p CallToReplace with a suitable
-/// function taking vector arguments, based on available mappings in the \p TLI.
-/// Currently only works when \p CallToReplace is a call to vectorized
-/// intrinsic.
+/// Returns true when successfully replaced \p I with a suitable function taking
+/// vector arguments, based on available mappings in the \p TLI. Currently only
+/// works when \p I is a call to vectorized intrinsic or the FRem Instruction.
 static bool replaceWithCallToVeclib(const TargetLibraryInfo &TLI,
-                                    CallInst &CallToReplace) {
-  if (!CallToReplace.getCalledFunction())
-    return false;
-
-  auto IntrinsicID = CallToReplace.getCalledFunction()->getIntrinsicID();
-  // Replacement is only performed for intrinsic functions.
-  if (IntrinsicID == Intrinsic::not_intrinsic)
-    return false;
-
+                                    Instruction &I) {
+  CallInst *CI = dyn_cast<CallInst>(&I);
+  Intrinsic::ID IID = Intrinsic::not_intrinsic;
+  if (CI)
+    IID = CI->getCalledFunction()->getIntrinsicID();
   // Compute arguments types of the corresponding scalar call. Additionally
   // checks if in the vector call, all vector operands have the same EC.
   ElementCount VF = ElementCount::getFixed(0);
-  SmallVector<Type *> ScalarArgTypes;
-  for (auto Arg : enumerate(CallToReplace.args())) {
+  SmallVector<Type *, 8> ScalarArgTypes;
+  for (auto Arg : enumerate(CI ? CI->args() : I.operands())) {
----------------
mgabka wrote:

this whole loop is executed to compute ScalarArgs which are used only for Callinst, there is no point to make it work for Instruction as for instruction you are calling below :

  if (!TLI.getLibFunc(I.getOpcode(), I.getType()->getScalarType(), Func)), it feels to me like you can check if the frem has vector operands either in  replaceWithCallToVeclib or in isSupportedInstruction and split the beginning of "replaceWithCallToVeclib" into 2 blocks, one working for CallInst and 2nd for frem instruction.

https://github.com/llvm/llvm-project/pull/76166