[PartiallyInlineLibCalls] Remove WriteOnly attribute before adding ReadNone

[homerdin]

Summary

After https://reviews.llvm.org/D46313, the sqrt function will be marked with the WriteOnly attribute. This update will remove the WriteOnly attribute before adding the ReadNone attribute as having both WriteOnly and ReadNone is an assertion failure.

lib/Transforms/Scalar/PartiallyInlineLibCalls.cpp

static bool optimizeSQRT(CallInst *Call, Function *CalledFunc,
   Builder.SetInsertPoint(LibCallBB);
   Instruction *LibCall = Call->clone();
   Builder.Insert(LibCall);
   Builder.CreateBr(JoinBB);
 
   // Add attribute "readnone" so that backend can use a native sqrt instruction
   // for this call. Insert a FP compare instruction and a conditional branch
   // at the end of CurrBB.
+  Call->removeAttribute(AttributeList::FunctionIndex, Attribute::WriteOnly);
   Call->addAttribute(AttributeList::FunctionIndex, Attribute::ReadNone);
   CurrBB.getTerminator()->eraseFromParent();
   Builder.SetInsertPoint(&CurrBB);
   Value *FCmp = TTI->isFCmpOrdCheaperThanFCmpZero(Ty)
                     ? Builder.CreateFCmpORD(Call, Call)
                     : Builder.CreateFCmpOGE(Call->getOperand(0),
                                             ConstantFP::get(Ty, 0.0));
   Builder.CreateCondBr(FCmp, JoinBB, LibCallBB);

test/Transforms/PartiallyInlineLibCalls/X86/good-prototype.ll

 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt -S -partially-inline-libcalls -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
 ; RUN: opt -S -passes=partially-inline-libcalls -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
 
 define float @f(float %val) {
 ; CHECK-LABEL: @f(
 ; CHECK-NEXT:  entry:
-; CHECK-NEXT:    [[RES:%.*]] = tail call float @sqrtf(float [[VAL:%.*]]) #0
+; CHECK-NEXT:    [[RES:%.*]] = tail call float @sqrtf(float [[VAL:%.*]]) [[RN:#[0-9]+]]
 ; CHECK-NEXT:    [[TMP0:%.*]] = fcmp oge float [[VAL]], 0.000000e+00
 ; CHECK-NEXT:    br i1 [[TMP0]], label [[ENTRY_SPLIT:%.*]], label [[CALL_SQRT:%.*]]
 ; CHECK:       call.sqrt:
 ; CHECK-NEXT:    [[TMP1:%.*]] = tail call float @sqrtf(float [[VAL]])
 ; CHECK-NEXT:    br label [[ENTRY_SPLIT]]
 ; CHECK:       entry.split:
 ; CHECK-NEXT:    [[TMP2:%.*]] = phi float [ [[RES]], [[ENTRY:%.*]] ], [ [[TMP1]], [[CALL_SQRT]] ]
 ; CHECK-NEXT:    ret float [[TMP2]]
 ;
 entry:
   %res = tail call float @sqrtf(float %val)
   ret float %res
 }
 
+define float @f2(float %val) {
+; CHECK-LABEL: @f2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[RES:%.*]] = tail call float @sqrtf(float [[VAL:%.*]]) [[RN]]
+; CHECK-NEXT:    [[TMP0:%.*]] = fcmp oge float [[VAL]], 0.000000e+00
+; CHECK-NEXT:    br i1 [[TMP0]], label [[ENTRY_SPLIT:%.*]], label [[CALL_SQRT:%.*]]
+; CHECK:       call.sqrt:
+; CHECK-NEXT:    [[TMP1:%.*]] = tail call float @sqrtf(float [[VAL]]) [[WO:#[0-9]+]]
+; CHECK-NEXT:    br label [[ENTRY_SPLIT]]
+; CHECK:       entry.split:
+; CHECK-NEXT:    [[TMP2:%.*]] = phi float [ [[RES]], [[ENTRY:%.*]] ], [ [[TMP1]], [[CALL_SQRT]] ]
+; CHECK-NEXT:    ret float [[TMP2]]
+;
+entry:
+  %res = tail call float @sqrtf(float %val) #0
+  ret float %res
+}
+
 declare float @sqrtf(float)
+
+; CHECK: attributes [[RN]] = { readnone }
+; CHECK: attributes [[WO]] = { writeonly }
+attributes #0 = { writeonly }