[TTI] Provide a cost for memset_pattern which matches the libcall

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -2408,6 +2408,11 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
                                           CmpInst::ICMP_ULT, CostKind);
       return Cost;
     }
+    case Intrinsic::experimental_memset_pattern:
+      // This cost is set to match the cost of the memset_pattern16 libcall.
+      // It should likely be re-evaluated after migration to this intrinsic
+      // is complete.
+      return TTI::TCC_Basic * 4;
     case Intrinsic::abs:
       ISD = ISD::ABS;
       break;

llvm/test/Analysis/CostModel/X86/memset-pattern.ll

@@ -0,0 +1,40 @@
+; NOTE: Assertions have been autogenerated by utils/update_analyze_test_checks.py UTC_ARGS: --version 4
+; RUN: opt < %s -mtriple=x86_64-apple-darwin10.0.0 -passes="print<cost-model>" 2>&1 -disable-output | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+
+target triple = "x86_64-apple-darwin10.0.0"
+
+@.memset_pattern = private unnamed_addr constant [4 x i32] [i32 2, i32 2, i32 2, i32 2], align 16
+
+define void @via_libcall(ptr %p) nounwind ssp {
+; CHECK-LABEL: 'via_libcall'
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: call void @memset_pattern4(ptr %p, ptr @.memset_pattern, i64 200)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: call void @memset_pattern8(ptr %p, ptr @.memset_pattern, i64 200)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: call void @memset_pattern16(ptr %p, ptr @.memset_pattern, i64 200)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret void
+;
+  call void @memset_pattern4(ptr %p, ptr @.memset_pattern, i64 200)
+  call void @memset_pattern8(ptr %p, ptr @.memset_pattern, i64 200)
+  call void @memset_pattern16(ptr %p, ptr @.memset_pattern, i64 200)
+  ret void
+}
+
+declare void @memset_pattern4(ptr, ptr, i64)
+declare void @memset_pattern8(ptr, ptr, i64)
+declare void @memset_pattern16(ptr, ptr, i64)
+
+define void @via_intrinsic(ptr %p) {
+; CHECK-LABEL: 'via_intrinsic'
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: call void @llvm.experimental.memset.pattern.p0.i16.i64(ptr align 4 %p, i16 2, i64 100, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: call void @llvm.experimental.memset.pattern.p0.i32.i64(ptr align 4 %p, i32 2, i64 50, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: call void @llvm.experimental.memset.pattern.p0.i64.i64(ptr align 4 %p, i64 2, i64 25, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 4 for instruction: call void @llvm.experimental.memset.pattern.p0.i128.i64(ptr align 4 %p, i128 2, i64 12, i1 false)
+; CHECK-NEXT:  Cost Model: Found an estimated cost of 0 for instruction: ret void
+;
+  call void @llvm.experimental.memset.pattern(ptr align 4 %p, i16 2, i64 100, i1 false)
+  call void @llvm.experimental.memset.pattern(ptr align 4 %p, i32 2, i64 50, i1 false)
+  call void @llvm.experimental.memset.pattern(ptr align 4 %p, i64 2, i64 25, i1 false)
+  call void @llvm.experimental.memset.pattern(ptr align 4 %p, i128 2, i64 12, i1 false)
+  ret void
+}