Add test to cover accurate-sample-profile.

[danielcdh]

Summary

This patch adds test to cover the logic guarded by "accurate-sample-profile" flag.

[davidxl]

What happens if caller is hot, and the callee (missing profile) is unconditionally called by the caller? Will it still be treated as cold?

[danielcdh]

In D37084#850855, @davidxl wrote:

What happens if caller is hot, and the callee (missing profile) is unconditionally called by the caller? Will it still be treated as cold?

Yes, it will be treated as cold. In practice, if the caller is hot and callsite is missing profile, it is most likely it is cold.

[davidxl]

lgtm

test/Transforms/Inline/inline-cold-callsite-samplepgo.ll

+; For SamplePGO, if -accurate-sample-profile is specified, cold callsite
+; heuristics should be honored if the caller has no profile.
+
+; RUN: opt < %s -inline -S -inline-cold-callsite-threshold=0 | FileCheck %s
+; RUN: opt < %s -inline -S -inline-cold-callsite-threshold=0 -accurate-sample-profile | FileCheck %s --check-prefix=ACCURATE
+
+define i32 @callee(i32 %x) {
+  %x1 = add i32 %x, 1
+  %x2 = add i32 %x1, 1
+  %x3 = add i32 %x2, 1
+  call void @extern()
+  call void @extern()
+  ret i32 %x3
+}
+
+define i32 @caller(i32 %y1) {
+; CHECK-NOT: call i32 @callee
+; ACCURATE: call i32 @callee
+  %y2 = call i32 @callee(i32 %y1)
+  ret i32 %y2
+}
+
+declare void @extern()
+
+!llvm.module.flags = !{!1}
+!1 = !{i32 1, !"ProfileSummary", !2}
+!2 = !{!3, !4, !5, !6, !7, !8, !9, !10}
+!3 = !{!"ProfileFormat", !"SampleProfile"}
+!4 = !{!"TotalCount", i64 10000}
+!5 = !{!"MaxCount", i64 1000}
+!6 = !{!"MaxInternalCount", i64 1}
+!7 = !{!"MaxFunctionCount", i64 1000}
+!8 = !{!"NumCounts", i64 3}
+!9 = !{!"NumFunctions", i64 3}
+!10 = !{!"DetailedSummary", !11}
+!11 = !{!12, !13, !14}
+!12 = !{i32 10000, i64 100, i32 1}
+!13 = !{i32 999000, i64 100, i32 1}
+!14 = !{i32 999999, i64 1, i32 2}