llvm-reduce: Add new pass to inline call sites

Added a primitive heuristic to avoid blowing up the code size
which could use more thought.

This helps cleanup some basic examples I've been looking at where
there is a worse result when just running a bug through the full
optimization pipeline vs. running just a single pass at the point
of failure.

Author: arsenm

llvm/test/tools/llvm-reduce/inline-call-sites-cost.ll

@@ -0,0 +1,95 @@
+; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=inline-call-sites -reduce-callsite-inline-threshold=3 --test FileCheck --test-arg --check-prefix=CHECK --test-arg %s --test-arg --input-file %s -o %t
+; RUN: FileCheck -check-prefixes=RESULT,CHECK %s < %t
+
+declare void @extern_b()
+declare void @extern_a()
+
+; RESULT: @gv_init = global ptr @no_inline_noncall_user
+@gv_init = global ptr @no_inline_noncall_user
+
+
+; CHECK-LABEL: define void @no_inline_noncall_user(
+define void @no_inline_noncall_user() {
+  call void @extern_a()
+  call void @extern_a()
+  call void @extern_a()
+  call void @extern_a()
+  ret void
+}
+
+; RESULT-LABEL: define void @noncall_user_call() {
+; RESULT-NEXT: call void @no_inline_noncall_user()
+; RESULT-NEXT: ret void
+define void @noncall_user_call() {
+  call void @no_inline_noncall_user()
+  ret void
+}
+
+; RESULT-LABEL: define void @big_callee_small_caller_callee() {
+define void @big_callee_small_caller_callee() {
+  call void @extern_a()
+  call void @extern_a()
+  call void @extern_a()
+  call void @extern_a()
+  ret void
+}
+
+; RESULT-LABEL: define void @big_callee_small_caller_caller() {
+; RESULT-NEXT: call void @extern_b()
+; RESULT-NEXT: call void @extern_a()
+; RESULT-NEXT: call void @extern_a()
+; RESULT-NEXT: call void @extern_a()
+; RESULT-NEXT: call void @extern_a()
+; RESULT-NEXT: ret void
+define void @big_callee_small_caller_caller() {
+  call void @extern_b()
+  call void @big_callee_small_caller_callee()
+  ret void
+}
+
+; RESULT-LABEL: define void @small_callee_big_caller_callee() {
+; RESULT-NEXT: call void @extern_a()
+; RESULT-NEXT: ret void
+define void @small_callee_big_caller_callee() {
+  call void @extern_a()
+  ret void
+}
+
+; RESULT-LABEL: define void @small_callee_big_caller_caller() {
+; RESULT-NEXT: call void @extern_b()
+; RESULT-NEXT: call void @extern_a()
+; RESULT-NEXT: call void @extern_b()
+; RESULT-NEXT: call void @extern_b()
+; RESULT-NEXT: ret void
+define void @small_callee_big_caller_caller() {
+  call void @extern_b()
+  call void @small_callee_big_caller_callee()
+  call void @extern_b()
+  call void @extern_b()
+  ret void
+}
+
+; RESULT-LABEL: define void @big_callee_big_caller_callee() {
+define void @big_callee_big_caller_callee() {
+  call void @extern_a()
+  call void @extern_a()
+  call void @extern_a()
+  call void @extern_a()
+  ret void
+}
+
+; RESULT-LABEL: define void @big_callee_big_caller_caller() {
+; RESULT-NEXT: call void @extern_b()
+; RESULT-NEXT: call void @big_callee_big_caller_callee()
+; RESULT-NEXT: call void @extern_b()
+; RESULT-NEXT: call void @extern_b()
+; RESULT-NEXT: call void @extern_b()
+; RESULT-NEXT: ret void
+define void @big_callee_big_caller_caller() {
+  call void @extern_b()
+  call void @big_callee_big_caller_callee()
+  call void @extern_b()
+  call void @extern_b()
+  call void @extern_b()
+  ret void
+}