GlobalOpt: Apply fastcc to internal x86_thiscallcc functions

We should apply fastcc whenever profitable.  We can expand this list,
but there are lots of conventions with performance implications that we
don't want to change.

Differential Revision: http://llvm-reviews.chandlerc.com/D2705

llvm-svn: 202293
diff --git a/llvm/test/Transforms/GlobalOpt/fastcc.ll b/llvm/test/Transforms/GlobalOpt/fastcc.ll
new file mode 100644
index 0000000..76122b2
--- /dev/null
+++ b/llvm/test/Transforms/GlobalOpt/fastcc.ll
@@ -0,0 +1,46 @@
+; RUN: opt < %s -globalopt -S | FileCheck %s
+
+define internal i32 @f(i32* %m) {
+; CHECK-LABEL: define internal fastcc i32 @f
+  %v = load i32* %m
+  ret i32 %v
+}
+
+define internal x86_thiscallcc i32 @g(i32* %m) {
+; CHECK-LABEL: define internal fastcc i32 @g
+  %v = load i32* %m
+  ret i32 %v
+}
+
+; Leave this one alone, because the user went out of their way to request this
+; convention.
+define internal coldcc i32 @h(i32* %m) {
+; CHECK-LABEL: define internal coldcc i32 @h
+  %v = load i32* %m
+  ret i32 %v
+}
+
+define internal i32 @j(i32* %m) {
+; CHECK-LABEL: define internal i32 @j
+  %v = load i32* %m
+  ret i32 %v
+}
+
+define void @call_things() {
+  %m = alloca i32
+  call i32 @f(i32* %m)
+  call x86_thiscallcc i32 @g(i32* %m)
+  call coldcc i32 @h(i32* %m)
+  call i32 @j(i32* %m)
+  ret void
+}
+
+@llvm.used = appending global [1 x i8*] [
+   i8* bitcast (i32(i32*)* @j to i8*)
+], section "llvm.metadata"
+
+; CHECK-LABEL: define void @call_things()
+; CHECK: call fastcc i32 @f
+; CHECK: call fastcc i32 @g
+; CHECK: call coldcc i32 @h
+; CHECK: call i32 @j