Change behavior of calling bitcasted alias functions.

It will now only convert the arguments / return value and call
the underlying function if the types are able to be bitcasted.
This avoids using fp<->int conversions that would occur before.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187444 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/apint-call-cast-target.ll

@@ -3,16 +3,17 @@
 target datalayout = "e-p:32:32"
 target triple = "i686-pc-linux-gnu"
 
-; CHECK-NOT: bitcast
-; CHECK: call
-; CHECK-NOT: bitcast
 define i32 @main() {
+; CHECK-LABEL: @main(
+; CHECK: call i32 bitcast
 entry:
 	%tmp = call i32 bitcast (i7* (i999*)* @ctime to i32 (i99*)*)( i99* null )
 	ret i32 %tmp
 }
 
 define i7* @ctime(i999*) {
+; CHECK-LABEL: @ctime(
+; CHECK: call i7* bitcast
 entry:
 	%tmp = call i7* bitcast (i32 ()* @main to i7* ()*)( )
 	ret i7* %tmp