Add constant support to object size handling and remove default

lowering. We'll either figure it out, or not and be lowered by
SelectionDAGBuild.

Add test.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94775 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/objsize.ll

@@ -0,0 +1,30 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+@a = common global [60 x i8] zeroinitializer, align 1 ; <[60 x i8]*>
+@.str = private constant [8 x i8] c"abcdefg\00"   ; <[8 x i8]*>
+
+define i32 @foo() nounwind {
+; CHECK: @foo
+; CHECK-NEXT: ret i32 60
+  %1 = call i32 @llvm.objectsize.i32(i8* getelementptr inbounds ([60 x i8]* @a, i32 0, i32 0), i1 false)
+  ret i32 %1
+}
+
+define i8* @bar() nounwind {
+; CHECK: @bar
+entry:
+  %retval = alloca i8*
+  %0 = call i32 @llvm.objectsize.i32(i8* getelementptr inbounds ([60 x i8]* @a, i32 0, i32 0), i1 false)
+  %cmp = icmp ne i32 %0, -1
+; CHECK: br i1 true
+  br i1 %cmp, label %cond.true, label %cond.false
+
+cond.true:
+  %1 = load i8** %retval;
+  ret i8* %1;
+
+cond.false:
+  %2 = load i8** %retval;
+  ret i8* %2;
+}
+
+declare i32 @llvm.objectsize.i32(i8*, i1) nounwind readonly