Allow the use of an alternate symbol for calculating a function's size.

The standard function epilog includes a .size directive, but ppc64 uses
an alternate local symbol to tag the actual start of each function.

Until recently, binutils accepted the .size directive as:
 .size	test1, .Ltmp0-test1
however, using this directive with recent binutils will result in the error:
 .size expression for XXX does not evaluate to a constant
so we must use the label which actually tags the start of the function.

llvm-svn: 151200
diff --git a/llvm/test/CodeGen/PowerPC/ppc64-linux-func-size.ll b/llvm/test/CodeGen/PowerPC/ppc64-linux-func-size.ll
new file mode 100644
index 0000000..faed197
--- /dev/null
+++ b/llvm/test/CodeGen/PowerPC/ppc64-linux-func-size.ll
@@ -0,0 +1,18 @@
+; RUN: llc < %s -mtriple=powerpc64-unknown-linux-gnu -mcpu=g5 | FileCheck %s
+
+; CHECK: test1:
+; CHECK-NEXT:	.quad .L.test1,.TOC.@tocbase
+; CHECK-NEXT:	.previous
+; CHECK-NEXT: .L.test1:
+
+define i32 @test1(i32 %a) nounwind {
+entry:
+  ret i32 %a
+}
+
+; Until recently, binutils accepted the .size directive as:
+;  .size	test1, .Ltmp0-test1
+; however, using this directive with recent binutils will result in the error:
+;  .size expression for XXX does not evaluate to a constant
+; so we must use the label which actually tags the start of the function.
+; CHECK: .size	test1, .Ltmp0-.L.test1