[IPSCCP] Don't propagate return values of functions marked as noinline.

This tries to address what Hal defined (in the post-commit review of
r293727) a long-standing problem with noinline, where we end up
de facto inlining trivial functions e.g.

__attribute__((noinline)) int patatino(void) { return 5; }

because of return value propagation.

llvm-svn: 293799

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/test/Transforms/IPConstantProp/noinline-return.ll b/llvm/test/Transforms/IPConstantProp/noinline-return.ll
new file mode 100644
index 00000000000..10950327327
--- /dev/null
+++ b/llvm/test/Transforms/IPConstantProp/noinline-return.ll
@@ -0,0 +1,21 @@
+; RUN: opt %s -ipsccp -S | FileCheck %s
+
+define i32 @tinkywinky() #0 {
+entry:
+  ret i32 5
+}
+
+define i32 @patatino() {
+entry:
+  %call = call i32 @tinkywinky()
+
+; Check that we don't propagate the return value of
+; @tinkywinky.
+; CHECK: call i32 @dipsy(i32 %call)
+  %call1 = call i32 @dipsy(i32 %call)
+  ret i32 %call1
+}
+
+declare i32 @dipsy(i32)
+
+attributes #0 = { noinline }