[FunctionAttrs][ArgumentPromotion][GlobalOpt] Disable some optimisations passes for naked functions

- Fix for bug 36078.
- Prevent the functionattrs, function-attrs, globalopt and argpromotion passes
  from changing naked functions.
- These passes can perform some alterations to the functions that should not be
  applied. An example is removing parameters that are seemingly not used because
  they are only referenced in the inline assembly. Another example is marking
  the function as fastcc.

llvm-svn: 325788

1 files changed, 25 insertions, 0 deletions

diff --git a/llvm/test/Transforms/FunctionAttrs/naked_functions.ll b/llvm/test/Transforms/FunctionAttrs/naked_functions.ll
new file mode 100644
index 00000000000..d34dc0c20d9
--- /dev/null
+++ b/llvm/test/Transforms/FunctionAttrs/naked_functions.ll
@@ -0,0 +1,25 @@
+; RUN: opt -S -functionattrs %s | FileCheck %s
+; RUN: opt -S -passes='function-attrs' %s | FileCheck %s
+
+; Don't change the attributes of parameters of naked functions, in particular
+; don't mark them as readnone
+
+@g = common global i32 0, align 4
+
+define i32 @bar() {
+entry:
+  %call = call i32 @foo(i32* @g)
+; CHECK: %call = call i32 @foo(i32* @g)
+  ret i32 %call
+}
+
+define internal i32 @foo(i32*) #0 {
+entry:
+  %retval = alloca i32, align 4
+  call void asm sideeffect "ldr r0, [r0] \0Abx lr        \0A", ""()
+  unreachable
+}
+
+; CHECK: define internal i32 @foo(i32*)
+
+attributes #0 = { naked }