From d690862bbcb9dd298b71f72da0c8595886597df2 Mon Sep 17 00:00:00 2001
From: Johannes Doerfert <doerfert@cs.uni-saarland.de>
Date: Tue, 11 Sep 2018 11:51:29 +0000
Subject: [PATCH] [FuncAttrs] Remove "access range attributes" for read-none
 functions

The presence of readnone and an access range attribute (argmemonly,
inaccessiblememonly, inaccessiblemem_or_argmemonly) is considered an
error by the verifier. This seems strict but also not wrong. This
patch makes sure function attribute detection will remove all access
range attributes for readnone functions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341927 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/IPO/FunctionAttrs.cpp          |  7 ++++
 .../FunctionAttrs/incompatible_fn_attrs.ll    | 32 +++++++++++++++++++
 2 files changed, 39 insertions(+)
 create mode 100644 test/Transforms/FunctionAttrs/incompatible_fn_attrs.ll

diff --git a/lib/Transforms/IPO/FunctionAttrs.cpp b/lib/Transforms/IPO/FunctionAttrs.cpp
index d40ee30f453..72c850fca99 100644
--- a/lib/Transforms/IPO/FunctionAttrs.cpp
+++ b/lib/Transforms/IPO/FunctionAttrs.cpp
@@ -281,6 +281,13 @@ static bool addReadAttrs(const SCCNodeSet &SCCNodes, AARGetterT &&AARGetter) {
     F->removeFnAttr(Attribute::ReadNone);
     F->removeFnAttr(Attribute::WriteOnly);
 
+    if (!WritesMemory && !ReadsMemory) {
+      // Clear out any "access range attributes" if readnone was deduced.
+      F->removeFnAttr(Attribute::ArgMemOnly);
+      F->removeFnAttr(Attribute::InaccessibleMemOnly);
+      F->removeFnAttr(Attribute::InaccessibleMemOrArgMemOnly);
+    }
+
     // Add in the new attribute.
     if (WritesMemory && !ReadsMemory)
       F->addFnAttr(Attribute::WriteOnly);
diff --git a/test/Transforms/FunctionAttrs/incompatible_fn_attrs.ll b/test/Transforms/FunctionAttrs/incompatible_fn_attrs.ll
new file mode 100644
index 00000000000..79af817ff03
--- /dev/null
+++ b/test/Transforms/FunctionAttrs/incompatible_fn_attrs.ll
@@ -0,0 +1,32 @@
+; RUN: opt -S -o - -functionattrs %s | FileCheck %s
+; RUN: opt -S -o - -passes=function-attrs %s | FileCheck %s
+
+; Verify we remove argmemonly/inaccessiblememonly/inaccessiblemem_or_argmemonly
+; function attributes when we derive readnone.
+
+; Function Attrs: argmemonly
+define i32* @given_argmem_infer_readnone(i32* %p) #0 {
+; CHECK: define i32* @given_argmem_infer_readnone(i32* readnone returned %p) #0 {
+entry:
+  ret i32* %p
+}
+
+; Function Attrs: inaccessiblememonly
+define i32* @given_inaccessible_infer_readnone(i32* %p) #1 {
+; CHECK: define i32* @given_inaccessible_infer_readnone(i32* readnone returned %p) #0 {
+entry:
+  ret i32* %p
+}
+
+; Function Attrs: inaccessiblemem_or_argmemonly
+define i32* @given_inaccessible_or_argmem_infer_readnone(i32* %p) #2 {
+; CHECK: define i32* @given_inaccessible_or_argmem_infer_readnone(i32* readnone returned %p) #0 {
+entry:
+  ret i32* %p
+}
+
+attributes #0 = { argmemonly }
+attributes #1 = { inaccessiblememonly }
+attributes #2 = { inaccessiblemem_or_argmemonly }
+; CHECK: attributes #0 = { norecurse nounwind readnone }
+; CHECK-NOT: attributes