[llvm] [Inliner] Don't propagate access attr to byval params (PR #112256)

[via llvm-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: None (goldsteinn)

<details>
<summary>Changes</summary>

- **[Inliner] Add tests for bad propagationg of access attr for `byval` param; NFC**
- **[Inliner] Don't propagate access attr to `byval` params**


---
Full diff: https://github.com/llvm/llvm-project/pull/112256.diff


2 Files Affected:

- (modified) llvm/lib/Transforms/Utils/InlineFunction.cpp (+11-6) 
- (modified) llvm/test/Transforms/Inline/access-attributes-prop.ll (+20) 


``````````diff
diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 110fd6de5c6968..c8a2fd95e3a970 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -1398,7 +1398,7 @@ static void AddParamAndFnBasicAttributes(const CallBase &CB,
         if (!Arg)
           continue;
 
-        if (AL.hasParamAttr(I, Attribute::ByVal))
+        if (NewInnerCB->getParamAttr(I, Attribute::ByVal).isValid())
           // It's unsound to propagate memory attributes to byval arguments.
           // Even if CalledFunction doesn't e.g. write to the argument,
           // the call to NewInnerCB may write to its by-value copy.
@@ -1407,24 +1407,29 @@ static void AddParamAndFnBasicAttributes(const CallBase &CB,
         unsigned ArgNo = Arg->getArgNo();
         // If so, propagate its access attributes.
         AL = AL.addParamAttributes(Context, I, ValidParamAttrs[ArgNo]);
+        auto NewCBHasParamAttr = [&](Attribute::AttrKind Kind) {
+          return AL.hasParamAttr(I, Kind) ||
+                 NewInnerCB->getParamAttr(I, Kind).isValid();
+        };
+
         // We can have conflicting attributes from the inner callsite and
         // to-be-inlined callsite. In that case, choose the most
         // restrictive.
 
         // readonly + writeonly means we can never deref so make readnone.
-        if (AL.hasParamAttr(I, Attribute::ReadOnly) &&
-            AL.hasParamAttr(I, Attribute::WriteOnly))
+        if (NewCBHasParamAttr(Attribute::ReadOnly) &&
+            NewCBHasParamAttr(Attribute::WriteOnly))
           AL = AL.addParamAttribute(Context, I, Attribute::ReadNone);
 
         // If have readnone, need to clear readonly/writeonly
-        if (AL.hasParamAttr(I, Attribute::ReadNone)) {
+        if (NewCBHasParamAttr(Attribute::ReadNone)) {
           AL = AL.removeParamAttribute(Context, I, Attribute::ReadOnly);
           AL = AL.removeParamAttribute(Context, I, Attribute::WriteOnly);
         }
 
         // Writable cannot exist in conjunction w/ readonly/readnone
-        if (AL.hasParamAttr(I, Attribute::ReadOnly) ||
-            AL.hasParamAttr(I, Attribute::ReadNone))
+        if (NewCBHasParamAttr(Attribute::ReadOnly) ||
+            NewCBHasParamAttr(Attribute::ReadNone))
           AL = AL.removeParamAttribute(Context, I, Attribute::Writable);
       }
       NewInnerCB->setAttributes(AL);
diff --git a/llvm/test/Transforms/Inline/access-attributes-prop.ll b/llvm/test/Transforms/Inline/access-attributes-prop.ll
index 2c55f5f3b1f6ca..5051c92345ec75 100644
--- a/llvm/test/Transforms/Inline/access-attributes-prop.ll
+++ b/llvm/test/Transforms/Inline/access-attributes-prop.ll
@@ -580,3 +580,23 @@ define ptr @callee_bad_param_prop(ptr readonly %x) {
   %r = tail call ptr @llvm.ptrmask(ptr %x, i64 -1)
   ret ptr %r
 }
+
+define dso_local void @foo_byval_readonly2(ptr readonly %p) {
+; CHECK-LABEL: define {{[^@]+}}@foo_byval_readonly2
+; CHECK-SAME: (ptr readonly [[P:%.*]]) {
+; CHECK-NEXT:    call void @bar4(ptr [[P]])
+; CHECK-NEXT:    ret void
+;
+  call void @bar4(ptr %p)
+  ret void
+}
+
+define void @prop_byval_readonly2(ptr %p) {
+; CHECK-LABEL: define {{[^@]+}}@prop_byval_readonly2
+; CHECK-SAME: (ptr [[P:%.*]]) {
+; CHECK-NEXT:    call void @bar4(ptr [[P]])
+; CHECK-NEXT:    ret void
+;
+  call void @foo_byval_readonly2(ptr %p)
+  ret void
+}

``````````

</details>


https://github.com/llvm/llvm-project/pull/112256