[PATCH] D136834: [IR] Take operand bundles into account for call argument readonly/writeonly

[Nikita Popov via Phabricator via llvm-commits]

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We currently only take operand bundle effects into account when querying the function-level memory attributes. However, I believe that we also need to do the same for parameter attributes. For example, a call with `deopt` bundle to a function with `readnone` parameter attribute cannot treat that parameter as `readnone`, because the `deopt` bundle may read it.


https://reviews.llvm.org/D136834

Files:
  llvm/lib/IR/Instructions.cpp
  llvm/test/Transforms/FunctionAttrs/readattrs.ll
  llvm/test/Transforms/FunctionAttrs/writeonly.ll


Index: llvm/test/Transforms/FunctionAttrs/writeonly.ll
===================================================================
--- llvm/test/Transforms/FunctionAttrs/writeonly.ll
+++ llvm/test/Transforms/FunctionAttrs/writeonly.ll
@@ -180,7 +180,7 @@
 
 define void @direct3c(ptr %p) {
 ; CHECK-LABEL: define {{[^@]+}}@direct3c
-; CHECK-SAME: (ptr nocapture writeonly [[P:%.*]]) {
+; CHECK-SAME: (ptr nocapture [[P:%.*]]) {
 ; CHECK-NEXT:    call void @direct3_callee(ptr [[P]]) [ "may-read"() ]
 ; CHECK-NEXT:    ret void
 ;
Index: llvm/test/Transforms/FunctionAttrs/readattrs.ll
===================================================================
--- llvm/test/Transforms/FunctionAttrs/readattrs.ll
+++ llvm/test/Transforms/FunctionAttrs/readattrs.ll
@@ -326,9 +326,10 @@
 declare void @readnone_param(ptr nocapture readnone %p)
 declare void @readonly_param(ptr nocapture readonly %p)
 
+; FIXME: While this can't be readnone, this could be readonly.
 define void @op_bundle_readnone_deopt(ptr %p) {
 ; CHECK-LABEL: define {{[^@]+}}@op_bundle_readnone_deopt
-; CHECK-SAME: (ptr nocapture readnone [[P:%.*]]) {
+; CHECK-SAME: (ptr nocapture [[P:%.*]]) {
 ; CHECK-NEXT:    call void @readnone_param(ptr [[P]]) [ "deopt"() ]
 ; CHECK-NEXT:    ret void
 ;
@@ -338,7 +339,7 @@
 
 define void @op_bundle_readnone_unknown(ptr %p) {
 ; CHECK-LABEL: define {{[^@]+}}@op_bundle_readnone_unknown
-; CHECK-SAME: (ptr nocapture readnone [[P:%.*]]) {
+; CHECK-SAME: (ptr nocapture [[P:%.*]]) {
 ; CHECK-NEXT:    call void @readnone_param(ptr [[P]]) [ "unknown"() ]
 ; CHECK-NEXT:    ret void
 ;
@@ -358,7 +359,7 @@
 
 define void @op_bundle_readonly_unknown(ptr %p) {
 ; CHECK-LABEL: define {{[^@]+}}@op_bundle_readonly_unknown
-; CHECK-SAME: (ptr nocapture readonly [[P:%.*]]) {
+; CHECK-SAME: (ptr nocapture [[P:%.*]]) {
 ; CHECK-NEXT:    call void @readonly_param(ptr [[P]]) [ "unknown"() ]
 ; CHECK-NEXT:    ret void
 ;
Index: llvm/lib/IR/Instructions.cpp
===================================================================
--- llvm/lib/IR/Instructions.cpp
+++ llvm/lib/IR/Instructions.cpp
@@ -344,9 +344,25 @@
 
   if (Attrs.hasParamAttr(ArgNo, Kind))
     return true;
-  if (const Function *F = getCalledFunction())
-    return F->getAttributes().hasParamAttr(ArgNo, Kind);
-  return false;
+
+  const Function *F = getCalledFunction();
+  if (!F)
+    return false;
+
+  if (!F->getAttributes().hasParamAttr(ArgNo, Kind))
+    return false;
+
+  // Take into account mod/ref by operand bundles.
+  switch (Kind) {
+  case Attribute::ReadNone:
+    return !hasReadingOperandBundles() && !hasClobberingOperandBundles();
+  case Attribute::ReadOnly:
+    return !hasClobberingOperandBundles();
+  case Attribute::WriteOnly:
+    return !hasReadingOperandBundles();
+  default:
+    return true;
+  }
 }
 
 bool CallBase::hasFnAttrOnCalledFunction(Attribute::AttrKind Kind) const {


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