[llvm] 849146b - [Attributor] Associate the callback callee with a call site argument (if any)

[Johannes Doerfert via llvm-commits]

Author: Johannes Doerfert
Date: 2020-09-09T00:52:17-05:00
New Revision: 849146ba93fe14989ea0b727b055854b23e5c5e5

URL: https://github.com/llvm/llvm-project/commit/849146ba93fe14989ea0b727b055854b23e5c5e5
DIFF: https://github.com/llvm/llvm-project/commit/849146ba93fe14989ea0b727b055854b23e5c5e5.diff

LOG: [Attributor] Associate the callback callee with a call site argument (if any)

If we have a callback, call site arguments were already associated with
the callback callee. Now we also associate the function with the
callback callee, thus we know ensure that the following holds true (if
all return nonnull):
   `getAssociatedArgument()->getParent() == getAssociatedFunction()`

To test this an early exit from
  `AAMemoryBehaviorCallSiteArgument::initialize``
is included as well. Without the change to getAssociatedFunction() this
kind of early exit for declarations would cause callback call site
arguments to miss out.

Added: 
    

Modified: 
    llvm/include/llvm/Transforms/IPO/Attributor.h
    llvm/lib/Transforms/IPO/AttributorAttributes.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/include/llvm/Transforms/IPO/Attributor.h b/llvm/include/llvm/Transforms/IPO/Attributor.h
index 9f021f7dc63e..5c0a90339150 100644
--- a/llvm/include/llvm/Transforms/IPO/Attributor.h
+++ b/llvm/include/llvm/Transforms/IPO/Attributor.h
@@ -339,8 +339,14 @@ struct IRPosition {
 
   /// Return the associated function, if any.
   Function *getAssociatedFunction() const {
-    if (auto *CB = dyn_cast<CallBase>(&getAnchorValue()))
+    if (auto *CB = dyn_cast<CallBase>(&getAnchorValue())) {
+      // We reuse the logic that associates callback calles to arguments of a
+      // call site here to identify the callback callee as the associated
+      // function.
+      if (Argument *Arg = getAssociatedArgument())
+        return Arg->getParent();
       return CB->getCalledFunction();
+    }
     return getAnchorScope();
   }
 

diff  --git a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
index b7ec899233e4..97d88895bbfc 100644
--- a/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
+++ b/llvm/lib/Transforms/IPO/AttributorAttributes.cpp
@@ -5936,14 +5936,21 @@ struct AAMemoryBehaviorCallSiteArgument final : AAMemoryBehaviorArgument {
 
   /// See AbstractAttribute::initialize(...).
   void initialize(Attributor &A) override {
-    if (Argument *Arg = getAssociatedArgument()) {
-      if (Arg->hasByValAttr()) {
-        addKnownBits(NO_WRITES);
-        removeKnownBits(NO_READS);
-        removeAssumedBits(NO_READS);
-      }
+    // If we don't have an associated attribute this is either a variadic call
+    // or an indirect call, either way, nothing to do here.
+    Argument *Arg = getAssociatedArgument();
+    if (!Arg) {
+      indicatePessimisticFixpoint();
+      return;
+    }
+    if (Arg->hasByValAttr()) {
+      addKnownBits(NO_WRITES);
+      removeKnownBits(NO_READS);
+      removeAssumedBits(NO_READS);
     }
     AAMemoryBehaviorArgument::initialize(A);
+    if (getAssociatedFunction()->isDeclaration())
+      indicatePessimisticFixpoint();
   }
 
   /// See AbstractAttribute::updateImpl(...).