commit cbab334e403b275d32d02763f0604e45edce79a1
author Hideto Ueno <uenoku.tokotoko@gmail.com> Thu Aug 29 05:52:00 2019 +0000
committer Hideto Ueno <uenoku.tokotoko@gmail.com> Thu Aug 29 05:52:00 2019 +0000
tree f32dba14489d83770442f531bc13e8190370a886
parent 1ec5c204b8fb813ac8501de6a689459ec91c3069

[Attributor] Deduce "noalias" attribute

Summary:
This patch adds very basic deduction for noalias.

Reviewers: jdoerfert, sstefan1

Reviewed By: jdoerfert

Tags: LLVM

Differential Revision: https://reviews.llvm.org/D66207

llvm-svn: 370295

llvm/lib/Transforms/IPO/Attributor.cpp

diff --git a/llvm/lib/Transforms/IPO/Attributor.cpp b/llvm/lib/Transforms/IPO/Attributor.cpp
index 2d386ae..c882f8c 100644
--- a/llvm/lib/Transforms/IPO/Attributor.cpp
+++ b/llvm/lib/Transforms/IPO/Attributor.cpp
@@ -1559,6 +1559,12 @@
 struct AANoAliasFloating final : AANoAliasImpl {
   AANoAliasFloating(const IRPosition &IRP) : AANoAliasImpl(IRP) {}
 
+  /// See AbstractAttribute::initialize(...).
+  void initialize(Attributor &A) override {
+    // TODO: It isn't sound to initialize as the same with `AANoAliasImpl`
+    // because `noalias` may not be valid in the current position.
+  }
+
   /// See AbstractAttribute::updateImpl(...).
   ChangeStatus updateImpl(Attributor &A) override {
     // TODO: Implement this.
@@ -1572,14 +1578,10 @@
 };
 
 /// NoAlias attribute for an argument.
-struct AANoAliasArgument final : AANoAliasImpl {
-  AANoAliasArgument(const IRPosition &IRP) : AANoAliasImpl(IRP) {}
-
-  /// See AbstractAttribute::updateImpl(...).
-  ChangeStatus updateImpl(Attributor &A) override {
-    // TODO: Implement this.
-    return indicatePessimisticFixpoint();
-  }
+struct AANoAliasArgument final
+    : AAArgumentFromCallSiteArguments<AANoAlias, AANoAliasImpl> {
+  AANoAliasArgument(const IRPosition &IRP)
+      : AAArgumentFromCallSiteArguments<AANoAlias, AANoAliasImpl>(IRP) {}
 
   /// See AbstractAttribute::trackStatistics()
   void trackStatistics() const override { STATS_DECLTRACK_ARG_ATTR(noalias) }
@@ -1588,6 +1590,12 @@
 struct AANoAliasCallSiteArgument final : AANoAliasImpl {
   AANoAliasCallSiteArgument(const IRPosition &IRP) : AANoAliasImpl(IRP) {}
 
+  /// See AbstractAttribute::initialize(...).
+  void initialize(Attributor &A) override {
+    // TODO: It isn't sound to initialize as the same with `AANoAliasImpl`
+    // because `noalias` may not be valid in the current position.
+  }
+
   /// See AbstractAttribute::updateImpl(...).
   ChangeStatus updateImpl(Attributor &A) override {
     // TODO: Implement this.
@@ -2814,6 +2822,9 @@
       // Every argument with pointer type might be marked nonnull.
       checkAndRegisterAA<AANonNullArgument>(ArgPos, *this, Whitelist);
 
+      // Every argument with pointer type might be marked noalias.
+      checkAndRegisterAA<AANoAliasArgument>(ArgPos, *this, Whitelist);
+
       // Every argument with pointer type might be marked dereferenceable.
       checkAndRegisterAA<AADereferenceableArgument>(ArgPos, *this, Whitelist);
 
@@ -2879,6 +2890,10 @@
         checkAndRegisterAA<AANonNullCallSiteArgument>(CSArgPos, *this,
                                                       Whitelist);
 
+        // Call site argument attribute "no-alias".
+        checkAndRegisterAA<AANoAliasCallSiteArgument>(CSArgPos, *this,
+                                                      Whitelist);
+
         // Call site argument attribute "dereferenceable".
         checkAndRegisterAA<AADereferenceableCallSiteArgument>(CSArgPos, *this,
                                                               Whitelist);