[IR] Mark assume/annotation as InaccessibleMemOnly

These intrinsics don't need to be marked as arbitrary writing,
it's sufficient to write inaccessible memory (aka "side effect")
to preserve control dependencies. This means less special-casing
in BasicAA. This is intended as an alternative to D98925.

Differential Revision: https://reviews.llvm.org/D99022

1 files changed, 6 insertions, 19 deletions

diff --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index a8c5b9c..86362f7 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -939,15 +939,9 @@ ModRefInfo BasicAAResult::getModRefInfo(const CallBase *Call,
     return rv;
   }
 
-  // While the assume intrinsic is marked as arbitrarily writing so that
-  // proper control dependencies will be maintained, it never aliases any
-  // particular memory location.
-  if (isIntrinsicCall(Call, Intrinsic::assume))
-    return ModRefInfo::NoModRef;
-
-  // Like assumes, guard intrinsics are also marked as arbitrarily writing so
-  // that proper control dependencies are maintained but they never mods any
-  // particular memory location.
+  // Guard intrinsics are marked as arbitrarily writing so that proper control
+  // dependencies are maintained but they never mods any particular memory
+  // location.
   //
   // *Unlike* assumes, guard intrinsics are modeled as reading memory since the
   // heap state at the point the guard is issued needs to be consistent in case
@@ -991,16 +985,9 @@ ModRefInfo BasicAAResult::getModRefInfo(const CallBase *Call,
 ModRefInfo BasicAAResult::getModRefInfo(const CallBase *Call1,
                                         const CallBase *Call2,
                                         AAQueryInfo &AAQI) {
-  // While the assume intrinsic is marked as arbitrarily writing so that
-  // proper control dependencies will be maintained, it never aliases any
-  // particular memory location.
-  if (isIntrinsicCall(Call1, Intrinsic::assume) ||
-      isIntrinsicCall(Call2, Intrinsic::assume))
-    return ModRefInfo::NoModRef;
-
-  // Like assumes, guard intrinsics are also marked as arbitrarily writing so
-  // that proper control dependencies are maintained but they never mod any
-  // particular memory location.
+  // Guard intrinsics are marked as arbitrarily writing so that proper control
+  // dependencies are maintained but they never mods any particular memory
+  // location.
   //
   // *Unlike* assumes, guard intrinsics are modeled as reading memory since the
   // heap state at the point the guard is issued needs to be consistent in case