[PATCH] D101541: BasicAA: Recognize inttoptr as isEscapeSource

[Joseph Tremoulet via Phabricator via llvm-commits]

JosephTremoulet created this revision.
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Pointers escape when converted to integers, so a pointer produced by
converting an integer to a pointer must not be a local non-escaping
object.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D101541

Files:
  llvm/lib/Analysis/BasicAliasAnalysis.cpp
  llvm/test/Analysis/BasicAA/noalias-inttoptr.ll


Index: llvm/test/Analysis/BasicAA/noalias-inttoptr.ll
===================================================================
--- /dev/null
+++ llvm/test/Analysis/BasicAA/noalias-inttoptr.ll
@@ -0,0 +1,10 @@
+; RUN: opt < %s -basic-aa -aa-eval -print-all-alias-modref-info -disable-output 2>&1 | FileCheck %s
+target datalayout = "p:64:64"
+
+define void @test1(i8* noalias %P, i64 %Q_as_int) {
+  ; CHECK: NoAlias:	i8* %P, i8* %Q
+  %Q = inttoptr i64 %Q_as_int to i8*
+  store i8 0, i8* %P
+  store i8 1, i8* %Q
+  ret void
+}
Index: llvm/lib/Analysis/BasicAliasAnalysis.cpp
===================================================================
--- llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -129,6 +129,14 @@
   if (isa<LoadInst>(V))
     return true;
 
+  // The inttoptr case works because isNonEscapingLocalObject considers all
+  // means of converting or equating a pointer to an int (ptrtoint, ptr store
+  // which could be followed by an integer load, ptr<->int compare) as
+  // escaping, and objects located at well-known addresses via platform-specific
+  // means cannot be considered non-escaping local objects.
+  if (isa<IntToPtrInst>(V))
+    return true;
+
   return false;
 }
 


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