[llvm] r275038 - Teach isDereferenceablePointer to look through returned-argument functions

[Hal Finkel via llvm-commits]

Author: hfinkel
Date: Sun Jul 10 22:08:49 2016
New Revision: 275038

URL: http://llvm.org/viewvc/llvm-project?rev=275038&view=rev
Log:
Teach isDereferenceablePointer to look through returned-argument functions

For functions which are known to return their argument,
isDereferenceableAndAlignedPointer can examine the argument value.

Differential Revision: http://reviews.llvm.org/D9384

Modified:
    llvm/trunk/lib/Analysis/Loads.cpp
    llvm/trunk/test/Analysis/ValueTracking/memory-dereferenceable.ll

Modified: llvm/trunk/lib/Analysis/Loads.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/Loads.cpp?rev=275038&r1=275037&r2=275038&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/Loads.cpp (original)
+++ llvm/trunk/lib/Analysis/Loads.cpp Sun Jul 10 22:08:49 2016
@@ -101,6 +101,11 @@ static bool isDereferenceableAndAlignedP
     return isDereferenceableAndAlignedPointer(ASC->getOperand(0), Align, Size,
                                               DL, CtxI, DT, Visited);
 
+  if (auto CS = ImmutableCallSite(V))
+    if (const Value *RV = CS.getReturnedArgOperand())
+      return isDereferenceableAndAlignedPointer(RV, Align, Size, DL, CtxI, DT,
+                                                Visited);
+
   // If we don't know, assume the worst.
   return false;
 }

Modified: llvm/trunk/test/Analysis/ValueTracking/memory-dereferenceable.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ValueTracking/memory-dereferenceable.ll?rev=275038&r1=275037&r2=275038&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ValueTracking/memory-dereferenceable.ll (original)
+++ llvm/trunk/test/Analysis/ValueTracking/memory-dereferenceable.ll Sun Jul 10 22:08:49 2016
@@ -43,7 +43,8 @@ entry:
     %load4 = load i32, i32 addrspace(1)* %relocate
 
 ; CHECK-NOT: %nparam
-    %nparam = getelementptr i32, i32 addrspace(1)* %dparam, i32 5
+    %dpa = call i32 addrspace(1)* @func1(i32 addrspace(1)* %dparam)
+    %nparam = getelementptr i32, i32 addrspace(1)* %dpa, i32 5
     %load5 = load i32, i32 addrspace(1)* %nparam
 
     ; Load from a non-dereferenceable load
@@ -162,6 +163,8 @@ if.end:
 declare token @llvm.experimental.gc.statepoint.p0f_i1f(i64, i32, i1 ()*, i32, i32, ...)
 declare i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(token, i32, i32)
 
+declare i32 addrspace(1)* @func1(i32 addrspace(1)* returned) nounwind argmemonly
+
 !0 = !{i64 4}
 !1 = !{i64 2}
 !2 = !{}