[llvm-commits] [llvm] r118617 - /llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp

[Dan Gohman]

Author: djg
Date: Tue Nov  9 13:56:27 2010
New Revision: 118617

URL: http://llvm.org/viewvc/llvm-project?rev=118617&view=rev
Log:
Teach FunctionAttrs about AccessesArgumentsReadonly.

Modified:
    llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp

Modified: llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp?rev=118617&r1=118616&r2=118617&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/FunctionAttrs.cpp Tue Nov  9 13:56:27 2010
@@ -152,6 +152,25 @@
           }
           // Only reads and writes local memory.
           continue;
+        case AliasAnalysis::AccessesArgumentsReadonly:
+          // Check whether all pointer arguments point to local memory, and
+          // ignore calls that only access local memory.
+          for (CallSite::arg_iterator CI = CS.arg_begin(), CE = CS.arg_end();
+               CI != CE; ++CI) {
+            Value *Arg = *CI;
+            if (Arg->getType()->isPointerTy()) {
+              AliasAnalysis::Location Loc(Arg,
+                                          AliasAnalysis::UnknownSize,
+                                          I->getMetadata(LLVMContext::MD_tbaa));
+              if (!AA->pointsToConstantMemory(Loc, /*OrLocal=*/true)) {
+                // Reads non-local memory.
+                ReadsMemory = true;
+                break;
+              }
+            }
+          }
+          // Only reads memory.
+          continue;
         default:
           // Otherwise, be conservative.
           break;