Generalize instcombine's isSafeToLoadUnconditionally() function

to ignore readonly calls, and factor it out of instcombine so
that it can be used by other passes.  Patch by Frits van Bommel!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@73506 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 0 deletions

diff --git a/include/llvm/Transforms/Utils/Local.h b/include/llvm/Transforms/Utils/Local.h
index 5ea1a500c5..7ab8721af7 100644
--- a/include/llvm/Transforms/Utils/Local.h
+++ b/include/llvm/Transforms/Utils/Local.h
@@ -31,6 +31,16 @@ struct DbgInfoIntrinsic;
 template<typename T> class SmallVectorImpl;
   
 //===----------------------------------------------------------------------===//
+//  Local analysis.
+//
+
+/// isSafeToLoadUnconditionally - Return true if we know that executing a load
+/// from this value cannot trap.  If it is not obviously safe to load from the
+/// specified pointer, we do a quick local scan of the basic block containing
+/// ScanFrom, to determine if the address is already accessed.
+bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom);
+
+//===----------------------------------------------------------------------===//
 //  Local constant propagation.
 //