Teach GVN to invalidate some memdep information when it does an RAUW
of a pointer. This allows is to catch more equivalencies. For example,
the type_lists_compatible_p function used to require two iterations of
the gvn pass (!) to delete its 18 redundant loads because the first pass
would CSE all the addressing computation cruft, which would unblock the
second memdep/gvn passes from recognizing them. This change allows
memdep/gvn to catch all 18 when run just once on the function (as is
typical :) instead of just 3.
On all of 403.gcc, this bumps up the # reundandancies found from:
63 gvn - Number of instructions PRE'd
153991 gvn - Number of instructions deleted
50069 gvn - Number of loads deleted
to:
63 gvn - Number of instructions PRE'd
154137 gvn - Number of instructions deleted
50185 gvn - Number of loads deleted
+120 loads deleted isn't bad.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@60799 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/MemoryDependenceAnalysis.cpp b/lib/Analysis/MemoryDependenceAnalysis.cpp
index 4211493..0b185b1 100644
--- a/lib/Analysis/MemoryDependenceAnalysis.cpp
+++ b/lib/Analysis/MemoryDependenceAnalysis.cpp
@@ -698,6 +698,21 @@
}
+/// invalidateCachedPointerInfo - This method is used to invalidate cached
+/// information about the specified pointer, because it may be too
+/// conservative in memdep. This is an optional call that can be used when
+/// the client detects an equivalence between the pointer and some other
+/// value and replaces the other value with ptr. This can make Ptr available
+/// in more places that cached info does not necessarily keep.
+void MemoryDependenceAnalysis::invalidateCachedPointerInfo(Value *Ptr) {
+ // If Ptr isn't really a pointer, just ignore it.
+ if (!isa<PointerType>(Ptr->getType())) return;
+ // Flush store info for the pointer.
+ RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, false));
+ // Flush load info for the pointer.
+ RemoveCachedNonLocalPointerDependencies(ValueIsLoadPair(Ptr, true));
+}
+
/// removeInstruction - Remove an instruction from the dependence analysis,
/// updating the dependence of instructions that previously depended on it.
/// This method attempts to keep the cache coherent using the reverse map.
@@ -864,7 +879,6 @@
AA->deleteValue(RemInst);
DEBUG(verifyRemoved(RemInst));
}
-
/// verifyRemoved - Verify that the specified instruction does not occur
/// in our internal data structures.
void MemoryDependenceAnalysis::verifyRemoved(Instruction *D) const {