[PPC] Inline expansion of memcmp

This patch does an inline expansion of memcmp.
It changes the memcmp library call into an inline expansion when the size is
known at compile time and is under a target specified threshold.
This expansion is implemented in CodeGenPrepare and expands into straight line
code. The target specifies a maximum load size and the expansion works by using
this size to load the two sources, compare, and exit early if a difference is
found. It also has a special case when the memcmp result is used in a compare
to zero equality.

Differential Revision: https://reviews.llvm.org/D28637

llvm-svn: 304313

1 files changed, 0 insertions, 14 deletions

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index 49effda5d83..cc6c47e8f97 100644
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -85,20 +85,6 @@ static bool isCallingConvCCompatible(CallInst *CI) {
   return false;
 }
 
-/// Return true if it only matters that the value is equal or not-equal to zero.
-static bool isOnlyUsedInZeroEqualityComparison(Value *V) {
-  for (User *U : V->users()) {
-    if (ICmpInst *IC = dyn_cast<ICmpInst>(U))
-      if (IC->isEquality())
-        if (Constant *C = dyn_cast<Constant>(IC->getOperand(1)))
-          if (C->isNullValue())
-            continue;
-    // Unknown instruction.
-    return false;
-  }
-  return true;
-}
-
 /// Return true if it is only used in equality comparisons with With.
 static bool isOnlyUsedInEqualityComparison(Value *V, Value *With) {
   for (User *U : V->users()) {