Implement new LibCallSimplifier class

This patch implements the new LibCallSimplifier class as outlined in [1].
In addition to providing the new base library simplification infrastructure,
all the fortified library call simplifications were moved over to the new
infrastructure.  The rest of the library simplification optimizations will
be moved over with follow up patches.

NOTE: The original fortified library call simplifier located in the
SimplifyFortifiedLibCalls class was not removed because it is still
used by CodeGenPrepare.  This class will eventually go away too.

[1] http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-August/052283.html

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@165873 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 9 insertions, 36 deletions

diff --git a/lib/Transforms/InstCombine/InstCombine.h b/lib/Transforms/InstCombine/InstCombine.h
index 325bb20fbe8..41017c52879 100644
--- a/lib/Transforms/InstCombine/InstCombine.h
+++ b/lib/Transforms/InstCombine/InstCombine.h
@@ -18,6 +18,7 @@
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Support/InstVisitor.h"
 #include "llvm/Support/TargetFolder.h"
+#include "llvm/Transforms/Utils/SimplifyLibCalls.h"
 
 namespace llvm {
   class CallSite;
@@ -74,6 +75,7 @@ class LLVM_LIBRARY_VISIBILITY InstCombiner
   DataLayout *TD;
   TargetLibraryInfo *TLI;
   bool MadeIRChange;
+  LibCallSimplifier *Simplifier;
 public:
   /// Worklist - All of the instructions that need to be simplified.
   InstCombineWorklist Worklist;
diff --git a/lib/Transforms/InstCombine/InstCombineCalls.cpp b/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 04b7b2146f6..34e16c7aeff 100644
--- a/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -778,39 +778,6 @@ static bool isSafeToEliminateVarargsCast(const CallSite CS,
   return true;
 }
 
-namespace {
-class InstCombineFortifiedLibCalls : public SimplifyFortifiedLibCalls {
-  InstCombiner *IC;
-protected:
-  void replaceCall(Value *With) {
-    NewInstruction = IC->ReplaceInstUsesWith(*CI, With);
-  }
-  bool isFoldable(unsigned SizeCIOp, unsigned SizeArgOp, bool isString) const {
-    if (CI->getArgOperand(SizeCIOp) == CI->getArgOperand(SizeArgOp))
-      return true;
-    if (ConstantInt *SizeCI =
-                           dyn_cast<ConstantInt>(CI->getArgOperand(SizeCIOp))) {
-      if (SizeCI->isAllOnesValue())
-        return true;
-      if (isString) {
-        uint64_t Len = GetStringLength(CI->getArgOperand(SizeArgOp));
-        // If the length is 0 we don't know how long it is and so we can't
-        // remove the check.
-        if (Len == 0) return false;
-        return SizeCI->getZExtValue() >= Len;
-      }
-      if (ConstantInt *Arg = dyn_cast<ConstantInt>(
-                                                  CI->getArgOperand(SizeArgOp)))
-        return SizeCI->getZExtValue() >= Arg->getZExtValue();
-    }
-    return false;
-  }
-public:
-  InstCombineFortifiedLibCalls(InstCombiner *IC) : IC(IC), NewInstruction(0) { }
-  Instruction *NewInstruction;
-};
-} // end anonymous namespace
-
 // Try to fold some different type of calls here.
 // Currently we're only working with the checking functions, memcpy_chk,
 // mempcpy_chk, memmove_chk, memset_chk, strcpy_chk, stpcpy_chk, strncpy_chk,
@@ -818,9 +785,10 @@ public:
 Instruction *InstCombiner::tryOptimizeCall(CallInst *CI, const DataLayout *TD) {
   if (CI->getCalledFunction() == 0) return 0;
 
-  InstCombineFortifiedLibCalls Simplifier(this);
-  Simplifier.fold(CI, TD, TLI);
-  return Simplifier.NewInstruction;
+  if (Value *With = Simplifier->optimizeCall(CI))
+    return ReplaceInstUsesWith(*CI, With);
+
+  return 0;
 }
 
 static IntrinsicInst *FindInitTrampolineFromAlloca(Value *TrampMem) {
diff --git a/lib/Transforms/InstCombine/InstructionCombining.cpp b/lib/Transforms/InstCombine/InstructionCombining.cpp
index edfc060888b..5356fdcba7c 100644
--- a/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2130,6 +2130,9 @@ bool InstCombiner::runOnFunction(Function &F) {
                InstCombineIRInserter(Worklist));
   Builder = &TheBuilder;
 
+  LibCallSimplifier TheSimplifier(TD, TLI);
+  Simplifier = &TheSimplifier;
+
   bool EverMadeChange = false;
 
   // Lower dbg.declare intrinsics otherwise their value may be clobbered