instcombine: Migrate memcpy optimizations

This patch migrates the memcpy optimizations from the simplify-libcalls
pass into the instcombine library call simplifier.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167686 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/SimplifyLibCalls.cpp

@@ -104,28 +104,6 @@ static bool CallHasFloatingPointArgument(const CallInst *CI) {
 //===----------------------------------------------------------------------===//
 
 namespace {
-//===---------------------------------------===//
-// 'memcpy' Optimizations
-
-struct MemCpyOpt : public LibCallOptimization {
-  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
-    // These optimizations require DataLayout.
-    if (!TD) return 0;
-
-    FunctionType *FT = Callee->getFunctionType();
-    if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
-        !FT->getParamType(0)->isPointerTy() ||
-        !FT->getParamType(1)->isPointerTy() ||
-        FT->getParamType(2) != TD->getIntPtrType(*Context))
-      return 0;
-
-    // memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1)
-    B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
-                   CI->getArgOperand(2), 1);
-    return CI->getArgOperand(0);
-  }
-};
-
 //===---------------------------------------===//
 // 'memmove' Optimizations
 
@@ -839,7 +817,7 @@ namespace {
 
     StringMap<LibCallOptimization*> Optimizations;
     // Memory LibCall Optimizations
-    MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
+    MemMoveOpt MemMove; MemSetOpt MemSet;
     // Math Library Optimizations
     CosOpt Cos; PowOpt Pow; Exp2Opt Exp2;
     UnaryDoubleFPOpt UnaryDoubleFP, UnsafeUnaryDoubleFP;
@@ -906,7 +884,6 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2,
 /// we know.
 void SimplifyLibCalls::InitOptimizations() {
   // Memory LibCall Optimizations
-  AddOpt(LibFunc::memcpy, &MemCpy);
   Optimizations["memmove"] = &MemMove;
   AddOpt(LibFunc::memset, &MemSet);
 

lib/Transforms/Utils/SimplifyLibCalls.cpp

@@ -959,6 +959,25 @@ struct MemCmpOpt : public LibCallOptimization {
   }
 };
 
+struct MemCpyOpt : public LibCallOptimization {
+  virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+    // These optimizations require DataLayout.
+    if (!TD) return 0;
+
+    FunctionType *FT = Callee->getFunctionType();
+    if (FT->getNumParams() != 3 || FT->getReturnType() != FT->getParamType(0) ||
+        !FT->getParamType(0)->isPointerTy() ||
+        !FT->getParamType(1)->isPointerTy() ||
+        FT->getParamType(2) != TD->getIntPtrType(*Context))
+      return 0;
+
+    // memcpy(x, y, n) -> llvm.memcpy(x, y, n, 1)
+    B.CreateMemCpy(CI->getArgOperand(0), CI->getArgOperand(1),
+                   CI->getArgOperand(2), 1);
+    return CI->getArgOperand(0);
+  }
+};
+
 } // End anonymous namespace.
 
 namespace llvm {
@@ -996,6 +1015,7 @@ class LibCallSimplifierImpl {
 
   // Memory library call optimizations.
   MemCmpOpt MemCmp;
+  MemCpyOpt MemCpy;
 
   void initOptimizations();
   void addOpt(LibFunc::Func F, LibCallOptimization* Opt);
@@ -1045,6 +1065,7 @@ void LibCallSimplifierImpl::initOptimizations() {
 
   // Memory library call optimizations.
   addOpt(LibFunc::memcmp, &MemCmp);
+  addOpt(LibFunc::memcpy, &MemCpy);
 }
 
 Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {

test/Transforms/InstCombine/memcpy-1.ll

@@ -0,0 +1,17 @@
+; Test that the memcpy library call simplifier works correctly.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+
+declare i8* @memcpy(i8*, i8*, i32)
+
+; Check memcpy(mem1, mem2, size) -> llvm.memcpy(mem1, mem2, size, 1).
+
+define i8* @test_simplify1(i8* %mem1, i8* %mem2, i32 %size) {
+; CHECK: @test_simplify1
+  %ret = call i8* @memcpy(i8* %mem1, i8* %mem2, i32 %size)
+; CHECK: call void @llvm.memcpy
+  ret i8* %ret
+; CHECK: ret i8* %mem1
+}

test/Transforms/InstCombine/memcpy-2.ll

@@ -0,0 +1,17 @@
+; Test that the memcpy library call simplifier works correctly.
+;
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
+
+declare i8 @memcpy(i8*, i8*, i32)
+
+; Check that memcpy functions with the wrong prototype aren't simplified.
+
+define i8 @test_no_simplify1(i8* %mem1, i8* %mem2, i32 %size) {
+; CHECK: @test_no_simplify1
+  %ret = call i8 @memcpy(i8* %mem1, i8* %mem2, i32 %size)
+; CHECK: call i8 @memcpy
+  ret i8 %ret
+; CHECK: ret i8 %ret
+}