instcombine: Migrate fwrite optimizations

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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168892 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Scalar/SimplifyLibCalls.cpp

@@ -86,42 +86,6 @@ namespace {
 // Formatting and IO Optimizations
 //===----------------------------------------------------------------------===//
 
-//===---------------------------------------===//
-// 'fwrite' Optimizations
-
-struct FWriteOpt : public LibCallOptimization {
-  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
-    // Require a pointer, an integer, an integer, a pointer, returning integer.
-    FunctionType *FT = Callee->getFunctionType();
-    if (FT->getNumParams() != 4 || !FT->getParamType(0)->isPointerTy() ||
-        !FT->getParamType(1)->isIntegerTy() ||
-        !FT->getParamType(2)->isIntegerTy() ||
-        !FT->getParamType(3)->isPointerTy() ||
-        !FT->getReturnType()->isIntegerTy())
-      return 0;
-
-    // Get the element size and count.
-    ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
-    ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getArgOperand(2));
-    if (!SizeC || !CountC) return 0;
-    uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue();
-
-    // If this is writing zero records, remove the call (it's a noop).
-    if (Bytes == 0)
-      return ConstantInt::get(CI->getType(), 0);
-
-    // If this is writing one byte, turn it into fputc.
-    // This optimisation is only valid, if the return value is unused.
-    if (Bytes == 1 && CI->use_empty()) {  // fwrite(S,1,1,F) -> fputc(S[0],F)
-      Value *Char = B.CreateLoad(CastToCStr(CI->getArgOperand(0), B), "char");
-      Value *NewCI = EmitFPutC(Char, CI->getArgOperand(3), B, TD, TLI);
-      return NewCI ? ConstantInt::get(CI->getType(), 1) : 0;
-    }
-
-    return 0;
-  }
-};
-
 //===---------------------------------------===//
 // 'fputs' Optimizations
 
@@ -189,7 +153,7 @@ namespace {
 
     StringMap<LibCallOptimization*> Optimizations;
     // Formatting and IO Optimizations
-    FWriteOpt FWrite; FPutsOpt FPuts;
+    FPutsOpt FPuts;
     PutsOpt Puts;
 
     bool Modified;  // This is only used by doInitialization.
@@ -246,7 +210,6 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2,
 /// we know.
 void SimplifyLibCalls::InitOptimizations() {
   // Formatting and IO Optimizations
-  AddOpt(LibFunc::fwrite, &FWrite);
   AddOpt(LibFunc::fputs, &FPuts);
   Optimizations["puts"] = &Puts;
 }

lib/Transforms/Utils/SimplifyLibCalls.cpp

@@ -1577,6 +1577,39 @@ struct FPrintFOpt : public LibCallOptimization {
   }
 };
 
+struct FWriteOpt : public LibCallOptimization {
+  virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+    // Require a pointer, an integer, an integer, a pointer, returning integer.
+    FunctionType *FT = Callee->getFunctionType();
+    if (FT->getNumParams() != 4 || !FT->getParamType(0)->isPointerTy() ||
+        !FT->getParamType(1)->isIntegerTy() ||
+        !FT->getParamType(2)->isIntegerTy() ||
+        !FT->getParamType(3)->isPointerTy() ||
+        !FT->getReturnType()->isIntegerTy())
+      return 0;
+
+    // Get the element size and count.
+    ConstantInt *SizeC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
+    ConstantInt *CountC = dyn_cast<ConstantInt>(CI->getArgOperand(2));
+    if (!SizeC || !CountC) return 0;
+    uint64_t Bytes = SizeC->getZExtValue()*CountC->getZExtValue();
+
+    // If this is writing zero records, remove the call (it's a noop).
+    if (Bytes == 0)
+      return ConstantInt::get(CI->getType(), 0);
+
+    // If this is writing one byte, turn it into fputc.
+    // This optimisation is only valid, if the return value is unused.
+    if (Bytes == 1 && CI->use_empty()) {  // fwrite(S,1,1,F) -> fputc(S[0],F)
+      Value *Char = B.CreateLoad(CastToCStr(CI->getArgOperand(0), B), "char");
+      Value *NewCI = EmitFPutC(Char, CI->getArgOperand(3), B, TD, TLI);
+      return NewCI ? ConstantInt::get(CI->getType(), 1) : 0;
+    }
+
+    return 0;
+  }
+};
+
 } // End anonymous namespace.
 
 namespace llvm {
@@ -1634,6 +1667,7 @@ class LibCallSimplifierImpl {
   PrintFOpt PrintF;
   SPrintFOpt SPrintF;
   FPrintFOpt FPrintF;
+  FWriteOpt FWrite;
 
   void initOptimizations();
   void addOpt(LibFunc::Func F, LibCallOptimization* Opt);
@@ -1760,6 +1794,7 @@ void LibCallSimplifierImpl::initOptimizations() {
   addOpt(LibFunc::printf, &PrintF);
   addOpt(LibFunc::sprintf, &SPrintF);
   addOpt(LibFunc::fprintf, &FPrintF);
+  addOpt(LibFunc::fwrite, &FWrite);
 }
 
 Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {

test/Transforms/InstCombine/fwrite-1.ll

@@ -0,0 +1,57 @@
+; Test that the fwrite 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"
+
+%FILE = type { }
+
+@str = constant [1 x i8] zeroinitializer
+@empty = constant [0 x i8] zeroinitializer
+
+declare i64 @fwrite(i8*, i64, i64, %FILE *)
+
+; Check fwrite(S, 1, 1, fp) -> fputc(S[0], fp).
+
+define void @test_simplify1(%FILE* %fp) {
+; CHECK: @test_simplify1
+  %str = getelementptr inbounds [1 x i8]* @str, i64 0, i64 0
+  call i64 @fwrite(i8* %str, i64 1, i64 1, %FILE* %fp)
+; CHECK-NEXT: call i32 @fputc(i32 0, %FILE* %fp)
+  ret void
+; CHECK-NEXT: ret void
+}
+
+define void @test_simplify2(%FILE* %fp) {
+; CHECK: @test_simplify2
+  %str = getelementptr inbounds [0 x i8]* @empty, i64 0, i64 0
+  call i64 @fwrite(i8* %str, i64 1, i64 0, %FILE* %fp)
+  ret void
+; CHECK-NEXT: ret void
+}
+
+define void @test_simplify3(%FILE* %fp) {
+; CHECK: @test_simplify3
+  %str = getelementptr inbounds [0 x i8]* @empty, i64 0, i64 0
+  call i64 @fwrite(i8* %str, i64 0, i64 1, %FILE* %fp)
+  ret void
+; CHECK-NEXT: ret void
+}
+
+define i64 @test_no_simplify1(%FILE* %fp) {
+; CHECK: @test_no_simplify1
+  %str = getelementptr inbounds [1 x i8]* @str, i64 0, i64 0
+  %ret = call i64 @fwrite(i8* %str, i64 1, i64 1, %FILE* %fp)
+; CHECK-NEXT: call i64 @fwrite
+  ret i64 %ret
+; CHECK-NEXT: ret i64 %ret
+}
+
+define void @test_no_simplify2(%FILE* %fp, i64 %size) {
+; CHECK: @test_no_simplify2
+  %str = getelementptr inbounds [1 x i8]* @str, i64 0, i64 0
+  call i64 @fwrite(i8* %str, i64 %size, i64 1, %FILE* %fp)
+; CHECK-NEXT: call i64 @fwrite
+  ret void
+; CHECK-NEXT: ret void
+}