instcombine: Migrate *abs optimizations

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

llvm-svn: 168574

llvm/lib/Transforms/Scalar/SimplifyLibCalls.cpp

@@ -136,27 +136,6 @@ struct IsAsciiOpt : public LibCallOptimization {
   }
 };
 
-//===---------------------------------------===//
-// 'abs', 'labs', 'llabs' Optimizations
-
-struct AbsOpt : public LibCallOptimization {
-  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
-    FunctionType *FT = Callee->getFunctionType();
-    // We require integer(integer) where the types agree.
-    if (FT->getNumParams() != 1 || !FT->getReturnType()->isIntegerTy() ||
-        FT->getParamType(0) != FT->getReturnType())
-      return 0;
-
-    // abs(x) -> x >s -1 ? x : -x
-    Value *Op = CI->getArgOperand(0);
-    Value *Pos = B.CreateICmpSGT(Op, Constant::getAllOnesValue(Op->getType()),
-                                 "ispos");
-    Value *Neg = B.CreateNeg(Op, "neg");
-    return B.CreateSelect(Pos, Op, Neg);
-  }
-};
-
-
 //===---------------------------------------===//
 // 'toascii' Optimizations
 
@@ -542,7 +521,7 @@ namespace {
 
     StringMap<LibCallOptimization*> Optimizations;
     // Integer Optimizations
-    AbsOpt Abs; IsDigitOpt IsDigit; IsAsciiOpt IsAscii;
+    IsDigitOpt IsDigit; IsAsciiOpt IsAscii;
     ToAsciiOpt ToAscii;
     // Formatting and IO Optimizations
     SPrintFOpt SPrintF; PrintFOpt PrintF;
@@ -603,9 +582,6 @@ void SimplifyLibCalls::AddOpt(LibFunc::Func F1, LibFunc::Func F2,
 /// we know.
 void SimplifyLibCalls::InitOptimizations() {
   // Integer Optimizations
-  Optimizations["abs"] = &Abs;
-  Optimizations["labs"] = &Abs;
-  Optimizations["llabs"] = &Abs;
   Optimizations["isdigit"] = &IsDigit;
   Optimizations["isascii"] = &IsAscii;
   Optimizations["toascii"] = &ToAscii;

llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp

@@ -1250,6 +1250,23 @@ struct FFSOpt : public LibCallOptimization {
   }
 };
 
+struct AbsOpt : public LibCallOptimization {
+  virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+    FunctionType *FT = Callee->getFunctionType();
+    // We require integer(integer) where the types agree.
+    if (FT->getNumParams() != 1 || !FT->getReturnType()->isIntegerTy() ||
+        FT->getParamType(0) != FT->getReturnType())
+      return 0;
+
+    // abs(x) -> x >s -1 ? x : -x
+    Value *Op = CI->getArgOperand(0);
+    Value *Pos = B.CreateICmpSGT(Op, Constant::getAllOnesValue(Op->getType()),
+                                 "ispos");
+    Value *Neg = B.CreateNeg(Op, "neg");
+    return B.CreateSelect(Pos, Op, Neg);
+  }
+};
+
 } // End anonymous namespace.
 
 namespace llvm {
@@ -1298,6 +1315,7 @@ class LibCallSimplifierImpl {
 
   // Integer library call optimizations.
   FFSOpt FFS;
+  AbsOpt Abs;
 
   void initOptimizations();
   void addOpt(LibFunc::Func F, LibCallOptimization* Opt);
@@ -1413,6 +1431,9 @@ void LibCallSimplifierImpl::initOptimizations() {
   addOpt(LibFunc::ffs, &FFS);
   addOpt(LibFunc::ffsl, &FFS);
   addOpt(LibFunc::ffsll, &FFS);
+  addOpt(LibFunc::abs, &Abs);
+  addOpt(LibFunc::labs, &Abs);
+  addOpt(LibFunc::llabs, &Abs);
 }
 
 Value *LibCallSimplifierImpl::optimizeCall(CallInst *CI) {

llvm/test/Transforms/InstCombine/abs-1.ll

@@ -0,0 +1,41 @@
+; Test that the abs 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 i32 @abs(i32)
+declare i64 @labs(i64)
+declare i64 @llabs(i64)
+
+; Check abs(x) -> x >s -1 ? x : -x.
+
+define i32 @test_simplify1(i32 %x) {
+; CHECK: @test_simplify1
+  %ret = call i32 @abs(i32 %x)
+; CHECK-NEXT: [[ISPOS:%[a-z0-9]+]] = icmp sgt i32 %x, -1
+; CHECK-NEXT: [[NEG:%[a-z0-9]+]] = sub i32 0, %x
+; CHECK-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[ISPOS]], i32 %x, i32 [[NEG]]
+  ret i32 %ret
+; CHECK-NEXT: ret i32 [[RET]]
+}
+
+define i64 @test_simplify2(i64 %x) {
+; CHECK: @test_simplify2
+  %ret = call i64 @labs(i64 %x)
+; CHECK-NEXT: [[ISPOS:%[a-z0-9]+]] = icmp sgt i64 %x, -1
+; CHECK-NEXT: [[NEG:%[a-z0-9]+]] = sub i64 0, %x
+; CHECK-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[ISPOS]], i64 %x, i64 [[NEG]]
+  ret i64 %ret
+; CHECK-NEXT: ret i64 [[RET]]
+}
+
+define i64 @test_simplify3(i64 %x) {
+; CHECK: @test_simplify3
+  %ret = call i64 @llabs(i64 %x)
+; CHECK-NEXT: [[ISPOS:%[a-z0-9]+]] = icmp sgt i64 %x, -1
+; CHECK-NEXT: [[NEG:%[a-z0-9]+]] = sub i64 0, %x
+; CHECK-NEXT: [[RET:%[a-z0-9]+]] = select i1 [[ISPOS]], i64 %x, i64 [[NEG]]
+  ret i64 %ret
+; CHECK-NEXT: ret i64 [[RET]]
+}

llvm/test/Transforms/SimplifyLibCalls/abs.ll

@@ -1,11 +0,0 @@
-; RUN: opt < %s -simplify-libcalls -S | grep "select i1 %ispos"
-; PR2337
-
-define i32 @test(i32 %x) {
-entry:
-	%call = call i32 @abs( i32 %x )		; <i32> [#uses=1]
-	ret i32 %call
-}
-
-declare i32 @abs(i32)
-