From a6b21ea4ba4ef7250346c9423807415be049ebfd Mon Sep 17 00:00:00 2001
From: Nick Lewycky <nicholas@mxc.ca>
Date: Tue, 27 Dec 2011 18:25:50 +0000
Subject: [PATCH] Turn cos(-x) into cos(x). Patch by Alexander Malyshev!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@147291 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/SimplifyLibCalls.cpp | 32 ++++++++++++++++++----
 test/Transforms/SimplifyLibCalls/cos.ll    | 14 ++++++++++
 2 files changed, 41 insertions(+), 5 deletions(-)
 create mode 100644 test/Transforms/SimplifyLibCalls/cos.ll

diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index f3184ecc860..dcfcf1a8764 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -840,6 +840,28 @@ struct MemSetOpt : public LibCallOptimization {
 // Math Library Optimizations
 //===----------------------------------------------------------------------===//
 
+//===---------------------------------------===//
+// 'cos*' Optimizations
+
+struct CosOpt : public LibCallOptimization {
+  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+    FunctionType *FT = Callee->getFunctionType();
+    // Just make sure this has 1 argument of FP type, which matches the
+    // result type.
+    if (FT->getNumParams() != 1 || FT->getReturnType() != FT->getParamType(0) ||
+        !FT->getParamType(0)->isFloatingPointTy())
+      return 0;
+
+    // cos(-x) -> cos(x)
+    Value *Op1 = CI->getArgOperand(0);
+    if (BinaryOperator::isFNeg(Op1)) {
+      BinaryOperator *BinExpr = cast<BinaryOperator>(Op1);
+      return B.CreateCall(Callee, BinExpr->getOperand(1), "cos");
+    }
+    return 0;
+  }
+};
+
 //===---------------------------------------===//
 // 'pow*' Optimizations
 
@@ -870,7 +892,7 @@ struct PowOpt : public LibCallOptimization {
     if (Op2C->isExactlyValue(0.5)) {
       // Expand pow(x, 0.5) to (x == -infinity ? +infinity : fabs(sqrt(x))).
       // This is faster than calling pow, and still handles negative zero
-      // and negative infinite correctly.
+      // and negative infinity correctly.
       // TODO: In fast-math mode, this could be just sqrt(x).
       // TODO: In finite-only mode, this could be just fabs(sqrt(x)).
       Value *Inf = ConstantFP::getInfinity(CI->getType());
@@ -1455,7 +1477,7 @@ namespace {
     StrToOpt StrTo; StrSpnOpt StrSpn; StrCSpnOpt StrCSpn; StrStrOpt StrStr;
     MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
     // Math Library Optimizations
-    PowOpt Pow; Exp2Opt Exp2; UnaryDoubleFPOpt UnaryDoubleFP;
+    CosOpt Cos; PowOpt Pow; Exp2Opt Exp2; UnaryDoubleFPOpt UnaryDoubleFP;
     // Integer Optimizations
     FFSOpt FFS; AbsOpt Abs; IsDigitOpt IsDigit; IsAsciiOpt IsAscii;
     ToAsciiOpt ToAscii;
@@ -1539,6 +1561,9 @@ void SimplifyLibCalls::InitOptimizations() {
   Optimizations["__strcpy_chk"] = &StrCpyChk;
 
   // Math Library Optimizations
+  Optimizations["cosf"] = &Cos;
+  Optimizations["cos"] = &Cos;
+  Optimizations["cosl"] = &Cos;
   Optimizations["powf"] = &Pow;
   Optimizations["pow"] = &Pow;
   Optimizations["powl"] = &Pow;
@@ -2352,9 +2377,6 @@ bool SimplifyLibCalls::doInitialization(Module &M) {
 //   * cbrt(sqrt(x))  -> pow(x,1/6)
 //   * cbrt(sqrt(x))  -> pow(x,1/9)
 //
-// cos, cosf, cosl:
-//   * cos(-x)  -> cos(x)
-//
 // exp, expf, expl:
 //   * exp(log(x))  -> x
 //
diff --git a/test/Transforms/SimplifyLibCalls/cos.ll b/test/Transforms/SimplifyLibCalls/cos.ll
new file mode 100644
index 00000000000..6a8ce8c3881
--- /dev/null
+++ b/test/Transforms/SimplifyLibCalls/cos.ll
@@ -0,0 +1,14 @@
+; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define double @foo(double %d) nounwind readnone {
+; CHECK: @foo
+    %1 = fsub double -0.000000e+00, %d
+    %2 = call double @cos(double %1) nounwind readnone
+; CHECK: call double @cos(double %d)
+    ret double %2
+}
+
+declare double @cos(double) nounwind readnone