From: Chris Lattner <sabre@nondot.org>
Date: Fri, 1 Jan 2010 01:52:15 +0000 (+0000)
Subject: add a few trivial instcombines for llvm.powi.
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=d27f911b2309ed7812bdd4da50a87fed0e253815;p=oota-llvm.git

add a few trivial instcombines for llvm.powi.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92383 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 72dc26ef858..cd553f0811a 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -10140,6 +10140,20 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
       if (Operand->getIntrinsicID() == Intrinsic::bswap)
         return ReplaceInstUsesWith(CI, Operand->getOperand(1));
     break;
+  case Intrinsic::powi:
+    if (ConstantInt *Power = dyn_cast<ConstantInt>(II->getOperand(2))) {
+      // powi(x, 0) -> 1.0
+      if (Power->isZero())
+        return ReplaceInstUsesWith(CI, ConstantFP::get(CI.getType(), 1.0));
+      // powi(x, 1) -> x
+      if (Power->isOne())
+        return ReplaceInstUsesWith(CI, II->getOperand(1));
+      // powi(x, -1) -> 1/x
+      return BinaryOperator::CreateFDiv(ConstantFP::get(CI.getType(), 1.0),
+                                        II->getOperand(1));
+    }
+    break;
+      
   case Intrinsic::uadd_with_overflow: {
     Value *LHS = II->getOperand(1), *RHS = II->getOperand(2);
     const IntegerType *IT = cast<IntegerType>(II->getOperand(1)->getType());
diff --git a/test/Transforms/InstCombine/intrinsics.ll b/test/Transforms/InstCombine/intrinsics.ll
index fda4386e943..135e7772eea 100644
--- a/test/Transforms/InstCombine/intrinsics.ll
+++ b/test/Transforms/InstCombine/intrinsics.ll
@@ -4,6 +4,7 @@
 
 declare %overflow.result @llvm.uadd.with.overflow.i8(i8, i8)
 declare %overflow.result @llvm.umul.with.overflow.i8(i8, i8)
+declare double @llvm.powi.f64(double, i32) nounwind readonly
 
 define i8 @test1(i8 %A, i8 %B) {
   %x = call %overflow.result @llvm.uadd.with.overflow.i8(i8 %A, i8 %B)
@@ -77,3 +78,24 @@ define i8 @test6(i8 %A, i1* %overflowPtr) {
 ; CHECK-NEXT: store i1 false, i1* %overflowPtr
 ; CHECK-NEXT: ret i8 %A
 }
+
+
+define void @powi(double %V, double *%P) {
+entry:
+  %A = tail call double @llvm.powi.f64(double %V, i32 -1) nounwind
+  volatile store double %A, double* %P
+
+  %B = tail call double @llvm.powi.f64(double %V, i32 0) nounwind
+  volatile store double %B, double* %P
+
+  %C = tail call double @llvm.powi.f64(double %V, i32 1) nounwind
+  volatile store double %C, double* %P
+  ret void
+; CHECK: @powi
+; CHECK: %A = fdiv double 1.0{{.*}}, %V
+; CHECK: volatile store double %A, 
+; CHECK: volatile store double 1.0 
+; CHECK: volatile store double %V
+}
+
+