[llvm] r174650 - Identify and simplify idempotent intrinsics. Test case included.

[Michael Ilseman]

Author: milseman
Date: Thu Feb  7 13:26:05 2013
New Revision: 174650

URL: http://llvm.org/viewvc/llvm-project?rev=174650&view=rev
Log:
Identify and simplify idempotent intrinsics. Test case included.

Modified:
    llvm/trunk/lib/Analysis/InstructionSimplify.cpp
    llvm/trunk/test/Transforms/InstSimplify/call.ll

Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=174650&r1=174649&r2=174650&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Thu Feb  7 13:26:05 2013
@@ -2925,6 +2925,37 @@ Value *llvm::SimplifyCmpInst(unsigned Pr
                            RecursionLimit);
 }
 
+static bool IsIdempotent(Intrinsic::ID ID) {
+  switch (ID) {
+  default: return false;
+
+  // Unary idempotent: f(f(x)) = f(x)
+  case Intrinsic::fabs:
+  case Intrinsic::floor:
+  case Intrinsic::ceil:
+  case Intrinsic::trunc:
+  case Intrinsic::rint:
+  case Intrinsic::nearbyint:
+    return true;
+  }
+}
+
+template <typename IterTy>
+static Value *SimplifyIntrinsic(Intrinsic::ID IID, IterTy ArgBegin, IterTy ArgEnd,
+                                const Query &Q, unsigned MaxRecurse) {
+  // Perform idempotent optimizations
+  if (!IsIdempotent(IID))
+    return 0;
+
+  // Unary Ops
+  if (std::distance(ArgBegin, ArgEnd) == 1)
+    if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(*ArgBegin))
+      if (II->getIntrinsicID() == IID)
+        return II;
+
+  return 0;
+}
+
 template <typename IterTy>
 static Value *SimplifyCall(Value *V, IterTy ArgBegin, IterTy ArgEnd,
                            const Query &Q, unsigned MaxRecurse) {
@@ -2941,6 +2972,11 @@ static Value *SimplifyCall(Value *V, Ite
   if (!F)
     return 0;
 
+  if (unsigned IID = F->getIntrinsicID())
+    if (Value *Ret =
+        SimplifyIntrinsic((Intrinsic::ID) IID, ArgBegin, ArgEnd, Q, MaxRecurse))
+      return Ret;
+
   if (!canConstantFoldCallTo(F))
     return 0;
 

Modified: llvm/trunk/test/Transforms/InstSimplify/call.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/call.ll?rev=174650&r1=174649&r2=174650&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/call.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/call.ll Thu Feb  7 13:26:05 2013
@@ -50,3 +50,54 @@ define float @test_fabs_libcall() {
   ret float %x
 ; CHECK-NEXT: ret float 4.2{{0+}}e+01
 }
+
+
+declare float @llvm.fabs.f32(float) nounwind readnone
+declare float @llvm.floor.f32(float) nounwind readnone
+declare float @llvm.ceil.f32(float) nounwind readnone
+declare float @llvm.trunc.f32(float) nounwind readnone
+declare float @llvm.rint.f32(float) nounwind readnone
+declare float @llvm.nearbyint.f32(float) nounwind readnone
+
+; Test idempotent intrinsics
+define float @test_idempotence(float %a) {
+; CHECK: @test_idempotence
+
+; CHECK: fabs
+; CHECK-NOT: fabs
+  %a0 = call float @llvm.fabs.f32(float %a)
+  %a1 = call float @llvm.fabs.f32(float %a0)
+
+; CHECK: floor
+; CHECK-NOT: floor
+  %b0 = call float @llvm.floor.f32(float %a)
+  %b1 = call float @llvm.floor.f32(float %b0)
+
+; CHECK: ceil
+; CHECK-NOT: ceil
+  %c0 = call float @llvm.ceil.f32(float %a)
+  %c1 = call float @llvm.ceil.f32(float %c0)
+
+; CHECK: trunc
+; CHECK-NOT: trunc
+  %d0 = call float @llvm.trunc.f32(float %a)
+  %d1 = call float @llvm.trunc.f32(float %d0)
+
+; CHECK: rint
+; CHECK-NOT: rint
+  %e0 = call float @llvm.rint.f32(float %a)
+  %e1 = call float @llvm.rint.f32(float %e0)
+
+; CHECK: nearbyint
+; CHECK-NOT: nearbyint
+  %f0 = call float @llvm.nearbyint.f32(float %a)
+  %f1 = call float @llvm.nearbyint.f32(float %f0)
+
+  %r0 = fadd float %a1, %b1
+  %r1 = fadd float %r0, %c1
+  %r2 = fadd float %r1, %d1
+  %r3 = fadd float %r2, %e1
+  %r4 = fadd float %r3, %f1
+
+  ret float %r4
+}