Do not translate rint into nearbyint, but truncate it like nearbyint.

A common way to implement nearbyint is by fiddling with the floating
point environment and calling rint. This is used at least by the BSD
libm and musl. As such, canonicalizing the latter to the former will
create infinite loops for libm and generally pessimize performance, at
least when the generic C versions are used.

This change preserves the rint in the libcall translation and also
handles the domain truncation logic, so that rint with float argument
will be reduced to rintf etc.

llvm-svn: 299247

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
index 71ca14d..af4c9ac 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -2091,6 +2091,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
   case Intrinsic::floor:
   case Intrinsic::round:
   case Intrinsic::nearbyint:
+  case Intrinsic::rint:
   case Intrinsic::trunc: {
     Value *ExtSrc;
     if (match(II->getArgOperand(0), m_FPExt(m_Value(ExtSrc))) &&

diff --git a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
index fa0ef17..cd2d7f9 100644 (file)
--- a/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -2160,8 +2160,9 @@ Value *LibCallSimplifier::optimizeCall(CallInst *CI) {
     case LibFunc_round:
       return replaceUnaryCall(CI, Builder, Intrinsic::round);
     case LibFunc_nearbyint:
-    case LibFunc_rint:
       return replaceUnaryCall(CI, Builder, Intrinsic::nearbyint);
+    case LibFunc_rint:
+      return replaceUnaryCall(CI, Builder, Intrinsic::rint);
     case LibFunc_trunc:
       return replaceUnaryCall(CI, Builder, Intrinsic::trunc);
     case LibFunc_acos:

diff --git a/llvm/test/Transforms/InstCombine/float-shrink-compare.ll b/llvm/test/Transforms/InstCombine/float-shrink-compare.ll
index a98f4cd..e092595 100644 (file)
--- a/llvm/test/Transforms/InstCombine/float-shrink-compare.ll
+++ b/llvm/test/Transforms/InstCombine/float-shrink-compare.ll
@@ -119,7 +119,7 @@ define i32 @test5(float %x, float %y) nounwind uwtable {
   %cmp.ext = zext i1 %cmp to i32
   ret i32 %cmp.ext
 ; CHECK-LABEL: @test5(
-; CHECK-NEXT: %rint = call float @llvm.nearbyint.f32(float %x)
+; CHECK-NEXT: %rint = call float @llvm.rint.f32(float %x)
 ; CHECK-NEXT: fcmp oeq float %rint, %y
 }
 
@@ -276,7 +276,7 @@ define i32 @test12(float %x, float %y) nounwind uwtable {
   %cmp.ext = zext i1 %cmp to i32
   ret i32 %cmp.ext
 ; CHECK-LABEL: @test12(
-; CHECK-NEXT: %rint = call float @llvm.nearbyint.f32(float %x)
+; CHECK-NEXT: %rint = call float @llvm.rint.f32(float %x)
 ; CHECK-NEXT: fcmp oeq float %rint, %y
 }