[PATCH] D140294: clang: Replace implementation of __builtin_isnormal

[Matt Arsenault via Phabricator via cfe-commits]

arsenm created this revision.
arsenm added reviewers: bkramer, foad, sepavloff, andrew.w.kaylor, kpn.
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arsenm requested review of this revision.
Herald added a subscriber: wdng.

This was doing an explicit non-canonical isnan check, then two
unordered comparisons. We can fold the ordered check into an ordered
compare. I recently fixed InstCombine to fold this pattern, but might
as well give it less work to do.

      

https://alive2.llvm.org/ce/z/ZWVHhT


https://reviews.llvm.org/D140294

Files:
  clang/lib/CodeGen/CGBuiltin.cpp
  clang/test/CodeGen/builtins.c


Index: clang/test/CodeGen/builtins.c
===================================================================
--- clang/test/CodeGen/builtins.c
+++ clang/test/CodeGen/builtins.c
@@ -261,20 +261,16 @@
   // CHECK: fcmp one double {{.*}}, 0x7FF0000000000000
 
   res = __builtin_isnormal(*H);
-  // CHECK: fcmp oeq half
-  // CHECK: call half @llvm.fabs.f16(half
-  // CHECK: fcmp ult half {{.*}}, 0xH7C00
-  // CHECK: fcmp uge half {{.*}}, 0xH0400
-  // CHECK: and i1
-  // CHECK: and i1
+  // CHECK: %[[FABS:.*]] = call half @llvm.fabs.f16(half %[[VAL:.*]])
+  // CHECK: %[[ISFINITE:.*]] = fcmp olt half %[[FABS]], 0xH7C00
+  // CHECK: %[[ISNORMAL:.*]] = fcmp uge half %[[FABS]], 0xH0400
+  // CHECK: and i1 %[[ISFINITE]], %[[ISNORMAL]]
 
   res = __builtin_isnormal(F);
-  // CHECK: fcmp oeq float
-  // CHECK: call float @llvm.fabs.f32(float
-  // CHECK: fcmp ult float {{.*}}, 0x7FF0000000000000
-  // CHECK: fcmp uge float {{.*}}, 0x3810000000000000
-  // CHECK: and i1
-  // CHECK: and i1
+  // CHECK: %[[FABS:.*]] = call float @llvm.fabs.f32(float %[[VAL:.*]])
+  // CHECK: %[[ISFINITE:.*]] = fcmp olt float %[[FABS]], 0x7FF0000000000000
+  // CHECK: %[[ISNORMAL:.*]] = fcmp uge float %[[FABS]], 0x3810000000000000
+  // CHECK: and i1 %[[ISFINITE]], %[[ISNORMAL]]
 
   res = __builtin_flt_rounds();
   // CHECK: call i32 @llvm.get.rounding(
Index: clang/lib/CodeGen/CGBuiltin.cpp
===================================================================
--- clang/lib/CodeGen/CGBuiltin.cpp
+++ clang/lib/CodeGen/CGBuiltin.cpp
@@ -3305,22 +3305,18 @@
   }
 
   case Builtin::BI__builtin_isnormal: {
-    // isnormal(x) --> x == x && fabsf(x) < infinity && fabsf(x) >= float_min
+    // isnormal(x) --> fabs(x) < infinity && !(fabs(x) < float_min)
     CodeGenFunction::CGFPOptionsRAII FPOptsRAII(*this, E);
     // FIXME: for strictfp/IEEE-754 we need to not trap on SNaN here.
     Value *V = EmitScalarExpr(E->getArg(0));
-    Value *Eq = Builder.CreateFCmpOEQ(V, V, "iseq");
-
     Value *Abs = EmitFAbs(*this, V);
-    Value *IsLessThanInf =
-      Builder.CreateFCmpULT(Abs, ConstantFP::getInfinity(V->getType()),"isinf");
-    APFloat Smallest = APFloat::getSmallestNormalized(
-                   getContext().getFloatTypeSemantics(E->getArg(0)->getType()));
-    Value *IsNormal =
-      Builder.CreateFCmpUGE(Abs, ConstantFP::get(V->getContext(), Smallest),
-                            "isnormal");
-    V = Builder.CreateAnd(Eq, IsLessThanInf, "and");
-    V = Builder.CreateAnd(V, IsNormal, "and");
+    Value *IsFinite = Builder.CreateFCmpOLT(
+        Abs, ConstantFP::getInfinity(V->getType()), "isfinite");
+    APFloat SmallestNormal = APFloat::getSmallestNormalized(
+        getContext().getFloatTypeSemantics(E->getArg(0)->getType()));
+    Value *IsNormal = Builder.CreateFCmpUGE(
+        Abs, ConstantFP::get(V->getContext(), SmallestNormal), "isnormal");
+    V = Builder.CreateAnd(IsFinite, IsNormal, "and");
     return RValue::get(Builder.CreateZExt(V, ConvertType(E->getType())));
   }
 


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