[clang] Missed rounding mode use in constant evaluation

[sepavloff]

Summary

Integer-to-float conversion was handled in constant evaluator with
default rounding mode. This change fixes the behavior and the conversion
is made using rounding mode stored in ImplicitCastExpr node.

[tbaeder]

clang/lib/AST/ExprConstant.cpp

2653

SrcType was already unused before, but not so is FPO.

[tbaeder]

clang/lib/AST/ExprConstant.cpp

2653

now so is FPO.

[sepavloff]

Removed unused parateters from HandleIntToFloatCast

[sepavloff]

Remove accidentally added file

[sepavloff]

Ping.

[aaron.ballman]

The changes look correct to me, but adding @jcranmer-intel for floating-point expertise.

clang/test/AST/const-fpfeatures.c

37

Should we add a test without the -fexperimental-strict-floating-point on the RUN line?

[rjmccall]

Looks good to me.

[sepavloff]

Thanks!

clang/test/AST/const-fpfeatures.c

37

Yes, I will remove it.

clang/lib/AST/ExprConstant.cpp

static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E,
   return Result;
 }
 
 static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E,
                                  const FPOptions FPO,
                                  QualType SrcType, const APSInt &Value,
                                  QualType DestType, APFloat &Result) {
   Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1);
-  APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(),
-       APFloat::rmNearestTiesToEven);
-  if (!Info.InConstantContext && St != llvm::APFloatBase::opOK &&
-      FPO.isFPConstrained()) {
-    Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict);
-    return false;
-  }
-  return true;
+  llvm::RoundingMode RM = getActiveRoundingMode(Info, E);
+  APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(), RM);
+  return checkFloatingPointResult(Info, E, St);
 }
 
 static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E,
                                   APValue &Value, const FieldDecl *FD) {
   assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield");
 
   if (!Value.isInt()) {
     // Trying to store a pointer-cast-to-integer into a bitfield.

clang/test/AST/const-fpfeatures.c

-// RUN: %clang_cc1 -fexperimental-strict-floating-point -S -emit-llvm -triple i386-linux -Wno-unknown-pragmas %s -o - | FileCheck %s
+// RUN: %clang_cc1 -S -emit-llvm -triple i386-linux -Wno-unknown-pragmas %s -o - | FileCheck %s
 
 // nextUp(1.F) == 0x1.000002p0F
 
 const double _Complex C0 = 0x1.000001p0 + 0x1.000001p0I;
 
 #pragma STDC FENV_ROUND FE_UPWARD
 
 float F1u = 1.0F + 0x0.000002p0F;
 float F2u = 1.0F + 0x0.000001p0F;
 float F3u = 0x1.000001p0;
 // CHECK: @F1u = {{.*}} float 0x3FF0000020000000
 // CHECK: @F2u = {{.*}} float 0x3FF0000020000000
 // CHECK: @F3u = {{.*}} float 0x3FF0000020000000
 
+float FI1u = 0xFFFFFFFFU;
+// CHECK: @FI1u = {{.*}} float 0x41F0000000000000
+
 float _Complex C1u = C0;
 // CHECK: @C1u = {{.*}} { float, float } { float 0x3FF0000020000000, float 0x3FF0000020000000 }
 
 
 #pragma STDC FENV_ROUND FE_DOWNWARD
 
 float F1d = 1.0F + 0x0.000002p0F;
 float F2d = 1.0F + 0x0.000001p0F;
 float F3d = 0x1.000001p0;
 
 // CHECK: @F1d = {{.*}} float 0x3FF0000020000000
 // CHECK: @F2d = {{.*}} float 1.000000e+00
 // CHECK: @F3d = {{.*}} float 1.000000e+00
 
+float FI1d = 0xFFFFFFFFU;
+// CHECK: @FI1d = {{.*}} float 0x41EFFFFFE0000000
+
 float _Complex C1d = C0;
 // CHECK: @C1d = {{.*}} { float, float } { float 1.000000e+00, float 1.000000e+00 }