easing the constraint for isNegatibleForFree and GetNegatedExpression

Summary:
Here we relax the old constraint which utilized unsafe with the TargetOption flag HonorSignDependentRoundingFPMathOption, with the assertion that unsafe is no longer needed or never was required for correctness on FDIV/FMUL.

Reviewers: spatel, hfinkel, wristow, arsenm, javed.absar

Reviewed By: spatel

Subscribers: efriedma, wdng, tpr

Differential Revision: https://reviews.llvm.org/D48057

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334769 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 33821c3..1b32870 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -729,8 +729,6 @@ static char isNegatibleForFree(SDValue Op, bool LegalOperations,
 
   case ISD::FMUL:
   case ISD::FDIV:
-    if (Options->HonorSignDependentRoundingFPMath()) return 0;
-
     // fold (fneg (fmul X, Y)) -> (fmul (fneg X), Y) or (fmul X, (fneg Y))
     if (char V = isNegatibleForFree(Op.getOperand(0), LegalOperations, TLI,
                                     Options, Depth + 1))
@@ -792,8 +790,6 @@ static SDValue GetNegatedExpression(SDValue Op, SelectionDAG &DAG,
 
   case ISD::FMUL:
   case ISD::FDIV:
-    assert(!Options.HonorSignDependentRoundingFPMath());
-
     // fold (fneg (fmul X, Y)) -> (fmul (fneg X), Y)
     if (isNegatibleForFree(Op.getOperand(0), LegalOperations,
                            DAG.getTargetLoweringInfo(), &Options, Depth+1))

diff --git a/test/CodeGen/ARM/fnmul.ll b/test/CodeGen/ARM/fnmul.ll
index e14e5ba..b021de8 100644 (file)
--- a/test/CodeGen/ARM/fnmul.ll
+++ b/test/CodeGen/ARM/fnmul.ll
@@ -1,17 +1,15 @@
-; RUN: llc -mtriple=arm-eabi -mattr=+v6,+vfp2 %s -o - | FileCheck %s
-
-; RUN: llc -mtriple=arm-eabi -mattr=+v6,+vfp2 -enable-sign-dependent-rounding-fp-math %s -o - \
-; RUN:  | FileCheck %s -check-prefix CHECK-ROUNDING
-
+; RUN: llc -mtriple=arm-eabi -mattr=+v6,+vfp2 %s -o -                        | FileCheck %s -check-prefix STRICT
 
+; RUN: llc -mtriple=arm-eabi -mattr=+v6,+vfp2 -enable-unsafe-fp-math %s -o - | FileCheck %s -check-prefix UNSAFE
 
 define double @t1(double %a, double %b) {
+; STRICT:    vnmul.f64
+;
+; UNSAFE:    vnmul.f64
 entry:
         %tmp2 = fsub double -0.000000e+00, %a            ; <double> [#uses=1]
         %tmp4 = fmul double %tmp2, %b            ; <double> [#uses=1]
         ret double %tmp4
 }
 
-; CHECK: vnmul.f64
-; CHECK-ROUNDING: vmul.f64