From 10e6427e7a5d9bd8f7cd65be55502b0cac969563 Mon Sep 17 00:00:00 2001
From: Michael Berg <michael_c_berg@apple.com>
Date: Thu, 14 Jun 2018 20:54:13 +0000
Subject: [PATCH] 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

llvm-svn: 334769
---
 lib/CodeGen/SelectionDAG/DAGCombiner.cpp |  4 ----
 test/CodeGen/ARM/fnmul.ll                | 12 +++++-------
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 33821c33bb7..1b32870cd79 100644
--- 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 e14e5baeb8a..b021de8b7ad 100644
--- 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