'optnone' should not disable DAG combiner.

Reverts the code change from r221168 and the relevant test.
It was a mistake to disable the combiner, and based on the ultimate
definition of 'optnone' we shouldn't have considered the test case
as failing in the first place.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233153 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -1183,11 +1183,6 @@ void DAGCombiner::Run(CombineLevel AtLevel) {
   LegalOperations = Level >= AfterLegalizeVectorOps;
   LegalTypes = Level >= AfterLegalizeTypes;
 
-  // Early exit if this basic block is in an optnone function.
-  if (DAG.getMachineFunction().getFunction()->hasFnAttribute(
-          Attribute::OptimizeNone))
-    return;
-
   // Add all the dag nodes to the worklist.
   for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
        E = DAG.allnodes_end(); I != E; ++I)

test/CodeGen/X86/fastmath-optnone.ll

@@ -1,35 +0,0 @@
-; RUN: llc < %s -mcpu=corei7 -march=x86-64 -mattr=+sse2 | FileCheck %s
-; Verify that floating-point operations inside 'optnone' functions
-; are not optimized even if unsafe-fp-math is set.
-
-define float @foo(float %x) #0 {
-entry:
-  %add = fadd fast float %x, %x
-  %add1 = fadd fast float %add, %x
-  ret float %add1
-}
-
-; CHECK-LABEL: @foo
-; CHECK-NOT: add
-; CHECK: mul
-; CHECK-NOT: add
-; CHECK: ret
-
-define float @fooWithOptnone(float %x) #1 {
-entry:
-  %add = fadd fast float %x, %x
-  %add1 = fadd fast float %add, %x
-  ret float %add1
-}
-
-; CHECK-LABEL: @fooWithOptnone
-; CHECK-NOT: mul
-; CHECK: add
-; CHECK-NOT: mul
-; CHECK: add
-; CHECK-NOT: mul
-; CHECK: ret
-
-
-attributes #0 = { "unsafe-fp-math"="true" }
-attributes #1 = { noinline optnone "unsafe-fp-math"="true" }