Fold bitconv(bitconv(x)) -> x. We now compile this:
void foo(double);
void bar(double X) { foo(X); }
to this:
bar:
save -96, %o6, %o6
or %g0, %i0, %o0
or %g0, %i1, %o1
call foo
nop
restore %g0, %g0, %g0
retl
nop
instead of this:
bar:
save -112, %o6, %o6
st %i1, [%i6+-4]
st %i0, [%i6+-8]
ldd [%i6+-8], %f0
std %f0, [%i6+-16]
ld [%i6+-12], %o1
ld [%i6+-16], %o0
call foo
nop
restore %g0, %g0, %g0
retl
nop
on V8.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@24981 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 76d983f..b510f1c 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -916,6 +916,8 @@
assert(MVT::getSizeInBits(VT)==MVT::getSizeInBits(Operand.getValueType()) &&
"Cannot BIT_CONVERT between two different types!");
if (VT == Operand.getValueType()) return Operand; // noop conversion.
+ if (OpOpcode == ISD::BIT_CONVERT) // bitconv(bitconv(x)) -> bitconv(x)
+ return getNode(ISD::BIT_CONVERT, VT, Operand.getOperand(0));
break;
case ISD::FNEG:
if (OpOpcode == ISD::FSUB) // -(X-Y) -> (Y-X)