Add ExpandFloatOp_FCOPYSIGN to handle ppcf128-related expansions

We had previously been asserting when faced with a FCOPYSIGN f64, ppcf128 node
because there was no way to expand the FCOPYSIGN node. Because ppcf128 is the
sum of two doubles, and the first double must have the larger magnitude, we
can take the sign from the first double. As a result, in addition to fixing the
crash, this is also an optimization.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188655 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 80 insertions, 0 deletions

diff --git a/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp b/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
index facd6948b75..83cad10e246 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeFloatTypes.cpp
@@ -1277,6 +1277,7 @@ bool DAGTypeLegalizer::ExpandFloatOperand(SDNode *N, unsigned OpNo) {
   case ISD::EXTRACT_ELEMENT: Res = ExpandOp_EXTRACT_ELEMENT(N); break;
 
   case ISD::BR_CC:      Res = ExpandFloatOp_BR_CC(N); break;
+  case ISD::FCOPYSIGN:  Res = ExpandFloatOp_FCOPYSIGN(N); break;
   case ISD::FP_ROUND:   Res = ExpandFloatOp_FP_ROUND(N); break;
   case ISD::FP_TO_SINT: Res = ExpandFloatOp_FP_TO_SINT(N); break;
   case ISD::FP_TO_UINT: Res = ExpandFloatOp_FP_TO_UINT(N); break;
@@ -1351,6 +1352,17 @@ SDValue DAGTypeLegalizer::ExpandFloatOp_BR_CC(SDNode *N) {
                                 N->getOperand(4)), 0);
 }
 
+SDValue DAGTypeLegalizer::ExpandFloatOp_FCOPYSIGN(SDNode *N) {
+  assert(N->getOperand(1).getValueType() == MVT::ppcf128 &&
+         "Logic only correct for ppcf128!");
+  SDValue Lo, Hi;
+  GetExpandedFloat(N->getOperand(1), Lo, Hi);
+  // The ppcf128 value is providing only the sign; take it from the
+  // higher-order double (which must have the larger magnitude).
+  return DAG.getNode(ISD::FCOPYSIGN, SDLoc(N),
+                     N->getValueType(0), N->getOperand(0), Hi);
+}
+
 SDValue DAGTypeLegalizer::ExpandFloatOp_FP_ROUND(SDNode *N) {
   assert(N->getOperand(0).getValueType() == MVT::ppcf128 &&
          "Logic only correct for ppcf128!");
diff --git a/lib/CodeGen/SelectionDAG/LegalizeTypes.h b/lib/CodeGen/SelectionDAG/LegalizeTypes.h
index a7262704575..d5d230a49a0 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeTypes.h
+++ b/lib/CodeGen/SelectionDAG/LegalizeTypes.h
@@ -482,6 +482,7 @@ private:
   // Float Operand Expansion.
   bool ExpandFloatOperand(SDNode *N, unsigned OperandNo);
   SDValue ExpandFloatOp_BR_CC(SDNode *N);
+  SDValue ExpandFloatOp_FCOPYSIGN(SDNode *N);
   SDValue ExpandFloatOp_FP_ROUND(SDNode *N);
   SDValue ExpandFloatOp_FP_TO_SINT(SDNode *N);
   SDValue ExpandFloatOp_FP_TO_UINT(SDNode *N);
diff --git a/test/CodeGen/PowerPC/copysignl.ll b/test/CodeGen/PowerPC/copysignl.ll
new file mode 100644
index 00000000000..4b801b791d6
--- /dev/null
+++ b/test/CodeGen/PowerPC/copysignl.ll
@@ -0,0 +1,67 @@
+; RUN: llc -mcpu=pwr7 -mtriple=powerpc64-unknown-linux-gnu < %s | FileCheck %s
+target datalayout = "E-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-f128:128:128-v128:128:128-n32:64"
+target triple = "powerpc64-unknown-linux-gnu"
+
+define double @foo_d_ll(ppc_fp128 %a, ppc_fp128 %b) #0 {
+entry:
+  %call = tail call ppc_fp128 @copysignl(ppc_fp128 %a, ppc_fp128 %b) #0
+  %conv = fptrunc ppc_fp128 %call to double
+  ret double %conv
+
+; CHECK-LABEL: @foo_d_ll
+; CHECK: fcpsgn 1, 3, 1
+; CHECK: blr
+}
+
+declare ppc_fp128 @copysignl(ppc_fp128, ppc_fp128) #0
+
+define double @foo_dl(double %a, ppc_fp128 %b) #0 {
+entry:
+  %conv = fptrunc ppc_fp128 %b to double
+  %call = tail call double @copysign(double %a, double %conv) #0
+  ret double %call
+
+; CHECK-LABEL: @foo_dl
+; CHECK: fcpsgn 1, 2, 1
+; CHECK: blr
+}
+
+declare double @copysign(double, double) #0
+
+define ppc_fp128 @foo_ll(double %a, ppc_fp128 %b) #0 {
+entry:
+  %conv = fpext double %a to ppc_fp128
+  %call = tail call ppc_fp128 @copysignl(ppc_fp128 %conv, ppc_fp128 %b) #0
+  ret ppc_fp128 %call
+
+; CHECK-LABEL: @foo_ll
+; CHECK: bl copysignl
+; CHECK: blr
+}
+
+define ppc_fp128 @foo_ld(double %a, double %b) #0 {
+entry:
+  %conv = fpext double %a to ppc_fp128
+  %conv1 = fpext double %b to ppc_fp128
+  %call = tail call ppc_fp128 @copysignl(ppc_fp128 %conv, ppc_fp128 %conv1) #0
+  ret ppc_fp128 %call
+
+; CHECK-LABEL: @foo_ld
+; CHECK: bl copysignl
+; CHECK: blr
+}
+
+define ppc_fp128 @foo_lf(double %a, float %b) #0 {
+entry:
+  %conv = fpext double %a to ppc_fp128
+  %conv1 = fpext float %b to ppc_fp128
+  %call = tail call ppc_fp128 @copysignl(ppc_fp128 %conv, ppc_fp128 %conv1) #0
+  ret ppc_fp128 %call
+
+; CHECK-LABEL: @foo_lf
+; CHECK: bl copysignl
+; CHECK: blr
+}
+
+attributes #0 = { nounwind readnone }
+