[PATCH 1/1] SelectionDAG: Add sext_inreg optimizations

[Jan Vesely]

Signed-off-by: Jan Vesely <jan.vesely at rutgers.edu>
---

 lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 22 ++++++++++++++++++++++
 test/CodeGen/R600/sext-eliminate.ll      | 26 ++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 test/CodeGen/R600/sext-eliminate.ll

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 76442fb..fdffd77 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -1680,6 +1680,17 @@ SDValue DAGCombiner::visitADD(SDNode *N) {
     return DAG.getNode(ISD::SUB, DL, VT, N1, ZExt);
   }
 
+  // add X, (sextinreg i1) -> sub X, (and i1 1)
+  if (N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
+    VTSDNode *TN = static_cast<VTSDNode*>(N1.getOperand(1).getNode());
+    if (TN->getVT() == MVT::i1) {
+      SDLoc DL(N);
+      SDValue ZExt = DAG.getNode(ISD::AND, DL, VT, N1.getOperand(0),
+                                 DAG.getConstant(1, VT));
+      return DAG.getNode(ISD::SUB, DL, VT, N0, ZExt);
+    }
+  }
+
   return SDValue();
 }
 
@@ -1845,6 +1856,17 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
                                  VT);
     }
 
+  // sub X, (sextinreg i1) -> add X, (and i1 1)
+  if (N1.getOpcode() == ISD::SIGN_EXTEND_INREG) {
+    VTSDNode *TN = static_cast<VTSDNode*>(N1.getOperand(1).getNode());
+    if (TN->getVT() == MVT::i1) {
+      SDLoc DL(N);
+      SDValue ZExt = DAG.getNode(ISD::AND, DL, VT, N1.getOperand(0),
+                                 DAG.getConstant(1, VT));
+      return DAG.getNode(ISD::ADD, DL, VT, N0, ZExt);
+    }
+  }
+
   return SDValue();
 }
 
diff --git a/test/CodeGen/R600/sext-eliminate.ll b/test/CodeGen/R600/sext-eliminate.ll
new file mode 100644
index 0000000..0c17a7a
--- /dev/null
+++ b/test/CodeGen/R600/sext-eliminate.ll
@@ -0,0 +1,26 @@
+; RUN: llc -march=r600 -mcpu=cypress -verify-machineinstrs < %s | FileCheck -check-prefix=EG -check-prefix=FUNC %s
+
+
+; FUNC-LABEL: {{^}}sext_in_reg_i1_i32_add:
+
+; EG: MEM_{{.*}} STORE_{{.*}} [[RES:T[0-9]+\.[XYZW]]], [[ADDR:T[0-9]+.[XYZW]]]
+; EG: SUB_INT {{[* ]*}}[[RES]]
+; EG-NOT: BFE
+define void @sext_in_reg_i1_i32_add(i32 addrspace(1)* %out, i1 %a, i32 %b) {
+  %sext = sext i1 %a to i32
+  %res = add i32 %b, %sext 
+  store i32 %res, i32 addrspace(1)* %out
+  ret void
+}
+
+; FUNC-LABEL: {{^}}sext_in_reg_i1_i32_sub:
+
+; EG: MEM_{{.*}} STORE_{{.*}} [[RES:T[0-9]+\.[XYZW]]], [[ADDR:T[0-9]+.[XYZW]]]
+; EG: ADD_INT {{[* ]*}}[[RES]]
+; EG-NOT: BFE
+define void @sext_in_reg_i1_i32_sub(i32 addrspace(1)* %out, i1 %a, i32 %b) {
+  %sext = sext i1 %a to i32
+  %res = sub i32 %b, %sext 
+  store i32 %res, i32 addrspace(1)* %out
+  ret void
+}
-- 
1.9.3