avoid using a constant table when a constant can be used inline

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@32580 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 92 insertions, 24 deletions

diff --git a/lib/Target/ARM/ARMISelDAGToDAG.cpp b/lib/Target/ARM/ARMISelDAGToDAG.cpp
index 6abc097c4c..fadeb2a09c 100644
--- a/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -660,14 +660,91 @@ static SDOperand GetARMCC(ISD::CondCode CC, MVT::ValueType vt,
     return DAG.getConstant(DAGFPCCToARMCC(CC), MVT::i32);
 }
 
+static bool isUInt8Immediate(uint32_t x) {
+  return x < (1 << 8);
+}
+
+static uint32_t rotateL(uint32_t x) {
+  uint32_t bit31 = (x & (1 << 31)) >> 31;
+  uint32_t     t = x << 1;
+  return t | bit31;
+}
+
+static bool isRotInt8Immediate(uint32_t x) {
+  int r;
+  for (r = 0; r < 16; r++) {
+    if (isUInt8Immediate(x))
+      return true;
+    x = rotateL(rotateL(x));
+  }
+  return false;
+}
+
+static void LowerCMP(SDOperand &Cmp, SDOperand &ARMCC, SDOperand LHS,
+                     SDOperand RHS, ISD::CondCode CC, SelectionDAG &DAG) {
+  MVT::ValueType vt = LHS.getValueType();
+  if (vt == MVT::i32) {
+    assert(!isa<ConstantSDNode>(LHS));
+    if (ConstantSDNode *SD_C = dyn_cast<ConstantSDNode>(RHS.Val)) {
+      uint32_t C = SD_C->getValue();
+
+      uint32_t NC;
+      switch(CC) {
+      default:
+        NC = C; break;
+      case ISD::SETLT:
+      case ISD::SETULT:
+      case ISD::SETGE:
+      case ISD::SETUGE:
+        NC = C - 1; break;
+      case ISD::SETLE:
+      case ISD::SETULE:
+      case ISD::SETGT:
+      case ISD::SETUGT:
+        NC = C + 1; break;
+      }
+
+      ISD::CondCode NCC;
+      switch(CC) {
+      default:
+        NCC = CC; break;
+      case ISD::SETLT:
+        NCC = ISD::SETLE; break;
+      case ISD::SETULT:
+        NCC = ISD::SETULE; break;
+      case ISD::SETGE:
+        NCC = ISD::SETGT; break;
+      case ISD::SETUGE:
+        NCC = ISD::SETUGT; break;
+      case ISD::SETLE:
+        NCC = ISD::SETLT; break;
+      case ISD::SETULE:
+        NCC = ISD::SETULT; break;
+      case ISD::SETGT:
+        NCC = ISD::SETGE; break;
+      case ISD::SETUGT:
+        NCC = ISD::SETUGE; break;
+      }
+
+      if (!isRotInt8Immediate(C) && isRotInt8Immediate(NC)) {
+        RHS = DAG.getConstant(NC, MVT::i32);
+        CC  = NCC;
+      }
+    }
+  }
+  Cmp   = GetCMP(CC, LHS, RHS, DAG);
+  ARMCC = GetARMCC(CC, vt, DAG);
+}
+
 static SDOperand LowerSELECT_CC(SDOperand Op, SelectionDAG &DAG) {
   SDOperand LHS = Op.getOperand(0);
   SDOperand RHS = Op.getOperand(1);
   ISD::CondCode CC = cast<CondCodeSDNode>(Op.getOperand(4))->get();
   SDOperand TrueVal = Op.getOperand(2);
   SDOperand FalseVal = Op.getOperand(3);
-  SDOperand      Cmp = GetCMP(CC, LHS, RHS, DAG);
-  SDOperand    ARMCC = GetARMCC(CC, LHS.getValueType(), DAG);
+  SDOperand Cmp;
+  SDOperand ARMCC;
+  LowerCMP(Cmp, ARMCC, LHS, RHS, CC, DAG);
   return DAG.getNode(ARMISD::SELECT, MVT::i32, TrueVal, FalseVal, ARMCC, Cmp);
 }
 
@@ -677,8 +754,9 @@ static SDOperand LowerBR_CC(SDOperand Op, SelectionDAG &DAG) {
   SDOperand    LHS = Op.getOperand(2);
   SDOperand    RHS = Op.getOperand(3);
   SDOperand   Dest = Op.getOperand(4);
-  SDOperand    Cmp = GetCMP(CC, LHS, RHS, DAG);
-  SDOperand  ARMCC = GetARMCC(CC, LHS.getValueType(), DAG);
+  SDOperand Cmp;
+  SDOperand ARMCC;
+  LowerCMP(Cmp, ARMCC, LHS, RHS, CC, DAG);
   return DAG.getNode(ARMISD::BR, MVT::Other, Chain, Dest, ARMCC, Cmp);
 }
 
@@ -820,26 +898,6 @@ static bool isInt12Immediate(SDOperand Op, short &Imm) {
   return isInt12Immediate(Op.Val, Imm);
 }
 
-static uint32_t rotateL(uint32_t x) {
-  uint32_t bit31 = (x & (1 << 31)) >> 31;
-  uint32_t     t = x << 1;
-  return t | bit31;
-}
-
-static bool isUInt8Immediate(uint32_t x) {
-  return x < (1 << 8);
-}
-
-static bool isRotInt8Immediate(uint32_t x) {
-  int r;
-  for (r = 0; r < 16; r++) {
-    if (isUInt8Immediate(x))
-      return true;
-    x = rotateL(rotateL(x));
-  }
-  return false;
-}
-
 bool ARMDAGToDAGISel::SelectAddrMode1(SDOperand Op,
                                       SDOperand N,
 				      SDOperand &Arg,
diff --git a/test/CodeGen/ARM/constants.ll b/test/CodeGen/ARM/constants.ll
index 0d69f53585..3d7b9a498b 100644
--- a/test/CodeGen/ARM/constants.ll
+++ b/test/CodeGen/ARM/constants.ll
@@ -5,6 +5,7 @@
 ; RUN: llvm-upgrade < %s | llvm-as | llc -march=arm | grep ".word.*257" | wc -l | grep 1 &&
 ; RUN: llvm-upgrade < %s | llvm-as | llc -march=arm | grep "mov r0, #-1073741761" | wc -l | grep 1 &&
 ; RUN: llvm-upgrade < %s | llvm-as | llc -march=arm | grep "mov r0, #1008" | wc -l | grep 1 &&
+; RUN: llvm-upgrade < %s | llvm-as | llc -march=arm | grep "cmp r0, #65536" | wc -l | grep 1 &&
 ; RUN: llvm-upgrade < %s | llvm-as | llc -march=arm | grep "\.comm.*a,4,4" | wc -l | grep 1
 
 %a = internal global int 0
@@ -32,3 +33,12 @@ uint %f5() {
 uint %f6() {
   ret uint 1008
 }
+
+void %f7(uint %a) {
+entry:
+	%b = setgt uint %a, 65536
+	br bool %b, label %r, label %r
+
+r:
+	ret void
+}