Optimize some vfp comparisons to integer ones. This patch implements the simplest...

1. The arguments are f32.
2. The arguments are loads and they have no uses other than the comparison.
3. The comparison code is EQ or NE.

e.g.
        vldr.32 s0, [r1]
        vldr.32 s1, [r0]
        vcmpe.f32       s1, s0
        vmrs    apsr_nzcv, fpscr
	beq     LBB0_2
=>
        ldr     r1, [r1]
        ldr     r0, [r0]
        cmp     r0, r1
        beq     LBB0_2

More complicated cases will be implemented in subsequent patches.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107852 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index 8670d37c83681a3eeffc7ebcfaf4b5c6565f56ff..e3db58329802132c345b42f766f5ea27522de9b9 100644 (file)
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -59,7 +59,7 @@ EnableARMTailCalls("arm-tail-calls", cl::Hidden,
 
 static cl::opt<bool>
 EnableARMLongCalls("arm-long-calls", cl::Hidden,
-  cl::desc("Generate calls via indirect call instructions."),
+  cl::desc("Generate calls via indirect call instructions"),
   cl::init(false));
 
 static cl::opt<bool>
@@ -69,7 +69,7 @@ ARMInterworking("arm-interworking", cl::Hidden,
 
 static cl::opt<bool>
 EnableARMCodePlacement("arm-code-placement", cl::Hidden,
-  cl::desc("Enable code placement pass for ARM."),
+  cl::desc("Enable code placement pass for ARM"),
   cl::init(false));
 
 static bool CC_ARM_APCS_Custom_f64(unsigned &ValNo, EVT &ValVT, EVT &LocVT,
@@ -2273,9 +2273,42 @@ ARMTargetLowering::getARMCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
   return DAG.getNode(CompareType, dl, MVT::Flag, LHS, RHS);
 }
 
+static bool canBitcastToInt(SDNode *Op) {
+  return Op->hasOneUse() && 
+    ISD::isNormalLoad(Op) &&
+    Op->getValueType(0) == MVT::f32;
+}
+
+static SDValue bitcastToInt(SDValue Op, SelectionDAG &DAG) {
+  if (LoadSDNode *Ld = dyn_cast<LoadSDNode>(Op))
+    return DAG.getLoad(MVT::i32, Op.getDebugLoc(),
+                       Ld->getChain(), Ld->getBasePtr(),
+                       Ld->getSrcValue(), Ld->getSrcValueOffset(),
+                       Ld->isVolatile(), Ld->isNonTemporal(),
+                       Ld->getAlignment());
+
+  llvm_unreachable("Unknown VFP cmp argument!");
+}
+
 /// Returns a appropriate VFP CMP (fcmp{s|d}+fmstat) for the given operands.
-static SDValue getVFPCmp(SDValue LHS, SDValue RHS, SelectionDAG &DAG,
-                         DebugLoc dl) {
+SDValue
+ARMTargetLowering::getVFPCmp(SDValue &LHS, SDValue &RHS, ISD::CondCode CC,
+                             SDValue &ARMCC, SelectionDAG &DAG,
+                             DebugLoc dl) const {
+  if ((CC == ISD::SETEQ || CC == ISD::SETOEQ ||
+       CC == ISD::SETNE || CC == ISD::SETUNE) &&
+      canBitcastToInt(LHS.getNode()) && canBitcastToInt(RHS.getNode())) {
+    // If there are no othter uses of the CMP operands, and the condition
+    // code is EQ oe NE, we can optimize it to an integer comparison.
+    if (CC == ISD::SETOEQ)
+      CC = ISD::SETEQ;
+    else if (CC == ISD::SETUNE)
+      CC = ISD::SETNE;
+    LHS = bitcastToInt(LHS, DAG);
+    RHS = bitcastToInt(RHS, DAG);
+    return getARMCmp(LHS, RHS, CC, ARMCC, DAG, dl);
+  }
+
   SDValue Cmp;
   if (!isFloatingPointZero(RHS))
     Cmp = DAG.getNode(ARMISD::CMPFP, dl, MVT::Flag, LHS, RHS);
@@ -2305,13 +2338,13 @@ SDValue ARMTargetLowering::LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const {
 
   SDValue ARMCC = DAG.getConstant(CondCode, MVT::i32);
   SDValue CCR = DAG.getRegister(ARM::CPSR, MVT::i32);
-  SDValue Cmp = getVFPCmp(LHS, RHS, DAG, dl);
+  SDValue Cmp = getVFPCmp(LHS, RHS, CC, ARMCC, DAG, dl);
   SDValue Result = DAG.getNode(ARMISD::CMOV, dl, VT, FalseVal, TrueVal,
-                                 ARMCC, CCR, Cmp);
+                               ARMCC, CCR, Cmp);
   if (CondCode2 != ARMCC::AL) {
     SDValue ARMCC2 = DAG.getConstant(CondCode2, MVT::i32);
     // FIXME: Needs another CMP because flag can have but one use.
-    SDValue Cmp2 = getVFPCmp(LHS, RHS, DAG, dl);
+    SDValue Cmp2 = getVFPCmp(LHS, RHS, CC, ARMCC2, DAG, dl);
     Result = DAG.getNode(ARMISD::CMOV, dl, VT,
                          Result, TrueVal, ARMCC2, CCR, Cmp2);
   }
@@ -2338,8 +2371,8 @@ SDValue ARMTargetLowering::LowerBR_CC(SDValue Op, SelectionDAG &DAG) const {
   ARMCC::CondCodes CondCode, CondCode2;
   FPCCToARMCC(CC, CondCode, CondCode2);
 
-  SDValue Cmp = getVFPCmp(LHS, RHS, DAG, dl);
   SDValue ARMCC = DAG.getConstant(CondCode, MVT::i32);
+  SDValue Cmp = getVFPCmp(LHS, RHS, CC, ARMCC, DAG, dl);
   SDValue CCR = DAG.getRegister(ARM::CPSR, MVT::i32);
   SDVTList VTList = DAG.getVTList(MVT::Other, MVT::Flag);
   SDValue Ops[] = { Chain, Dest, ARMCC, CCR, Cmp };
@@ -2427,7 +2460,7 @@ static SDValue LowerINT_TO_FP(SDValue Op, SelectionDAG &DAG) {
   return DAG.getNode(Opc, dl, VT, Op);
 }
 
-static SDValue LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) {
+SDValue ARMTargetLowering::LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) const {
   // Implement fcopysign with a fabs and a conditional fneg.
   SDValue Tmp0 = Op.getOperand(0);
   SDValue Tmp1 = Op.getOperand(1);
@@ -2435,8 +2468,10 @@ static SDValue LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) {
   EVT VT = Op.getValueType();
   EVT SrcVT = Tmp1.getValueType();
   SDValue AbsVal = DAG.getNode(ISD::FABS, dl, VT, Tmp0);
-  SDValue Cmp = getVFPCmp(Tmp1, DAG.getConstantFP(0.0, SrcVT), DAG, dl);
   SDValue ARMCC = DAG.getConstant(ARMCC::LT, MVT::i32);
+  SDValue FP0 = DAG.getConstantFP(0.0, SrcVT);
+  SDValue Cmp = getVFPCmp(Tmp1, FP0,
+                          ISD::SETLT, ARMCC, DAG, dl);
   SDValue CCR = DAG.getRegister(ARM::CPSR, MVT::i32);
   return DAG.getNode(ARMISD::CNEG, dl, VT, AbsVal, AbsVal, ARMCC, CCR, Cmp);
 }

diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index c85832499c06a26e54ef64b4997ecc523e84ad8d..3a3866928a0e99246b3e578cec08e28220f09d0b 100644 (file)
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -313,6 +313,7 @@ namespace llvm {
     SDValue LowerBR_JT(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerSELECT_CC(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerBR_CC(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerFCOPYSIGN(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerRETURNADDR(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerFRAMEADDR(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
@@ -363,6 +364,8 @@ namespace llvm {
 
     SDValue getARMCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
                       SDValue &ARMCC, SelectionDAG &DAG, DebugLoc dl) const;
+    SDValue getVFPCmp(SDValue &LHS, SDValue &RHS, ISD::CondCode CC,
+                      SDValue &ARMCC, SelectionDAG &DAG, DebugLoc dl) const;
 
     MachineBasicBlock *EmitAtomicCmpSwap(MachineInstr *MI,
                                          MachineBasicBlock *BB,

diff --git a/test/CodeGen/ARM/fpcmp-opt.ll b/test/CodeGen/ARM/fpcmp-opt.ll
new file mode 100644 (file)
index 0000000..ed515cc
--- /dev/null
+++ b/test/CodeGen/ARM/fpcmp-opt.ll
@@ -0,0 +1,29 @@
+; RUN: llc < %s -march=arm -mattr=+vfp2 | FileCheck %s
+; rdar://7461510
+
+define arm_apcscc i32 @t1(float* %a, float* %b) nounwind {
+entry:
+; CHECK: t1:
+; CHECK-NOT: vldr
+; CHECK: ldr
+; CHECK: ldr
+; CHECK: cmp r0, r1
+; CHECK-NOT: vcmpe.f32
+; CHECK-NOT: vmrs
+; CHECK: beq
+  %0 = load float* %a
+  %1 = load float* %b
+  %2 = fcmp une float %0, %1
+  br i1 %2, label %bb1, label %bb2
+
+bb1:
+  %3 = call i32 @bar()
+  ret i32 %3
+
+bb2:
+  %4 = call i32 @foo()
+  ret i32 %4
+}
+
+declare i32 @bar()
+declare i32 @foo()