[Power9]Legalize and emit code for quad-precision convert from single-precision

[lei]

Summary

Legalize and emit code for quad-precision floating point operation conversion of single-precision value to quad-precision.

[nemanjai]

lib/Target/PowerPC/PPCISelLowering.cpp

801 ↗

(On Diff #149230)

I imagine this just goes away since it's handled in the other patch.

lib/Target/PowerPC/PPCInstrVSX.td

3386 ↗

(On Diff #149230)

Huh? We are copying the sign of the input to itself? That seems like an unnecessary noop. Why do we need that?

3388 ↗

(On Diff #149230)

These two patterns seem:

1. Redundant since we can handle loading and extending separately already anyway
2. Wrong if the weird sign copying sequence is actually necessary

We will produce a different sequence for these two equivalent snippets of code and that seems wrong:

__float128 test1(float *Ptr) {
  return *Ptr;
}

vs.

float __attribute__((noinline)) getFromPtr(float *Ptr) { return *Ptr; }
__float128 test2(float *Ptr) {
  return getFromPtr(Ptr);
}

[nemanjai]

lib/Target/PowerPC/PPCInstrVSX.td

3386 ↗

(On Diff #149230)

Oh I see the motivation here - I imagine it's because of the code coming out of GCC. If that's the case, please remove this. We do not need to replicate this. The reason they use a copy-sign instruction is actually to move the value from the FPR into a VR (we use xxlor).

On a side note, the instruction they use to copy scalar values between VSR's is a bit better since it allows for more parallelism (even if it doesn't provide shorter latency). But that's for a separate patch.

[lei]

address review comments.

[lei]

lib/Target/PowerPC/PPCISelLowering.cpp

801 ↗

(On Diff #149230)

correct!

lib/Target/PowerPC/PPCInstrVSX.td

3386 ↗

(On Diff #149230)

k

[lei]

lib/Target/PowerPC/PPCInstrVSX.td

3388 ↗

(On Diff #149230)

Is this equivalent? test1 returns *Ptr which is pass in via GPR as it's a pointer to a float, whereas test2 is returning the return value from getFromPtr which is in a FPR.

[nemanjai]

lib/Target/PowerPC/PPCInstrVSX.td

3388 ↗

(On Diff #149230)

Well sure. Semantically they're exactly the same thing - load a 4-byte float from memory, convert to __float128 and return.

[nemanjai]

LGTM. Thanks for the updates.

llvm/trunk/lib/Target/PowerPC/PPCISelLowering.cpp

bool PPCTargetLowering::isZExtFree(SDValue Val, EVT VT2) const {
   //  - zext after and by a constant mask
 
   return TargetLowering::isZExtFree(Val, VT2);
 }
 
 bool PPCTargetLowering::isFPExtFree(EVT DestVT, EVT SrcVT) const {
   assert(DestVT.isFloatingPoint() && SrcVT.isFloatingPoint() &&
          "invalid fpext types");
+  // Extending to float128 is not free.
+  if (DestVT == MVT::f128)
+    return false;
   return true;
 }
 
 bool PPCTargetLowering::isLegalICmpImmediate(int64_t Imm) const {
   return isInt<16>(Imm) || isUInt<16>(Imm);
 }
 
 bool PPCTargetLowering::isLegalAddImmediate(int64_t Imm) const {

llvm/trunk/lib/Target/PowerPC/PPCInstrVSX.td

def XSCMPGEDP : XX3_XT5_XA5_XB5<60, 19, "xscmpgedp", vsrc, vsfrc, vsfrc,
                                   IIC_FPCompare, []>;
   def XSCMPGTDP : XX3_XT5_XA5_XB5<60, 11, "xscmpgtdp", vsrc, vsfrc, vsfrc,
                                   IIC_FPCompare, []>;
 
   //===--------------------------------------------------------------------===//
   // Quad-Precision Floating-Point Conversion Instructions:
 
   // Convert DP -> QP
-  def XSCVDPQP  : X_VT5_XO5_VB5_TyVB<63, 22, 836, "xscvdpqp", vfrc, []>;
-  def : Pat<(f128 (fpextend f64:$src)), (f128 (XSCVDPQP $src))>;
+  def XSCVDPQP  : X_VT5_XO5_VB5_TyVB<63, 22, 836, "xscvdpqp", vfrc,
+                                     [(set f128:$vT, (fpextend f64:$vB))]>;
 
   // Round & Convert QP -> DP (dword[1] is set to zero)
   def XSCVQPDP  : X_VT5_XO5_VB5_VSFR<63, 20, 836, "xscvqpdp" , []>;
   def XSCVQPDPO : X_VT5_XO5_VB5_VSFR_Ro<63, 20, 836, "xscvqpdpo", []>;
 
   // Truncate & Convert QP -> (Un)Signed (D)Word (dword[1] is set to zero)
   def XSCVQPSDZ : X_VT5_XO5_VB5<63, 25, 836, "xscvqpsdz", []>;
   def XSCVQPSWZ : X_VT5_XO5_VB5<63,  9, 836, "xscvqpswz", []>;
def : Pat<(PPCstore_scal_int_from_vsr
             (STXSIHX (XSCVDPUXWS f64:$src), xoaddr:$dst)>;
   def : Pat<(PPCstore_scal_int_from_vsr
               (f64 (PPCcv_fp_to_uint_in_vsr f64:$src)), xoaddr:$dst, 1),
             (STXSIBX (XSCVDPUXWS f64:$src), xoaddr:$dst)>;
 
   // Round & Convert QP -> DP/SP
   def : Pat<(f64 (fpround f128:$src)), (f64 (XSCVQPDP $src))>;
   def : Pat<(f32 (fpround f128:$src)), (f32 (XSRSP (XSCVQPDPO $src)))>;
+
+  // Convert SP -> QP
+  def : Pat<(f128 (fpextend f32:$src)),
+            (f128 (XSCVDPQP (COPY_TO_REGCLASS $src, VFRC)))>;
+
 } // end HasP9Vector, AddedComplexity
 
 let Predicates = [HasP9Vector] in {
   let isPseudo = 1 in {
     let mayStore = 1 in {
       def SPILLTOVSR_STX : PseudoXFormMemOp<(outs),
                                             (ins spilltovsrrc:$XT, memrr:$dst),
                                             "#SPILLTOVSR_STX", []>;

llvm/trunk/test/CodeGen/PowerPC/f128-arith.ll

entry:
   ret void
 
 ; CHECK-LABEL: qpNeg
 ; CHECK-NOT: bl __subtf3
 ; CHECK: xsnegqp
 ; CHECK: stxv
 ; CHECK: blr
 }
-
-; Function Attrs: norecurse nounwind
-define void @dpConv2qp(double* nocapture readonly %a, fp128* nocapture %res) {
-entry:
-  %0 = load double, double* %a, align 8
-  %conv = fpext double %0 to fp128
-  store fp128 %conv, fp128* %res, align 16
-  ret void
-; CHECK-LABEL: dpConv2qp
-; CHECK-NOT: bl __extenddftf2
-; CHECK: lxsd
-; CHECK: xscvdpqp
-; CHECK: blr
-}
-
-; Function Attrs: norecurse nounwind
-define void @dpConv2qp_02(double %a, fp128* nocapture %res) {
-entry:
-  %conv = fpext double %a to fp128
-  store fp128 %conv, fp128* %res, align 16
-  ret void
-; CHECK-LABEL: dpConv2qp_02
-; CHECK-NOT: bl __extenddftf2
-; CHECK: xxlor
-; CHECK: xscvdpqp
-; CHECK: blr
-}

llvm/trunk/test/CodeGen/PowerPC/f128-conv.ll

 entry:
   %0 = load fp128, fp128* %a, align 16
   %1 = load fp128, fp128* %b, align 16
   %add = fadd fp128 %0, %1
   %conv = fptrunc fp128 %add to float
   store float %conv, float* %res, align 4
   ret void
 }
+
+@f128Glob = common global fp128 0xL00000000000000000000000000000000, align 16
+
+; Function Attrs: norecurse nounwind readnone
+define fp128 @dpConv2qp(double %a) {
+; CHECK-LABEL: dpConv2qp:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xxlor 2, 1, 1
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    blr
+entry:
+  %conv = fpext double %a to fp128
+  ret fp128 %conv
+}
+
+; Function Attrs: norecurse nounwind
+define void @dpConv2qp_02(double* nocapture readonly %a) {
+; CHECK-LABEL: dpConv2qp_02:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lxsd 2, 0(3)
+; CHECK-NEXT:    addis 3, 2, .LC8@toc@ha
+; CHECK-NEXT:    ld 3, .LC8@toc@l(3)
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    stxvx 2, 0, 3
+; CHECK-NEXT:    blr
+entry:
+  %0 = load double, double* %a, align 8
+  %conv = fpext double %0 to fp128
+  store fp128 %conv, fp128* @f128Glob, align 16
+  ret void
+}
+
+; Function Attrs: norecurse nounwind
+define void @dpConv2qp_02b(double* nocapture readonly %a, i32 signext %idx) {
+; CHECK-LABEL: dpConv2qp_02b:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    sldi 4, 4, 3
+; CHECK-NEXT:    lxsdx 2, 3, 4
+; CHECK-NEXT:    addis 3, 2, .LC8@toc@ha
+; CHECK-NEXT:    ld 3, .LC8@toc@l(3)
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    stxvx 2, 0, 3
+; CHECK-NEXT:    blr
+entry:
+  %idxprom = sext i32 %idx to i64
+  %arrayidx = getelementptr inbounds double, double* %a, i64 %idxprom
+  %0 = load double, double* %arrayidx, align 8
+  %conv = fpext double %0 to fp128
+  store fp128 %conv, fp128* @f128Glob, align 16
+  ret void
+}
+
+; Function Attrs: norecurse nounwind
+define void @dpConv2qp_03(fp128* nocapture %res, i32 signext %idx, double %a) {
+; CHECK-LABEL: dpConv2qp_03:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xxlor 2, 1, 1
+; CHECK-NEXT:    sldi 4, 4, 4
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    stxvx 2, 3, 4
+; CHECK-NEXT:    blr
+entry:
+  %conv = fpext double %a to fp128
+  %idxprom = sext i32 %idx to i64
+  %arrayidx = getelementptr inbounds fp128, fp128* %res, i64 %idxprom
+  store fp128 %conv, fp128* %arrayidx, align 16
+  ret void
+}
+
+; Function Attrs: norecurse nounwind
+define void @dpConv2qp_04(double %a, fp128* nocapture %res) {
+; CHECK-LABEL: dpConv2qp_04:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xxlor 2, 1, 1
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    stxv 2, 0(4)
+; CHECK-NEXT:    blr
+entry:
+  %conv = fpext double %a to fp128
+  store fp128 %conv, fp128* %res, align 16
+  ret void
+}
+
+; Function Attrs: norecurse nounwind readnone
+define fp128 @spConv2qp(float %a) {
+; CHECK-LABEL: spConv2qp:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xxlor 2, 1, 1
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    blr
+entry:
+  %conv = fpext float %a to fp128
+  ret fp128 %conv
+}
+
+; Function Attrs: norecurse nounwind
+define void @spConv2qp_02(float* nocapture readonly %a) {
+; CHECK-LABEL: spConv2qp_02:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    lxssp 2, 0(3)
+; CHECK-NEXT:    addis 3, 2, .LC8@toc@ha
+; CHECK-NEXT:    ld 3, .LC8@toc@l(3)
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    stxvx 2, 0, 3
+; CHECK-NEXT:    blr
+entry:
+  %0 = load float, float* %a, align 4
+  %conv = fpext float %0 to fp128
+  store fp128 %conv, fp128* @f128Glob, align 16
+  ret void
+}
+
+; Function Attrs: norecurse nounwind
+define void @spConv2qp_02b(float* nocapture readonly %a, i32 signext %idx) {
+; CHECK-LABEL: spConv2qp_02b:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    sldi 4, 4, 2
+; CHECK-NEXT:    lxsspx 2, 3, 4
+; CHECK-NEXT:    addis 3, 2, .LC8@toc@ha
+; CHECK-NEXT:    ld 3, .LC8@toc@l(3)
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    stxvx 2, 0, 3
+; CHECK-NEXT:    blr
+entry:
+  %idxprom = sext i32 %idx to i64
+  %arrayidx = getelementptr inbounds float, float* %a, i64 %idxprom
+  %0 = load float, float* %arrayidx, align 4
+  %conv = fpext float %0 to fp128
+  store fp128 %conv, fp128* @f128Glob, align 16
+  ret void
+}
+
+; Function Attrs: norecurse nounwind
+define void @spConv2qp_03(fp128* nocapture %res, i32 signext %idx, float %a) {
+; CHECK-LABEL: spConv2qp_03:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xxlor 2, 1, 1
+; CHECK-NEXT:    sldi 4, 4, 4
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    stxvx 2, 3, 4
+; CHECK-NEXT:    blr
+entry:
+  %conv = fpext float %a to fp128
+  %idxprom = sext i32 %idx to i64
+  %arrayidx = getelementptr inbounds fp128, fp128* %res, i64 %idxprom
+  store fp128 %conv, fp128* %arrayidx, align 16
+  ret void
+}
+
+; Function Attrs: norecurse nounwind
+define void @spConv2qp_04(float %a, fp128* nocapture %res) {
+; CHECK-LABEL: spConv2qp_04:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    xxlor 2, 1, 1
+; CHECK-NEXT:    xscvdpqp 2, 2
+; CHECK-NEXT:    stxv 2, 0(4)
+; CHECK-NEXT:    blr
+entry:
+  %conv = fpext float %a to fp128
+  store fp128 %conv, fp128* %res, align 16
+  ret void
+}