[SelectionDAG] Widen vector results of SMULFIX/UMULFIX/SMULFIXSAT

[bjope]

Summary

After the commits that changed x86 backend to widen vectors
instead of using promotion some of our downstream tests
started to fail. It was noticed that WidenVectorResult has
been missing support for SMULFIX/UMULFIX/SMULFIXSAT. This
patch adds the missing functionality.

[craig.topper]

LGTM

llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeTypes.h

private:
   SDValue WidenVecRes_SELECT_CC(SDNode* N);
   SDValue WidenVecRes_SETCC(SDNode* N);
   SDValue WidenVecRes_UNDEF(SDNode *N);
   SDValue WidenVecRes_VECTOR_SHUFFLE(ShuffleVectorSDNode *N);
 
   SDValue WidenVecRes_Ternary(SDNode *N);
   SDValue WidenVecRes_Binary(SDNode *N);
   SDValue WidenVecRes_BinaryCanTrap(SDNode *N);
+  SDValue WidenVecRes_BinaryWithExtraScalarOp(SDNode *N);
   SDValue WidenVecRes_StrictFP(SDNode *N);
   SDValue WidenVecRes_OverflowOp(SDNode *N, unsigned ResNo);
   SDValue WidenVecRes_Convert(SDNode *N);
   SDValue WidenVecRes_Convert_StrictFP(SDNode *N);
   SDValue WidenVecRes_FCOPYSIGN(SDNode *N);
   SDValue WidenVecRes_POWI(SDNode *N);
   SDValue WidenVecRes_Shift(SDNode *N);
   SDValue WidenVecRes_Unary(SDNode *N);

llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeVectorOps.cpp

SDValue VectorLegalizer::Expand(SDValue Op) {
   case ISD::USUBSAT:
   case ISD::SSUBSAT:
   case ISD::UADDSAT:
   case ISD::SADDSAT:
     return ExpandAddSubSat(Op);
   case ISD::SMULFIX:
   case ISD::UMULFIX:
     return ExpandFixedPointMul(Op);
+  case ISD::SMULFIXSAT:
+    // FIXME: We do not expand SMULFIXSAT here yet, not sure why. Maybe it
+    // results in worse codegen compared to the default unroll? This should
+    // probably be investigated. And if we still prefer to unroll an explanation
+    // could be helpful, otherwise it just looks like something that hasn't been
+    // "implemented" yet.
+    return DAG.UnrollVectorOp(Op.getNode());
   case ISD::STRICT_FADD:
   case ISD::STRICT_FSUB:
   case ISD::STRICT_FMUL:
   case ISD::STRICT_FDIV:
   case ISD::STRICT_FREM:
   case ISD::STRICT_FSQRT:
   case ISD::STRICT_FMA:
   case ISD::STRICT_FPOW:

llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

#endif
   case ISD::FREM:
   case ISD::SDIV:
   case ISD::UDIV:
   case ISD::SREM:
   case ISD::UREM:
     Res = WidenVecRes_BinaryCanTrap(N);
     break;
 
+  case ISD::SMULFIX:
+  case ISD::SMULFIXSAT:
+  case ISD::UMULFIX:
+    // These are binary operations, but with an extra operand that shouldn't
+    // be widened (the scale).
+    Res = WidenVecRes_BinaryWithExtraScalarOp(N);
+    break;
+
   case ISD::STRICT_FADD:
   case ISD::STRICT_FSUB:
   case ISD::STRICT_FMUL:
   case ISD::STRICT_FDIV:
   case ISD::STRICT_FREM:
   case ISD::STRICT_FSQRT:
   case ISD::STRICT_FMA:
   case ISD::STRICT_FPOW:
SDValue DAGTypeLegalizer::WidenVecRes_Binary(SDNode *N) {
   // Binary op widening.
   SDLoc dl(N);
   EVT WidenVT = TLI.getTypeToTransformTo(*DAG.getContext(), N->getValueType(0));
   SDValue InOp1 = GetWidenedVector(N->getOperand(0));
   SDValue InOp2 = GetWidenedVector(N->getOperand(1));
   return DAG.getNode(N->getOpcode(), dl, WidenVT, InOp1, InOp2, N->getFlags());
 }
 
+SDValue DAGTypeLegalizer::WidenVecRes_BinaryWithExtraScalarOp(SDNode *N) {
+  // Binary op widening, but with an extra operand that shouldn't be widened.
+  SDLoc dl(N);
+  EVT WidenVT = TLI.getTypeToTransformTo(*DAG.getContext(), N->getValueType(0));
+  SDValue InOp1 = GetWidenedVector(N->getOperand(0));
+  SDValue InOp2 = GetWidenedVector(N->getOperand(1));
+  SDValue InOp3 = N->getOperand(2);
+  return DAG.getNode(N->getOpcode(), dl, WidenVT, InOp1, InOp2, InOp3,
+                     N->getFlags());
+}
+
 // Given a vector of operations that have been broken up to widen, see
 // if we can collect them together into the next widest legal VT. This
 // implementation is trap-safe.
 static SDValue CollectOpsToWiden(SelectionDAG &DAG, const TargetLowering &TLI,
                                  SmallVectorImpl<SDValue> &ConcatOps,
                                  unsigned ConcatEnd, EVT VT, EVT MaxVT,
                                  EVT WidenVT) {
   // Check to see if we have a single operation with the widen type.

llvm/trunk/test/CodeGen/X86/vector-mulfix-legalize.ll

+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -O1 -mtriple=x86_64-unknown-unknown -o - | FileCheck %s
+
+; We used to assert on widening the SMULFIX/UMULFIX/SMULFIXSAT node result,
+; so primiary goal with the test is to see that we support legalization for
+; such vectors.
+
+declare <4 x i16> @llvm.smul.fix.v4i16(<4 x i16>, <4 x i16>, i32 immarg)
+declare <4 x i16> @llvm.umul.fix.v4i16(<4 x i16>, <4 x i16>, i32 immarg)
+declare <4 x i16> @llvm.smul.fix.sat.v4i16(<4 x i16>, <4 x i16>, i32 immarg)
+
+define <4 x i16> @smulfix(<4 x i16> %a) {
+; CHECK-LABEL: smulfix:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movdqa {{.*#+}} xmm1 = <1,2,3,4,u,u,u,u>
+; CHECK-NEXT:    movdqa %xmm0, %xmm2
+; CHECK-NEXT:    pmullw %xmm1, %xmm2
+; CHECK-NEXT:    psrlw $15, %xmm2
+; CHECK-NEXT:    pmulhw %xmm1, %xmm0
+; CHECK-NEXT:    psllw $1, %xmm0
+; CHECK-NEXT:    por %xmm2, %xmm0
+; CHECK-NEXT:    retq
+  %t = call <4 x i16> @llvm.smul.fix.v4i16(<4 x i16> <i16 1, i16 2, i16 3, i16 4>, <4 x i16> %a, i32 15)
+  ret <4 x i16> %t
+}
+
+define <4 x i16> @umulfix(<4 x i16> %a) {
+; CHECK-LABEL: umulfix:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movdqa {{.*#+}} xmm1 = <1,2,3,4,u,u,u,u>
+; CHECK-NEXT:    movdqa %xmm0, %xmm2
+; CHECK-NEXT:    pmullw %xmm1, %xmm2
+; CHECK-NEXT:    psrlw $15, %xmm2
+; CHECK-NEXT:    pmulhuw %xmm1, %xmm0
+; CHECK-NEXT:    psllw $1, %xmm0
+; CHECK-NEXT:    por %xmm2, %xmm0
+; CHECK-NEXT:    retq
+  %t = call <4 x i16> @llvm.umul.fix.v4i16(<4 x i16> <i16 1, i16 2, i16 3, i16 4>, <4 x i16> %a, i32 15)
+  ret <4 x i16> %t
+}
+
+define <4 x i16> @smulfixsat(<4 x i16> %a) {
+; CHECK-LABEL: smulfixsat:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    movdqa %xmm0, %xmm1
+; CHECK-NEXT:    pextrw $1, %xmm0, %eax
+; CHECK-NEXT:    cwtl
+; CHECK-NEXT:    movl %eax, %ecx
+; CHECK-NEXT:    shrl $15, %ecx
+; CHECK-NEXT:    leal (%rax,%rax), %edx
+; CHECK-NEXT:    shrdw $15, %cx, %dx
+; CHECK-NEXT:    sarl $15, %eax
+; CHECK-NEXT:    cmpl $16383, %eax # imm = 0x3FFF
+; CHECK-NEXT:    movl $32767, %ecx # imm = 0x7FFF
+; CHECK-NEXT:    cmovgl %ecx, %edx
+; CHECK-NEXT:    cmpl $-16384, %eax # imm = 0xC000
+; CHECK-NEXT:    movl $32768, %eax # imm = 0x8000
+; CHECK-NEXT:    cmovll %eax, %edx
+; CHECK-NEXT:    movd %edx, %xmm2
+; CHECK-NEXT:    movd %xmm0, %edx
+; CHECK-NEXT:    movswl %dx, %edx
+; CHECK-NEXT:    movl %edx, %esi
+; CHECK-NEXT:    shrl $16, %esi
+; CHECK-NEXT:    shldw $1, %dx, %si
+; CHECK-NEXT:    sarl $16, %edx
+; CHECK-NEXT:    cmpl $16383, %edx # imm = 0x3FFF
+; CHECK-NEXT:    cmovgl %ecx, %esi
+; CHECK-NEXT:    cmpl $-16384, %edx # imm = 0xC000
+; CHECK-NEXT:    cmovll %eax, %esi
+; CHECK-NEXT:    movd %esi, %xmm0
+; CHECK-NEXT:    punpcklwd {{.*#+}} xmm0 = xmm0[0],xmm2[0],xmm0[1],xmm2[1],xmm0[2],xmm2[2],xmm0[3],xmm2[3]
+; CHECK-NEXT:    pextrw $2, %xmm1, %edx
+; CHECK-NEXT:    movswl %dx, %edx
+; CHECK-NEXT:    leal (%rdx,%rdx,2), %edx
+; CHECK-NEXT:    movl %edx, %esi
+; CHECK-NEXT:    shrl $16, %esi
+; CHECK-NEXT:    shldw $1, %dx, %si
+; CHECK-NEXT:    sarl $16, %edx
+; CHECK-NEXT:    cmpl $16383, %edx # imm = 0x3FFF
+; CHECK-NEXT:    cmovgl %ecx, %esi
+; CHECK-NEXT:    cmpl $-16384, %edx # imm = 0xC000
+; CHECK-NEXT:    cmovll %eax, %esi
+; CHECK-NEXT:    movd %esi, %xmm2
+; CHECK-NEXT:    pextrw $3, %xmm1, %edx
+; CHECK-NEXT:    movswl %dx, %edx
+; CHECK-NEXT:    movl %edx, %esi
+; CHECK-NEXT:    shrl $14, %esi
+; CHECK-NEXT:    leal (,%rdx,4), %edi
+; CHECK-NEXT:    shrdw $15, %si, %di
+; CHECK-NEXT:    sarl $14, %edx
+; CHECK-NEXT:    cmpl $16383, %edx # imm = 0x3FFF
+; CHECK-NEXT:    cmovgl %ecx, %edi
+; CHECK-NEXT:    cmpl $-16384, %edx # imm = 0xC000
+; CHECK-NEXT:    cmovll %eax, %edi
+; CHECK-NEXT:    movd %edi, %xmm1
+; CHECK-NEXT:    punpcklwd {{.*#+}} xmm2 = xmm2[0],xmm1[0],xmm2[1],xmm1[1],xmm2[2],xmm1[2],xmm2[3],xmm1[3]
+; CHECK-NEXT:    punpckldq {{.*#+}} xmm0 = xmm0[0],xmm2[0],xmm0[1],xmm2[1]
+; CHECK-NEXT:    xorl %edx, %edx
+; CHECK-NEXT:    shrdw $15, %dx, %dx
+; CHECK-NEXT:    movl $16383, %esi # imm = 0x3FFF
+; CHECK-NEXT:    negl %esi
+; CHECK-NEXT:    cmovgl %ecx, %edx
+; CHECK-NEXT:    movl $-16384, %ecx # imm = 0xC000
+; CHECK-NEXT:    negl %ecx
+; CHECK-NEXT:    cmovll %eax, %edx
+; CHECK-NEXT:    movd %edx, %xmm1
+; CHECK-NEXT:    punpcklwd {{.*#+}} xmm1 = xmm1[0,0,1,1,2,2,3,3]
+; CHECK-NEXT:    punpckldq {{.*#+}} xmm1 = xmm1[0,0,1,1]
+; CHECK-NEXT:    punpcklqdq {{.*#+}} xmm0 = xmm0[0],xmm1[0]
+; CHECK-NEXT:    retq
+  %t = call <4 x i16> @llvm.smul.fix.sat.v4i16(<4 x i16> <i16 1, i16 2, i16 3, i16 4>, <4 x i16> %a, i32 15)
+  ret <4 x i16> %t
+}
+
+