[llvm] r198113 - [X86] Teach the backend how to fold target specific dag node for packed

Andrea Di Biagio Andrea_DiBiagio at sn.scee.net
Sat Dec 28 03:11:52 PST 2013


Author: adibiagio
Date: Sat Dec 28 05:11:52 2013
New Revision: 198113

URL: http://llvm.org/viewvc/llvm-project?rev=198113&view=rev
Log:
[X86] Teach the backend how to fold target specific dag node for packed
vector shift by immedate count (VSHLI/VSRLI/VSRAI) into a build_vector when
the vector in input to the shift is a build_vector of all constants or UNDEFs.

Target specific nodes for packed shifts by immediate count are in
general introduced by function 'getTargetVShiftByConstNode' (in
X86ISelLowering.cpp) when lowering shift operations, SSE/AVX immediate
shift intrinsics and (only in very few cases) SIGN_EXTEND_INREG dag
nodes.

This patch adds extra rules for simplifying vector shifts inside
function 'getTargetVShiftByConstNode'.

Added file test/CodeGen/X86/vec_shift5.ll to verify that packed
shifts by immediate are correctly folded into a build_vector when the
input vector to the shift dag node is a vector of constants or undefs.

Added:
    llvm/trunk/test/CodeGen/X86/vec_shift5.ll
Modified:
    llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

Modified: llvm/trunk/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=198113&r1=198112&r2=198113&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86ISelLowering.cpp Sat Dec 28 05:11:52 2013
@@ -11103,11 +11103,12 @@ static SDValue LowerVACOPY(SDValue Op, c
 static SDValue getTargetVShiftByConstNode(unsigned Opc, SDLoc dl, EVT VT,
                                           SDValue SrcOp, uint64_t ShiftAmt,
                                           SelectionDAG &DAG) {
+  EVT ElementType = VT.getVectorElementType();
 
   // Check for ShiftAmt >= element width
-  if (ShiftAmt >= VT.getVectorElementType().getSizeInBits()) {
+  if (ShiftAmt >= ElementType.getSizeInBits()) {
     if (Opc == X86ISD::VSRAI)
-      ShiftAmt = VT.getVectorElementType().getSizeInBits() - 1;
+      ShiftAmt = ElementType.getSizeInBits() - 1;
     else
       return DAG.getConstant(0, VT);
   }
@@ -11115,6 +11116,56 @@ static SDValue getTargetVShiftByConstNod
   assert((Opc == X86ISD::VSHLI || Opc == X86ISD::VSRLI || Opc == X86ISD::VSRAI)
          && "Unknown target vector shift-by-constant node");
 
+  // Fold this packed vector shift into a build vector if SrcOp is a
+  // vector of ConstantSDNodes or UNDEFs.
+  if (ISD::isBuildVectorOfConstantSDNodes(SrcOp.getNode())) {
+    SmallVector<SDValue, 8> Elts;
+    unsigned NumElts = SrcOp->getNumOperands();
+    ConstantSDNode *ND;
+
+    switch(Opc) {
+    default: llvm_unreachable(0);
+    case X86ISD::VSHLI:
+      for (unsigned i=0; i!=NumElts; ++i) {
+        SDValue CurrentOp = SrcOp->getOperand(i);
+        if (CurrentOp->getOpcode() == ISD::UNDEF) {
+          Elts.push_back(CurrentOp);
+          continue;
+        }
+        ND = cast<ConstantSDNode>(CurrentOp);
+        const APInt &C = ND->getAPIntValue();
+        Elts.push_back(DAG.getConstant(C.shl(ShiftAmt), ElementType));
+      }
+      break;
+    case X86ISD::VSRLI:
+      for (unsigned i=0; i!=NumElts; ++i) {
+        SDValue CurrentOp = SrcOp->getOperand(i);
+        if (CurrentOp->getOpcode() == ISD::UNDEF) {
+          Elts.push_back(CurrentOp);
+          continue;
+        }
+        ND = cast<ConstantSDNode>(CurrentOp);
+        const APInt &C = ND->getAPIntValue();
+        Elts.push_back(DAG.getConstant(C.lshr(ShiftAmt), ElementType));
+      }
+      break;
+    case X86ISD::VSRAI:
+      for (unsigned i=0; i!=NumElts; ++i) {
+        SDValue CurrentOp = SrcOp->getOperand(i);
+        if (CurrentOp->getOpcode() == ISD::UNDEF) {
+          Elts.push_back(CurrentOp);
+          continue;
+        }
+        ND = cast<ConstantSDNode>(CurrentOp);
+        const APInt &C = ND->getAPIntValue();
+        Elts.push_back(DAG.getConstant(C.ashr(ShiftAmt), ElementType));
+      }
+      break;
+    }
+
+    return DAG.getNode(ISD::BUILD_VECTOR, dl, VT, &Elts[0], NumElts);
+  }
+
   return DAG.getNode(Opc, dl, VT, SrcOp, DAG.getConstant(ShiftAmt, MVT::i8));
 }
 

Added: llvm/trunk/test/CodeGen/X86/vec_shift5.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/vec_shift5.ll?rev=198113&view=auto
==============================================================================
--- llvm/trunk/test/CodeGen/X86/vec_shift5.ll (added)
+++ llvm/trunk/test/CodeGen/X86/vec_shift5.ll Sat Dec 28 05:11:52 2013
@@ -0,0 +1,160 @@
+; RUN: llc -march=x86-64 -mcpu=corei7 -mattr=-sse4.1 < %s | FileCheck %s
+
+; Verify that we correctly fold target specific packed vector shifts by
+; immediate count into a simple build_vector when the elements of the vector
+; in input to the packed shift are all constants or undef.
+
+define <8 x i16> @test1() {
+  %1 = tail call <8 x i16> @llvm.x86.sse2.pslli.w(<8 x i16> <i16 1, i16 2, i16 4, i16 8, i16 1, i16 2, i16 4, i16 8>, i32 3)
+  ret <8 x i16> %1
+}
+; CHECK-LABEL: test1
+; CHECK-NOT: psll
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <8 x i16> @test2() {
+  %1 = tail call <8 x i16> @llvm.x86.sse2.psrli.w(<8 x i16> <i16 4, i16 8, i16 16, i16 32, i16 4, i16 8, i16 16, i16 32>, i32 3)
+  ret <8 x i16> %1
+}
+; CHECK-LABEL: test2
+; CHECK-NOT: psrl
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <8 x i16> @test3() {
+  %1 = tail call <8 x i16> @llvm.x86.sse2.psrai.w(<8 x i16> <i16 4, i16 8, i16 16, i16 32, i16 4, i16 8, i16 16, i16 32>, i32 3)
+  ret <8 x i16> %1
+}
+; CHECK-LABEL: test3
+; CHECK-NOT: psra
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <4 x i32> @test4() {
+  %1 = tail call <4 x i32> @llvm.x86.sse2.pslli.d(<4 x i32> <i32 1, i32 2, i32 4, i32 8>, i32 3)
+  ret <4 x i32> %1
+}
+; CHECK-LABEL: test4
+; CHECK-NOT: psll
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <4 x i32> @test5() {
+  %1 = tail call <4 x i32> @llvm.x86.sse2.psrli.d(<4 x i32> <i32 4, i32 8, i32 16, i32 32>, i32 3)
+  ret <4 x i32> %1
+}
+; CHECK-LABEL: test5
+; CHECK-NOT: psrl
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <4 x i32> @test6() {
+  %1 = tail call <4 x i32> @llvm.x86.sse2.psrai.d(<4 x i32> <i32 4, i32 8, i32 16, i32 32>, i32 3)
+  ret <4 x i32> %1
+}
+; CHECK-LABEL: test6
+; CHECK-NOT: psra
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <2 x i64> @test7() {
+  %1 = tail call <2 x i64> @llvm.x86.sse2.pslli.q(<2 x i64> <i64 1, i64 2>, i32 3)
+  ret <2 x i64> %1
+}
+; CHECK-LABEL: test7
+; CHECK-NOT: psll
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <2 x i64> @test8() {
+  %1 = tail call <2 x i64> @llvm.x86.sse2.psrli.q(<2 x i64> <i64 8, i64 16>, i32 3)
+  ret <2 x i64> %1
+}
+; CHECK-LABEL: test8
+; CHECK-NOT: psrl
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <8 x i16> @test9() {
+  %1 = tail call <8 x i16> @llvm.x86.sse2.psrai.w(<8 x i16> <i16 15, i16 8, i16 undef, i16 undef, i16 31, i16 undef, i16 64, i16 128>, i32 3)
+  ret <8 x i16> %1
+}
+; CHECK-LABEL: test9
+; CHECK-NOT: psra
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <4 x i32> @test10() {
+  %1 = tail call <4 x i32> @llvm.x86.sse2.psrai.d(<4 x i32> <i32 undef, i32 8, i32 undef, i32 32>, i32 3)
+  ret <4 x i32> %1
+}
+; CHECK-LABEL: test10
+; CHECK-NOT: psra
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <2 x i64> @test11() {
+  %1 = tail call <2 x i64> @llvm.x86.sse2.psrli.q(<2 x i64> <i64 undef, i64 31>, i32 3)
+  ret <2 x i64> %1
+}
+; CHECK-LABEL: test11
+; CHECK-NOT: psrl
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <8 x i16> @test12() {
+  %1 = tail call <8 x i16> @llvm.x86.sse2.psrai.w(<8 x i16> <i16 15, i16 8, i16 undef, i16 undef, i16 31, i16 undef, i16 64, i16 128>, i32 3)
+  ret <8 x i16> %1
+}
+; CHECK-LABEL: test12
+; CHECK-NOT: psra
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <4 x i32> @test13() {
+  %1 = tail call <4 x i32> @llvm.x86.sse2.psrli.d(<4 x i32> <i32 undef, i32 8, i32 undef, i32 32>, i32 3)
+  ret <4 x i32> %1
+}
+; CHECK-LABEL: test13
+; CHECK-NOT: psrl
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <8 x i16> @test14() {
+  %1 = tail call <8 x i16> @llvm.x86.sse2.psrli.w(<8 x i16> <i16 15, i16 8, i16 undef, i16 undef, i16 31, i16 undef, i16 64, i16 128>, i32 3)
+  ret <8 x i16> %1
+}
+; CHECK-LABEL: test14
+; CHECK-NOT: psrl
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <4 x i32> @test15() {
+  %1 = tail call <4 x i32> @llvm.x86.sse2.pslli.d(<4 x i32> <i32 undef, i32 8, i32 undef, i32 32>, i32 3)
+  ret <4 x i32> %1
+}
+; CHECK-LABEL: test15
+; CHECK-NOT: psll
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+define <2 x i64> @test16() {
+  %1 = tail call <2 x i64> @llvm.x86.sse2.pslli.q(<2 x i64> <i64 undef, i64 31>, i32 3)
+  ret <2 x i64> %1
+}
+; CHECK-LABEL: test16
+; CHECK-NOT: psll
+; CHECK: movaps
+; CHECK-NEXT: ret
+
+
+declare <8 x i16> @llvm.x86.sse2.pslli.w(<8 x i16>, i32)
+declare <8 x i16> @llvm.x86.sse2.psrli.w(<8 x i16>, i32)
+declare <8 x i16> @llvm.x86.sse2.psrai.w(<8 x i16>, i32)
+declare <4 x i32> @llvm.x86.sse2.pslli.d(<4 x i32>, i32)
+declare <4 x i32> @llvm.x86.sse2.psrli.d(<4 x i32>, i32)
+declare <4 x i32> @llvm.x86.sse2.psrai.d(<4 x i32>, i32)
+declare <2 x i64> @llvm.x86.sse2.pslli.q(<2 x i64>, i32)
+declare <2 x i64> @llvm.x86.sse2.psrli.q(<2 x i64>, i32)
+





More information about the llvm-commits mailing list