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Fix pr11266.

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On x86: (shl V, 1) -> add V,V

Hardware support for vector-shift is sparse and in many cases we scalarize the
result. Additionally, on sandybridge padd is faster than shl.

llvm-svn: 143311
This commit is contained in:
Nadav Rotem 2011-10-30 13:24:22 +00:00
parent eb62811647
commit 8282fc9e3b
3 changed files with 56 additions and 6 deletions
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26
lib/Target/X86/X86ISelLowering.cpp
View File

@ -13042,7 +13042,8 @@ static SDValue PerformSHLCombine(SDNode *N, SelectionDAG &DAG) {
// fold (shl (and (setcc_c), c1), c2) -> (and setcc_c, (c1 << c2))
// since the result of setcc_c is all zero's or all ones.
if (N1C && N0.getOpcode() == ISD::AND &&
if (VT.isInteger() && !VT.isVector() &&
N1C && N0.getOpcode() == ISD::AND &&
N0.getOperand(1).getOpcode() == ISD::Constant) {
SDValue N00 = N0.getOperand(0);
if (N00.getOpcode() == X86ISD::SETCC_CARRY ||
@ -13058,6 +13059,22 @@ static SDValue PerformSHLCombine(SDNode *N, SelectionDAG &DAG) {
}
}
// Hardware support for vector shifts is sparse which makes us scalarize the
// vector operations in many cases. Also, on sandybridge ADD is faster than
// shl.
// (shl V, 1) -> add V,V
if (isSplatVector(N1.getNode())) {
assert(N0.getValueType().isVector() && "Invalid vector shift type");
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1->getOperand(0));
// We shift all of the values by one. In many cases we do not have
// hardware support for this operation. This is better expressed as an ADD
// of two values.
if (N1C && (1 == N1C->getZExtValue())) {
return DAG.getNode(ISD::ADD, N->getDebugLoc(), VT, N0, N0);
}
}
return SDValue();
}
@ -13066,9 +13083,10 @@ static SDValue PerformSHLCombine(SDNode *N, SelectionDAG &DAG) {
static SDValue PerformShiftCombine(SDNode* N, SelectionDAG &DAG,
const X86Subtarget *Subtarget) {
EVT VT = N->getValueType(0);
if (!VT.isVector() && VT.isInteger() &&
N->getOpcode() == ISD::SHL)
return PerformSHLCombine(N, DAG);
if (N->getOpcode() == ISD::SHL) {
SDValue V = PerformSHLCombine(N, DAG);
if (V.getNode()) return V;
}
// On X86 with SSE2 support, we can transform this to a vector shift if
// all elements are shifted by the same amount. We can't do this in legalize

20
test/CodeGen/X86/2011-10-30-padd.ll Normal file
View File

@ -0,0 +1,20 @@
; RUN: llc < %s -march=x86 -mcpu=corei7 | FileCheck %s
;CHECK: addXX_test
;CHECK: padd
;CHECK: ret
define <16 x i8> @addXX_test(<16 x i8> %a) {
%b = add <16 x i8> %a, %a
ret <16 x i8> %b
}
;CHECK: instcombine_test
;CHECK: padd
;CHECK: ret
define <16 x i8> @instcombine_test(<16 x i8> %a) {
%b = shl <16 x i8> %a, <i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1, i8 1>
ret <16 x i8> %b
}

16
test/CodeGen/X86/x86-shifts.ll
View File

@ -6,8 +6,9 @@
define <4 x i32> @shl4(<4 x i32> %A) nounwind {
entry:
; CHECK: shl4
; CHECK: padd
; CHECK: pslld
; CHECK-NEXT: pslld
; CHECK: ret
%B = shl <4 x i32> %A, < i32 2, i32 2, i32 2, i32 2>
%C = shl <4 x i32> %A, < i32 1, i32 1, i32 1, i32 1>
%K = xor <4 x i32> %B, %C
@ -19,6 +20,7 @@ entry:
; CHECK: shr4
; CHECK: psrld
; CHECK-NEXT: psrld
; CHECK: ret
%B = lshr <4 x i32> %A, < i32 2, i32 2, i32 2, i32 2>
%C = lshr <4 x i32> %A, < i32 1, i32 1, i32 1, i32 1>
%K = xor <4 x i32> %B, %C
@ -30,6 +32,7 @@ entry:
; CHECK: sra4
; CHECK: psrad
; CHECK-NEXT: psrad
; CHECK: ret
%B = ashr <4 x i32> %A, < i32 2, i32 2, i32 2, i32 2>
%C = ashr <4 x i32> %A, < i32 1, i32 1, i32 1, i32 1>
%K = xor <4 x i32> %B, %C
@ -41,6 +44,7 @@ entry:
; CHECK: shl2
; CHECK: psllq
; CHECK-NEXT: psllq
; CHECK: ret
%B = shl <2 x i64> %A, < i64 2, i64 2>
%C = shl <2 x i64> %A, < i64 9, i64 9>
%K = xor <2 x i64> %B, %C
@ -52,6 +56,7 @@ entry:
; CHECK: shr2
; CHECK: psrlq
; CHECK-NEXT: psrlq
; CHECK: ret
%B = lshr <2 x i64> %A, < i64 8, i64 8>
%C = lshr <2 x i64> %A, < i64 1, i64 1>
%K = xor <2 x i64> %B, %C
@ -62,8 +67,9 @@ entry:
define <8 x i16> @shl8(<8 x i16> %A) nounwind {
entry:
; CHECK: shl8
; CHECK: padd
; CHECK: psllw
; CHECK-NEXT: psllw
; CHECK: ret
%B = shl <8 x i16> %A, < i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
%C = shl <8 x i16> %A, < i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
%K = xor <8 x i16> %B, %C
@ -75,6 +81,7 @@ entry:
; CHECK: shr8
; CHECK: psrlw
; CHECK-NEXT: psrlw
; CHECK: ret
%B = lshr <8 x i16> %A, < i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
%C = lshr <8 x i16> %A, < i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
%K = xor <8 x i16> %B, %C
@ -86,6 +93,7 @@ entry:
; CHECK: sra8
; CHECK: psraw
; CHECK-NEXT: psraw
; CHECK: ret
%B = ashr <8 x i16> %A, < i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2, i16 2>
%C = ashr <8 x i16> %A, < i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1, i16 1>
%K = xor <8 x i16> %B, %C
@ -100,6 +108,7 @@ entry:
; CHECK: sll8_nosplat
; CHECK-NOT: psll
; CHECK-NOT: psll
; CHECK: ret
%B = shl <8 x i16> %A, < i16 1, i16 2, i16 3, i16 6, i16 2, i16 2, i16 2, i16 2>
%C = shl <8 x i16> %A, < i16 9, i16 7, i16 5, i16 1, i16 4, i16 1, i16 1, i16 1>
%K = xor <8 x i16> %B, %C
@ -112,6 +121,7 @@ entry:
; CHECK: shr2_nosplat
; CHECK-NOT: psrlq
; CHECK-NOT: psrlq
; CHECK: ret
%B = lshr <2 x i64> %A, < i64 8, i64 1>
%C = lshr <2 x i64> %A, < i64 1, i64 0>
%K = xor <2 x i64> %B, %C
@ -125,6 +135,7 @@ define <2 x i32> @shl2_other(<2 x i32> %A) nounwind {
entry:
; CHECK: shl2_other
; CHECK: psllq
; CHECK: ret
%B = shl <2 x i32> %A, < i32 2, i32 2>
%C = shl <2 x i32> %A, < i32 9, i32 9>
%K = xor <2 x i32> %B, %C
@ -135,6 +146,7 @@ define <2 x i32> @shr2_other(<2 x i32> %A) nounwind {
entry:
; CHECK: shr2_other
; CHECK: psrlq
; CHECK: ret
%B = lshr <2 x i32> %A, < i32 8, i32 8>
%C = lshr <2 x i32> %A, < i32 1, i32 1>
%K = xor <2 x i32> %B, %C