[llvm] r213754 - ARM: spot SBFX-compatbile code expressed with sign_extend_inreg
Tim Northover
tnorthover at apple.com
Wed Jul 23 06:59:12 PDT 2014
Author: tnorthover
Date: Wed Jul 23 08:59:12 2014
New Revision: 213754
URL: http://llvm.org/viewvc/llvm-project?rev=213754&view=rev
Log:
ARM: spot SBFX-compatbile code expressed with sign_extend_inreg
We were assuming all SBFX-like operations would have the shl/asr form, but
often when the field being extracted is an i8 or i16, we end up with a
SIGN_EXTEND_INREG acting on a shift instead. Simple enough to check for though.
Modified:
llvm/trunk/lib/Target/ARM/ARMISelDAGToDAG.cpp
llvm/trunk/test/CodeGen/ARM/sbfx.ll
llvm/trunk/test/CodeGen/Thumb2/thumb2-sxt_rot.ll
Modified: llvm/trunk/lib/Target/ARM/ARMISelDAGToDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMISelDAGToDAG.cpp?rev=213754&r1=213753&r2=213754&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMISelDAGToDAG.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMISelDAGToDAG.cpp Wed Jul 23 08:59:12 2014
@@ -2361,6 +2361,25 @@ SDNode *ARMDAGToDAGISel::SelectV6T2Bitfi
return CurDAG->SelectNodeTo(N, Opc, MVT::i32, Ops);
}
}
+
+ if (N->getOpcode() == ISD::SIGN_EXTEND_INREG) {
+ unsigned Width = cast<VTSDNode>(N->getOperand(1))->getVT().getSizeInBits();
+ unsigned LSB = 0;
+ if (!isOpcWithIntImmediate(N->getOperand(0).getNode(), ISD::SRL, LSB) &&
+ !isOpcWithIntImmediate(N->getOperand(0).getNode(), ISD::SRA, LSB))
+ return nullptr;
+
+ if (LSB + Width > 32)
+ return nullptr;
+
+ SDValue Reg0 = CurDAG->getRegister(0, MVT::i32);
+ SDValue Ops[] = { N->getOperand(0).getOperand(0),
+ CurDAG->getTargetConstant(LSB, MVT::i32),
+ CurDAG->getTargetConstant(Width - 1, MVT::i32),
+ getAL(CurDAG), Reg0 };
+ return CurDAG->SelectNodeTo(N, Opc, MVT::i32, Ops);
+ }
+
return nullptr;
}
@@ -2509,6 +2528,7 @@ SDNode *ARMDAGToDAGISel::Select(SDNode *
if (SDNode *I = SelectV6T2BitfieldExtractOp(N, false))
return I;
break;
+ case ISD::SIGN_EXTEND_INREG:
case ISD::SRA:
if (SDNode *I = SelectV6T2BitfieldExtractOp(N, true))
return I;
Modified: llvm/trunk/test/CodeGen/ARM/sbfx.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ARM/sbfx.ll?rev=213754&r1=213753&r2=213754&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/ARM/sbfx.ll (original)
+++ llvm/trunk/test/CodeGen/ARM/sbfx.ll Wed Jul 23 08:59:12 2014
@@ -45,3 +45,21 @@ entry:
%tmp2 = ashr i32 %tmp, 1
ret i32 %tmp2
}
+
+define signext i8 @f6(i32 %a) {
+; CHECK-LABEL: f6:
+; CHECK: sbfx r0, r0, #23, #8
+
+ %tmp = lshr i32 %a, 23
+ %res = trunc i32 %tmp to i8
+ ret i8 %res
+}
+
+define signext i8 @f7(i32 %a) {
+; CHECK-LABEL: f7:
+; CHECK-NOT: sbfx
+
+ %tmp = lshr i32 %a, 25
+ %res = trunc i32 %tmp to i8
+ ret i8 %res
+}
Modified: llvm/trunk/test/CodeGen/Thumb2/thumb2-sxt_rot.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/Thumb2/thumb2-sxt_rot.ll?rev=213754&r1=213753&r2=213754&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/Thumb2/thumb2-sxt_rot.ll (original)
+++ llvm/trunk/test/CodeGen/Thumb2/thumb2-sxt_rot.ll Wed Jul 23 08:59:12 2014
@@ -10,8 +10,7 @@ define i32 @test0(i8 %A) {
define signext i8 @test1(i32 %A) {
; CHECK-LABEL: test1:
-; CHECK: lsrs r0, r0, #8
-; CHECK: sxtb r0, r0
+; CHECK: sbfx r0, r0, #8, #8
%B = lshr i32 %A, 8
%C = shl i32 %A, 24
%D = or i32 %B, %C
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