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[mips] Account for constant-zero operands in ADDE nodes.

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Summary:
We identify the cases where the operand to an ADDE node is a constant
zero. In such cases, we can avoid generating an extra ADDu instruction
disguised as an identity move alias (ie. addu $r, $r, 0 --> move $r, $r).

Reviewers: dsanders

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D7906

llvm-svn: 230742
This commit is contained in:
Vasileios Kalintiris 2015-02-27 09:01:39 +00:00
parent 492074fb03
commit 38b77a1ef8
2 changed files with 41 additions and 2 deletions
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8
lib/Target/Mips/MipsSEISelDAGToDAG.cpp
View File

@ -258,8 +258,12 @@ SDNode *MipsSEDAGToDAGISel::selectAddESubE(unsigned MOp, SDValue InFlag,
CurDAG->getTargetConstant(Mips::sub_32, VT));
}
SDNode *AddCarry = CurDAG->getMachineNode(ADDuOp, DL, VT,
SDValue(Carry, 0), RHS);
// Generate a second addition only if we know that RHS is not a
// constant-zero node.
SDNode *AddCarry = Carry;
ConstantSDNode *C = dyn_cast<ConstantSDNode>(RHS);
if (!C || C->getZExtValue())
AddCarry = CurDAG->getMachineNode(ADDuOp, DL, VT, SDValue(Carry, 0), RHS);
return CurDAG->SelectNodeTo(Node, MOp, VT, MVT::Glue, LHS,
SDValue(AddCarry, 0));

35
test/CodeGen/Mips/check-adde-redundant-moves.ll Normal file
View File

@ -0,0 +1,35 @@
; RUN: llc < %s -march=mips -mcpu=mips2 | FileCheck %s \
; RUN: -check-prefix=ALL -check-prefix=GP32
; RUN: llc < %s -march=mips -mcpu=mips32 | FileCheck %s \
; RUN: -check-prefix=ALL -check-prefix=GP32
; RUN: llc < %s -march=mips -mcpu=mips32r2 | FileCheck %s \
; RUN: -check-prefix=ALL -check-prefix=GP32
; RUN: llc < %s -march=mips -mcpu=mips32r3 | FileCheck %s \
; RUN: -check-prefix=ALL -check-prefix=GP32
; RUN: llc < %s -march=mips -mcpu=mips32r5 | FileCheck %s \
; RUN: -check-prefix=ALL -check-prefix=GP32
; RUN: llc < %s -march=mips -mcpu=mips32r6 | FileCheck %s \
; RUN: -check-prefix=ALL -check-prefix=GP32
; RUN: llc < %s -march=mips64 -mcpu=mips3 | FileCheck %s -check-prefix=ALL
; RUN: llc < %s -march=mips64 -mcpu=mips4 | FileCheck %s -check-prefix=ALL
; RUN: llc < %s -march=mips64 -mcpu=mips64 | FileCheck %s -check-prefix=ALL
; RUN: llc < %s -march=mips64 -mcpu=mips64r2 | FileCheck %s -check-prefix=ALL
; RUN: llc < %s -march=mips64 -mcpu=mips64r3 | FileCheck %s -check-prefix=ALL
; RUN: llc < %s -march=mips64 -mcpu=mips64r5 | FileCheck %s -check-prefix=ALL
; RUN: llc < %s -march=mips64 -mcpu=mips64r6 | FileCheck %s -check-prefix=ALL
define i64 @add_i64(i64 %a) {
; GP32-LABEL: add_i64
; GP32-NOT: move $[[T0:[0-9]+]], $[[T0]]
%r = add i64 5, %a
ret i64 %r
}
define i128 @add_i128(i128 %a) {
; ALL-LABEL: add_i128
; ALL-NOT: move $[[T0:[0-9]+]], $[[T0]]
%r = add i128 5, %a
ret i128 %r
}