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When doing the very-late shift-and address-mode optimization, 

create a new DAG node to represent the new shift to keep the
DAG consistent, even though it'll almost always be folded into
the address.

If a user of the resulting address has multiple uses, the
nodes may get revisited by a later MatchAddress call, in which
case DAG inconsistencies do matter.

This fixes PR2849.

llvm-svn: 57465
This commit is contained in:
Dan Gohman 2008-10-13 20:52:04 +00:00
parent 591ef273e3
commit 56b6885104
2 changed files with 41 additions and 0 deletions
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3
llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
View File

@ -989,8 +989,11 @@ DOUT << "AlreadySelected " << AlreadySelected << "\n";
SDValue(C2, 0), SDValue(C1, 0));
SDValue NewAND = CurDAG->getNode(ISD::AND, N.getValueType(),
Shift.getOperand(0), NewANDMask);
SDValue NewSHIFT = CurDAG->getNode(ISD::SHL, N.getValueType(),
NewAND, SDValue(C1, 0));
NewANDMask.getNode()->setNodeId(Shift.getNode()->getNodeId());
NewAND.getNode()->setNodeId(N.getNode()->getNodeId());
CurDAG->ReplaceAllUsesWith(N, NewSHIFT);
AM.Scale = 1 << ShiftCst;
AM.IndexReg = NewAND;

38
llvm/test/CodeGen/X86/pr2849.ll Normal file
View File

@ -0,0 +1,38 @@
; RUN: llvm-as < %s | llc
; PR2849
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
target triple = "x86_64-unknown-linux-gnu"
%struct.BaseBoundPtrs = type { i8*, i8* }
%struct.HashEntry = type { %struct.BaseBoundPtrs }
%struct.NODE = type { i8, i8, %struct.anon }
%struct.anon = type { %struct.xlist }
%struct.xlist = type { %struct.NODE*, %struct.NODE* }
%struct.xvect = type { %struct.NODE** }
@hash_table_begin = external global %struct.HashEntry*
define void @obshow() {
entry:
%tmp = load %struct.HashEntry** @hash_table_begin, align 8
br i1 false, label %xlygetvalue.exit, label %xlygetvalue.exit
xlygetvalue.exit:
%storemerge.in.i = phi %struct.NODE** [ null, %entry ], [ null, %entry ]
%storemerge.i = load %struct.NODE** %storemerge.in.i
%tmp1 = ptrtoint %struct.NODE** %storemerge.in.i to i64
%tmp2 = lshr i64 %tmp1, 3
%tmp3 = and i64 %tmp2, 2147483647
%tmp4 = getelementptr %struct.HashEntry* %tmp, i64 %tmp3, i32 0, i32 1
%tmp7 = load i8** %tmp4, align 8
%tmp8 = getelementptr %struct.NODE* %storemerge.i, i64 0, i32 2
%tmp9 = bitcast %struct.anon* %tmp8 to %struct.NODE***
%tmp11 = load %struct.NODE*** %tmp9, align 8
%tmp12 = ptrtoint %struct.NODE** %tmp11 to i64
%tmp13 = lshr i64 %tmp12, 3
%tmp14 = and i64 %tmp13, 2147483647
%tmp15 = getelementptr %struct.HashEntry* %tmp, i64 %tmp14, i32 0, i32 1
call fastcc void @xlprint(i8** %tmp4, i8* %tmp7, i8** %tmp15)
ret void
}
declare fastcc void @xlprint(i8**, i8*, i8**)