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[DAGCombiner] Fix ReplaceExtractVectorEltOfLoadWithNarrowedLoad for BE

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For little-endian, the function would convert (extract_vector_elt (load X), Y)
to X + Y*sizeof(elt).  For big-endian it would instead use
X + sizeof(vec) - Y*sizeof(elt).  The big-endian case wasn't right since
vector index order always follows memory/array order, even for big-endian.
(Note that the current handling has to be wrong for Y==0 since it would
access beyond the end of the vector.)

Original patch by Richard Sandiford.

llvm-svn: 236529
This commit is contained in:
Ulrich Weigand 2015-05-05 19:33:37 +00:00
parent aab0c45488
commit 8229aae81f
2 changed files with 13 additions and 7 deletions
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7
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
View File

@ -11413,19 +11413,12 @@ SDValue DAGCombiner::ReplaceExtractVectorEltOfLoadWithNarrowedLoad(
if (auto *ConstEltNo = dyn_cast<ConstantSDNode>(EltNo)) {
int Elt = ConstEltNo->getZExtValue();
unsigned PtrOff = VecEltVT.getSizeInBits() * Elt / 8;
if (TLI.isBigEndian())
PtrOff = InVecVT.getSizeInBits() / 8 - PtrOff;
Offset = DAG.getConstant(PtrOff, DL, PtrType);
MPI = OriginalLoad->getPointerInfo().getWithOffset(PtrOff);
} else {
Offset = DAG.getNode(
ISD::MUL, DL, EltNo.getValueType(), EltNo,
DAG.getConstant(VecEltVT.getStoreSize(), DL, EltNo.getValueType()));
if (TLI.isBigEndian())
Offset = DAG.getNode(
ISD::SUB, DL, EltNo.getValueType(),
DAG.getConstant(InVecVT.getStoreSize(), DL, EltNo.getValueType()),
Offset);
MPI = OriginalLoad->getPointerInfo();
}
NewPtr = DAG.getNode(ISD::ADD, DL, PtrType, NewPtr, Offset);

13
test/CodeGen/SystemZ/vec-extract-01.ll Normal file
View File

@ -0,0 +1,13 @@
; Verify ReplaceExtractVectorEltOfLoadWithNarrowedLoad fixes
;
; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13 | FileCheck %s
; Test a memory copy of a v2i32 (via the constant pool).
define void @f1(<2 x i32> *%dest) {
; CHECK-LABEL: f1:
; CHECK: lgrl [[REG:%r[0-5]]], {{[._A-Za-z0-9]}}
; CHECK: stg [[REG]], 0(%r2)
; CHECK: br %r14
store <2 x i32> <i32 1000000, i32 99999>, <2 x i32> *%dest
ret void
}