RPCS3/llvm-mirror
1
0
Fork 0
mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-11-23 11:13:28 +01:00
Code Issues Projects Releases Wiki Activity

[SystemZ] Bugfix in isFusableLoadOpStorePattern()

Browse Source 
This function is responsible for checking the legality of fusing an instance
of load -> op -> store into a single operation. In the SystemZ backend the
check was incomplete and a test case emerged with a cycle in the instruction
selection DAG as a result.

Instead of using the NodeIds to determine node relationships,
hasPredecessorHelper() now is used just like in the X86 backend. This handled
the failing tests and as well gave a few additional transformations on
benchmarks.

The SystemZ isFusableLoadOpStorePattern() is now a very near copy of the X86
function, and it seems this could be made a utility function in common code
instead.

Review: Ulrich Weigand
https://reviews.llvm.org/D60255

llvm-svn: 357688
This commit is contained in:
Jonas Paulsson 2019-04-04 12:12:35 +00:00
parent ca7466f39a
commit 9a45e65673
2 changed files with 50 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
View File

@ -1275,6 +1275,9 @@ static bool isFusableLoadOpStorePattern(StoreSDNode *StoreNode,
InputChain = LoadNode->getChain();
} else if (Chain.getOpcode() == ISD::TokenFactor) {
SmallVector<SDValue, 4> ChainOps;
SmallVector<const SDNode *, 4> LoopWorklist;
SmallPtrSet<const SDNode *, 16> Visited;
const unsigned int Max = 1024;
for (unsigned i = 0, e = Chain.getNumOperands(); i != e; ++i) {
SDValue Op = Chain.getOperand(i);
if (Op == Load.getValue(1)) {
@ -1283,28 +1286,26 @@ static bool isFusableLoadOpStorePattern(StoreSDNode *StoreNode,
ChainOps.push_back(Load.getOperand(0));
continue;
}
// Make sure using Op as part of the chain would not cause a cycle here.
// In theory, we could check whether the chain node is a predecessor of
// the load. But that can be very expensive. Instead visit the uses and
// make sure they all have smaller node id than the load.
int LoadId = LoadNode->getNodeId();
for (SDNode::use_iterator UI = Op.getNode()->use_begin(),
UE = UI->use_end(); UI != UE; ++UI) {
if (UI.getUse().getResNo() != 0)
continue;
if (UI->getNodeId() > LoadId)
return false;
}
LoopWorklist.push_back(Op.getNode());
ChainOps.push_back(Op);
}
if (ChainCheck)
if (ChainCheck) {
// Add the other operand of StoredVal to worklist.
for (SDValue Op : StoredVal->ops())
if (Op.getNode() != LoadNode)
LoopWorklist.push_back(Op.getNode());
// Check if Load is reachable from any of the nodes in the worklist.
if (SDNode::hasPredecessorHelper(Load.getNode(), Visited, LoopWorklist, Max,
true))
return false;
// Make a new TokenFactor with all the other input chains except
// for the load.
InputChain = CurDAG->getNode(ISD::TokenFactor, SDLoc(Chain),
MVT::Other, ChainOps);
}
}
if (!ChainCheck)
return false;

34
test/CodeGen/SystemZ/int-uadd-12.ll Normal file
View File

@ -0,0 +1,34 @@
; Test that this test case does not abort after the folding of load -> add ->
; store into an alsi. This folding is suppose to not happen as it would
; introduce a loop in the DAG.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu -mcpu=z13 -disable-basicaa -consthoist-gep | FileCheck %s
@g_295 = external dso_local unnamed_addr global i32, align 4
@g_672 = external dso_local unnamed_addr global i64, align 8
@g_1484 = external dso_local global <{ i8, i64, { i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, [2 x i8], i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, i8 }, i32 }>, align 2
define void @fun() {
; CHECK-LABEL: fun:
bb:
br label %bb1
bb1: ; preds = %bb1, %bb
store i32 2, i32* getelementptr inbounds (<{ i8, i64, { i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, [2 x i8], i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, i8 }, i32 }>, <{ i8, i64, { i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, [2 x i8], i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, i8 }, i32 }>* @g_1484, i64 0, i32 2, i32 16)
%tmp = icmp slt i32 undef, 3
br i1 %tmp, label %bb1, label %bb2
bb2: ; preds = %bb1
%tmp3 = load i32, i32* getelementptr inbounds (<{ i8, i64, { i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, [2 x i8], i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, i8 }, i32 }>, <{ i8, i64, { i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, [2 x i8], i8, i8, i8, i8, i8, i8, i8, i8, i32, i8, i8, i8 }, i32 }>* @g_1484, i64 0, i32 2, i32 28)
%tmp4 = load i64, i64* @g_672
%tmp5 = add i64 %tmp4, 1
store i64 %tmp5, i64* @g_672
%tmp6 = icmp eq i64 %tmp5, 0
%tmp7 = zext i1 %tmp6 to i32
%tmp8 = icmp ult i32 %tmp3, %tmp7
%tmp9 = zext i1 %tmp8 to i32
store i32 %tmp9, i32* @g_295
ret void
}