diff options
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 20 | ||||
| -rw-r--r-- | test/CodeGen/PowerPC/load-shift-combine.ll | 34 |
2 files changed, 49 insertions, 5 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 359c4cf..a82410a 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -5100,16 +5100,26 @@ SDValue DAGCombiner::ReduceLoadWidth(SDNode *N) { // If we haven't found a load, we can't narrow it. Don't transform one with // multiple uses, this would require adding a new load. - if (!isa<LoadSDNode>(N0) || !N0.hasOneUse() || - // Don't change the width of a volatile load. - cast<LoadSDNode>(N0)->isVolatile()) + if (!isa<LoadSDNode>(N0) || !N0.hasOneUse()) + return SDValue(); + + // Don't change the width of a volatile load. + LoadSDNode *LN0 = cast<LoadSDNode>(N0); + if (LN0->isVolatile()) return SDValue(); // Verify that we are actually reducing a load width here. - if (cast<LoadSDNode>(N0)->getMemoryVT().getSizeInBits() < EVTBits) + if (LN0->getMemoryVT().getSizeInBits() < EVTBits) + return SDValue(); + + // For the transform to be legal, the load must produce only two values + // (the value loaded and the chain). Don't transform a pre-increment + // load, for example, which produces an extra value. Otherwise the + // transformation is not equivalent, and the downstream logic to replace + // uses gets things wrong. + if (LN0->getNumValues() > 2) return SDValue(); - LoadSDNode *LN0 = cast<LoadSDNode>(N0); EVT PtrType = N0.getOperand(1).getValueType(); if (PtrType == MVT::Untyped || PtrType.isExtended()) diff --git a/test/CodeGen/PowerPC/load-shift-combine.ll b/test/CodeGen/PowerPC/load-shift-combine.ll new file mode 100644 index 0000000..a5d1224 --- /dev/null +++ b/test/CodeGen/PowerPC/load-shift-combine.ll @@ -0,0 +1,34 @@ +; RUN: llc < %s + +; This used to cause a crash. A standard load is converted to a pre-increment +; load. Later the pre-increment load is combined with a subsequent SRL to +; produce a smaller load. This transform invalidly created a standard load +; and propagated the produced value into uses of both produced values of the +; pre-increment load. The result was a crash when attempting to process an +; add with a token-chain operand. + +%struct.Info = type { i32, i32, i8*, i8*, i8*, [32 x i8*], i64, [32 x i64], i64, i64, i64, [32 x i64] } +%struct.S1847 = type { [12 x i8], [4 x i8], [8 x i8], [4 x i8], [8 x i8], [2 x i8], i8, [4 x i64], i8, [3 x i8], [4 x i8], i8, i16, [4 x %struct.anon.76], i16, i8, i8* } +%struct.anon.76 = type { i32 } +@info = common global %struct.Info zeroinitializer, align 8 +@fails = common global i32 0, align 4 +@a1847 = external global [5 x %struct.S1847] +define void @test1847() nounwind { +entry: + %j = alloca i32, align 4 + %0 = load i64* getelementptr inbounds (%struct.Info* @info, i32 0, i32 8), align 8 + %1 = load i32* @fails, align 4 + %bf.load1 = load i96* bitcast (%struct.S1847* getelementptr inbounds ([5 x %struct.S1847]* @a1847, i32 0, i64 2) to i96*), align 8 + %bf.clear2 = and i96 %bf.load1, 302231454903657293676543 + %bf.set3 = or i96 %bf.clear2, -38383394772764476296921088 + store i96 %bf.set3, i96* bitcast (%struct.S1847* getelementptr inbounds ([5 x %struct.S1847]* @a1847, i32 0, i64 2) to i96*), align 8 + %2 = load i32* %j, align 4 + %3 = load i32* %j, align 4 + %inc11 = add nsw i32 %3, 1 + store i32 %inc11, i32* %j, align 4 + %bf.load15 = load i96* bitcast (%struct.S1847* getelementptr inbounds ([5 x %struct.S1847]* @a1847, i32 0, i64 2) to i96*), align 8 + %bf.clear16 = and i96 %bf.load15, -18446744069414584321 + %bf.set17 = or i96 %bf.clear16, 18446743532543672320 + store i96 %bf.set17, i96* bitcast (%struct.S1847* getelementptr inbounds ([5 x %struct.S1847]* @a1847, i32 0, i64 2) to i96*), align 8 + ret void +} |