[llvm] r193518 - [DAGCombiner] Respect volatility when checking for aliases
Richard Sandiford
rsandifo at linux.vnet.ibm.com
Mon Oct 28 05:00:01 PDT 2013
Author: rsandifo
Date: Mon Oct 28 07:00:00 2013
New Revision: 193518
URL: http://llvm.org/viewvc/llvm-project?rev=193518&view=rev
Log:
[DAGCombiner] Respect volatility when checking for aliases
Making useAA() default to true for SystemZ showed that the combiner alias
analysis wasn't handling volatile accesses. This hit many of the SystemZ
tests, but I arbitrarily picked one for the purpose of this patch.
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
llvm/trunk/test/CodeGen/SystemZ/bswap-02.ll
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=193518&r1=193517&r2=193518&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Mon Oct 28 07:00:00 2013
@@ -296,11 +296,11 @@ namespace {
/// isAlias - Return true if there is any possibility that the two addresses
/// overlap.
- bool isAlias(SDValue Ptr1, int64_t Size1,
+ bool isAlias(SDValue Ptr1, int64_t Size1, bool IsVolatile1,
const Value *SrcValue1, int SrcValueOffset1,
unsigned SrcValueAlign1,
const MDNode *TBAAInfo1,
- SDValue Ptr2, int64_t Size2,
+ SDValue Ptr2, int64_t Size2, bool IsVolatile2,
const Value *SrcValue2, int SrcValueOffset2,
unsigned SrcValueAlign2,
const MDNode *TBAAInfo2) const;
@@ -312,7 +312,7 @@ namespace {
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
bool FindAliasInfo(SDNode *N,
- SDValue &Ptr, int64_t &Size,
+ SDValue &Ptr, int64_t &Size, bool &IsVolatile,
const Value *&SrcValue, int &SrcValueOffset,
unsigned &SrcValueAlignment,
const MDNode *&TBAAInfo) const;
@@ -10789,17 +10789,20 @@ static bool FindBaseOffset(SDValue Ptr,
/// isAlias - Return true if there is any possibility that the two addresses
/// overlap.
-bool DAGCombiner::isAlias(SDValue Ptr1, int64_t Size1,
+bool DAGCombiner::isAlias(SDValue Ptr1, int64_t Size1, bool IsVolatile1,
const Value *SrcValue1, int SrcValueOffset1,
unsigned SrcValueAlign1,
const MDNode *TBAAInfo1,
- SDValue Ptr2, int64_t Size2,
+ SDValue Ptr2, int64_t Size2, bool IsVolatile2,
const Value *SrcValue2, int SrcValueOffset2,
unsigned SrcValueAlign2,
const MDNode *TBAAInfo2) const {
// If they are the same then they must be aliases.
if (Ptr1 == Ptr2) return true;
+ // If they are both volatile then they cannot be reordered.
+ if (IsVolatile1 && IsVolatile2) return true;
+
// Gather base node and offset information.
SDValue Base1, Base2;
int64_t Offset1, Offset2;
@@ -10865,24 +10868,25 @@ bool DAGCombiner::isAlias(SDValue Ptr1,
bool DAGCombiner::isAlias(LSBaseSDNode *Op0, LSBaseSDNode *Op1) {
SDValue Ptr0, Ptr1;
int64_t Size0, Size1;
+ bool IsVolatile0, IsVolatile1;
const Value *SrcValue0, *SrcValue1;
int SrcValueOffset0, SrcValueOffset1;
unsigned SrcValueAlign0, SrcValueAlign1;
const MDNode *SrcTBAAInfo0, *SrcTBAAInfo1;
- FindAliasInfo(Op0, Ptr0, Size0, SrcValue0, SrcValueOffset0,
+ FindAliasInfo(Op0, Ptr0, Size0, IsVolatile0, SrcValue0, SrcValueOffset0,
SrcValueAlign0, SrcTBAAInfo0);
- FindAliasInfo(Op1, Ptr1, Size1, SrcValue1, SrcValueOffset1,
+ FindAliasInfo(Op1, Ptr1, Size1, IsVolatile1, SrcValue1, SrcValueOffset1,
SrcValueAlign1, SrcTBAAInfo1);
- return isAlias(Ptr0, Size0, SrcValue0, SrcValueOffset0,
+ return isAlias(Ptr0, Size0, IsVolatile0, SrcValue0, SrcValueOffset0,
SrcValueAlign0, SrcTBAAInfo0,
- Ptr1, Size1, SrcValue1, SrcValueOffset1,
+ Ptr1, Size1, IsVolatile1, SrcValue1, SrcValueOffset1,
SrcValueAlign1, SrcTBAAInfo1);
}
/// FindAliasInfo - Extracts the relevant alias information from the memory
-/// node. Returns true if the operand was a load.
+/// node. Returns true if the operand was a nonvolatile load.
bool DAGCombiner::FindAliasInfo(SDNode *N,
- SDValue &Ptr, int64_t &Size,
+ SDValue &Ptr, int64_t &Size, bool &IsVolatile,
const Value *&SrcValue,
int &SrcValueOffset,
unsigned &SrcValueAlign,
@@ -10891,11 +10895,12 @@ bool DAGCombiner::FindAliasInfo(SDNode *
Ptr = LS->getBasePtr();
Size = LS->getMemoryVT().getSizeInBits() >> 3;
+ IsVolatile = LS->isVolatile();
SrcValue = LS->getSrcValue();
SrcValueOffset = LS->getSrcValueOffset();
SrcValueAlign = LS->getOriginalAlignment();
TBAAInfo = LS->getTBAAInfo();
- return isa<LoadSDNode>(LS);
+ return isa<LoadSDNode>(LS) && !IsVolatile;
}
/// GatherAllAliases - Walk up chain skipping non-aliasing memory nodes,
@@ -10908,12 +10913,13 @@ void DAGCombiner::GatherAllAliases(SDNod
// Get alias information for node.
SDValue Ptr;
int64_t Size;
+ bool IsVolatile;
const Value *SrcValue;
int SrcValueOffset;
unsigned SrcValueAlign;
const MDNode *SrcTBAAInfo;
- bool IsLoad = FindAliasInfo(N, Ptr, Size, SrcValue, SrcValueOffset,
- SrcValueAlign, SrcTBAAInfo);
+ bool IsLoad = FindAliasInfo(N, Ptr, Size, IsVolatile, SrcValue,
+ SrcValueOffset, SrcValueAlign, SrcTBAAInfo);
// Starting off.
Chains.push_back(OriginalChain);
@@ -10954,20 +10960,21 @@ void DAGCombiner::GatherAllAliases(SDNod
// Get alias information for Chain.
SDValue OpPtr;
int64_t OpSize;
+ bool OpIsVolatile;
const Value *OpSrcValue;
int OpSrcValueOffset;
unsigned OpSrcValueAlign;
const MDNode *OpSrcTBAAInfo;
bool IsOpLoad = FindAliasInfo(Chain.getNode(), OpPtr, OpSize,
- OpSrcValue, OpSrcValueOffset,
+ OpIsVolatile, OpSrcValue, OpSrcValueOffset,
OpSrcValueAlign,
OpSrcTBAAInfo);
// If chain is alias then stop here.
if (!(IsLoad && IsOpLoad) &&
- isAlias(Ptr, Size, SrcValue, SrcValueOffset, SrcValueAlign,
- SrcTBAAInfo,
- OpPtr, OpSize, OpSrcValue, OpSrcValueOffset,
+ isAlias(Ptr, Size, IsVolatile, SrcValue, SrcValueOffset,
+ SrcValueAlign, SrcTBAAInfo,
+ OpPtr, OpSize, OpIsVolatile, OpSrcValue, OpSrcValueOffset,
OpSrcValueAlign, OpSrcTBAAInfo)) {
Aliases.push_back(Chain);
} else {
Modified: llvm/trunk/test/CodeGen/SystemZ/bswap-02.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/SystemZ/bswap-02.ll?rev=193518&r1=193517&r2=193518&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/SystemZ/bswap-02.ll (original)
+++ llvm/trunk/test/CodeGen/SystemZ/bswap-02.ll Mon Oct 28 07:00:00 2013
@@ -1,6 +1,7 @@
; Test 32-bit byteswaps from memory to registers.
;
-; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
+; RUN: llc < %s -mtriple=s390x-linux-gnu -combiner-alias-analysis \
+; RUN: -combiner-global-alias-analysis | FileCheck %s
declare i32 @llvm.bswap.i32(i32 %a)
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