[llvm-commits] [llvm] r43421 - in /llvm/trunk: include/llvm/Support/Alignment.h lib/CodeGen/SelectionDAG/DAGCombiner.cpp lib/CodeGen/SelectionDAG/LegalizeDAG.cpp lib/CodeGen/SelectionDAG/LegalizeDAGTypes.cpp
Duncan Sands
baldrick at free.fr
Sun Oct 28 05:59:45 PDT 2007
Author: baldrick
Date: Sun Oct 28 07:59:45 2007
New Revision: 43421
URL: http://llvm.org/viewvc/llvm-project?rev=43421&view=rev
Log:
The guaranteed alignment of ptr+offset is only the minimum of
of offset and the alignment of ptr if these are both powers of
2. While the ptr alignment is guaranteed to be a power of 2,
there is no reason to think that offset is. For example, if
offset is 12 (the size of a long double on x86-32 linux) and
the alignment of ptr is 8, then the alignment of ptr+offset
will in general be 4, not 8. Introduce a function MinAlign,
lifted from gcc, for computing the minimum guaranteed alignment.
I've tried to fix up everywhere under lib/CodeGen/SelectionDAG/.
I also changed some places that weren't wrong (because both values
were a power of 2), as a defensive change against people copying
and pasting the code.
Hopefully someone who cares about alignment will review the rest
of LLVM and fix up the remaining places. Since I'm on x86 I'm
not very motivated to do this myself...
Added:
llvm/trunk/include/llvm/Support/Alignment.h
Modified:
llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAGTypes.cpp
Added: llvm/trunk/include/llvm/Support/Alignment.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Support/Alignment.h?rev=43421&view=auto
==============================================================================
--- llvm/trunk/include/llvm/Support/Alignment.h (added)
+++ llvm/trunk/include/llvm/Support/Alignment.h Sun Oct 28 07:59:45 2007
@@ -0,0 +1,28 @@
+//===----------- Alignment.h - Alignment computation ------------*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by Duncan Sands and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines utilities for computing alignments.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_SUPPORT_ALIGNMENT_H
+#define LLVM_SUPPORT_ALIGNMENT_H
+
+namespace llvm {
+
+/// MinAlign - A and B are either alignments or offsets. Return the minimum
+/// alignment that may be assumed after adding the two together.
+
+static inline unsigned MinAlign(unsigned A, unsigned B) {
+ // The largest power of 2 that divides both A and B.
+ return (A | B) & -(A | B);
+}
+
+} // end namespace llvm
+#endif
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp?rev=43421&r1=43420&r2=43421&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Sun Oct 28 07:59:45 2007
@@ -37,6 +37,7 @@
#include "llvm/Target/TargetOptions.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
+#include "llvm/Support/Alignment.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
@@ -1713,15 +1714,18 @@
// read fewer bytes from the same pointer.
unsigned PtrOff =
(MVT::getSizeInBits(LoadedVT) - MVT::getSizeInBits(EVT)) / 8;
+ unsigned Alignment = LN0->getAlignment();
SDOperand NewPtr = LN0->getBasePtr();
- if (!TLI.isLittleEndian())
+ if (!TLI.isLittleEndian()) {
NewPtr = DAG.getNode(ISD::ADD, PtrType, NewPtr,
DAG.getConstant(PtrOff, PtrType));
+ Alignment = MinAlign(Alignment, PtrOff);
+ }
AddToWorkList(NewPtr.Val);
SDOperand Load =
DAG.getExtLoad(ISD::ZEXTLOAD, VT, LN0->getChain(), NewPtr,
LN0->getSrcValue(), LN0->getSrcValueOffset(), EVT,
- LN0->isVolatile(), LN0->getAlignment());
+ LN0->isVolatile(), Alignment);
AddToWorkList(N);
CombineTo(N0.Val, Load, Load.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
@@ -2879,16 +2883,17 @@
if (!TLI.isLittleEndian())
ShAmt = MVT::getSizeInBits(N0.getValueType()) - ShAmt - EVTBits;
uint64_t PtrOff = ShAmt / 8;
+ unsigned NewAlign = MinAlign(LN0->getAlignment(), PtrOff);
SDOperand NewPtr = DAG.getNode(ISD::ADD, PtrType, LN0->getBasePtr(),
DAG.getConstant(PtrOff, PtrType));
AddToWorkList(NewPtr.Val);
SDOperand Load = (ExtType == ISD::NON_EXTLOAD)
? DAG.getLoad(VT, LN0->getChain(), NewPtr,
LN0->getSrcValue(), LN0->getSrcValueOffset(),
- LN0->isVolatile(), LN0->getAlignment())
+ LN0->isVolatile(), NewAlign)
: DAG.getExtLoad(ExtType, VT, LN0->getChain(), NewPtr,
LN0->getSrcValue(), LN0->getSrcValueOffset(), EVT,
- LN0->isVolatile(), LN0->getAlignment());
+ LN0->isVolatile(), NewAlign);
AddToWorkList(N);
if (CombineSRL) {
DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), Load.getValue(1));
@@ -3905,8 +3910,8 @@
// Replace the chain to void dependency.
if (LD->getExtensionType() == ISD::NON_EXTLOAD) {
ReplLoad = DAG.getLoad(N->getValueType(0), BetterChain, Ptr,
- LD->getSrcValue(), LD->getSrcValueOffset(),
- LD->isVolatile(), LD->getAlignment());
+ LD->getSrcValue(), LD->getSrcValueOffset(),
+ LD->isVolatile(), LD->getAlignment());
} else {
ReplLoad = DAG.getExtLoad(LD->getExtensionType(),
LD->getValueType(0),
@@ -3980,7 +3985,7 @@
ST->getSrcValueOffset(), ST->isVolatile(),
ST->getAlignment());
} else if (TLI.isTypeLegal(MVT::i32)) {
- // Many FP stores are not make apparent until after legalize, e.g. for
+ // Many FP stores are not made apparent until after legalize, e.g. for
// argument passing. Since this is so common, custom legalize the
// 64-bit integer store into two 32-bit stores.
uint64_t Val = CFP->getValueAPF().convertToAPInt().getZExtValue();
@@ -3998,8 +4003,7 @@
Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
DAG.getConstant(4, Ptr.getValueType()));
SVOffset += 4;
- if (Alignment > 4)
- Alignment = 4;
+ Alignment = MinAlign(Alignment, 4U);
SDOperand St1 = DAG.getStore(Chain, Hi, Ptr, ST->getSrcValue(),
SVOffset, isVolatile, Alignment);
return DAG.getNode(ISD::TokenFactor, MVT::Other, St0, St1);
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp?rev=43421&r1=43420&r2=43421&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp Sun Oct 28 07:59:45 2007
@@ -23,9 +23,10 @@
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
-#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/Alignment.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Compiler.h"
+#include "llvm/Support/MathExtras.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/SmallPtrSet.h"
@@ -602,6 +603,7 @@
ST->isVolatile(), Alignment);
Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
DAG.getConstant(IncrementSize, TLI.getPointerTy()));
+ Alignment = MinAlign(Alignment, IncrementSize);
Store2 = DAG.getTruncStore(Chain, TLI.isLittleEndian()?Hi:Lo, Ptr,
ST->getSrcValue(), SVOffset + IncrementSize,
NewStoredVT, ST->isVolatile(), Alignment);
@@ -660,7 +662,7 @@
DAG.getConstant(IncrementSize, TLI.getPointerTy()));
Hi = DAG.getExtLoad(HiExtType, VT, Chain, Ptr, LD->getSrcValue(),
SVOffset + IncrementSize, NewLoadedVT, LD->isVolatile(),
- Alignment);
+ MinAlign(Alignment, IncrementSize));
} else {
Hi = DAG.getExtLoad(HiExtType, VT, Chain, Ptr, LD->getSrcValue(), SVOffset,
NewLoadedVT,LD->isVolatile(), Alignment);
@@ -668,7 +670,7 @@
DAG.getConstant(IncrementSize, TLI.getPointerTy()));
Lo = DAG.getExtLoad(ISD::ZEXTLOAD, VT, Chain, Ptr, LD->getSrcValue(),
SVOffset + IncrementSize, NewLoadedVT, LD->isVolatile(),
- Alignment);
+ MinAlign(Alignment, IncrementSize));
}
// aggregate the two parts
@@ -2055,7 +2057,7 @@
Tmp2 = DAG.getNode(ISD::ADD, Tmp2.getValueType(), Tmp2,
getIntPtrConstant(4));
Hi = DAG.getStore(Tmp1, Hi, Tmp2, ST->getSrcValue(), SVOffset+4,
- isVolatile, std::max(Alignment, 4U));
+ isVolatile, MinAlign(Alignment, 4U));
Result = DAG.getNode(ISD::TokenFactor, MVT::Other, Lo, Hi);
break;
@@ -2164,8 +2166,7 @@
assert(isTypeLegal(Tmp2.getValueType()) &&
"Pointers must be legal!");
SVOffset += IncrementSize;
- if (Alignment > IncrementSize)
- Alignment = IncrementSize;
+ Alignment = MinAlign(Alignment, IncrementSize);
Hi = DAG.getStore(Tmp1, Hi, Tmp2, ST->getSrcValue(),
SVOffset, isVolatile, Alignment);
Result = DAG.getNode(ISD::TokenFactor, MVT::Other, Lo, Hi);
@@ -5429,8 +5430,7 @@
Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
getIntPtrConstant(IncrementSize));
SVOffset += IncrementSize;
- if (Alignment > IncrementSize)
- Alignment = IncrementSize;
+ Alignment = MinAlign(Alignment, IncrementSize);
Hi = DAG.getLoad(NVT, Ch, Ptr, LD->getSrcValue(), SVOffset,
isVolatile, Alignment);
@@ -6336,8 +6336,7 @@
Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
getIntPtrConstant(IncrementSize));
SVOffset += IncrementSize;
- if (Alignment > IncrementSize)
- Alignment = IncrementSize;
+ Alignment = MinAlign(Alignment, IncrementSize);
Hi = DAG.getLoad(NewVT, Ch, Ptr, SV, SVOffset, isVolatile, Alignment);
// Build a factor node to remember that this load is independent of the
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAGTypes.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAGTypes.cpp?rev=43421&r1=43420&r2=43421&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAGTypes.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/LegalizeDAGTypes.cpp Sun Oct 28 07:59:45 2007
@@ -18,6 +18,7 @@
#include "llvm/DerivedTypes.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/Support/Alignment.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
using namespace llvm;
@@ -946,7 +947,7 @@
Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
getIntPtrConstant(IncrementSize));
Hi = DAG.getLoad(NVT, Ch, Ptr, N->getSrcValue(), SVOffset+IncrementSize,
- isVolatile, std::max(Alignment, IncrementSize));
+ isVolatile, MinAlign(Alignment, IncrementSize));
// Build a factor node to remember that this load is independent of the
// other one.
@@ -994,7 +995,7 @@
getIntPtrConstant(IncrementSize));
Hi = DAG.getExtLoad(ExtType, NVT, Ch, Ptr, N->getSrcValue(),
SVOffset+IncrementSize, NEVT,
- isVolatile, std::max(Alignment, IncrementSize));
+ isVolatile, MinAlign(Alignment, IncrementSize));
// Build a factor node to remember that this load is independent of the
// other one.
@@ -1019,7 +1020,7 @@
// Load the rest of the low bits.
Lo = DAG.getExtLoad(ISD::ZEXTLOAD, NVT, Ch, Ptr, N->getSrcValue(),
SVOffset+IncrementSize, MVT::getIntegerType(ExcessBits),
- isVolatile, std::max(Alignment, IncrementSize));
+ isVolatile, MinAlign(Alignment, IncrementSize));
// Build a factor node to remember that this load is independent of the
// other one.
@@ -2002,7 +2003,7 @@
getIntPtrConstant(IncrementSize));
assert(isTypeLegal(Ptr.getValueType()) && "Pointers must be legal!");
Hi = DAG.getStore(Chain, Hi, Ptr, N->getSrcValue(), SVOffset+IncrementSize,
- isVolatile, std::max(Alignment, IncrementSize));
+ isVolatile, MinAlign(Alignment, IncrementSize));
return DAG.getNode(ISD::TokenFactor, MVT::Other, Lo, Hi);
}
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