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Stack Alignment: when creating stack objects in MachineFrameInfo, make sure 

the alignment is clamped to TargetFrameLowering.getStackAlignment if the target
does not support stack realignment or the option "realign-stack" is off.

This will cause miscompile if the address is treated as aligned and add is
replaced with or in DAGCombine.

Added a bool StackRealignable to TargetFrameLowering to check whether stack
realignment is implemented for the target. Also added a bool RealignOption
to MachineFrameInfo to check whether the option "realign-stack" is on.

rdar://12713765

llvm-svn: 169197
This commit is contained in:
Manman Ren 2012-12-04 00:52:33 +00:00
parent bac8ae6506
commit f563941adc
4 changed files with 85 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
llvm/include/llvm/CodeGen/MachineFrameInfo.h
View File

@ -221,8 +221,11 @@ class MachineFrameInfo {
/// just allocate them normally.
bool UseLocalStackAllocationBlock;
/// Whether the "realign-stack" option is on.
bool RealignOption;
public:
explicit MachineFrameInfo(const TargetFrameLowering &tfi) : TFI(tfi) {
explicit MachineFrameInfo(const TargetFrameLowering &tfi, bool RealignOpt)
: TFI(tfi), RealignOption(RealignOpt) {
StackSize = NumFixedObjects = OffsetAdjustment = MaxAlignment = 0;
HasVarSizedObjects = false;
FrameAddressTaken = false;

11
llvm/include/llvm/Target/TargetFrameLowering.h
View File

@ -47,11 +47,12 @@ private:
unsigned StackAlignment;
unsigned TransientStackAlignment;
int LocalAreaOffset;
bool StackRealignable;
public:
TargetFrameLowering(StackDirection D, unsigned StackAl, int LAO,
unsigned TransAl = 1)
unsigned TransAl = 1, bool StackReal = true)
: StackDir(D), StackAlignment(StackAl), TransientStackAlignment(TransAl),
LocalAreaOffset(LAO) {}
LocalAreaOffset(LAO), StackRealignable(StackReal) {}
virtual ~TargetFrameLowering();
@ -76,6 +77,12 @@ public:
return TransientStackAlignment;
}
/// isStackRealignable - This method returns whether the stack can be
/// realigned.
bool isStackRealignable() const {
return StackRealignable;
}
/// getOffsetOfLocalArea - This method returns the offset of the local area
/// from the stack pointer on entrance to a function.
///

25
llvm/lib/CodeGen/MachineFunction.cpp
View File

@ -58,7 +58,8 @@ MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
else
RegInfo = 0;
MFInfo = 0;
FrameInfo = new (Allocator) MachineFrameInfo(*TM.getFrameLowering());
FrameInfo = new (Allocator) MachineFrameInfo(*TM.getFrameLowering(),
TM.Options.RealignStack);
if (Fn->getFnAttributes().hasAttribute(Attributes::StackAlignment))
FrameInfo->ensureMaxAlignment(Fn->getAttributes().
getFnAttributes().getStackAlignment());
@ -448,15 +449,31 @@ MCSymbol *MachineFunction::getPICBaseSymbol() const {
/// ensureMaxAlignment - Make sure the function is at least Align bytes
/// aligned.
void MachineFrameInfo::ensureMaxAlignment(unsigned Align) {
if (!TFI.isStackRealignable() || !RealignOption)
assert(Align <= TFI.getStackAlignment() &&
"For targets without stack realignment, Align is out of limit!");
if (MaxAlignment < Align) MaxAlignment = Align;
}
/// clampStackAlignment - Clamp the alignment if requested and emit a warning.
static inline unsigned clampStackAlignment(bool ShouldClamp, unsigned Align,
unsigned StackAlign) {
if (!ShouldClamp || Align <= StackAlign)
return Align;
DEBUG(dbgs() << "Warning: requested alignment " << Align
<< " exceeds the stack alignment " << StackAlign
<< " when stack realignment is off" << '\n');
return StackAlign;
}
/// CreateStackObject - Create a new statically sized stack object, returning
/// a nonnegative identifier to represent it.
///
int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
bool isSS, bool MayNeedSP, const AllocaInst *Alloca) {
assert(Size != 0 && "Cannot allocate zero size stack objects!");
Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
Alignment, TFI.getStackAlignment());
Objects.push_back(StackObject(Size, Alignment, 0, false, isSS, MayNeedSP,
Alloca));
int Index = (int)Objects.size() - NumFixedObjects - 1;
@ -471,6 +488,8 @@ int MachineFrameInfo::CreateStackObject(uint64_t Size, unsigned Alignment,
///
int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
unsigned Alignment) {
Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
Alignment, TFI.getStackAlignment());
CreateStackObject(Size, Alignment, true, false);
int Index = (int)Objects.size() - NumFixedObjects - 1;
ensureMaxAlignment(Alignment);
@ -484,6 +503,8 @@ int MachineFrameInfo::CreateSpillStackObject(uint64_t Size,
///
int MachineFrameInfo::CreateVariableSizedObject(unsigned Alignment) {
HasVarSizedObjects = true;
Alignment = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
Alignment, TFI.getStackAlignment());
Objects.push_back(StackObject(0, Alignment, 0, false, false, true, 0));
ensureMaxAlignment(Alignment);
return (int)Objects.size()-NumFixedObjects-1;
@ -503,6 +524,8 @@ int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
// object is 16-byte aligned.
unsigned StackAlign = TFI.getStackAlignment();
unsigned Align = MinAlign(SPOffset, StackAlign);
Align = clampStackAlignment(!TFI.isStackRealignable() || !RealignOption,
Align, TFI.getStackAlignment());
Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
/*isSS*/ false,
/*NeedSP*/ false,

48
llvm/test/CodeGen/ARM/alloc-no-stack-realign.ll Normal file
View File

@ -0,0 +1,48 @@
; RUN: llc < %s -mtriple=armv7-apple-ios -O0 -realign-stack=0 | FileCheck %s -check-prefix=NO-REALIGN
; RUN: llc < %s -mtriple=armv7-apple-ios -O0 | FileCheck %s
; rdar://12713765
; When realign-stack is set to false, make sure we are not creating stack
; objects that are assumed to be 64-byte aligned.
@T3_retval = common global <16 x float> zeroinitializer, align 16
define void @test(<16 x float>* noalias sret %agg.result) nounwind ssp {
entry:
; CHECK: test
; CHECK: bic sp, sp, #63
; CHECK: orr [[R2:r[0-9]+]], [[R1:r[0-9]+]], #48
; CHECK: vst1.64
; CHECK: orr [[R2:r[0-9]+]], [[R1:r[0-9]+]], #32
; CHECK: vst1.64
; CHECK: orr [[R2:r[0-9]+]], [[R1:r[0-9]+]], #16
; CHECK: vst1.64
; CHECK: vst1.64
; CHECK: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #48
; CHECK: vst1.64
; CHECK: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #32
; CHECK: vst1.64
; CHECK: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #16
; CHECK: vst1.64
; CHECK: vst1.64
; NO-REALIGN: test
; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #48
; NO-REALIGN: vst1.64
; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #32
; NO-REALIGN: vst1.64
; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #16
; NO-REALIGN: vst1.64
; NO-REALIGN: vst1.64
; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #48
; NO-REALIGN: vst1.64
; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #32
; NO-REALIGN: vst1.64
; NO-REALIGN: add [[R2:r[0-9]+]], [[R1:r[0-9]+]], #16
; NO-REALIGN: vst1.64
; NO-REALIGN: vst1.64
%retval = alloca <16 x float>, align 16
%0 = load <16 x float>* @T3_retval, align 16
store <16 x float> %0, <16 x float>* %retval
%1 = load <16 x float>* %retval
store <16 x float> %1, <16 x float>* %agg.result, align 16
ret void
}