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[CodeGen] Don't assume that fixed stack objects are aligned in a stack-realigned function.

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Summary:
After we make the adjustment, we can assume that for local allocas, but
not for stack parameters, the return address, or any other fixed stack
object (which has a negative offset and therefore lies prior to the
adjusted SP).

Fixes PR26662.

Reviewers: hfinkel, qcolombet, rnk

Subscribers: rnk, llvm-commits

Differential Revision: http://reviews.llvm.org/D18471

llvm-svn: 265886
This commit is contained in:
Charles Davis
2016-04-09 23:34:42 +00:00
parent eeae124faf
commit 2f65f35c27
3 changed files with 49 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
llvm/lib/CodeGen/MachineFunction.cpp
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@@ -84,6 +84,13 @@ void ilist_traits<MachineBasicBlock>::deleteNode(MachineBasicBlock *MBB) {
MBB->getParent()->DeleteMachineBasicBlock(MBB);
}
static inline unsigned getFnStackAlignment(const TargetSubtargetInfo *STI,
const Function *Fn) {
if (Fn->hasFnAttribute(Attribute::StackAlignment))
return Fn->getFnStackAlignment();
return STI->getFrameLowering()->getStackAlignment();
}
MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
unsigned FunctionNum, MachineModuleInfo &mmi)
: Fn(F), Target(TM), STI(TM.getSubtargetImpl(*F)), Ctx(mmi.getContext()),
@@ -97,9 +104,11 @@ MachineFunction::MachineFunction(const Function *F, const TargetMachine &TM,
MFInfo = nullptr;
FrameInfo = new (Allocator)
MachineFrameInfo(STI->getFrameLowering()->getStackAlignment(),
MachineFrameInfo(getFnStackAlignment(STI, Fn),
STI->getFrameLowering()->isStackRealignable(),
!F->hasFnAttribute("no-realign-stack"));
!F->hasFnAttribute("no-realign-stack"),
!F->hasFnAttribute("no-realign-stack") &&
F->hasFnAttribute(Attribute::StackAlignment));
if (Fn->hasFnAttribute(Attribute::StackAlignment))
FrameInfo->ensureMaxAlignment(Fn->getFnStackAlignment());
@@ -613,8 +622,10 @@ int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
// The alignment of the frame index can be determined from its offset from
// the incoming frame position. If the frame object is at offset 32 and
// the stack is guaranteed to be 16-byte aligned, then we know that the
// object is 16-byte aligned.
unsigned Align = MinAlign(SPOffset, StackAlignment);
// object is 16-byte aligned. Note that unlike the non-fixed case, if the
// stack needs realignment, we can't assume that the stack will in fact be
// aligned.
unsigned Align = MinAlign(SPOffset, ForcedRealign ? 1 : StackAlignment);
Align = clampStackAlignment(!StackRealignable || !RealignOption, Align,
StackAlignment);
Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset, Immutable,
@@ -627,7 +638,7 @@ int MachineFrameInfo::CreateFixedObject(uint64_t Size, int64_t SPOffset,
/// Returns an index with a negative value.
int MachineFrameInfo::CreateFixedSpillStackObject(uint64_t Size,
int64_t SPOffset) {
unsigned Align = MinAlign(SPOffset, StackAlignment);
unsigned Align = MinAlign(SPOffset, ForcedRealign ? 1 : StackAlignment);
Align = clampStackAlignment(!StackRealignable || !RealignOption, Align,
StackAlignment);
Objects.insert(Objects.begin(), StackObject(Size, Align, SPOffset,