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- If a dynamic_stackalloc alignment requirement is <= stack alignment, then the alignment argument is ignored.

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- *Always* round up the size of the allocation to multiples of stack
alignment to ensure the stack ptr is never left in an invalid state after a dynamic_stackalloc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41132 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-08-16 23:46:29 +00:00
parent 1defe2df5d
commit 4515779fa3
1 changed files with 12 additions and 12 deletions
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24
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@ -2329,21 +2329,21 @@ void SelectionDAGLowering::visitAlloca(AllocaInst &I) {
AllocSize = DAG.getNode(ISD::MUL, IntPtr, AllocSize, AllocSize = DAG.getNode(ISD::MUL, IntPtr, AllocSize,
getIntPtrConstant(TySize)); getIntPtrConstant(TySize));
// Handle alignment. If the requested alignment is less than the stack // Handle alignment. If the requested alignment is less than or equal to
// alignment, ignore it and round the size of the allocation up to the stack // the stack alignment, ignore it. If the size is greater than or equal to
// alignment size. If the size is greater than or equal to the stack // the stack alignment, we note this in the DYNAMIC_STACKALLOC node.
// alignment, we note this in the DYNAMIC_STACKALLOC node.
unsigned StackAlign = unsigned StackAlign =
TLI.getTargetMachine().getFrameInfo()->getStackAlignment(); TLI.getTargetMachine().getFrameInfo()->getStackAlignment();
if (Align < StackAlign) { if (Align <= StackAlign)
Align = 0; Align = 0;
// Add SA-1 to the size.
AllocSize = DAG.getNode(ISD::ADD, AllocSize.getValueType(), AllocSize, // Round the size of the allocation up to the stack alignment size
getIntPtrConstant(StackAlign-1)); // by add SA-1 to the size.
// Mask out the low bits for alignment purposes. AllocSize = DAG.getNode(ISD::ADD, AllocSize.getValueType(), AllocSize,
AllocSize = DAG.getNode(ISD::AND, AllocSize.getValueType(), AllocSize, getIntPtrConstant(StackAlign-1));
getIntPtrConstant(~(uint64_t)(StackAlign-1))); // Mask out the low bits for alignment purposes.
} AllocSize = DAG.getNode(ISD::AND, AllocSize.getValueType(), AllocSize,
getIntPtrConstant(~(uint64_t)(StackAlign-1)));
SDOperand Ops[] = { getRoot(), AllocSize, getIntPtrConstant(Align) }; SDOperand Ops[] = { getRoot(), AllocSize, getIntPtrConstant(Align) };
const MVT::ValueType *VTs = DAG.getNodeValueTypes(AllocSize.getValueType(), const MVT::ValueType *VTs = DAG.getNodeValueTypes(AllocSize.getValueType(),