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

- *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.

llvm-svn: 41132
This commit is contained in:
Evan Cheng 2007-08-16 23:46:29 +00:00
parent f5023a7a84
commit 95667c532c
1 changed files with 12 additions and 12 deletions
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24
llvm/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,
getIntPtrConstant(TySize));
// Handle alignment. If the requested alignment is less than the stack
// alignment, ignore it and round the size of the allocation up to the stack
// alignment size. If the size is greater than or equal to the stack
// alignment, we note this in the DYNAMIC_STACKALLOC node.
// Handle alignment. If the requested alignment is less than or equal to
// the stack alignment, ignore it. If the size is greater than or equal to
// the stack alignment, we note this in the DYNAMIC_STACKALLOC node.
unsigned StackAlign =
TLI.getTargetMachine().getFrameInfo()->getStackAlignment();
if (Align < StackAlign) {
if (Align <= StackAlign)
Align = 0;
// Add SA-1 to the size.
AllocSize = DAG.getNode(ISD::ADD, AllocSize.getValueType(), AllocSize,
getIntPtrConstant(StackAlign-1));
// Mask out the low bits for alignment purposes.
AllocSize = DAG.getNode(ISD::AND, AllocSize.getValueType(), AllocSize,
getIntPtrConstant(~(uint64_t)(StackAlign-1)));
}
// Round the size of the allocation up to the stack alignment size
// by add SA-1 to the size.
AllocSize = DAG.getNode(ISD::ADD, AllocSize.getValueType(), AllocSize,
getIntPtrConstant(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) };
const MVT::ValueType *VTs = DAG.getNodeValueTypes(AllocSize.getValueType(),