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Fix the prolog epilog code inserter to match the documentation and support 

targets whose stack grows up.

Patch contributed by Vladimir Prus

llvm-svn: 14111
This commit is contained in:
Chris Lattner 2004-06-10 06:23:35 +00:00
parent 6d6b3b3ce9
commit 175532bb1e
1 changed files with 32 additions and 8 deletions
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38
llvm/lib/CodeGen/PrologEpilogInserter.cpp
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@ -195,7 +195,6 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
bool StackGrowsDown =
TFI.getStackGrowthDirection() == TargetFrameInfo::StackGrowsDown;
assert(StackGrowsDown && "Only tested on stack down growing targets!");
// Loop over all of the stack objects, assigning sequential addresses...
MachineFrameInfo *FFI = Fn.getFrameInfo();
@ -203,26 +202,51 @@ void PEI::calculateFrameObjectOffsets(MachineFunction &Fn) {
unsigned StackAlignment = TFI.getStackAlignment();
// Start at the beginning of the local area.
// The Offset is the distance from the stack top in the direction
// of stack growth -- so it's always positive.
int Offset = TFI.getOffsetOfLocalArea();
if (StackGrowsDown)
Offset = -Offset;
assert(Offset >= 0
&& "Local area offset should be in direction of stack growth");
// Check to see if there are any fixed sized objects that are preallocated in
// the local area. We currently don't support filling in holes in between
// fixed sized objects, so we just skip to the end of the last fixed sized
// If there are fixed sized objects that are preallocated in the local area,
// non-fixed objects can't be allocated right at the start of local area.
// We currently don't support filling in holes in between fixed sized objects,
// so we adjust 'Offset' to point to the end of last fixed sized
// preallocated object.
for (int i = FFI->getObjectIndexBegin(); i != 0; ++i) {
int FixedOff = -FFI->getObjectOffset(i);
int FixedOff;
if (StackGrowsDown) {
// The maximum distance from the stack pointer is at lower address of
// the object -- which is given by offset. For down growing stack
// the offset is negative, so we negate the offset to get the distance.
FixedOff = -FFI->getObjectOffset(i);
} else {
// The maximum distance from the start pointer is at the upper
// address of the object.
FixedOff = FFI->getObjectOffset(i) + FFI->getObjectSize(i);
}
if (FixedOff > Offset) Offset = FixedOff;
}
for (unsigned i = 0, e = FFI->getObjectIndexEnd(); i != e; ++i) {
Offset += FFI->getObjectSize(i); // Allocate Size bytes...
// If stack grows down, we need to add size of find the lowest
// address of the object.
if (StackGrowsDown)
Offset += FFI->getObjectSize(i);
unsigned Align = FFI->getObjectAlignment(i);
assert(Align <= StackAlignment && "Cannot align stack object to higher "
"alignment boundary than the stack itself!");
Offset = (Offset+Align-1)/Align*Align; // Adjust to Alignment boundary...
FFI->setObjectOffset(i, -Offset); // Set the computed offset
if (StackGrowsDown) {
FFI->setObjectOffset(i, -Offset); // Set the computed offset
} else {
FFI->setObjectOffset(i, Offset);
Offset += FFI->getObjectSize(i);
}
}
// Align the final stack pointer offset, but only if there are calls in the