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Fix PR3724 by searching for the largest free block when 

allocating memory in the JIT.  This is insanely inefficient, but
hey, most people implement their own memory managers anyway.

Patch by Eric Yew!

llvm-svn: 66472
This commit is contained in:
Chris Lattner 2009-03-09 21:34:10 +00:00
parent 4a1b0776b3
commit 26161cdc6c
1 changed files with 19 additions and 2 deletions
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21
llvm/lib/ExecutionEngine/JIT/JITMemoryManager.cpp
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@ -278,10 +278,27 @@ namespace {
/// startFunctionBody - When a function starts, allocate a block of free
/// executable memory, returning a pointer to it and its actual size.
unsigned char *startFunctionBody(const Function *F, uintptr_t &ActualSize) {
CurBlock = FreeMemoryList;
FreeRangeHeader* candidateBlock = FreeMemoryList;
FreeRangeHeader* head = FreeMemoryList;
FreeRangeHeader* iter = head->Next;
uintptr_t largest = candidateBlock->BlockSize;
// Search for the largest free block
while (iter != head) {
if (iter->BlockSize > largest) {
largest = iter->BlockSize;
candidateBlock = iter;
}
iter = iter->Next;
}
// Select this candidate block for allocation
CurBlock = candidateBlock;
// Allocate the entire memory block.
FreeMemoryList = FreeMemoryList->AllocateBlock();
FreeMemoryList = candidateBlock->AllocateBlock();
ActualSize = CurBlock->BlockSize-sizeof(MemoryRangeHeader);
return (unsigned char *)(CurBlock+1);
}