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simple optimization for the type table

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@36741 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2007-05-04 05:05:48 +00:00
parent 39b2e8b56f
commit 12f535b937
1 changed files with 29 additions and 5 deletions
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34
lib/Bitcode/Writer/ValueEnumerator.cpp
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@ -16,8 +16,21 @@
#include "llvm/Module.h" #include "llvm/Module.h"
#include "llvm/TypeSymbolTable.h" #include "llvm/TypeSymbolTable.h"
#include "llvm/ValueSymbolTable.h" #include "llvm/ValueSymbolTable.h"
#include <algorithm>
using namespace llvm; using namespace llvm;
static bool isFirstClassType(const std::pair<const llvm::Type*,
unsigned int> &P) {
return P.first->isFirstClassType();
}
static bool CompareByFrequency(const std::pair<const llvm::Type*,
unsigned int> &P1,
const std::pair<const llvm::Type*,
unsigned int> &P2) {
return P1.second > P2.second;
}
/// ValueEnumerator - Enumerate module-level information. /// ValueEnumerator - Enumerate module-level information.
ValueEnumerator::ValueEnumerator(const Module *M) { ValueEnumerator::ValueEnumerator(const Module *M) {
// Enumerate the global variables. // Enumerate the global variables.
@ -69,13 +82,24 @@ ValueEnumerator::ValueEnumerator(const Module *M) {
EnumerateType(I->getType()); EnumerateType(I->getType());
} }
} }
// Sort the type table by frequency so that most commonly used types are early
// in the table (have low bit-width).
std::stable_sort(Types.begin(), Types.end(), CompareByFrequency);
// Partition the Type ID's so that the first-class types occur before the
// aggregate types. This allows the aggregate types to be dropped from the
// type table after parsing the global variable initializers.
std::partition(Types.begin(), Types.end(), isFirstClassType);
// Now that we rearranged the type table, rebuild TypeMap.
for (unsigned i = 0, e = Types.size(); i != e; ++i)
TypeMap[Types[i].first] = i+1;
// FIXME: Emit a marker into the module indicating which aggregates types can
// be dropped form the table.
// FIXME: std::partition the type and value tables so that first-class types // FIXME: Sort value tables by frequency.
// come earlier than aggregates. FIXME: Emit a marker into the module
// indicating which aggregates types AND values can be dropped form the table.
// FIXME: Sort type/value tables by frequency.
// FIXME: Sort constants by type to reduce size. // FIXME: Sort constants by type to reduce size.
} }