[llvm] r250956 - [JIT] Towards a working small memory model.
Davide Italiano via llvm-commits
llvm-commits at lists.llvm.org
Wed Oct 21 15:12:04 PDT 2015
Author: davide
Date: Wed Oct 21 17:12:03 2015
New Revision: 250956
URL: http://llvm.org/viewvc/llvm-project?rev=250956&view=rev
Log:
[JIT] Towards a working small memory model.
This commit introduces an option, --preallocate, so that we can get memory
upfront and use it in small memory model tests (in order to get
reliable results).
Differential Revision: http://reviews.llvm.org/D13630
Modified:
llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp
Modified: llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp?rev=250956&r1=250955&r2=250956&view=diff
==============================================================================
--- llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp (original)
+++ llvm/trunk/tools/llvm-rtdyld/llvm-rtdyld.cpp Wed Oct 21 17:12:03 2015
@@ -94,6 +94,11 @@ CheckFiles("check",
cl::ZeroOrMore);
static cl::opt<uint64_t>
+PreallocMemory("preallocate",
+ cl::desc("Allocate memory upfront rather than on-demand"),
+ cl::init(0));
+
+static cl::opt<uint64_t>
TargetAddrStart("target-addr-start",
cl::desc("For -verify only: start of phony target address "
"range."),
@@ -173,14 +178,48 @@ public:
size_t Size) override {}
void deregisterEHFrames(uint8_t *Addr, uint64_t LoadAddr,
size_t Size) override {}
+
+ void preallocateSlab(uint64_t Size) {
+ std::string Err;
+ sys::MemoryBlock MB = sys::Memory::AllocateRWX(Size, nullptr, &Err);
+ if (!MB.base())
+ report_fatal_error("Can't allocate enough memory: " + Err);
+
+ PreallocSlab = MB;
+ UsePreallocation = true;
+ SlabSize = Size;
+ }
+
+ uint8_t *allocateFromSlab(uintptr_t Size, unsigned Alignment, bool isCode) {
+ Size = RoundUpToAlignment(Size, Alignment);
+ if (CurrentSlabOffset + Size > SlabSize)
+ report_fatal_error("Can't allocate enough memory. Tune --preallocate");
+
+ uintptr_t OldSlabOffset = CurrentSlabOffset;
+ sys::MemoryBlock MB((void *)OldSlabOffset, Size);
+ if (isCode)
+ FunctionMemory.push_back(MB);
+ else
+ DataMemory.push_back(MB);
+ CurrentSlabOffset += Size;
+ return (uint8_t*)OldSlabOffset;
+ }
+
private:
std::map<std::string, uint64_t> DummyExterns;
+ sys::MemoryBlock PreallocSlab;
+ bool UsePreallocation = false;
+ uintptr_t SlabSize = 0;
+ uintptr_t CurrentSlabOffset = 0;
};
uint8_t *TrivialMemoryManager::allocateCodeSection(uintptr_t Size,
unsigned Alignment,
unsigned SectionID,
StringRef SectionName) {
+ if (UsePreallocation)
+ return allocateFromSlab(Size, Alignment, true /* isCode */);
+
std::string Err;
sys::MemoryBlock MB = sys::Memory::AllocateRWX(Size, nullptr, &Err);
if (!MB.base())
@@ -194,6 +233,9 @@ uint8_t *TrivialMemoryManager::allocateD
unsigned SectionID,
StringRef SectionName,
bool IsReadOnly) {
+ if (UsePreallocation)
+ return allocateFromSlab(Size, Alignment, false /* isCode */);
+
std::string Err;
sys::MemoryBlock MB = sys::Memory::AllocateRWX(Size, nullptr, &Err);
if (!MB.base())
@@ -332,12 +374,24 @@ static int printLineInfoForInput(bool Lo
return 0;
}
+static void doPreallocation(TrivialMemoryManager &MemMgr) {
+ // Allocate a slab of memory upfront, if required. This is used if
+ // we want to test small code models.
+ if (static_cast<intptr_t>(PreallocMemory) < 0)
+ report_fatal_error("Pre-allocated bytes of memory must be a positive integer.");
+
+ // FIXME: Limit the amount of memory that can be preallocated?
+ if (PreallocMemory != 0)
+ MemMgr.preallocateSlab(PreallocMemory);
+}
+
static int executeInput() {
// Load any dylibs requested on the command line.
loadDylibs();
// Instantiate a dynamic linker.
TrivialMemoryManager MemMgr;
+ doPreallocation(MemMgr);
RuntimeDyld Dyld(MemMgr, MemMgr);
// FIXME: Preserve buffers until resolveRelocations time to work around a bug
@@ -613,6 +667,7 @@ static int linkAndVerify() {
// Instantiate a dynamic linker.
TrivialMemoryManager MemMgr;
+ doPreallocation(MemMgr);
RuntimeDyld Dyld(MemMgr, MemMgr);
Dyld.setProcessAllSections(true);
RuntimeDyldChecker Checker(Dyld, Disassembler.get(), InstPrinter.get(),
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