[llvm-commits] [llvm] r57846 - in /llvm/trunk: include/llvm/System/Memory.h lib/System/Unix/Memory.inc lib/System/Win32/Memory.inc lib/Target/ARM/ARMJITInfo.cpp
Jim Grosbach
grosbach at apple.com
Mon Oct 20 14:39:24 PDT 2008
Author: grosbach
Date: Mon Oct 20 16:39:23 2008
New Revision: 57846
URL: http://llvm.org/viewvc/llvm-project?rev=57846&view=rev
Log:
Update the stub and callback code to handle lazy compilation. The stub
is re-written by the callback to branch directly to the compiled code
in future invocations.
Added back in range-based memory permission functions for the updating of
the stub on Darwin.
Modified:
llvm/trunk/include/llvm/System/Memory.h
llvm/trunk/lib/System/Unix/Memory.inc
llvm/trunk/lib/System/Win32/Memory.inc
llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp
Modified: llvm/trunk/include/llvm/System/Memory.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/System/Memory.h?rev=57846&r1=57845&r2=57846&view=diff
==============================================================================
--- llvm/trunk/include/llvm/System/Memory.h (original)
+++ llvm/trunk/include/llvm/System/Memory.h Mon Oct 20 16:39:23 2008
@@ -79,6 +79,14 @@
/// to mark a block of code as RW since the protections are on page
/// boundaries, and the JIT internal allocations are not page aligned.
static bool setWritable (MemoryBlock &M, std::string *ErrMsg = 0);
+
+ /// setRangeExecutable - Mark the page containing a range of addresses
+ /// as executable.
+ static bool setRangeExecutable(const void *Addr, size_t Size);
+
+ /// setRangeWritable - Mark the page containing a range of addresses
+ /// as writable.
+ static bool setRangeWritable(const void *Addr, size_t Size);
};
}
}
Modified: llvm/trunk/lib/System/Unix/Memory.inc
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/System/Unix/Memory.inc?rev=57846&r1=57845&r2=57846&view=diff
==============================================================================
--- llvm/trunk/lib/System/Unix/Memory.inc (original)
+++ llvm/trunk/lib/System/Unix/Memory.inc Mon Oct 20 16:39:23 2008
@@ -127,3 +127,24 @@
#endif
}
+bool llvm::sys::Memory::setRangeWritable(const void *Addr, size_t Size) {
+#if defined(__APPLE__) && defined(__arm__)
+ kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
+ (vm_size_t)Size, 0,
+ VM_PROT_READ | VM_PROT_WRITE);
+ return KERN_SUCCESS == kr;
+#else
+ return true;
+#endif
+}
+
+bool llvm::sys::Memory::setRangeExecutable(const void *Addr, size_t Size) {
+#if defined(__APPLE__) && defined(__arm__)
+ kern_return_t kr = vm_protect(mach_task_self(), (vm_address_t)Addr,
+ (vm_size_t)Size, 0,
+ VM_PROT_READ | VM_PROT_EXECUTE | VM_PROT_COPY);
+ return KERN_SUCCESS == kr;
+#else
+ return true;
+#endif
+}
Modified: llvm/trunk/lib/System/Win32/Memory.inc
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/System/Win32/Memory.inc?rev=57846&r1=57845&r2=57846&view=diff
==============================================================================
--- llvm/trunk/lib/System/Win32/Memory.inc (original)
+++ llvm/trunk/lib/System/Win32/Memory.inc Mon Oct 20 16:39:23 2008
@@ -53,13 +53,20 @@
return false;
}
-bool Memory::setWritable (MemoryBlock &M, std::string *ErrMsg) {
+bool Memory::setWritable(MemoryBlock &M, std::string *ErrMsg) {
return true;
}
-bool Memory::setExecutable (MemoryBlock &M, std::string *ErrMsg) {
+bool Memory::setExecutable(MemoryBlock &M, std::string *ErrMsg) {
return false;
}
+bool Memory::setRangeWritable(const void *Addr, size_t Size) {
+ return true;
}
+bool Memory::setRangeExecutable(const void *Addr, size_t Size) {
+ return false;
+}
+
+}
Modified: llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp?rev=57846&r1=57845&r2=57846&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMJITInfo.cpp Mon Oct 20 16:39:23 2008
@@ -18,6 +18,8 @@
#include "llvm/Function.h"
#include "llvm/CodeGen/MachineCodeEmitter.h"
#include "llvm/Config/alloca.h"
+#include "llvm/Support/Streams.h"
+#include "llvm/System/Memory.h"
#include <cstdlib>
using namespace llvm;
@@ -38,9 +40,10 @@
#define ASMPREFIX GETASMPREFIX(__USER_LABEL_PREFIX__)
// CompilationCallback stub - We can't use a C function with inline assembly in
-// it, because we the prolog/epilog inserted by GCC won't work for us. Instead,
-// write our own wrapper, which does things our way, so we have complete control
-// over register saving and restoring.
+// it, because we the prolog/epilog inserted by GCC won't work for us (we need
+// to preserve more context and manipulate the stack directly). Instead,
+// write our own wrapper, which does things our way, so we have complete
+// control over register saving and restoring.
extern "C" {
#if defined(__arm__)
void ARMCompilationCallback(void);
@@ -49,33 +52,42 @@
".align 2\n"
".globl " ASMPREFIX "ARMCompilationCallback\n"
ASMPREFIX "ARMCompilationCallback:\n"
- // save main registers
-#if defined(__APPLE__)
- "stmfd sp!, {r4, r5, r6, r7, lr}\n"
- "mov r0, r7\n" // stub's frame
- "stmfd sp!, {r8, r10, r11}\n"
-#else
- "mov ip, sp\n"
- "stmfd sp!, {fp, ip, lr, pc}\n"
- "sub fp, ip, #4\n"
-#endif // __APPLE__
- // arguments to Compilation Callback
- // r0 - our lr (address of the call instruction in stub plus 4)
- // r1 - stub's lr (address of instruction that called the stub plus 4)
-#if defined(__APPLE__)
- "mov r0, r7\n" // stub's frame
-#else
- "mov r0, fp\n" // stub's frame
-#endif // __APPLE__
- "mov r1, lr\n" // stub's lr
- "bl " ASMPREFIX "ARMCompilationCallbackC\n"
- // restore main registers
-#if defined(__APPLE__)
- "ldmfd sp!, {r8, r10, r11}\n"
- "ldmfd sp!, {r4, r5, r6, r7, pc}\n"
-#else
- "ldmfd sp, {fp, sp, pc}\n"
-#endif // __APPLE__
+ // Save caller saved registers since they may contain stuff
+ // for the real target function right now. We have to act as if this
+ // whole compilation callback doesn't exist as far as the caller is
+ // concerned, so we can't just preserve the callee saved regs.
+ "push {r0, r1, r2, r3, lr}\n"
+ // The LR contains the address of the stub function on entry.
+ // pass it as the argument to the C part of the callback
+ "mov r0, lr\n"
+ "sub sp, sp, #4\n"
+ // Call the C portion of the callback
+ "bl " ASMPREFIX "ARMCompilationCallbackC\n"
+ "add sp, sp, #4\n"
+ // Restoring the LR to the return address of the function that invoked
+ // the stub and de-allocating the stack space for it requires us to
+ // swap the two saved LR values on the stack, as they're backwards
+ // for what we need since the pop instruction has a pre-determined
+ // order for the registers.
+ // +--------+
+ // 0 | LR | Original return address
+ // +--------+
+ // 1 | LR | Stub address (start of stub)
+ // 2-5 | R3..R0 | Saved registers (we need to preserve all regs)
+ // +--------+
+ //
+ // We need to exchange the values in slots 0 and 1 so we can
+ // return to the address in slot 1 with the address in slot 0
+ // restored to the LR.
+ "ldr r0, [sp,#20]\n"
+ "ldr r1, [sp,#16]\n"
+ "str r1, [sp,#20]\n"
+ "str r0, [sp,#16]\n"
+ // Return to the (newly modified) stub to invoke the real function.
+ // The above twiddling of the saved return addresses allows us to
+ // deallocate everything, including the LR the stub saved, all in one
+ // pop instruction.
+ "pop {r0, r1, r2, r3, lr, pc}\n"
);
#else // Not an ARM host
void ARMCompilationCallback() {
@@ -85,31 +97,37 @@
#endif
}
-/// ARMCompilationCallbackC - This is the target-specific function invoked by the
-/// function stub when we did not know the real target of a call. This function
-/// must locate the start of the stub or call site and pass it into the JIT
-/// compiler function.
-extern "C" void ARMCompilationCallbackC(intptr_t *StackPtr, intptr_t RetAddr) {
- intptr_t *RetAddrLoc = &StackPtr[-1];
-
- assert(*RetAddrLoc == RetAddr &&
- "Could not find return address on the stack!");
-#if 0
- DOUT << "In callback! Addr=" << (void*)RetAddr
- << " FP=" << (void*)StackPtr
- << ": Resolving call to function: "
- << TheVM->getFunctionReferencedName((void*)RetAddr) << "\n";
-#endif
- intptr_t Addr = RetAddr - 4;
-
- intptr_t NewVal = (intptr_t)JITCompilerFunction((void*)Addr);
+/// ARMCompilationCallbackC - This is the target-specific function invoked
+/// by the function stub when we did not know the real target of a call.
+/// This function must locate the start of the stub or call site and pass
+/// it into the JIT compiler function.
+extern "C" void ARMCompilationCallbackC(intptr_t StubAddr) {
+ // Get the address of the compiled code for this function.
+ intptr_t NewVal = (intptr_t)JITCompilerFunction((void*)StubAddr);
// Rewrite the call target... so that we don't end up here every time we
- // execute the call.
- *(intptr_t *)Addr = NewVal;
-
- // Change the return address to reexecute the branch and link instruction...
- *RetAddrLoc -= 12;
+ // execute the call. We're replacing the first two instructions of the
+ // stub with:
+ // ldr pc, [pc,#-4]
+ // <addr>
+#if defined(__APPLE__)
+ bool ok = sys::Memory::setRangeWritable ((void*)StubAddr, 8);
+ if (!ok)
+ {
+ cerr << "ERROR: Unable to mark stub writable\n";
+ abort();
+ }
+#endif
+ *(intptr_t *)StubAddr = 0xe51ff004;
+ *(intptr_t *)(StubAddr+4) = NewVal;
+#if defined(__APPLE__)
+ ok = sys::Memory::setRangeExecutable ((void*)StubAddr, 8);
+ if (!ok)
+ {
+ cerr << "ERROR: Unable to mark stub executable\n";
+ abort();
+ }
+#endif
}
TargetJITInfo::LazyResolverFn
@@ -127,17 +145,27 @@
// branch to the corresponding function addr
// the stub is 8-byte size and 4-aligned
MCE.startFunctionStub(F, 8, 4);
- MCE.emitWordLE(0xE51FF004); // LDR PC, [PC,#-4]
+ MCE.emitWordLE(0xe51ff004); // LDR PC, [PC,#-4]
MCE.emitWordLE(addr); // addr of function
} else {
- // branch and link to the corresponding function addr
- // the stub is 20-byte size and 4-aligned
- MCE.startFunctionStub(F, 20, 4);
- MCE.emitWordLE(0xE92D4800); // STMFD SP!, [R11, LR]
- MCE.emitWordLE(0xE28FE004); // ADD LR, PC, #4
- MCE.emitWordLE(0xE51FF004); // LDR PC, [PC,#-4]
- MCE.emitWordLE(addr); // addr of function
- MCE.emitWordLE(0xE8BD8800); // LDMFD SP!, [R11, PC]
+ // The compilation callback will overwrite the first two words of this
+ // stub with indirect branch instructions targeting the compiled code.
+ // This stub sets the return address to restart the stub, so that
+ // the new branch will be invoked when we come back.
+ //
+ // branch and link to the compilation callback.
+ // the stub is 16-byte size and 4-byte aligned.
+ MCE.startFunctionStub(F, 16, 4);
+ // Save LR so the callback can determine which stub called it.
+ // The compilation callback is responsible for popping this prior
+ // to returning.
+ MCE.emitWordLE(0xe92d4000); // PUSH {lr}
+ // Set the return address to go back to the start of this stub
+ MCE.emitWordLE(0xe24fe00c); // SUB LR, PC, #12
+ // Invoke the compilation callback
+ MCE.emitWordLE(0xe51ff004); // LDR PC, [PC,#-4]
+ // The address of the compilation callback
+ MCE.emitWordLE((intptr_t)ARMCompilationCallback);
}
return MCE.finishFunctionStub(F);
More information about the llvm-commits
mailing list