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No functionality changes, but cleaner code with correct comments.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@27966 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2006-04-25 04:45:59 +00:00
parent a2137b592e
commit b3f70d7d55
1 changed files with 37 additions and 31 deletions
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68
lib/Target/PowerPC/PPCJITInfo.cpp
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@ -86,49 +86,55 @@ void PPC32CompilationCallback() {
#endif
extern "C" void PPC32CompilationCallbackC(unsigned *IntRegs, double *FPRegs) {
unsigned *CameFromStub = (unsigned*)__builtin_return_address(0+1);
unsigned *CameFromOrig = (unsigned*)__builtin_return_address(1+1);
unsigned *CCStackPtr = (unsigned*)__builtin_frame_address(0);
//unsigned *StubStackPtr = (unsigned*)__builtin_frame_address(1);
unsigned *OrigStackPtr = (unsigned*)__builtin_frame_address(2+1);
unsigned *StubCallAddrPlus4 = (unsigned*)__builtin_return_address(0+1);
unsigned *OrigCallAddrPlus4 = (unsigned*)__builtin_return_address(1+1);
unsigned *CurStackPtr = (unsigned*)__builtin_frame_address(0);
unsigned *OrigStackPtr = (unsigned*)__builtin_frame_address(2+1);
// Adjust pointer to the branch, not the return address.
--CameFromStub;
// Adjust the pointer to the address of the call instruction in the stub
// emitted by emitFunctionStub, rather than the instruction after it.
unsigned *StubCallAddr = StubCallAddrPlus4 - 1;
unsigned *OrigCallAddr = OrigCallAddrPlus4 - 1;
void *Target = JITCompilerFunction(CameFromStub);
void *Target = JITCompilerFunction(StubCallAddr);
// Check to see if CameFromOrig[-1] is a 'bl' instruction, and if we can
// rewrite it to branch directly to the destination. If so, rewrite it so it
// does not need to go through the stub anymore.
unsigned CameFromOrigInst = CameFromOrig[-1];
if ((CameFromOrigInst >> 26) == 18) { // Direct call.
intptr_t Offset = ((intptr_t)Target-(intptr_t)CameFromOrig+4) >> 2;
// Check to see if *OrigCallAddr is a 'bl' instruction, and if we can rewrite
// it to branch directly to the destination. If so, rewrite it so it does not
// need to go through the stub anymore.
unsigned OrigCallInst = *OrigCallAddr;
if ((OrigCallInst >> 26) == 18) { // Direct call.
intptr_t Offset = ((intptr_t)Target - (intptr_t)OrigCallAddr) >> 2;
if (Offset >= -(1 << 23) && Offset < (1 << 23)) { // In range?
// Clear the original target out.
CameFromOrigInst &= (63 << 26) | 3;
OrigCallInst &= (63 << 26) | 3;
// Fill in the new target.
CameFromOrigInst |= (Offset & ((1 << 24)-1)) << 2;
OrigCallInst |= (Offset & ((1 << 24)-1)) << 2;
// Replace the call.
CameFromOrig[-1] = CameFromOrigInst;
*OrigCallAddr = OrigCallInst;
}
}
// Locate the start of the stub. If this is a short call, adjust backwards
// the short amount, otherwise the full amount.
bool isShortStub = (*CameFromStub >> 26) == 18;
CameFromStub -= isShortStub ? 2 : 6;
// Assert that we are coming from a stub that was created with our
// emitFunctionStub.
assert((*StubCallAddr >> 26) == 19 && "Call in stub is not indirect!");
StubCallAddr -= 6;
// Rewrite the stub with an unconditional branch to the target, for any users
// who took the address of the stub.
EmitBranchToAt(CameFromStub, Target, false);
EmitBranchToAt(StubCallAddr, Target, false);
// Change the SP so that we pop two stack frames off when we return.
*CCStackPtr = (intptr_t)OrigStackPtr;
// Change the stored stack pointer so that we pop three stack frames:
// 1. PPC32CompilationCallbackC's frame
// 2. _PPC32CompilationCallback's frame
// 3. the stub's frame
*CurStackPtr = (intptr_t)OrigStackPtr;
// Put the address of the stub and the LR value that originally came into the
// stub in a place that is easy to get on the stack after we restore all regs.
CCStackPtr[2] = (intptr_t)Target;
CCStackPtr[1] = (intptr_t)CameFromOrig;
// Put the address of the target function to call and the address to return to
// after calling the target function in a place that is easy to get on the
// stack after we restore all regs.
CurStackPtr[2] = (intptr_t)Target;
CurStackPtr[1] = (intptr_t)OrigCallAddrPlus4;
// Note, this is not a standard epilog!
#if defined(__POWERPC__) || defined (__ppc__) || defined(_POWER)
@ -141,12 +147,12 @@ extern "C" void PPC32CompilationCallbackC(unsigned *IntRegs, double *FPRegs) {
"lfd f10, 72(%0)\n" "lfd f11, 80(%0)\n" "lfd f12, 88(%0)\n"
"lfd f13, 96(%0)\n"
"lmw r3, 0(%1)\n" // Load all integer regs
"lwz r0,4(r1)\n" // Get CameFromOrig (LR into stub)
"lwz r0,4(r1)\n" // Get OrigCallAddrPlus4 (LR value when stub was called)
"mtlr r0\n" // Put it in the LR register
"lwz r0,8(r1)\n" // Get target function pointer
"mtctr r0\n" // Put it into the CTR register
"lwz r1,0(r1)\n" // Pop two frames off
"bctr\n" :: // Return to stub!
"lwz r1,0(r1)\n" // Pop three frames off
"bctr\n" :: // Call target function
"b" (FRR), "b" (IRR));
#endif
}