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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 #endif
extern "C" void PPC32CompilationCallbackC(unsigned *IntRegs, double *FPRegs) { extern "C" void PPC32CompilationCallbackC(unsigned *IntRegs, double *FPRegs) {
unsigned *CameFromStub = (unsigned*)__builtin_return_address(0+1); unsigned *StubCallAddrPlus4 = (unsigned*)__builtin_return_address(0+1);
unsigned *CameFromOrig = (unsigned*)__builtin_return_address(1+1); unsigned *OrigCallAddrPlus4 = (unsigned*)__builtin_return_address(1+1);
unsigned *CCStackPtr = (unsigned*)__builtin_frame_address(0); unsigned *CurStackPtr = (unsigned*)__builtin_frame_address(0);
//unsigned *StubStackPtr = (unsigned*)__builtin_frame_address(1); unsigned *OrigStackPtr = (unsigned*)__builtin_frame_address(2+1);
unsigned *OrigStackPtr = (unsigned*)__builtin_frame_address(2+1);
// Adjust pointer to the branch, not the return address. // Adjust the pointer to the address of the call instruction in the stub
--CameFromStub; // 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 // Check to see if *OrigCallAddr is a 'bl' instruction, and if we can rewrite
// rewrite it to branch directly to the destination. If so, rewrite it so it // it to branch directly to the destination. If so, rewrite it so it does not
// does not need to go through the stub anymore. // need to go through the stub anymore.
unsigned CameFromOrigInst = CameFromOrig[-1]; unsigned OrigCallInst = *OrigCallAddr;
if ((CameFromOrigInst >> 26) == 18) { // Direct call. if ((OrigCallInst >> 26) == 18) { // Direct call.
intptr_t Offset = ((intptr_t)Target-(intptr_t)CameFromOrig+4) >> 2; intptr_t Offset = ((intptr_t)Target - (intptr_t)OrigCallAddr) >> 2;
if (Offset >= -(1 << 23) && Offset < (1 << 23)) { // In range? if (Offset >= -(1 << 23) && Offset < (1 << 23)) { // In range?
// Clear the original target out. // Clear the original target out.
CameFromOrigInst &= (63 << 26) | 3; OrigCallInst &= (63 << 26) | 3;
// Fill in the new target. // Fill in the new target.
CameFromOrigInst |= (Offset & ((1 << 24)-1)) << 2; OrigCallInst |= (Offset & ((1 << 24)-1)) << 2;
// Replace the call. // Replace the call.
CameFromOrig[-1] = CameFromOrigInst; *OrigCallAddr = OrigCallInst;
} }
} }
// Locate the start of the stub. If this is a short call, adjust backwards // Assert that we are coming from a stub that was created with our
// the short amount, otherwise the full amount. // emitFunctionStub.
bool isShortStub = (*CameFromStub >> 26) == 18; assert((*StubCallAddr >> 26) == 19 && "Call in stub is not indirect!");
CameFromStub -= isShortStub ? 2 : 6; StubCallAddr -= 6;
// Rewrite the stub with an unconditional branch to the target, for any users // Rewrite the stub with an unconditional branch to the target, for any users
// who took the address of the stub. // 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. // Change the stored stack pointer so that we pop three stack frames:
*CCStackPtr = (intptr_t)OrigStackPtr; // 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 // Put the address of the target function to call and the address to return to
// stub in a place that is easy to get on the stack after we restore all regs. // after calling the target function in a place that is easy to get on the
CCStackPtr[2] = (intptr_t)Target; // stack after we restore all regs.
CCStackPtr[1] = (intptr_t)CameFromOrig; CurStackPtr[2] = (intptr_t)Target;
CurStackPtr[1] = (intptr_t)OrigCallAddrPlus4;
// Note, this is not a standard epilog! // Note, this is not a standard epilog!
#if defined(__POWERPC__) || defined (__ppc__) || defined(_POWER) #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 f10, 72(%0)\n" "lfd f11, 80(%0)\n" "lfd f12, 88(%0)\n"
"lfd f13, 96(%0)\n" "lfd f13, 96(%0)\n"
"lmw r3, 0(%1)\n" // Load all integer regs "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 "mtlr r0\n" // Put it in the LR register
"lwz r0,8(r1)\n" // Get target function pointer "lwz r0,8(r1)\n" // Get target function pointer
"mtctr r0\n" // Put it into the CTR register "mtctr r0\n" // Put it into the CTR register
"lwz r1,0(r1)\n" // Pop two frames off "lwz r1,0(r1)\n" // Pop three frames off
"bctr\n" :: // Return to stub! "bctr\n" :: // Call target function
"b" (FRR), "b" (IRR)); "b" (FRR), "b" (IRR));
#endif #endif
} }