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1 //===-- PPCJITInfo.cpp - Implement the JIT interfaces for the PowerPC -----===//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This file implements the JIT interfaces for the 32-bit PowerPC target.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "PPCJITInfo.h"
15 #include "PPCRelocations.h"
16 #include "PPCSubtarget.h"
17 #include "llvm/IR/Function.h"
18 #include "llvm/Support/Debug.h"
19 #include "llvm/Support/ErrorHandling.h"
20 #include "llvm/Support/Memory.h"
21 #include "llvm/Support/raw_ostream.h"
22 using namespace llvm;
23 
24 #define DEBUG_TYPE "jit"
25 
26 static TargetJITInfo::JITCompilerFn JITCompilerFunction;
27 
PPCJITInfo(PPCSubtarget & STI)28 PPCJITInfo::PPCJITInfo(PPCSubtarget &STI)
29     : Subtarget(STI), is64Bit(STI.isPPC64()) {
30   useGOT = 0;
31 }
32 
33 #define BUILD_ADDIS(RD,RS,IMM16) \
34   ((15 << 26) | ((RD) << 21) | ((RS) << 16) | ((IMM16) & 65535))
35 #define BUILD_ORI(RD,RS,UIMM16) \
36   ((24 << 26) | ((RS) << 21) | ((RD) << 16) | ((UIMM16) & 65535))
37 #define BUILD_ORIS(RD,RS,UIMM16) \
38   ((25 << 26) | ((RS) << 21) | ((RD) << 16) | ((UIMM16) & 65535))
39 #define BUILD_RLDICR(RD,RS,SH,ME) \
40   ((30 << 26) | ((RS) << 21) | ((RD) << 16) | (((SH) & 31) << 11) | \
41    (((ME) & 63) << 6) | (1 << 2) | ((((SH) >> 5) & 1) << 1))
42 #define BUILD_MTSPR(RS,SPR)      \
43   ((31 << 26) | ((RS) << 21) | ((SPR) << 16) | (467 << 1))
44 #define BUILD_BCCTRx(BO,BI,LINK) \
45   ((19 << 26) | ((BO) << 21) | ((BI) << 16) | (528 << 1) | ((LINK) & 1))
46 #define BUILD_B(TARGET, LINK) \
47   ((18 << 26) | (((TARGET) & 0x00FFFFFF) << 2) | ((LINK) & 1))
48 
49 // Pseudo-ops
50 #define BUILD_LIS(RD,IMM16)    BUILD_ADDIS(RD,0,IMM16)
51 #define BUILD_SLDI(RD,RS,IMM6) BUILD_RLDICR(RD,RS,IMM6,63-IMM6)
52 #define BUILD_MTCTR(RS)        BUILD_MTSPR(RS,9)
53 #define BUILD_BCTR(LINK)       BUILD_BCCTRx(20,0,LINK)
54 
EmitBranchToAt(uint64_t At,uint64_t To,bool isCall,bool is64Bit)55 static void EmitBranchToAt(uint64_t At, uint64_t To, bool isCall, bool is64Bit){
56   intptr_t Offset = ((intptr_t)To - (intptr_t)At) >> 2;
57   unsigned *AtI = (unsigned*)(intptr_t)At;
58 
59   if (Offset >= -(1 << 23) && Offset < (1 << 23)) {   // In range?
60     AtI[0] = BUILD_B(Offset, isCall);     // b/bl target
61   } else if (!is64Bit) {
62     AtI[0] = BUILD_LIS(12, To >> 16);     // lis r12, hi16(address)
63     AtI[1] = BUILD_ORI(12, 12, To);       // ori r12, r12, lo16(address)
64     AtI[2] = BUILD_MTCTR(12);             // mtctr r12
65     AtI[3] = BUILD_BCTR(isCall);          // bctr/bctrl
66   } else {
67     AtI[0] = BUILD_LIS(12, To >> 48);      // lis r12, hi16(address)
68     AtI[1] = BUILD_ORI(12, 12, To >> 32);  // ori r12, r12, lo16(address)
69     AtI[2] = BUILD_SLDI(12, 12, 32);       // sldi r12, r12, 32
70     AtI[3] = BUILD_ORIS(12, 12, To >> 16); // oris r12, r12, hi16(address)
71     AtI[4] = BUILD_ORI(12, 12, To);        // ori r12, r12, lo16(address)
72     AtI[5] = BUILD_MTCTR(12);              // mtctr r12
73     AtI[6] = BUILD_BCTR(isCall);           // bctr/bctrl
74   }
75 }
76 
77 extern "C" void PPC32CompilationCallback();
78 extern "C" void PPC64CompilationCallback();
79 
80 // The first clause of the preprocessor directive looks wrong, but it is
81 // necessary when compiling this code on non-PowerPC hosts.
82 #if (!defined(__ppc__) && !defined(__powerpc__)) || defined(__powerpc64__) || defined(__ppc64__)
PPC32CompilationCallback()83 void PPC32CompilationCallback() {
84   llvm_unreachable("This is not a 32bit PowerPC, you can't execute this!");
85 }
86 #elif !defined(__ELF__)
87 // CompilationCallback stub - We can't use a C function with inline assembly in
88 // it, because we the prolog/epilog inserted by GCC won't work for us.  Instead,
89 // write our own wrapper, which does things our way, so we have complete control
90 // over register saving and restoring.
91 asm(
92     ".text\n"
93     ".align 2\n"
94     ".globl _PPC32CompilationCallback\n"
95 "_PPC32CompilationCallback:\n"
96     // Make space for 8 ints r[3-10] and 13 doubles f[1-13] and the
97     // FIXME: need to save v[0-19] for altivec?
98     // FIXME: could shrink frame
99     // Set up a proper stack frame
100     // FIXME Layout
101     //   PowerPC32 ABI linkage    -  24 bytes
102     //                 parameters -  32 bytes
103     //   13 double registers      - 104 bytes
104     //   8 int registers          -  32 bytes
105     "mflr r0\n"
106     "stw r0,  8(r1)\n"
107     "stwu r1, -208(r1)\n"
108     // Save all int arg registers
109     "stw r10, 204(r1)\n"    "stw r9,  200(r1)\n"
110     "stw r8,  196(r1)\n"    "stw r7,  192(r1)\n"
111     "stw r6,  188(r1)\n"    "stw r5,  184(r1)\n"
112     "stw r4,  180(r1)\n"    "stw r3,  176(r1)\n"
113     // Save all call-clobbered FP regs.
114     "stfd f13, 168(r1)\n"   "stfd f12, 160(r1)\n"
115     "stfd f11, 152(r1)\n"   "stfd f10, 144(r1)\n"
116     "stfd f9,  136(r1)\n"   "stfd f8,  128(r1)\n"
117     "stfd f7,  120(r1)\n"   "stfd f6,  112(r1)\n"
118     "stfd f5,  104(r1)\n"   "stfd f4,   96(r1)\n"
119     "stfd f3,   88(r1)\n"   "stfd f2,   80(r1)\n"
120     "stfd f1,   72(r1)\n"
121     // Arguments to Compilation Callback:
122     // r3 - our lr (address of the call instruction in stub plus 4)
123     // r4 - stub's lr (address of instruction that called the stub plus 4)
124     // r5 - is64Bit - always 0.
125     "mr   r3, r0\n"
126     "lwz  r2, 208(r1)\n" // stub's frame
127     "lwz  r4, 8(r2)\n" // stub's lr
128     "li   r5, 0\n"       // 0 == 32 bit
129     "bl _LLVMPPCCompilationCallback\n"
130     "mtctr r3\n"
131     // Restore all int arg registers
132     "lwz r10, 204(r1)\n"    "lwz r9,  200(r1)\n"
133     "lwz r8,  196(r1)\n"    "lwz r7,  192(r1)\n"
134     "lwz r6,  188(r1)\n"    "lwz r5,  184(r1)\n"
135     "lwz r4,  180(r1)\n"    "lwz r3,  176(r1)\n"
136     // Restore all FP arg registers
137     "lfd f13, 168(r1)\n"    "lfd f12, 160(r1)\n"
138     "lfd f11, 152(r1)\n"    "lfd f10, 144(r1)\n"
139     "lfd f9,  136(r1)\n"    "lfd f8,  128(r1)\n"
140     "lfd f7,  120(r1)\n"    "lfd f6,  112(r1)\n"
141     "lfd f5,  104(r1)\n"    "lfd f4,   96(r1)\n"
142     "lfd f3,   88(r1)\n"    "lfd f2,   80(r1)\n"
143     "lfd f1,   72(r1)\n"
144     // Pop 3 frames off the stack and branch to target
145     "lwz  r1, 208(r1)\n"
146     "lwz  r2, 8(r1)\n"
147     "mtlr r2\n"
148     "bctr\n"
149     );
150 
151 #else
152 // ELF PPC 32 support
153 
154 // CompilationCallback stub - We can't use a C function with inline assembly in
155 // it, because we the prolog/epilog inserted by GCC won't work for us.  Instead,
156 // write our own wrapper, which does things our way, so we have complete control
157 // over register saving and restoring.
158 asm(
159     ".text\n"
160     ".align 2\n"
161     ".globl PPC32CompilationCallback\n"
162 "PPC32CompilationCallback:\n"
163     // Make space for 8 ints r[3-10] and 8 doubles f[1-8] and the
164     // FIXME: need to save v[0-19] for altivec?
165     // FIXME: could shrink frame
166     // Set up a proper stack frame
167     // FIXME Layout
168     //   8 double registers       -  64 bytes
169     //   8 int registers          -  32 bytes
170     "mflr 0\n"
171     "stw 0,  4(1)\n"
172     "stwu 1, -104(1)\n"
173     // Save all int arg registers
174     "stw 10, 100(1)\n"   "stw 9,  96(1)\n"
175     "stw 8,  92(1)\n"    "stw 7,  88(1)\n"
176     "stw 6,  84(1)\n"    "stw 5,  80(1)\n"
177     "stw 4,  76(1)\n"    "stw 3,  72(1)\n"
178     // Save all call-clobbered FP regs.
179     "stfd 8,  64(1)\n"
180     "stfd 7,  56(1)\n"   "stfd 6,  48(1)\n"
181     "stfd 5,  40(1)\n"   "stfd 4,  32(1)\n"
182     "stfd 3,  24(1)\n"   "stfd 2,  16(1)\n"
183     "stfd 1,  8(1)\n"
184     // Arguments to Compilation Callback:
185     // r3 - our lr (address of the call instruction in stub plus 4)
186     // r4 - stub's lr (address of instruction that called the stub plus 4)
187     // r5 - is64Bit - always 0.
188     "mr   3, 0\n"
189     "lwz  5, 104(1)\n" // stub's frame
190     "lwz  4, 4(5)\n" // stub's lr
191     "li   5, 0\n"       // 0 == 32 bit
192     "bl LLVMPPCCompilationCallback\n"
193     "mtctr 3\n"
194     // Restore all int arg registers
195     "lwz 10, 100(1)\n"   "lwz 9,  96(1)\n"
196     "lwz 8,  92(1)\n"    "lwz 7,  88(1)\n"
197     "lwz 6,  84(1)\n"    "lwz 5,  80(1)\n"
198     "lwz 4,  76(1)\n"    "lwz 3,  72(1)\n"
199     // Restore all FP arg registers
200     "lfd 8,  64(1)\n"
201     "lfd 7,  56(1)\n"    "lfd 6,  48(1)\n"
202     "lfd 5,  40(1)\n"    "lfd 4,  32(1)\n"
203     "lfd 3,  24(1)\n"    "lfd 2,  16(1)\n"
204     "lfd 1,  8(1)\n"
205     // Pop 3 frames off the stack and branch to target
206     "lwz  1, 104(1)\n"
207     "lwz  0, 4(1)\n"
208     "mtlr 0\n"
209     "bctr\n"
210     );
211 #endif
212 
213 #if !defined(__powerpc64__) && !defined(__ppc64__)
PPC64CompilationCallback()214 void PPC64CompilationCallback() {
215   llvm_unreachable("This is not a 64bit PowerPC, you can't execute this!");
216 }
217 #else
218 #  ifdef __ELF__
219 asm(
220     ".text\n"
221     ".align 2\n"
222     ".globl PPC64CompilationCallback\n"
223 #if _CALL_ELF == 2
224     ".type PPC64CompilationCallback,@function\n"
225 "PPC64CompilationCallback:\n"
226 #else
227     ".section \".opd\",\"aw\",@progbits\n"
228     ".align 3\n"
229 "PPC64CompilationCallback:\n"
230     ".quad .L.PPC64CompilationCallback,.TOC.@tocbase,0\n"
231     ".size PPC64CompilationCallback,24\n"
232     ".previous\n"
233     ".align 4\n"
234     ".type PPC64CompilationCallback,@function\n"
235 ".L.PPC64CompilationCallback:\n"
236 #endif
237 #  else
238 asm(
239     ".text\n"
240     ".align 2\n"
241     ".globl _PPC64CompilationCallback\n"
242 "_PPC64CompilationCallback:\n"
243 #  endif
244     // Make space for 8 ints r[3-10] and 13 doubles f[1-13] and the
245     // FIXME: need to save v[0-19] for altivec?
246     // Set up a proper stack frame
247     // Layout
248     //   PowerPC64 ABI linkage    -  48 bytes
249     //                 parameters -  64 bytes
250     //   13 double registers      - 104 bytes
251     //   8 int registers          -  64 bytes
252     "mflr 0\n"
253     "std  0,  16(1)\n"
254     "stdu 1, -280(1)\n"
255     // Save all int arg registers
256     "std 10, 272(1)\n"    "std 9,  264(1)\n"
257     "std 8,  256(1)\n"    "std 7,  248(1)\n"
258     "std 6,  240(1)\n"    "std 5,  232(1)\n"
259     "std 4,  224(1)\n"    "std 3,  216(1)\n"
260     // Save all call-clobbered FP regs.
261     "stfd 13, 208(1)\n"    "stfd 12, 200(1)\n"
262     "stfd 11, 192(1)\n"    "stfd 10, 184(1)\n"
263     "stfd 9,  176(1)\n"    "stfd 8,  168(1)\n"
264     "stfd 7,  160(1)\n"    "stfd 6,  152(1)\n"
265     "stfd 5,  144(1)\n"    "stfd 4,  136(1)\n"
266     "stfd 3,  128(1)\n"    "stfd 2,  120(1)\n"
267     "stfd 1,  112(1)\n"
268     // Arguments to Compilation Callback:
269     // r3 - our lr (address of the call instruction in stub plus 4)
270     // r4 - stub's lr (address of instruction that called the stub plus 4)
271     // r5 - is64Bit - always 1.
272     "mr   3, 0\n"      // return address (still in r0)
273     "ld   5, 280(1)\n" // stub's frame
274     "ld   4, 16(5)\n"  // stub's lr
275     "li   5, 1\n"      // 1 == 64 bit
276 #  ifdef __ELF__
277     "bl LLVMPPCCompilationCallback\n"
278     "nop\n"
279 #  else
280     "bl _LLVMPPCCompilationCallback\n"
281 #  endif
282     "mtctr 3\n"
283     // Restore all int arg registers
284     "ld 10, 272(1)\n"    "ld 9,  264(1)\n"
285     "ld 8,  256(1)\n"    "ld 7,  248(1)\n"
286     "ld 6,  240(1)\n"    "ld 5,  232(1)\n"
287     "ld 4,  224(1)\n"    "ld 3,  216(1)\n"
288     // Restore all FP arg registers
289     "lfd 13, 208(1)\n"    "lfd 12, 200(1)\n"
290     "lfd 11, 192(1)\n"    "lfd 10, 184(1)\n"
291     "lfd 9,  176(1)\n"    "lfd 8,  168(1)\n"
292     "lfd 7,  160(1)\n"    "lfd 6,  152(1)\n"
293     "lfd 5,  144(1)\n"    "lfd 4,  136(1)\n"
294     "lfd 3,  128(1)\n"    "lfd 2,  120(1)\n"
295     "lfd 1,  112(1)\n"
296     // Pop 3 frames off the stack and branch to target
297     "ld  1, 280(1)\n"
298     "ld  0, 16(1)\n"
299     "mtlr 0\n"
300     // XXX: any special TOC handling in the ELF case for JIT?
301     "bctr\n"
302     );
303 #endif
304 
305 extern "C" {
306 LLVM_LIBRARY_VISIBILITY void *
LLVMPPCCompilationCallback(unsigned * StubCallAddrPlus4,unsigned * OrigCallAddrPlus4,bool is64Bit)307 LLVMPPCCompilationCallback(unsigned *StubCallAddrPlus4,
308                            unsigned *OrigCallAddrPlus4,
309                            bool is64Bit) {
310   // Adjust the pointer to the address of the call instruction in the stub
311   // emitted by emitFunctionStub, rather than the instruction after it.
312   unsigned *StubCallAddr = StubCallAddrPlus4 - 1;
313   unsigned *OrigCallAddr = OrigCallAddrPlus4 - 1;
314 
315   void *Target = JITCompilerFunction(StubCallAddr);
316 
317   // Check to see if *OrigCallAddr is a 'bl' instruction, and if we can rewrite
318   // it to branch directly to the destination.  If so, rewrite it so it does not
319   // need to go through the stub anymore.
320   unsigned OrigCallInst = *OrigCallAddr;
321   if ((OrigCallInst >> 26) == 18) {     // Direct call.
322     intptr_t Offset = ((intptr_t)Target - (intptr_t)OrigCallAddr) >> 2;
323 
324     if (Offset >= -(1 << 23) && Offset < (1 << 23)) {   // In range?
325       // Clear the original target out.
326       OrigCallInst &= (63 << 26) | 3;
327       // Fill in the new target.
328       OrigCallInst |= (Offset & ((1 << 24)-1)) << 2;
329       // Replace the call.
330       *OrigCallAddr = OrigCallInst;
331     }
332   }
333 
334   // Assert that we are coming from a stub that was created with our
335   // emitFunctionStub.
336   if ((*StubCallAddr >> 26) == 18)
337     StubCallAddr -= 3;
338   else {
339   assert((*StubCallAddr >> 26) == 19 && "Call in stub is not indirect!");
340     StubCallAddr -= is64Bit ? 9 : 6;
341   }
342 
343   // Rewrite the stub with an unconditional branch to the target, for any users
344   // who took the address of the stub.
345   EmitBranchToAt((intptr_t)StubCallAddr, (intptr_t)Target, false, is64Bit);
346   sys::Memory::InvalidateInstructionCache(StubCallAddr, 7*4);
347 
348   // Put the address of the target function to call and the address to return to
349   // after calling the target function in a place that is easy to get on the
350   // stack after we restore all regs.
351   return Target;
352 }
353 }
354 
355 
356 
357 TargetJITInfo::LazyResolverFn
getLazyResolverFunction(JITCompilerFn Fn)358 PPCJITInfo::getLazyResolverFunction(JITCompilerFn Fn) {
359   JITCompilerFunction = Fn;
360   return is64Bit ? PPC64CompilationCallback : PPC32CompilationCallback;
361 }
362 
getStubLayout()363 TargetJITInfo::StubLayout PPCJITInfo::getStubLayout() {
364   // The stub contains up to 10 4-byte instructions, aligned at 4 bytes: 3
365   // instructions to save the caller's address if this is a lazy-compilation
366   // stub, plus a 1-, 4-, or 7-instruction sequence to load an arbitrary address
367   // into a register and jump through it.
368   StubLayout Result = {10*4, 4};
369   return Result;
370 }
371 
372 #if (defined(__POWERPC__) || defined (__ppc__) || defined(_POWER)) && \
373 defined(__APPLE__)
374 extern "C" void sys_icache_invalidate(const void *Addr, size_t len);
375 #endif
376 
emitFunctionStub(const Function * F,void * Fn,JITCodeEmitter & JCE)377 void *PPCJITInfo::emitFunctionStub(const Function* F, void *Fn,
378                                    JITCodeEmitter &JCE) {
379   // If this is just a call to an external function, emit a branch instead of a
380   // call.  The code is the same except for one bit of the last instruction.
381   if (Fn != (void*)(intptr_t)PPC32CompilationCallback &&
382       Fn != (void*)(intptr_t)PPC64CompilationCallback) {
383     void *Addr = (void*)JCE.getCurrentPCValue();
384     JCE.emitWordBE(0);
385     JCE.emitWordBE(0);
386     JCE.emitWordBE(0);
387     JCE.emitWordBE(0);
388     JCE.emitWordBE(0);
389     JCE.emitWordBE(0);
390     JCE.emitWordBE(0);
391     EmitBranchToAt((intptr_t)Addr, (intptr_t)Fn, false, is64Bit);
392     sys::Memory::InvalidateInstructionCache(Addr, 7*4);
393     return Addr;
394   }
395 
396   void *Addr = (void*)JCE.getCurrentPCValue();
397   if (is64Bit) {
398     JCE.emitWordBE(0xf821ffb1);     // stdu r1,-80(r1)
399     JCE.emitWordBE(0x7d6802a6);     // mflr r11
400     JCE.emitWordBE(0xf9610060);     // std r11, 96(r1)
401   } else if (Subtarget.isDarwinABI()){
402     JCE.emitWordBE(0x9421ffe0);     // stwu r1,-32(r1)
403     JCE.emitWordBE(0x7d6802a6);     // mflr r11
404     JCE.emitWordBE(0x91610028);     // stw r11, 40(r1)
405   } else {
406     JCE.emitWordBE(0x9421ffe0);     // stwu r1,-32(r1)
407     JCE.emitWordBE(0x7d6802a6);     // mflr r11
408     JCE.emitWordBE(0x91610024);     // stw r11, 36(r1)
409   }
410   intptr_t BranchAddr = (intptr_t)JCE.getCurrentPCValue();
411   JCE.emitWordBE(0);
412   JCE.emitWordBE(0);
413   JCE.emitWordBE(0);
414   JCE.emitWordBE(0);
415   JCE.emitWordBE(0);
416   JCE.emitWordBE(0);
417   JCE.emitWordBE(0);
418   EmitBranchToAt(BranchAddr, (intptr_t)Fn, true, is64Bit);
419   sys::Memory::InvalidateInstructionCache(Addr, 10*4);
420   return Addr;
421 }
422 
423 
relocate(void * Function,MachineRelocation * MR,unsigned NumRelocs,unsigned char * GOTBase)424 void PPCJITInfo::relocate(void *Function, MachineRelocation *MR,
425                           unsigned NumRelocs, unsigned char* GOTBase) {
426   for (unsigned i = 0; i != NumRelocs; ++i, ++MR) {
427     unsigned *RelocPos = (unsigned*)Function + MR->getMachineCodeOffset()/4;
428     intptr_t ResultPtr = (intptr_t)MR->getResultPointer();
429     switch ((PPC::RelocationType)MR->getRelocationType()) {
430     default: llvm_unreachable("Unknown relocation type!");
431     case PPC::reloc_pcrel_bx:
432       // PC-relative relocation for b and bl instructions.
433       ResultPtr = (ResultPtr-(intptr_t)RelocPos) >> 2;
434       assert(ResultPtr >= -(1 << 23) && ResultPtr < (1 << 23) &&
435              "Relocation out of range!");
436       *RelocPos |= (ResultPtr & ((1 << 24)-1))  << 2;
437       break;
438     case PPC::reloc_pcrel_bcx:
439       // PC-relative relocation for BLT,BLE,BEQ,BGE,BGT,BNE, or other
440       // bcx instructions.
441       ResultPtr = (ResultPtr-(intptr_t)RelocPos) >> 2;
442       assert(ResultPtr >= -(1 << 13) && ResultPtr < (1 << 13) &&
443              "Relocation out of range!");
444       *RelocPos |= (ResultPtr & ((1 << 14)-1))  << 2;
445       break;
446     case PPC::reloc_absolute_high:     // high bits of ref -> low 16 of instr
447     case PPC::reloc_absolute_low: {    // low bits of ref  -> low 16 of instr
448       ResultPtr += MR->getConstantVal();
449 
450       // If this is a high-part access, get the high-part.
451       if (MR->getRelocationType() == PPC::reloc_absolute_high) {
452         // If the low part will have a carry (really a borrow) from the low
453         // 16-bits into the high 16, add a bit to borrow from.
454         if (((int)ResultPtr << 16) < 0)
455           ResultPtr += 1 << 16;
456         ResultPtr >>= 16;
457       }
458 
459       // Do the addition then mask, so the addition does not overflow the 16-bit
460       // immediate section of the instruction.
461       unsigned LowBits  = (*RelocPos + ResultPtr) & 65535;
462       unsigned HighBits = *RelocPos & ~65535;
463       *RelocPos = LowBits | HighBits;  // Slam into low 16-bits
464       break;
465     }
466     case PPC::reloc_absolute_low_ix: {  // low bits of ref  -> low 14 of instr
467       ResultPtr += MR->getConstantVal();
468       // Do the addition then mask, so the addition does not overflow the 16-bit
469       // immediate section of the instruction.
470       unsigned LowBits  = (*RelocPos + ResultPtr) & 0xFFFC;
471       unsigned HighBits = *RelocPos & 0xFFFF0003;
472       *RelocPos = LowBits | HighBits;  // Slam into low 14-bits.
473       break;
474     }
475     }
476   }
477 }
478 
replaceMachineCodeForFunction(void * Old,void * New)479 void PPCJITInfo::replaceMachineCodeForFunction(void *Old, void *New) {
480   EmitBranchToAt((intptr_t)Old, (intptr_t)New, false, is64Bit);
481   sys::Memory::InvalidateInstructionCache(Old, 7*4);
482 }
483