LinkBuffer should not keep a reference to the MacroAssembler
[WebKit-https.git] / Source / JavaScriptCore / jit / RegisterPreservationWrapperGenerator.cpp
1 /*
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8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 
24  */
25
26 #include "config.h"
27 #include "RegisterPreservationWrapperGenerator.h"
28
29 #if ENABLE(JIT)
30
31 #include "AssemblyHelpers.h"
32 #include "LinkBuffer.h"
33 #include "JSCInlines.h"
34 #include "StackAlignment.h"
35
36 namespace JSC {
37
38 RegisterSet registersToPreserve()
39 {
40     RegisterSet calleeSaves = RegisterSet::calleeSaveRegisters();
41     
42     // No need to preserve FP since that always gets preserved anyway.
43     calleeSaves.clear(GPRInfo::callFrameRegister);
44     
45     return calleeSaves;
46 }
47
48 ptrdiff_t registerPreservationOffset()
49 {
50     unsigned numberOfCalleeSaves = registersToPreserve().numberOfSetRegisters();
51     
52     // Need to preserve the old return PC.
53     unsigned numberOfValuesToSave = numberOfCalleeSaves + 1;
54     
55     // Alignment. Preserve the same alignment invariants that the caller imposed.
56     unsigned numberOfNewStackSlots =
57         WTF::roundUpToMultipleOf(stackAlignmentRegisters(), numberOfValuesToSave);
58     
59     return sizeof(Register) * numberOfNewStackSlots;
60 }
61
62 MacroAssemblerCodeRef generateRegisterPreservationWrapper(VM& vm, ExecutableBase* executable, MacroAssemblerCodePtr target)
63 {
64 #if ENABLE(FTL_JIT)
65     // We shouldn't ever be generating wrappers for native functions.
66     RegisterSet toSave = registersToPreserve();
67     ptrdiff_t offset = registerPreservationOffset();
68     
69     AssemblyHelpers jit(&vm, 0);
70     
71     jit.preserveReturnAddressAfterCall(GPRInfo::regT1);
72     jit.load32(
73         AssemblyHelpers::Address(
74             AssemblyHelpers::stackPointerRegister,
75             (JSStack::ArgumentCount - JSStack::CallerFrameAndPCSize) * sizeof(Register) + PayloadOffset),
76         GPRInfo::regT2);
77     
78     // Place the stack pointer where we want it to be.
79     jit.subPtr(AssemblyHelpers::TrustedImm32(offset), AssemblyHelpers::stackPointerRegister);
80     
81     // Compute the number of things we will be copying.
82     jit.add32(
83         AssemblyHelpers::TrustedImm32(
84             JSStack::CallFrameHeaderSize - JSStack::CallerFrameAndPCSize),
85         GPRInfo::regT2);
86
87     ASSERT(!toSave.get(GPRInfo::regT4));
88     jit.move(AssemblyHelpers::stackPointerRegister, GPRInfo::regT4);
89     
90     AssemblyHelpers::Label loop = jit.label();
91     jit.sub32(AssemblyHelpers::TrustedImm32(1), GPRInfo::regT2);
92     jit.load64(AssemblyHelpers::Address(GPRInfo::regT4, offset), GPRInfo::regT0);
93     jit.store64(GPRInfo::regT0, GPRInfo::regT4);
94     jit.addPtr(AssemblyHelpers::TrustedImm32(sizeof(Register)), GPRInfo::regT4);
95     jit.branchTest32(AssemblyHelpers::NonZero, GPRInfo::regT2).linkTo(loop, &jit);
96
97     // At this point regT4 + offset points to where we save things.
98     ptrdiff_t currentOffset = 0;
99     jit.storePtr(GPRInfo::regT1, AssemblyHelpers::Address(GPRInfo::regT4, currentOffset));
100     
101     for (GPRReg gpr = AssemblyHelpers::firstRegister(); gpr <= AssemblyHelpers::lastRegister(); gpr = static_cast<GPRReg>(gpr + 1)) {
102         if (!toSave.get(gpr))
103             continue;
104         currentOffset += sizeof(Register);
105         jit.store64(gpr, AssemblyHelpers::Address(GPRInfo::regT4, currentOffset));
106     }
107     for (FPRReg fpr = AssemblyHelpers::firstFPRegister(); fpr <= AssemblyHelpers::lastFPRegister(); fpr = static_cast<FPRReg>(fpr + 1)) {
108         if (!toSave.get(fpr))
109             continue;
110         currentOffset += sizeof(Register);
111         jit.storeDouble(fpr, AssemblyHelpers::Address(GPRInfo::regT4, currentOffset));
112     }
113     
114     // Assume that there aren't any saved FP registers.
115     
116     // Restore the tag registers.
117     jit.move(AssemblyHelpers::TrustedImm64(TagTypeNumber), GPRInfo::tagTypeNumberRegister);
118     jit.add64(AssemblyHelpers::TrustedImm32(TagMask - TagTypeNumber), GPRInfo::tagTypeNumberRegister, GPRInfo::tagMaskRegister);
119     
120     jit.move(
121         AssemblyHelpers::TrustedImmPtr(
122             vm.getCTIStub(registerRestorationThunkGenerator).code().executableAddress()),
123         GPRInfo::nonArgGPR0);
124     jit.restoreReturnAddressBeforeReturn(GPRInfo::nonArgGPR0);
125     AssemblyHelpers::Jump jump = jit.jump();
126     
127     LinkBuffer linkBuffer(vm, jit, GLOBAL_THUNK_ID);
128     linkBuffer.link(jump, CodeLocationLabel(target));
129
130     if (Options::verboseFTLToJSThunk())
131         dataLog("Need a thunk for calls from FTL to non-FTL version of ", *executable, "\n");
132     
133     return FINALIZE_DFG_CODE(linkBuffer, ("Register preservation wrapper for %s/%s, %p", toCString(executable->hashFor(CodeForCall)).data(), toCString(executable->hashFor(CodeForConstruct)).data(), target.executableAddress()));
134 #else // ENABLE(FTL_JIT)
135     UNUSED_PARAM(vm);
136     UNUSED_PARAM(executable);
137     UNUSED_PARAM(target);
138     // We don't support non-FTL builds for two reasons:
139     // - It just so happens that currently only the FTL bottoms out in this code.
140     // - The code above uses 64-bit instructions. It doesn't necessarily have to; it would be
141     //   easy to change it so that it doesn't. But obviously making that change would be a
142     //   prerequisite to removing this #if.
143     UNREACHABLE_FOR_PLATFORM();
144     return MacroAssemblerCodeRef();
145 #endif // ENABLE(FTL_JIT)
146 }
147
148 static void generateRegisterRestoration(AssemblyHelpers& jit)
149 {
150 #if ENABLE(FTL_JIT)
151     RegisterSet toSave = registersToPreserve();
152     ptrdiff_t offset = registerPreservationOffset();
153     
154     ASSERT(!toSave.get(GPRInfo::regT4));
155
156     // We need to place the stack pointer back to where the caller thought they left it.
157     // But also, in order to recover the registers, we need to figure out how big the
158     // arguments area is.
159     
160     jit.load32(
161         AssemblyHelpers::Address(
162             AssemblyHelpers::stackPointerRegister,
163             (JSStack::ArgumentCount - JSStack::CallerFrameAndPCSize) * sizeof(Register) + PayloadOffset),
164         GPRInfo::regT4);
165     
166     jit.move(GPRInfo::regT4, GPRInfo::regT2);
167     jit.lshift32(AssemblyHelpers::TrustedImm32(3), GPRInfo::regT2);
168     
169     jit.addPtr(AssemblyHelpers::TrustedImm32(offset), AssemblyHelpers::stackPointerRegister);
170     jit.addPtr(AssemblyHelpers::stackPointerRegister, GPRInfo::regT2);
171     
172     // We saved things at:
173     //
174     //     adjSP + (JSStack::CallFrameHeaderSize - JSStack::CallerFrameAndPCSize + NumArgs) * 8
175     //
176     // Where:
177     //
178     //     adjSP = origSP - offset
179     //
180     // regT2 now points at:
181     //
182     //     origSP + NumArgs * 8
183     //   = adjSP + offset + NumArgs * 8
184     // 
185     // So if we subtract offset and then add JSStack::CallFrameHeaderSize and subtract
186     // JSStack::CallerFrameAndPCSize, we'll get the thing we want.
187     ptrdiff_t currentOffset = -offset + sizeof(Register) * (
188         JSStack::CallFrameHeaderSize - JSStack::CallerFrameAndPCSize);
189     jit.loadPtr(AssemblyHelpers::Address(GPRInfo::regT2, currentOffset), GPRInfo::regT1);
190     
191     for (GPRReg gpr = AssemblyHelpers::firstRegister(); gpr <= AssemblyHelpers::lastRegister(); gpr = static_cast<GPRReg>(gpr + 1)) {
192         if (!toSave.get(gpr))
193             continue;
194         currentOffset += sizeof(Register);
195         jit.load64(AssemblyHelpers::Address(GPRInfo::regT2, currentOffset), gpr);
196     }
197     for (FPRReg fpr = AssemblyHelpers::firstFPRegister(); fpr <= AssemblyHelpers::lastFPRegister(); fpr = static_cast<FPRReg>(fpr + 1)) {
198         if (!toSave.get(fpr))
199             continue;
200         currentOffset += sizeof(Register);
201         jit.loadDouble(AssemblyHelpers::Address(GPRInfo::regT2, currentOffset), fpr);
202     }
203     
204     // Thunks like this rely on the ArgumentCount being intact. Pay it forward.
205     jit.store32(
206         GPRInfo::regT4,
207         AssemblyHelpers::Address(
208             AssemblyHelpers::stackPointerRegister,
209             (JSStack::ArgumentCount - JSStack::CallerFrameAndPCSize) * sizeof(Register) + PayloadOffset));
210     
211     if (!ASSERT_DISABLED) {
212         AssemblyHelpers::Jump ok = jit.branchPtr(
213             AssemblyHelpers::Above, GPRInfo::regT1, AssemblyHelpers::TrustedImmPtr(static_cast<size_t>(0x1000)));
214         jit.abortWithReason(RPWUnreasonableJumpTarget);
215         ok.link(&jit);
216     }
217     
218     jit.jump(GPRInfo::regT1);
219 #else // ENABLE(FTL_JIT)
220     UNUSED_PARAM(jit);
221     UNREACHABLE_FOR_PLATFORM();
222 #endif // ENABLE(FTL_JIT)
223 }
224
225 MacroAssemblerCodeRef registerRestorationThunkGenerator(VM* vm)
226 {
227     AssemblyHelpers jit(vm, 0);
228     generateRegisterRestoration(jit);
229     LinkBuffer linkBuffer(*vm, jit, GLOBAL_THUNK_ID);
230     return FINALIZE_CODE(linkBuffer, ("Register restoration thunk"));
231 }
232
233 } // namespace JSC
234
235 #endif // ENABLE(JIT)
236