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Issue 141030: X64 implementation: if-then-else (Closed) Base URL: http://v8.googlecode.com/svn/branches/bleeding_edge/
Patch Set: '' Created 11 years, 6 months ago
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1 // Copyright 2009 the V8 project authors. All rights reserved. 1 // Copyright 2009 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without 2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are 3 // modification, are permitted provided that the following conditions are
4 // met: 4 // met:
5 // 5 //
6 // * Redistributions of source code must retain the above copyright 6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer. 7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above 8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following 9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided 10 // disclaimer in the documentation and/or other materials provided
11 // with the distribution. 11 // with the distribution.
12 // * Neither the name of Google Inc. nor the names of its 12 // * Neither the name of Google Inc. nor the names of its
13 // contributors may be used to endorse or promote products derived 13 // contributors may be used to endorse or promote products derived
14 // from this software without specific prior written permission. 14 // from this software without specific prior written permission.
15 // 15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 27
28 #include "v8.h"
29
30 #include "codegen-inl.h"
31 #include "jump-target-inl.h"
32 #include "register-allocator-inl.h"
33
34 namespace v8 {
35 namespace internal {
36
37 // -------------------------------------------------------------------------
38 // JumpTarget implementation.
39
40 #define __ ACCESS_MASM(cgen()->masm())
41
42 void JumpTarget::DoJump() {
43 ASSERT(cgen()->has_valid_frame());
44 // Live non-frame registers are not allowed at unconditional jumps
45 // because we have no way of invalidating the corresponding results
46 // which are still live in the C++ code.
47 ASSERT(cgen()->HasValidEntryRegisters());
48
49 if (is_bound()) {
50 // Backward jump. There is an expected frame to merge to.
51 ASSERT(direction_ == BIDIRECTIONAL);
52 cgen()->frame()->PrepareMergeTo(entry_frame_);
53 cgen()->frame()->MergeTo(entry_frame_);
54 cgen()->DeleteFrame();
55 __ jmp(&entry_label_);
56 } else if (entry_frame_ != NULL) {
57 // Forward jump with a preconfigured entry frame. Assert the
58 // current frame matches the expected one and jump to the block.
59 ASSERT(cgen()->frame()->Equals(entry_frame_));
60 cgen()->DeleteFrame();
61 __ jmp(&entry_label_);
62 } else {
63 // Forward jump. Remember the current frame and emit a jump to
64 // its merge code.
65 AddReachingFrame(cgen()->frame());
66 RegisterFile empty;
67 cgen()->SetFrame(NULL, &empty);
68 __ jmp(&merge_labels_.last());
69 }
70 }
71
72
73 void JumpTarget::DoBranch(Condition cc, Hint b) {
74 ASSERT(cgen() != NULL);
75 ASSERT(cgen()->has_valid_frame());
76
77 if (is_bound()) {
78 ASSERT(direction_ == BIDIRECTIONAL);
79 // Backward branch. We have an expected frame to merge to on the
80 // backward edge.
81
82 // Swap the current frame for a copy (we do the swapping to get
83 // the off-frame registers off the fall through) to use for the
84 // branch.
85 VirtualFrame* fall_through_frame = cgen()->frame();
86 VirtualFrame* branch_frame = new VirtualFrame(fall_through_frame);
87 RegisterFile non_frame_registers;
88 cgen()->SetFrame(branch_frame, &non_frame_registers);
89
90 // Check if we can avoid merge code.
91 cgen()->frame()->PrepareMergeTo(entry_frame_);
92 if (cgen()->frame()->Equals(entry_frame_)) {
93 // Branch right in to the block.
94 cgen()->DeleteFrame();
95 __ j(cc, &entry_label_);
96 cgen()->SetFrame(fall_through_frame, &non_frame_registers);
97 return;
98 }
99
100 // Check if we can reuse existing merge code.
101 for (int i = 0; i < reaching_frames_.length(); i++) {
102 if (reaching_frames_[i] != NULL &&
103 cgen()->frame()->Equals(reaching_frames_[i])) {
104 // Branch to the merge code.
105 cgen()->DeleteFrame();
106 __ j(cc, &merge_labels_[i]);
107 cgen()->SetFrame(fall_through_frame, &non_frame_registers);
108 return;
109 }
110 }
111
112 // To emit the merge code here, we negate the condition and branch
113 // around the merge code on the fall through path.
114 Label original_fall_through;
115 __ j(NegateCondition(cc), &original_fall_through);
116 cgen()->frame()->MergeTo(entry_frame_);
117 cgen()->DeleteFrame();
118 __ jmp(&entry_label_);
119 cgen()->SetFrame(fall_through_frame, &non_frame_registers);
120 __ bind(&original_fall_through);
121
122 } else if (entry_frame_ != NULL) {
123 // Forward branch with a preconfigured entry frame. Assert the
124 // current frame matches the expected one and branch to the block.
125 ASSERT(cgen()->frame()->Equals(entry_frame_));
126 // Explicitly use the macro assembler instead of __ as forward
127 // branches are expected to be a fixed size (no inserted
128 // coverage-checking instructions please). This is used in
129 // Reference::GetValue.
130 cgen()->masm()->j(cc, &entry_label_);
131
132 } else {
133 // Forward branch. A copy of the current frame is remembered and
134 // a branch to the merge code is emitted. Explicitly use the
135 // macro assembler instead of __ as forward branches are expected
136 // to be a fixed size (no inserted coverage-checking instructions
137 // please). This is used in Reference::GetValue.
138 AddReachingFrame(new VirtualFrame(cgen()->frame()));
139 cgen()->masm()->j(cc, &merge_labels_.last());
140 }
141 }
142
143
144 void JumpTarget::Call() {
145 // Call is used to push the address of the catch block on the stack as
146 // a return address when compiling try/catch and try/finally. We
147 // fully spill the frame before making the call. The expected frame
148 // at the label (which should be the only one) is the spilled current
149 // frame plus an in-memory return address. The "fall-through" frame
150 // at the return site is the spilled current frame.
151 ASSERT(cgen() != NULL);
152 ASSERT(cgen()->has_valid_frame());
153 // There are no non-frame references across the call.
154 ASSERT(cgen()->HasValidEntryRegisters());
155 ASSERT(!is_linked());
156
157 cgen()->frame()->SpillAll();
158 VirtualFrame* target_frame = new VirtualFrame(cgen()->frame());
159 target_frame->Adjust(1);
160 // We do not expect a call with a preconfigured entry frame.
161 ASSERT(entry_frame_ == NULL);
162 AddReachingFrame(target_frame);
163 __ call(&merge_labels_.last());
164 }
165
166
167 void JumpTarget::DoBind() {
168 ASSERT(cgen() != NULL);
169 ASSERT(!is_bound());
170
171 // Live non-frame registers are not allowed at the start of a basic
172 // block.
173 ASSERT(!cgen()->has_valid_frame() || cgen()->HasValidEntryRegisters());
174
175 // Fast case: the jump target was manually configured with an entry
176 // frame to use.
177 if (entry_frame_ != NULL) {
178 // Assert no reaching frames to deal with.
179 ASSERT(reaching_frames_.is_empty());
180 ASSERT(!cgen()->has_valid_frame());
181
182 RegisterFile empty;
183 if (direction_ == BIDIRECTIONAL) {
184 // Copy the entry frame so the original can be used for a
185 // possible backward jump.
186 cgen()->SetFrame(new VirtualFrame(entry_frame_), &empty);
187 } else {
188 // Take ownership of the entry frame.
189 cgen()->SetFrame(entry_frame_, &empty);
190 entry_frame_ = NULL;
191 }
192 __ bind(&entry_label_);
193 return;
194 }
195
196 if (!is_linked()) {
197 ASSERT(cgen()->has_valid_frame());
198 if (direction_ == FORWARD_ONLY) {
199 // Fast case: no forward jumps and no possible backward jumps.
200 // The stack pointer can be floating above the top of the
201 // virtual frame before the bind. Afterward, it should not.
202 VirtualFrame* frame = cgen()->frame();
203 int difference = frame->stack_pointer_ - (frame->element_count() - 1);
204 if (difference > 0) {
205 frame->stack_pointer_ -= difference;
206 __ addq(rsp, Immediate(difference * kPointerSize));
207 }
208 } else {
209 ASSERT(direction_ == BIDIRECTIONAL);
210 // Fast case: no forward jumps, possible backward ones. Remove
211 // constants and copies above the watermark on the fall-through
212 // frame and use it as the entry frame.
213 cgen()->frame()->MakeMergable();
214 entry_frame_ = new VirtualFrame(cgen()->frame());
215 }
216 __ bind(&entry_label_);
217 return;
218 }
219
220 if (direction_ == FORWARD_ONLY &&
221 !cgen()->has_valid_frame() &&
222 reaching_frames_.length() == 1) {
223 // Fast case: no fall-through, a single forward jump, and no
224 // possible backward jumps. Pick up the only reaching frame, take
225 // ownership of it, and use it for the block about to be emitted.
226 VirtualFrame* frame = reaching_frames_[0];
227 RegisterFile empty;
228 cgen()->SetFrame(frame, &empty);
229 reaching_frames_[0] = NULL;
230 __ bind(&merge_labels_[0]);
231
232 // The stack pointer can be floating above the top of the
233 // virtual frame before the bind. Afterward, it should not.
234 int difference = frame->stack_pointer_ - (frame->element_count() - 1);
235 if (difference > 0) {
236 frame->stack_pointer_ -= difference;
237 __ addq(rsp, Immediate(difference * kPointerSize));
238 }
239
240 __ bind(&entry_label_);
241 return;
242 }
243
244 // If there is a current frame, record it as the fall-through. It
245 // is owned by the reaching frames for now.
246 bool had_fall_through = false;
247 if (cgen()->has_valid_frame()) {
248 had_fall_through = true;
249 AddReachingFrame(cgen()->frame()); // Return value ignored.
250 RegisterFile empty;
251 cgen()->SetFrame(NULL, &empty);
252 }
253
254 // Compute the frame to use for entry to the block.
255 ComputeEntryFrame();
256
257 // Some moves required to merge to an expected frame require purely
258 // frame state changes, and do not require any code generation.
259 // Perform those first to increase the possibility of finding equal
260 // frames below.
261 for (int i = 0; i < reaching_frames_.length(); i++) {
262 if (reaching_frames_[i] != NULL) {
263 reaching_frames_[i]->PrepareMergeTo(entry_frame_);
264 }
265 }
266
267 if (is_linked()) {
268 // There were forward jumps. Handle merging the reaching frames
269 // to the entry frame.
270
271 // Loop over the (non-null) reaching frames and process any that
272 // need merge code. Iterate backwards through the list to handle
273 // the fall-through frame first. Set frames that will be
274 // processed after 'i' to NULL if we want to avoid processing
275 // them.
276 for (int i = reaching_frames_.length() - 1; i >= 0; i--) {
277 VirtualFrame* frame = reaching_frames_[i];
278
279 if (frame != NULL) {
280 // Does the frame (probably) need merge code?
281 if (!frame->Equals(entry_frame_)) {
282 // We could have a valid frame as the fall through to the
283 // binding site or as the fall through from a previous merge
284 // code block. Jump around the code we are about to
285 // generate.
286 if (cgen()->has_valid_frame()) {
287 cgen()->DeleteFrame();
288 __ jmp(&entry_label_);
289 }
290 // Pick up the frame for this block. Assume ownership if
291 // there cannot be backward jumps.
292 RegisterFile empty;
293 if (direction_ == BIDIRECTIONAL) {
294 cgen()->SetFrame(new VirtualFrame(frame), &empty);
295 } else {
296 cgen()->SetFrame(frame, &empty);
297 reaching_frames_[i] = NULL;
298 }
299 __ bind(&merge_labels_[i]);
300
301 // Loop over the remaining (non-null) reaching frames,
302 // looking for any that can share merge code with this one.
303 for (int j = 0; j < i; j++) {
304 VirtualFrame* other = reaching_frames_[j];
305 if (other != NULL && other->Equals(cgen()->frame())) {
306 // Set the reaching frame element to null to avoid
307 // processing it later, and then bind its entry label.
308 reaching_frames_[j] = NULL;
309 __ bind(&merge_labels_[j]);
310 }
311 }
312
313 // Emit the merge code.
314 cgen()->frame()->MergeTo(entry_frame_);
315 } else if (i == reaching_frames_.length() - 1 && had_fall_through) {
316 // If this is the fall through frame, and it didn't need
317 // merge code, we need to pick up the frame so we can jump
318 // around subsequent merge blocks if necessary.
319 RegisterFile empty;
320 cgen()->SetFrame(frame, &empty);
321 reaching_frames_[i] = NULL;
322 }
323 }
324 }
325
326 // The code generator may not have a current frame if there was no
327 // fall through and none of the reaching frames needed merging.
328 // In that case, clone the entry frame as the current frame.
329 if (!cgen()->has_valid_frame()) {
330 RegisterFile empty;
331 cgen()->SetFrame(new VirtualFrame(entry_frame_), &empty);
332 }
333
334 // There may be unprocessed reaching frames that did not need
335 // merge code. They will have unbound merge labels. Bind their
336 // merge labels to be the same as the entry label and deallocate
337 // them.
338 for (int i = 0; i < reaching_frames_.length(); i++) {
339 if (!merge_labels_[i].is_bound()) {
340 reaching_frames_[i] = NULL;
341 __ bind(&merge_labels_[i]);
342 }
343 }
344
345 // There are non-NULL reaching frames with bound labels for each
346 // merge block, but only on backward targets.
347 } else {
348 // There were no forward jumps. There must be a current frame and
349 // this must be a bidirectional target.
350 ASSERT(reaching_frames_.length() == 1);
351 ASSERT(reaching_frames_[0] != NULL);
352 ASSERT(direction_ == BIDIRECTIONAL);
353
354 // Use a copy of the reaching frame so the original can be saved
355 // for possible reuse as a backward merge block.
356 RegisterFile empty;
357 cgen()->SetFrame(new VirtualFrame(reaching_frames_[0]), &empty);
358 __ bind(&merge_labels_[0]);
359 cgen()->frame()->MergeTo(entry_frame_);
360 }
361
362 __ bind(&entry_label_);
363 }
364
365 #undef __
366
367
368 } } // namespace v8::internal
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