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Issue 6811012: Remove some dead code. (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Created 9 years, 8 months ago
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1 // Copyright 2008 the V8 project authors. All rights reserved.
2 // Redistribution and use in source and binary forms, with or without
3 // modification, are permitted provided that the following conditions are
4 // met:
5 //
6 // * Redistributions of source code must retain the above copyright
7 // notice, this list of conditions and the following disclaimer.
8 // * Redistributions in binary form must reproduce the above
9 // copyright notice, this list of conditions and the following
10 // disclaimer in the documentation and/or other materials provided
11 // with the distribution.
12 // * Neither the name of Google Inc. nor the names of its
13 // contributors may be used to endorse or promote products derived
14 // from this software without specific prior written permission.
15 //
16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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.
27
28 #include "v8.h"
29
30 #if defined(V8_TARGET_ARCH_ARM)
31
32 #include "codegen-inl.h"
33 #include "jump-target-inl.h"
34 #include "register-allocator-inl.h"
35 #include "virtual-frame-inl.h"
36
37 namespace v8 {
38 namespace internal {
39
40 // -------------------------------------------------------------------------
41 // JumpTarget implementation.
42
43 #define __ ACCESS_MASM(cgen()->masm())
44
45 void JumpTarget::DoJump() {
46 ASSERT(cgen()->has_valid_frame());
47 // Live non-frame registers are not allowed at unconditional jumps
48 // because we have no way of invalidating the corresponding results
49 // which are still live in the C++ code.
50 ASSERT(cgen()->HasValidEntryRegisters());
51
52 if (entry_frame_set_) {
53 if (entry_label_.is_bound()) {
54 // If we already bound and generated code at the destination then it
55 // is too late to ask for less optimistic type assumptions.
56 ASSERT(entry_frame_.IsCompatibleWith(cgen()->frame()));
57 }
58 // There already a frame expectation at the target.
59 cgen()->frame()->MergeTo(&entry_frame_);
60 cgen()->DeleteFrame();
61 } else {
62 // Clone the current frame to use as the expected one at the target.
63 set_entry_frame(cgen()->frame());
64 // Zap the fall-through frame since the jump was unconditional.
65 RegisterFile empty;
66 cgen()->SetFrame(NULL, &empty);
67 }
68 if (entry_label_.is_bound()) {
69 // You can't jump backwards to an already bound label unless you admitted
70 // up front that this was a bidirectional jump target. Bidirectional jump
71 // targets will zap their type info when bound in case some later virtual
72 // frame with less precise type info branches to them.
73 ASSERT(direction_ != FORWARD_ONLY);
74 }
75 __ jmp(&entry_label_);
76 }
77
78
79 void JumpTarget::DoBranch(Condition cond, Hint ignored) {
80 ASSERT(cgen()->has_valid_frame());
81
82 if (entry_frame_set_) {
83 if (entry_label_.is_bound()) {
84 // If we already bound and generated code at the destination then it
85 // is too late to ask for less optimistic type assumptions.
86 ASSERT(entry_frame_.IsCompatibleWith(cgen()->frame()));
87 }
88 // We have an expected frame to merge to on the backward edge.
89 cgen()->frame()->MergeTo(&entry_frame_, cond);
90 } else {
91 // Clone the current frame to use as the expected one at the target.
92 set_entry_frame(cgen()->frame());
93 }
94 if (entry_label_.is_bound()) {
95 // You can't branch backwards to an already bound label unless you admitted
96 // up front that this was a bidirectional jump target. Bidirectional jump
97 // targets will zap their type info when bound in case some later virtual
98 // frame with less precise type info branches to them.
99 ASSERT(direction_ != FORWARD_ONLY);
100 }
101 __ b(cond, &entry_label_);
102 if (cond == al) {
103 cgen()->DeleteFrame();
104 }
105 }
106
107
108 void JumpTarget::Call() {
109 // Call is used to push the address of the catch block on the stack as
110 // a return address when compiling try/catch and try/finally. We
111 // fully spill the frame before making the call. The expected frame
112 // at the label (which should be the only one) is the spilled current
113 // frame plus an in-memory return address. The "fall-through" frame
114 // at the return site is the spilled current frame.
115 ASSERT(cgen()->has_valid_frame());
116 // There are no non-frame references across the call.
117 ASSERT(cgen()->HasValidEntryRegisters());
118 ASSERT(!is_linked());
119
120 // Calls are always 'forward' so we use a copy of the current frame (plus
121 // one for a return address) as the expected frame.
122 ASSERT(!entry_frame_set_);
123 VirtualFrame target_frame = *cgen()->frame();
124 target_frame.Adjust(1);
125 set_entry_frame(&target_frame);
126
127 __ bl(&entry_label_);
128 }
129
130
131 void JumpTarget::DoBind() {
132 ASSERT(!is_bound());
133
134 // Live non-frame registers are not allowed at the start of a basic
135 // block.
136 ASSERT(!cgen()->has_valid_frame() || cgen()->HasValidEntryRegisters());
137
138 if (cgen()->has_valid_frame()) {
139 if (direction_ != FORWARD_ONLY) cgen()->frame()->ForgetTypeInfo();
140 // If there is a current frame we can use it on the fall through.
141 if (!entry_frame_set_) {
142 entry_frame_ = *cgen()->frame();
143 entry_frame_set_ = true;
144 } else {
145 cgen()->frame()->MergeTo(&entry_frame_);
146 // On fall through we may have to merge both ways.
147 if (direction_ != FORWARD_ONLY) {
148 // This will not need to adjust the virtual frame entries that are
149 // register allocated since that was done above and they now match.
150 // But it does need to adjust the entry_frame_ of this jump target
151 // to make it potentially less optimistic. Later code can branch back
152 // to this jump target and we need to assert that that code does not
153 // have weaker assumptions about types.
154 entry_frame_.MergeTo(cgen()->frame());
155 }
156 }
157 } else {
158 // If there is no current frame we must have an entry frame which we can
159 // copy.
160 ASSERT(entry_frame_set_);
161 RegisterFile empty;
162 cgen()->SetFrame(new VirtualFrame(&entry_frame_), &empty);
163 }
164
165 __ bind(&entry_label_);
166 }
167
168
169 #undef __
170
171
172 } } // namespace v8::internal
173
174 #endif // V8_TARGET_ARCH_ARM
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