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<dt>Revision</dt> <dd><a href="http://trac.webkit.org/projects/webkit/changeset/159400">159400</a></dd>
<dt>Author</dt> <dd>commit-queue@webkit.org</dd>
<dt>Date</dt> <dd>2013-11-17 23:51:26 -0800 (Sun, 17 Nov 2013)</dd>
</dl>

<h3>Log Message</h3>
<pre>[sh4] Fix revertJumpReplacementToBranchPtrWithPatch in MacroAssembler.
https://bugs.webkit.org/show_bug.cgi?id=124468

Patch by Julien Brianceau &lt;jbriance@cisco.com&gt; on 2013-11-17
Reviewed by Michael Saboff.

Current implementation of revertJumpReplacementToBranchPtrWithPatch is wrong in
the sh4 MacroAssembler part, leading to random instabilities. This patch fixes it
and also renames the bad-named revertJumpToMove to revertJumpReplacementToBranchPtrWithPatch
in the SH4Assembler.

* assembler/MacroAssemblerSH4.h:
(JSC::MacroAssemblerSH4::revertJumpReplacementToBranchPtrWithPatch):
* assembler/SH4Assembler.h:
(JSC::SH4Assembler::replaceWithJump):
(JSC::SH4Assembler::revertJumpReplacementToBranchPtrWithPatch):</pre>

<h3>Modified Paths</h3>
<ul>
<li><a href="#trunkSourceJavaScriptCoreChangeLog">trunk/Source/JavaScriptCore/ChangeLog</a></li>
<li><a href="#trunkSourceJavaScriptCoreassemblerMacroAssemblerSH4h">trunk/Source/JavaScriptCore/assembler/MacroAssemblerSH4.h</a></li>
<li><a href="#trunkSourceJavaScriptCoreassemblerSH4Assemblerh">trunk/Source/JavaScriptCore/assembler/SH4Assembler.h</a></li>
</ul>

</div>
<div id="patch">
<h3>Diff</h3>
<a id="trunkSourceJavaScriptCoreChangeLog"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/ChangeLog (159399 => 159400)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/ChangeLog        2013-11-18 07:37:12 UTC (rev 159399)
+++ trunk/Source/JavaScriptCore/ChangeLog        2013-11-18 07:51:26 UTC (rev 159400)
</span><span class="lines">@@ -1,3 +1,21 @@
</span><ins>+2013-11-17  Julien Brianceau  &lt;jbriance@cisco.com&gt;
+
+        [sh4] Fix revertJumpReplacementToBranchPtrWithPatch in MacroAssembler.
+        https://bugs.webkit.org/show_bug.cgi?id=124468
+
+        Reviewed by Michael Saboff.
+
+        Current implementation of revertJumpReplacementToBranchPtrWithPatch is wrong in
+        the sh4 MacroAssembler part, leading to random instabilities. This patch fixes it
+        and also renames the bad-named revertJumpToMove to revertJumpReplacementToBranchPtrWithPatch
+        in the SH4Assembler.
+
+        * assembler/MacroAssemblerSH4.h:
+        (JSC::MacroAssemblerSH4::revertJumpReplacementToBranchPtrWithPatch):
+        * assembler/SH4Assembler.h:
+        (JSC::SH4Assembler::replaceWithJump):
+        (JSC::SH4Assembler::revertJumpReplacementToBranchPtrWithPatch):
+
</ins><span class="cx"> 2013-11-16  Filip Pizlo  &lt;fpizlo@apple.com&gt;
</span><span class="cx"> 
</span><span class="cx">         Simplify WatchpointSet state tracking
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreassemblerMacroAssemblerSH4h"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/assembler/MacroAssemblerSH4.h (159399 => 159400)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/assembler/MacroAssemblerSH4.h        2013-11-18 07:37:12 UTC (rev 159399)
+++ trunk/Source/JavaScriptCore/assembler/MacroAssemblerSH4.h        2013-11-18 07:51:26 UTC (rev 159400)
</span><span class="lines">@@ -2447,7 +2447,7 @@
</span><span class="cx"> 
</span><span class="cx">     static void revertJumpReplacementToBranchPtrWithPatch(CodeLocationLabel instructionStart, RegisterID rd, void* initialValue)
</span><span class="cx">     {
</span><del>-        SH4Assembler::revertJumpToMove(instructionStart.dataLocation(), rd, reinterpret_cast&lt;int&gt;(initialValue));
</del><ins>+        SH4Assembler::revertJumpReplacementToBranchPtrWithPatch(instructionStart.dataLocation(), rd, reinterpret_cast&lt;int&gt;(initialValue));
</ins><span class="cx">     }
</span><span class="cx"> 
</span><span class="cx">     static CodeLocationLabel startOfPatchableBranchPtrWithPatchOnAddress(CodeLocationDataLabelPtr)
</span></span></pre></div>
<a id="trunkSourceJavaScriptCoreassemblerSH4Assemblerh"></a>
<div class="modfile"><h4>Modified: trunk/Source/JavaScriptCore/assembler/SH4Assembler.h (159399 => 159400)</h4>
<pre class="diff"><span>
<span class="info">--- trunk/Source/JavaScriptCore/assembler/SH4Assembler.h        2013-11-18 07:37:12 UTC (rev 159399)
+++ trunk/Source/JavaScriptCore/assembler/SH4Assembler.h        2013-11-18 07:51:26 UTC (rev 159400)
</span><span class="lines">@@ -1503,9 +1503,13 @@
</span><span class="cx">     static void replaceWithJump(void *instructionStart, void *to)
</span><span class="cx">     {
</span><span class="cx">         SH4Word* instruction = reinterpret_cast&lt;SH4Word*&gt;(instructionStart);
</span><del>-        intptr_t difference = reinterpret_cast&lt;intptr_t&gt;(to) - (reinterpret_cast&lt;intptr_t&gt;(instruction) + 2 * sizeof(SH4Word));
</del><ins>+        intptr_t difference = reinterpret_cast&lt;intptr_t&gt;(to) - (reinterpret_cast&lt;intptr_t&gt;(instruction) + 3 * sizeof(SH4Word));
</ins><span class="cx"> 
</span><span class="cx">         if ((instruction[0] &amp; 0xf000) == MOVL_READ_OFFPC_OPCODE) {
</span><ins>+            // We have an entry in constant pool and we potentially replace a branchPtrWithPatch, so let's backup what would be the
+            // condition (CMP/xx and Bx opcodes) for later use in revertJumpReplacementToBranchPtrWithPatch before putting the jump.
+            instruction[4] = instruction[1];
+            instruction[5] = instruction[2];
</ins><span class="cx">             instruction[1] = (BRAF_OPCODE | (instruction[0] &amp; 0x0f00));
</span><span class="cx">             instruction[2] = NOP_OPCODE;
</span><span class="cx">             cacheFlush(&amp;instruction[1], 2 * sizeof(SH4Word));
</span><span class="lines">@@ -1516,22 +1520,32 @@
</span><span class="cx">             cacheFlush(instruction, 3 * sizeof(SH4Word));
</span><span class="cx">         }
</span><span class="cx"> 
</span><del>-        changePCrelativeAddress(instruction[0] &amp; 0x00ff, instruction, difference - 2);
</del><ins>+        changePCrelativeAddress(instruction[0] &amp; 0x00ff, instruction, difference);
</ins><span class="cx">     }
</span><span class="cx"> 
</span><del>-    static void revertJumpToMove(void* instructionStart, RegisterID rd, int imm)
</del><ins>+    static void revertJumpReplacementToBranchPtrWithPatch(void* instructionStart, RegisterID rd, int imm)
</ins><span class="cx">     {
</span><span class="cx">         SH4Word *insn = reinterpret_cast&lt;SH4Word*&gt;(instructionStart);
</span><span class="cx">         ASSERT((insn[0] &amp; 0xf000) == MOVL_READ_OFFPC_OPCODE);
</span><ins>+        ASSERT((insn[0] &amp; 0x00ff) != 1);
</ins><span class="cx"> 
</span><del>-        if ((insn[1] &amp; 0xf000) == CMPEQ_OPCODE) {
-            insn[0] = getOpcodeGroup3(MOVL_READ_OFFPC_OPCODE, SH4Registers::r13, insn[0] &amp; 0x00ff);
</del><ins>+        insn[0] = getOpcodeGroup3(MOVL_READ_OFFPC_OPCODE, SH4Registers::r13, insn[0] &amp; 0x00ff);
+        if ((insn[1] &amp; 0xf0ff) == BRAF_OPCODE) {
+            insn[1] = (insn[4] &amp; 0xf00f) | (rd &lt;&lt; 8) | (SH4Registers::r13 &lt;&lt; 4); // Restore CMP/xx opcode.
+            insn[2] = insn[5];
+            ASSERT(((insn[2] &amp; 0xff00) == BT_OPCODE) || ((insn[2] &amp; 0xff00) == BF_OPCODE));
+            ASSERT((insn[3] &amp; 0xf000) == MOVL_READ_OFFPC_OPCODE);
+            insn[4] = (BRAF_OPCODE | (insn[3] &amp; 0x0f00));
+            insn[5] = NOP_OPCODE;
+            cacheFlush(insn, 6 * sizeof(SH4Word));
+        } else {
+            // The branchPtrWithPatch has already been restored, so we just patch the immediate value and ASSERT all is as expected.
+            ASSERT((insn[1] &amp; 0xf000) == 0x3000);
</ins><span class="cx">             insn[1] = (insn[1] &amp; 0xf00f) | (rd &lt;&lt; 8) | (SH4Registers::r13 &lt;&lt; 4);
</span><span class="cx">             cacheFlush(insn, 2 * sizeof(SH4Word));
</span><del>-        } else {
-            insn[1] = getOpcodeGroup6(BRA_OPCODE, 3);
-            insn[2] = NOP_OPCODE;
-            cacheFlush(&amp;insn[1], 2 * sizeof(SH4Word));
</del><ins>+            ASSERT(((insn[2] &amp; 0xff00) == BT_OPCODE) || ((insn[2] &amp; 0xff00) == BF_OPCODE));
+            ASSERT((insn[3] &amp; 0xf000) == MOVL_READ_OFFPC_OPCODE);
+            ASSERT(insn[5] == NOP_OPCODE);
</ins><span class="cx">         }
</span><span class="cx"> 
</span><span class="cx">         changePCrelativeAddress(insn[0] &amp; 0x00ff, insn, imm);
</span></span></pre>
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