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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Self hosting broken with -enable-aa-sched-mi"
href="http://llvm.org/bugs/show_bug.cgi?id=18497">18497</a>
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</tr>
<tr>
<th>Summary</th>
<td>Self hosting broken with -enable-aa-sched-mi
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Common Code Generator Code
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>hfinkel@anl.gov
</td>
</tr>
<tr>
<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
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<div>
<pre>Created <span class=""><a href="attachment.cgi?id=11877" name="attach_11877" title="The miscompiled function">attachment 11877</a> <a href="attachment.cgi?id=11877&action=edit" title="The miscompiled function">[details]</a></span>
The miscompiled function
Self hosting is currently broken when the -enable-aa-sched-mi feature is used.
This is true on both x86_64 and PPC64 (at least).
Here I've isolated one particular problem spot (using r198803 on x86_64): The
function _ZN4llvm16DAGTypeLegalizer18WidenVecRes_BinaryEPNS_6SDNodeE in
lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp is being miscompiled. I've
extracted that function in the attached file.
More specifically:
llc -enable-misched -misched-bottomup=0 -misched-topdown=0 -misched=shuffle
-enable-aa-sched-mi -misched-only-block=6 -misched-cutoff=7
Will give correct code, while:
llc -enable-misched -misched-bottomup=0 -misched-topdown=0 -misched=shuffle
-enable-aa-sched-mi -misched-only-block=6 -misched-cutoff=8
will give incorrect code.
The difference in output is:
--- /tmp/good_func.s 2014-01-15 18:48:27.254951945 -0600
+++ /tmp/bad_func.s 2014-01-15 18:48:35.335177403 -0600
@@ -59,15 +59,15 @@
cmpw $0, 56(%rbx)
je .LBB0_9
# BB#3: # %_ZNK4llvm6SDNode10getOperandEj.exit
- movl 88(%rsp), %r12d
- movq 96(%rsp), %rax
- movq %rax, 40(%rsp) # 8-byte Spill
+ movq 96(%rsp), %r12
movq 32(%rbx), %rax
movq (%rax), %rcx
movl 8(%rax), %eax
movq %rcx, 80(%rsp)
movl %eax, 88(%rsp)
leaq 2048(%r14), %r13
+ movl 88(%rsp), %eax
+ movl %eax, 44(%rsp) # 4-byte Spill
movq %r13, %rdi
leaq 80(%rsp), %rsi
callq
_ZN4llvm12DenseMapBaseINS_13SmallDenseMapINS_7SDValueES2_Lj8ENS_12DenseMapInfoIS2_EEEES2_S2_S4_EixERKS2_
(and a couple of changes later because the spill changed from an 8-byte spill
to a 4-byte one).
The miscompiled version will cause an anomalous assertion failure when llc is
run on test/CodeGen/X86/vec_ext_inreg.ll</pre>
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