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<base href="http://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - generate more efficient code for logical and operation"
href="http://llvm.org/bugs/show_bug.cgi?id=17109">17109</a>
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<th>Summary</th>
<td>generate more efficient code for logical and operation
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>kkhoo@perfwizard.com
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
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</tr></table>
<p>
<div>
<pre>$ ./clang -v
clang version 3.4 (trunk 189776)
Target: x86_64-apple-darwin11.4.2
Thread model: posix
$ cat and.c
#include <stdbool.h>
bool and(unsigned int x, unsigned int y) {
return (x != 0 && y != 0);
}
$ ./clang -S -O3 -fomit-frame-pointer and.c -o /dev/stdout
.section __TEXT,__text,regular,pure_instructions
.globl _and
.align 4, 0x90
_and: ## @and
.cfi_startproc
## BB#0: ## %entry
testl %edi, %edi
setne %cl
testl %esi, %esi
setne %al
andb %cl, %al
ret
...
I think this codegen can be improved in size and speed by taking advantage of
the fact that the x86 'test' instruction does a bitwise 'and' operation.
Something like this:
testl %edi, %esi
setne %al
ret</pre>
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