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Testcase noticed from PR906
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30269 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -594,3 +594,37 @@ or eax, 2
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cmp eax, 6
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jz label
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//===---------------------------------------------------------------------===//
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Compile:
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int %test(ulong *%tmp) {
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%tmp = load ulong* %tmp ; <ulong> [#uses=1]
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%tmp.mask = shr ulong %tmp, ubyte 50 ; <ulong> [#uses=1]
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%tmp.mask = cast ulong %tmp.mask to ubyte ; <ubyte> [#uses=1]
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%tmp2 = and ubyte %tmp.mask, 3 ; <ubyte> [#uses=1]
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%tmp2 = cast ubyte %tmp2 to int ; <int> [#uses=1]
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ret int %tmp2
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}
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to:
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_test:
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movl 4(%esp), %eax
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movl 4(%eax), %eax
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shrl $18, %eax
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andl $3, %eax
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ret
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instead of:
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_test:
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movl 4(%esp), %eax
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movl 4(%eax), %eax
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shrl $18, %eax
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# TRUNCATE movb %al, %al
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andb $3, %al
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movzbl %al, %eax
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ret
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This saves a movzbl, and saves a truncate if it doesn't get coallesced right.
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This is a simple DAGCombine to propagate the zext through the and.
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