зеркало из https://github.com/microsoft/clang-1.git
33 строки
1.1 KiB
Plaintext
33 строки
1.1 KiB
Plaintext
IRgen optimization opportunities.
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//===---------------------------------------------------------------------===//
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The common pattern of
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--
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short x; // or char, etc
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(x == 10)
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--
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generates an zext/sext of x which can easily be avoided.
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//===---------------------------------------------------------------------===//
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Bitfields accesses can be shifted to simplify masking and sign
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extension. For example, if the bitfield width is 8 and it is
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appropriately aligned then is is a lot shorter to just load the char
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directly.
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//===---------------------------------------------------------------------===//
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It may be worth avoiding creation of alloca's for formal arguments
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for the common situation where the argument is never written to or has
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its address taken. The idea would be to begin generating code by using
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the argument directly and if its address is taken or it is stored to
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then generate the alloca and patch up the existing code.
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In theory, the same optimization could be a win for block local
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variables as long as the declaration dominates all statements in the
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block.
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//===---------------------------------------------------------------------===//
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