forked from OSchip/llvm-project
1705a999fa
Original message: The attached is the fix to radar://11663049. The optimization can be outlined by following rules: (select (x != c), e, c) -> select (x != c), e, x), (select (x == c), c, e) -> select (x == c), x, e) where the <c> is an integer constant. The reason for this change is that : on x86, conditional-move-from-constant needs two instructions; however, conditional-move-from-register need only one instruction. While the LowerSELECT() sounds to be the most convenient place for this optimization, it turns out to be a bad place. The reason is that by replacing the constant <c> with a symbolic value, it obscure some instruction-combining opportunities which would otherwise be very easy to spot. For that reason, I have to postpone the change to last instruction-combining phase. The change passes the test of "make check-all -C <build-root/test" and "make -C project/test-suite/SingleSource". Original message since r165661: My previous change has a bug: I negated the condition code of a CMOV, and go ahead creating a new CMOV using the *ORIGINAL* condition code. llvm-svn: 166017 |
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| clang | ||
| clang-tools-extra | ||
| compiler-rt | ||
| debuginfo-tests | ||
| libclc | ||
| libcxx | ||
| libcxxabi | ||
| lld | ||
| lldb | ||
| llvm | ||
| polly | ||