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author | Philip Reames <listmail@philipreames.com> | 2019-11-21 10:44:13 -0800 |
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committer | Philip Reames <listmail@philipreames.com> | 2019-11-21 10:46:16 -0800 |
commit | aaea24802bf5de0420f1ef5f3660a9765e23dea8 (patch) | |
tree | 95393e40d8833c969d1d340916c50e93c7c6aa48 /llvm/lib/IRReader | |
parent | d9426c3360895f265a19e25e2d2bae3348ad9ce8 (diff) | |
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Broaden the definition of a "widenable branch"
As a reminder, a "widenable branch" is the pattern "br i1 (and i1 X, WC()), label %taken, label %untaken" where "WC" is the widenable condition intrinsics. The semantics of such a branch (derived from the semantics of WC) is that a new condition can be added into the condition arbitrarily without violating legality.
Broaden the definition in two ways:
Allow swapped operands to the br (and X, WC()) form
Allow widenable branch w/trivial condition (i.e. true) which takes form of br i1 WC()
The former is just general robustness (e.g. for X = non-instruction this is what instcombine produces). The later is specifically important as partial unswitching of a widenable range check produces exactly this form above the loop.
Differential Revision: https://reviews.llvm.org/D70502
Diffstat (limited to 'llvm/lib/IRReader')
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