David Green 99f589780c [CPG][ARM] Optimize towards branch on zero in codegenprepare ... This adds a simple fold into codegenprepare that converts comparison of branches towards comparison with zero if possible. For example: %c = icmp ult %x, 8 br %c, bla, blb %tc = lshr %x, 3 becomes %tc = lshr %x, 3 %c = icmp eq %tc, 0 br %c, bla, blb As a first order approximation, this can reduce the number of instructions needed to perform the branch as the shift is (often) needed anyway. At the moment this does not effect very much, as llvm tends to prefer the opposite form. But it can protect against regressions from commits like rG9423f78240a2. Simple cases of Add and Sub are added along with Shift, equally as the comparison to zero can often be folded with cpsr flags. Differential Revision: https://reviews.llvm.org/D101778		2021-05-16 17:54:06 +01:00
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llvm	[CPG][ARM] Optimize towards branch on zero in codegenprepare	2021-05-16 17:54:06 +01:00
llvm-c	Support unwinding from inline assembly	2021-05-13 19:13:03 +01:00