Juneyoung Lee 1977c53b2a [InstCombine] Fold overflow bit of [u|s]mul.with.overflow in a poison-safe way ... As discussed in D101191, this patch adds a poison-safe folding of overflow bit check: ``` %Op0 = icmp ne i4 %X, 0 %Agg = call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %Y) %Op1 = extractvalue { i4, i1 } %Agg, 1 %ret = select i1 %Op0, i1 %Op1, i1 false => %Y.fr = freeze %Y %Agg = call { i4, i1 } @llvm.[us]mul.with.overflow.i4(i4 %X, i4 %Y.fr) %Op1 = extractvalue { i4, i1 } %Agg, 1 %ret = %Op1 ``` https://alive2.llvm.org/ce/z/zgPUGT https://alive2.llvm.org/ce/z/h2gZ_6 Note that there are cases where inserting freeze is not necessary: e.g. %Y is `noundef`. In this case, LLVM is already good because `%ret` is already successfully folded into `and`, triggering the pre-existing optimization in InstSimplify: https://godbolt.org/z/v6qena15K Differential Revision: https://reviews.llvm.org/D101423		2021-05-02 11:54:12 +09:00
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llvm	[InstCombine] Fold overflow bit of [u|s]mul.with.overflow in a poison-safe way	2021-05-02 11:54:12 +09:00
llvm-c	[ORC] Make LLVMOrcLLJITBuilderSetJITTargetMachineBuilder consume as advertised.	2021-04-26 22:26:38 -07:00