[PATCH] D154791: [InstCombine] Transform bitwise (A >> C - 1, zext(icmp)) -> zext (bitwise(A < 0, icmp)) fold.

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

Looks mostly fine, but I think the one-use check isn't quite correct.



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Comment at: llvm/test/Transforms/InstCombine/and-or-icmps.ll:2670
 
 define <2 x i64> @icmp_slt_0_or_icmp_sgt_0_i64x2_fail(<2 x i64> %x) {
 ; CHECK-LABEL: @icmp_slt_0_or_icmp_sgt_0_i64x2_fail(
----------------
Not _fail?


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Comment at: llvm/test/Transforms/InstCombine/and-or-icmps.ll:2912
+; CHECK-NEXT:    [[TMP2:%.*]] = or i1 [[TMP1]], [[A]]
+; CHECK-NEXT:    [[D:%.*]] = zext i1 [[TMP2]] to i32
 ; CHECK-NEXT:    call void @use32(i32 [[C]])
----------------
Creating more instructions here. You should probably always require one-use on the lshr rather than one-use on one of the operands.


Repository:
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https://reviews.llvm.org/D154791