[llvm] [SeparateConstOffsetFromGEP] Fix incorrect inbounds flag in case of non-negative index but negative offset (PR #190192)

[Eli Friedman via llvm-commits]

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@@ -41,8 +41,8 @@ define ptr @sign_bit_clear(ptr %p, i64 %i) {
 ; CHECK-LABEL: @sign_bit_clear(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[IDX:%.*]] = and i64 [[I:%.*]], 9223372036854775807
-; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr inbounds i32, ptr [[P:%.*]], i64 [[IDX]]
-; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i8, ptr [[TMP0]], i64 4
+; CHECK-NEXT:    [[TMP0:%.*]] = getelementptr i32, ptr [[P:%.*]], i64 [[IDX]]
+; CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr i8, ptr [[TMP0]], i64 4
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efriedma-quic wrote:

We know idx.add is positive: if it was negative, the GEP would overflow.  Given that, idx itself is positive, so splitting like this should be fine.

https://github.com/llvm/llvm-project/pull/190192