[llvm] [InstCombine] Guard foldICmpSRemConstant against zero divisors (PR #173702)

[Nikita Popov via llvm-commits]

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@@ -119,6 +119,21 @@ define i1 @icmp_ugt_srem5_m5(i32 %x) {
   ret i1 %c
 }
 
+define i64 @srem_zero_ult_poison(i1 %c) {
+; CHECK-LABEL: define i64 @srem_zero_ult_poison(
+; CHECK-SAME: i1 [[C:%.*]]) {
+; CHECK-NEXT:    ret i64 poison
+;
+  %sel = select i1 %c, i64 3, i64 0
+  %trunc = trunc i64 %sel to i8
+  %div = sdiv i8 -1, %trunc
+  %rem = srem i8 -1, %div
+  %cmp = icmp ult i8 %trunc, %rem
+  %zext = zext i1 %cmp to i64
+  %res = select i1 false, i64 %sel, i64 %zext
+  ret i64 %res
+}
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nikic wrote:

nit: I'd move this test to the end of the file, so it's not in the middle of tests that check different icmp constants.

https://github.com/llvm/llvm-project/pull/173702