Too many Simplifier iterations
After fixing #24944 (closed) we get four simplifier iterations on the test program of that ticket:
WARNING:
Simplifier bailing out
T24944, after 4 iterations [4, 3, 3, 1]
Size = {terms: 257, types: 117, coercions: 0, joins: 0/0}
Four iterations seems like a lot. Here is what happens:
Iteration 1
1 PreInlineUnconditionally 1 sc_sDz
1 RuleFired 1 SC:$j0
1 BetaReduction 1 sc_sDz
1 KnownBranch 1 myTyCon1_r4D
Now $j_sDm
occurs just once; but $s$j_sDB
occurs twice, once in the RULE of $j_sDm
Iteration 2
2 PreInlineUnconditionally
1 ds_dBD
1 $j_sDm
1 BetaReduction 1 ds_dBD
Now that $j_sDm
has been inlinined, $s$s_sDB
occurs just once
Iteration 3
2 PreInlineUnconditionally
1 sc_sDz
1 $s$j_sDB
1 BetaReduction 1 sc_sDz
It happens that we can now do a case-merge
Iteration 4
1 AltMerge 1 wild_X1