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2020-08-12

Today

Today, I'll try implementing a graph coloring algorithm for my interference graph.

Ugh, there are still problems with the sexps… bfast-cloudy.fut does not produce an isomorph sexp. It looks like some aliasing information is lost?

Here is the diff between the IR before and af sexp-ization: 

[munksgaard@church:~/src/futhark/futhark-benchmarks]$ diff -u bfast-cloudy.ir.orig bfast-cloudy.ir
--- bfast-cloudy.ir.orig        2020-08-12 09:50:30.728831671 +0200
+++ bfast-cloudy.ir     2020-08-12 09:50:08.308701607 +0200
@@ -22,7 +22,7 @@
   let {bool dim_match_912} = eq_i32(N_901, N_903)
   let {cert empty_or_match_cert_913} =
     assert(dim_match_912, "function arguments of wrong shape",
-           "misc/bfast/bfast-cloudy.fut:106:1-235:10")
+           "unknown location")
   let {i32 x_915} = mul32(2i32, k_905)
   let {i32 k2p2_916} = add32(2i32, x_915)
   let {bool cond_917} = slt32(0i32, trend_904)
@@ -61,7 +61,7 @@
       let {bool valid_922} = not bounds_invalid_upwards_921
       let {cert range_valid_c_923} =
         assert(valid_922, "Range ", 0i32, "..", 1i32, "..<", k2p2'_918,
-                          " is invalid.", "/prelude/math.fut:461:23-30")
+                          " is invalid.", "unknown location")
       let {i64 k2p2'_1487} = binop_x_5073
       let {i64 N_1488} = binop_y_5074
       let {i64 nest_size_1490} = binop_x_5075
@@ -131,7 +131,6 @@
             }
           return {returns res_1499}
         }
-      -- res_945 aliases res_1495
       -- res_945 : [k2p2'_918][N_901]f32@@mem_5076->
       -- {base: [k2p2'_918, N_901]; contiguous: True; LMADs: [{offset: 0i32;
       --                                                       strides: [N_901, 1i32];
@@ -148,7 +147,7 @@
       let {bool valid_947} = not bounds_invalid_upwards_946
       let {cert range_valid_c_948} =
         assert(valid_947, "Range ", 0i32, "..", 1i32, "..<", k2p2'_918,
-                          " is invalid.", "/prelude/math.fut:461:23-30")
+                          " is invalid.", "unknown location")
       let {i64 k2p2'_1683} = binop_x_5073
       let {i64 N_1684} = binop_y_5074
       let {i64 nest_size_1686} = binop_x_5075
@@ -205,7 +204,6 @@
             }
           return {returns res_1695}
         }
-      -- res_968 aliases res_1691
       -- res_968 : [k2p2'_918][N_901]f32@@mem_5082->
       -- {base: [k2p2'_918, N_901]; contiguous: True; LMADs: [{offset: 0i32;
       --                                                       strides: [N_901, 1i32];
@@ -218,7 +216,6 @@
         res_1691
       in {mem_5082, res_968}
     }
-  -- res_969 aliases binop_p_920
   -- res_969 : [k2p2'_918][N_901]f32@@binop_p_mem_5083->
   -- {base: [k2p2'_918, N_901]; contiguous: True; LMADs: [{offset: 0i32;
   --                                                       strides: [N_901, 1i32];
@@ -235,8 +232,7 @@
   let {bool zero_975} = eq_i32(y_974, 0i32)
   let {bool nonzero_976} = not zero_975
   let {cert nonzero_cert_977} =
-    assert(nonzero_976, "division by zero",
-           "misc/bfast/bfast-cloudy.fut:123:21-45")
+    assert(nonzero_976, "division by zero", "unknown location")
   let {i32 x_978} =
     <nonzero_cert_977>
     sdiv32(x_973, y_974)
@@ -288,7 +284,6 @@
       let {f32 res_1798} = fadd32(res_981, x_1797)
       return {returns res_1798}
     }
-  -- res_988 aliases res_1796
   -- res_988 : [N_901][k2p2'_918]f32@@mem_5094->
   -- {base: [N_901, k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32;
   --                                                       strides: [k2p2'_918, 1i32];
@@ -317,13 +312,11 @@
   let {cert index_certs_1006} =
     assert(index_ok_1005, "Index [", 0i32, ":, :", n_906,
                           "] out of bounds for array of shape [", k2p2'_918,
-                          "][", N_901, "].",
-           "misc/bfast/bfast-cloudy.fut:127:15-21")
+                          "][", N_901, "].", "unknown location")
   let {cert index_certs_1008} =
     assert(index_ok_1005, "Index [:", n_906, ", ", 0i32,
                           ":] out of bounds for array of shape [", N_901, "][",
-                          k2p2'_918, "].",
-           "misc/bfast/bfast-cloudy.fut:128:15-22")
+                          k2p2'_918, "].", "unknown location")
   let {bool empty_slice_1010} = eq_i32(m_902, 0i32)
   let {i32 m_1011} = sub32(m_902, 1i32)
   let {bool zero_leq_i_p_m_t_s_1012} = sle32(0i32, m_1011)
@@ -336,7 +329,7 @@
   let {cert index_certs_1019} =
     assert(index_ok_1018, "Index [", 0i32, ":, :", n_906,
                           "] out of bounds for array of shape [", m_902, "][",
-                          N_901, "].", "misc/bfast/bfast-cloudy.fut:129:15-26")
+                          N_901, "].", "unknown location")
   let {bool suff_outer_par_1801} =
     get_size(suff_outer_par_6, threshold ()) <= m_902
   let {i64 m_1827} = sext i32 m_902 to i64
@@ -482,7 +475,6 @@
           --                                                           permutation: [0, 1];
           --                                                           monotonicity: [Inc, Inc]}]}
           let {[k2p2'_918][k2p2'_918]f32 res_1834} =
-            -- Consumes result_5014
             -- mapout_5015 : *[k2p2'_918][k2p2'_918]f32@@mem_5105->
             -- {base: [k2p2'_918, k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32;
             --                                                           strides: [k2p2'_918, 1i32];
@@ -500,7 +492,6 @@
               --                                                           permutation: [0, 1];
               --                                                           monotonicity: [Inc, Inc]}]}
               let {[k2p2'_918][k2p2'_918]f32 lw_dest_5017} =
-                -- Consumes mapout_5015
                 -- lowered_array_5064 : *[k2p2'_918][k2p2'_918]f32@@mem_5105->
                 -- {base: [k2p2'_918, k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32;
                 --                                                           strides: [k2p2'_918, 1i32];
@@ -541,7 +532,6 @@
                   --                                                           permutation: [0, 1];
                   --                                                           monotonicity: [Inc, Inc]}]}
                   let {[k2p2'_918][k2p2'_918]f32 lowered_array_updated_5068} =
-                    -- Consumes lowered_array_5064
                     lowered_array_5064 with [i_5016, i_5020] <- res_1838
                   in {lowered_array_updated_5068}
                 }
@@ -610,7 +600,6 @@
               --                                                permutation: [0];
               --                                                monotonicity: [Inc]}]}
               let {[k2p2'_918]f32 res_2042} =
-                -- Consumes result_5024
                 -- mapout_5025 : *[k2p2'_918]f32@@mem_5156->
                 -- {base: [k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
                 --                                                rotates: [0i32];
@@ -649,7 +638,6 @@
                   --                                                permutation: [0];
                   --                                                monotonicity: [Inc]}]}
                   let {[k2p2'_918]f32 lw_dest_5027} =
-                    -- Consumes mapout_5025
                     mapout_5025 with [i_5026] <- res_2044
                   in {lw_dest_5027}
                 }
@@ -788,7 +776,6 @@
         }
       in {res_mem_5206, res_2038}
     }
-  -- res_1039 aliases res_1022
   -- res_1039 : [m_902][k2p2'_918][k2p2'_918]f32@@res_mem_5215->
   -- {base: [m_902, k2p2'_918, k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32;
   --                                                                  strides: [mul_nw32 (k2p2'_918) (k2p2'_918), k2p2'_918, 1i32];
@@ -803,18 +790,16 @@
   let {bool valid_1043} = not bounds_invalid_upwards_1042
   let {cert range_valid_c_1044} =
     assert(valid_1043, "Range ", 0i32, "..", 1i32, "..<", nm_1041,
-                       " is invalid.", "/prelude/math.fut:461:23-30")
+                       " is invalid.", "unknown location")
   let {bool zero_1046} = eq_i32(m_1040, 0i32)
   let {bool nonzero_1047} = not zero_1046
   let {cert nonzero_cert_1048} =
-    assert(nonzero_1047, "division by zero",
-           "misc/bfast/bfast-cloudy.fut:74:41-47")
+    assert(nonzero_1047, "division by zero", "unknown location")
   let {bool loop_nonempty_1049} = slt32(0i32, k2p2'_918)
   let {bool loop_not_taken_1050} = not loop_nonempty_1049
   let {bool protect_assert_disj_1051} = logor(nonzero_1047, loop_not_taken_1050)
   let {cert nonzero_cert_1052} =
-    assert(protect_assert_disj_1051, "division by zero",
-           "misc/bfast/bfast-cloudy.fut:61:43-49")
+    assert(protect_assert_disj_1051, "division by zero", "unknown location")
   let {i32 j_m_i_1053} = sub32(m_1040, k2p2'_918)
   let {bool empty_slice_1054} = eq_i32(j_m_i_1053, 0i32)
   let {i32 m_1055} = sub32(j_m_i_1053, 1i32)
@@ -831,14 +816,13 @@
   let {cert index_certs_1066} =
     assert(index_ok_1065, "Index [", 0i32, ":", k2p2'_918, ", ", k2p2'_918, ":",
                           m_1040, "] out of bounds for array of shape [",
-                          k2p2'_918, "][", m_1040, "].",
-           "misc/bfast/bfast-cloudy.fut:82:8-37")
+                          k2p2'_918, "][", m_1040, "].", "unknown location")
   let {bool dim_match_1067} = eq_i32(k2p2'_918, j_m_i_1053)
   let {cert empty_or_match_cert_1068} =
     assert(dim_match_1067, "Value of (core language) shape (", k2p2'_918, ", ",
                            j_m_i_1053, ") cannot match shape of type `[",
                            k2p2'_918, "][", k2p2'_918, "]f32`.",
-           "misc/bfast/bfast-cloudy.fut:82:8-50")
+           "unknown location")
   let {i32 max_group_size_2261} =
     get_size_max(group_size)
   let {bool fits_2262} = sle32(nm_1041, max_group_size_2261)
@@ -997,7 +981,6 @@
           --                                              permutation: [0];
           --                                              monotonicity: [Inc]}]}
           let {[nm_1041]f32 res_2276} =
-            -- Consumes res_2266
             -- A_2278 : *[nm_1041]f32@@mem_5220->
             -- {base: [nm_1041]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
             --                                              rotates: [0i32]; shape: [nm_1041];
@@ -1009,7 +992,7 @@
               let {cert index_certs_2280} =
                 assert(y_2279, "Index [", i_2277,
                                "] out of bounds for array of shape [", nm_1041,
-                               "].", "misc/bfast/bfast-cloudy.fut:60:16-19")
+                               "].", "unknown location")
               let {f32 v1_2281} =
                 <index_certs_2280>
                 A_2278[i_2277]
@@ -1066,7 +1049,6 @@
               --                                              permutation: [0];
               --                                              monotonicity: [Inc]}]}
               let {[nm_1041]f32 res_2304} =
-                -- Consumes A_2278
                 <range_valid_c_1044>
                 segmap_thread
                 (#groups=m_902; groupsize=nm_1041)
@@ -1076,7 +1058,6 @@
                 }
               in {res_2304}
             }
-          -- res_2307 aliases res_2276
           -- res_2307 : [k2p2'_918][m_1040]f32@@mem_5220->
           -- {base: [k2p2'_918, m_1040]; contiguous: True; LMADs: [{offset: 0i32;
           --                                                        strides: [m_1040, 1i32];
@@ -1086,7 +1067,6 @@
           --                                                        monotonicity: [Inc, Inc]}]}
           let {[k2p2'_918][m_1040]f32 res_2307} = reshape((k2p2'_918, m_1040),
                                                           res_2276)
-          -- res_2308 aliases res_2307
           -- res_2308 : [k2p2'_918][j_m_i_1053]f32@@mem_5220->
           -- {base: [k2p2'_918, m_1040]; contiguous: False; LMADs: [{offset: k2p2'_918;
           --                                                         strides: [m_1040, 1i32];
@@ -1097,7 +1077,6 @@
           let {[k2p2'_918][j_m_i_1053]f32 res_2308} =
             <index_certs_1066>
             res_2307[0i32:+k2p2'_918*1i32, k2p2'_918:+j_m_i_1053*1i32]
-          -- res_2309 aliases res_2308
           -- res_2309 : [k2p2'_918][k2p2'_918]f32@@mem_5220->
           -- {base: [k2p2'_918, k2p2'_918]; contiguous: False; LMADs: [{offset: k2p2'_918;
           --                                                            strides: [m_1040, 1i32];
@@ -1153,7 +1132,6 @@
             }
           return {returns res_2765}
         }
-      -- res_r_mem_5302 aliases mem_5250
       -- res_r_2771 : [m_902][nm_1041]f32@@res_r_mem_5302->
       -- {base: [res_r_ixfn_5295, res_r_ixfn_5296]; contiguous: True;
       --  LMADs: [{offset: res_r_ixfn_5297; strides: [res_r_ixfn_5298, res_r_ixfn_5300];
@@ -1163,7 +1141,6 @@
            i32 res_r_ixfn_5298, i32 res_r_ixfn_5299, i32 res_r_ixfn_5300,
            i32 res_r_ixfn_5301, mem res_r_mem_5302;
            [m_902][nm_1041]f32 res_r_2771} =
-        -- Consumes res_r_2759
         -- A_expanded_2773 : *[m_902][nm_1041]f32@@mem_param_5258->
         -- {base: [ctx_param_ext_5251, ctx_param_ext_5252]; contiguous: True;
         --  LMADs: [{offset: ctx_param_ext_5253;
@@ -1184,7 +1161,7 @@
           let {cert index_certs_2775} =
             assert(y_2774, "Index [", i_2772,
                            "] out of bounds for array of shape [", nm_1041,
-                           "].", "misc/bfast/bfast-cloudy.fut:60:16-19")
+                           "].", "unknown location")
           let {i32 res_ixfn_5287} =
             -- Branch returns: {i32}
             if <equiv> intra_suff_and_fits_2784
@@ -1213,7 +1190,6 @@
             -- Branch returns: {i32}
             if <equiv> intra_suff_and_fits_2784
             then {0i32} else {ctx_param_ext_5253}
-          -- res_mem_5294 aliases mem_param_5258
           -- res_2785 : [m_902][nm_1041]f32@@res_mem_5294->
           -- {base: [res_ixfn_5289, res_ixfn_5290]; contiguous: True;
           --  LMADs: [{offset: res_ixfn_5293; strides: [res_ixfn_5291, res_ixfn_5292];
@@ -1221,7 +1197,6 @@
           --           permutation: [0, 1]; monotonicity: [Inc, Inc]}]}
           let {mem res_mem_5294;
                [m_902][nm_1041]f32 res_2785} =
-            -- Consumes A_expanded_2773
             -- Branch returns: {[m_902][nm_1041]f32@?0->
             --                  {base: [res_ixfn_5289, res_ixfn_5290]; contiguous: True;
             --                   LMADs: [{offset: res_ixfn_5293;
@@ -1253,11 +1228,9 @@
               --                                                     permutation: [0, 1];
               --                                                     monotonicity: [Inc, Inc]}]}
               let {[m_902][nm_1041]f32 res_2786} =
-                -- Consumes A_expanded_coalesced_4402
                 segmap_group
                 (#groups=m_902; groupsize=nm_1041)
                 (gtid_2337 < m_902) (~phys_tid_2364) : {[nm_1041]f32} {
-                  -- A_2787 aliases A_expanded_coalesced_4402
                   -- A_2787 : [nm_1041]f32@@mem_5265->
                   -- {base: [nm_1041, m_902]; contiguous: False; LMADs: [{offset: gtid_2337;
                   --                                                      strides: [m_902];
@@ -1331,7 +1304,6 @@
                   --                                                      permutation: [0];
                   --                                                      monotonicity: [Inc]}]}
                   let {[nm_1041]f32 res_2811} =
-                    -- Consumes A_2787
                     <range_valid_c_1044>
                     segmap_thread
                     (#groups=m_902; groupsize=nm_1041)
@@ -1423,7 +1395,6 @@
               --           shape: [ctx_param_ext_5255, ctx_param_ext_5257]; permutation: [0, 1];
               --           monotonicity: [Inc, Inc]}]}
               let {[m_902][nm_1041]f32 res_2877} =
-                -- Consumes A_expanded_2773
                 <range_valid_c_1044>
                 segmap_thread
                 (#groups=segmap_usable_groups_2876; groupsize=segmap_group_size_2873)
@@ -1470,7 +1441,6 @@
             res_r_2771[new_index_4373, new_index_4386]
           return {returns v_2897}
         }
-      -- res_2898 aliases res_r_2894
       -- res_2898 : [m_902][k2p2'_918][k2p2'_918]f32@@mem_5310->
       -- {base: [m_902, k2p2'_918, k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32;
       --                                                                  strides: [mul_nw32 (k2p2'_918) (k2p2'_918), k2p2'_918, 1i32];
@@ -1483,7 +1453,6 @@
         reshape((m_902, k2p2'_918, k2p2'_918), res_r_2894)
       in {mem_5310, res_2898}
     }
-  -- res_1115 aliases res_1069
   -- res_1115 : [m_902][k2p2'_918][k2p2'_918]f32@@res_mem_5311->
   -- {base: [m_902, k2p2'_918, k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32;
   --                                                                  strides: [mul_nw32 (k2p2'_918) (k2p2'_918), k2p2'_918, 1i32];
@@ -1619,7 +1588,6 @@
           --                                                permutation: [0];
           --                                                monotonicity: [Inc]}]}
           let {[k2p2'_918]f32 res_2930} =
-            -- Consumes result_5032
             -- mapout_5033 : *[k2p2'_918]f32@@mem_5320->
             -- {base: [k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
             --                                                rotates: [0i32];
@@ -1656,7 +1624,6 @@
               --                                                permutation: [0];
               --                                                monotonicity: [Inc]}]}
               let {[k2p2'_918]f32 lw_dest_5035} =
-                -- Consumes mapout_5033
                 mapout_5033 with [i_5034] <- res_2932
               in {lw_dest_5035}
             }
@@ -1738,7 +1705,6 @@
               --           monotonicity: [Unknown, Unknown]}]}
               let {mem@f32 accs_mem_5383;
                    [tile_size_4443][tile_size_4443]f32 accs_4575} =
-                -- Consumes mergeinit_4474
                 -- x_merge_4475 : *[tile_size_4443][tile_size_4443]f32@@mem_param_5352->
                 -- {base: [tile_size_4443, tile_size_4443]; contiguous: True;
                 --  LMADs: [{offset: 0i32; strides: [0i32, 0i32]; rotates: [0i32, 0i32];
@@ -2010,7 +1976,6 @@
         }
       in {res_mem_5420, res_3025}
     }
-  -- res_1129 aliases res_1116
   -- res_1129 : [m_902][k2p2'_918]f32@@res_mem_5427->
   -- {base: [m_902, k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32;
   --                                                       strides: [k2p2'_918, 1i32];
@@ -2140,7 +2105,6 @@
           --                                                permutation: [0];
           --                                                monotonicity: [Inc]}]}
           let {[k2p2'_918]f32 res_3090} =
-            -- Consumes result_5042
             -- mapout_5043 : *[k2p2'_918]f32@@mem_5443->
             -- {base: [k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
             --                                                rotates: [0i32];
@@ -2166,7 +2130,6 @@
               --                                                permutation: [0];
               --                                                monotonicity: [Inc]}]}
               let {[k2p2'_918]f32 lw_dest_5045} =
-                -- Consumes mapout_5043
                 mapout_5043 with [i_5044] <- res_3092
               in {lw_dest_5045}
             }
@@ -2271,7 +2234,6 @@
         }
       in {res_mem_5480, res_3179}
     }
-  -- res_1142 aliases res_1130
   -- res_1142 : [m_902][k2p2'_918]f32@@res_mem_5487->
   -- {base: [m_902, k2p2'_918]; contiguous: True; LMADs: [{offset: 0i32;
   --                                                       strides: [k2p2'_918, 1i32];
@@ -2413,7 +2375,6 @@
           --                                            permutation: [0];
           --                                            monotonicity: [Inc]}]}
           let {[N_901]f32 res_3239} =
-            -- Consumes result_5050
             -- mapout_5051 : *[N_901]f32@@mem_5496->
             -- {base: [N_901]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
             --                                            rotates: [0i32]; shape: [N_901];
@@ -2436,7 +2397,6 @@
               --                                            permutation: [0];
               --                                            monotonicity: [Inc]}]}
               let {[N_901]f32 lw_dest_5053} =
-                -- Consumes mapout_5051
                 mapout_5051 with [i_5052] <- res_3241
               in {lw_dest_5053}
             }
@@ -2531,7 +2491,6 @@
               --           monotonicity: [Unknown, Unknown]}]}
               let {mem@f32 accs_mem_5564;
                    [tile_size_4735][tile_size_4735]f32 accs_4863} =
-                -- Consumes mergeinit_4766
                 -- x_merge_4767 : *[tile_size_4735][tile_size_4735]f32@@mem_param_5533->
                 -- {base: [tile_size_4735, tile_size_4735]; contiguous: True;
                 --  LMADs: [{offset: 0i32; strides: [0i32, 0i32]; rotates: [0i32, 0i32];
@@ -2769,7 +2728,6 @@
         }
       in {res_mem_5601, res_3326}
     }
-  -- res_1154 aliases res_1143
   -- res_1154 : [m_902][N_901]f32@@res_mem_5608->
   -- {base: [m_902, N_901]; contiguous: True; LMADs: [{offset: 0i32;
   --                                                   strides: [N_901, 1i32];
@@ -2785,7 +2743,7 @@
   let {cert index_certs_1159} =
     assert(bounds_check_1158, "Index [", i_1155,
                               "] out of bounds for array of shape [", N_901,
-                              "].", "/prelude/array.fut:18:29-34")
+                              "].", "unknown location")
   let {bool fits_3436} = sle32(N_901, max_group_size_2261)
   let {bool suff_intra_par_3434} =
     get_size(suff_intra_par_22, threshold (!suff_outer_par_21)) <= N_901
@@ -2834,7 +2792,6 @@
   let {i64 bytes_5640} = bytes_5602
   let {i64 binop_x_5646} = m_1827
   let {i64 bytes_5645} = bytes_5626
-  -- res_mem_5650 aliases mem_5613
   -- res_1160 : [m_902]i32@@res_mem_5649->
   -- {base: [m_902]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
   --                                            rotates: [0i32]; shape: [m_902];
@@ -2849,7 +2806,6 @@
   --                                                   monotonicity: [Inc, Inc]}]}
   let {mem res_mem_5649, mem res_mem_5650;
        [m_902]i32 res_1160, [m_902][N_901]f32 res_1161} =
-    -- Consumes res_r_3618
     -- Branch returns: {[m_902]i32@?0->
     --                  {base: [m_902]; contiguous: True; LMADs: [{offset: 0i32;
     --                                                             strides: [1i32];
@@ -2946,7 +2902,6 @@
           --                                            permutation: [0];
           --                                            monotonicity: [Inc]}]}
           let {[N_901]f32 res_3458} =
-            -- Consumes res_3457
             segmap_thread
             (#groups=m_902; groupsize=N_901)
             (write_i_3364 < N_901) (~phys_tid_3365) : {f32} {
@@ -3015,7 +2970,6 @@
           let {i32 res_3589} = btoi bool res_3588 to i32
           return {returns res_3589, returns res_3585}
         }
-      -- res_precopy_4363 aliases res_r_3574
       -- res_precopy_4363 : [m_902]i32@@mem_5639->
       -- {base: [m_902, N_901]; contiguous: False; LMADs: [{offset: i_1155;
       --                                                    strides: [N_901];
@@ -3044,7 +2998,6 @@
       --                                                   permutation: [0, 1];
       --                                                   monotonicity: [Inc, Inc]}]}
       let {[m_902][N_901]f32 res_3629} =
-        -- Consumes res_r_3618
         segmap_thread
         (#groups=segmap_usable_groups_3628; groupsize=segmap_group_size_3625)
         (gtid_3468 < m_902, gtid_3469 < N_901) (~phys_tid_3470) : {f32} {
@@ -3065,14 +3018,12 @@
         }
       in {mem_5647, mem_5613, res_3596, res_3629}
     }
-  -- res_1196 aliases res_1160
   -- res_1196 : [m_902]i32@@res_mem_5649->
   -- {base: [m_902]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
   --                                            rotates: [0i32]; shape: [m_902];
   --                                            permutation: [0];
   --                                            monotonicity: [Inc]}]}
   let {[m_902]i32 res_1196} = opaque(res_1160)
-  -- res_1197 aliases res_1161
   -- res_1197 : [m_902][N_901]f32@@res_mem_5650->
   -- {base: [m_902, N_901]; contiguous: True; LMADs: [{offset: 0i32;
   --                                                   strides: [N_901, 1i32];
@@ -3469,21 +3420,18 @@
       in {res_mem_5698, res_mem_5699, res_mem_5700, res_3867, res_3868,
           res_3869}
     }
-  -- res_1229 aliases res_1200
   -- res_1229 : [m_902]i32@@res_mem_5701->
   -- {base: [m_902]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
   --                                            rotates: [0i32]; shape: [m_902];
   --                                            permutation: [0];
   --                                            monotonicity: [Inc]}]}
   let {[m_902]i32 res_1229} = opaque(res_1200)
-  -- res_1230 aliases res_1201
   -- res_1230 : [m_902]i32@@res_mem_5702->
   -- {base: [m_902]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
   --                                            rotates: [0i32]; shape: [m_902];
   --                                            permutation: [0];
   --                                            monotonicity: [Inc]}]}
   let {[m_902]i32 res_1230} = opaque(res_1201)
-  -- res_1231 aliases res_1202
   -- res_1231 : [m_902]f32@@res_mem_5703->
   -- {base: [m_902]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
   --                                            rotates: [0i32]; shape: [m_902];
@@ -3617,7 +3565,6 @@
         }
       in {mem_5714, res_3962}
     }
-  -- res_1253 aliases res_1238
   -- res_1253 : [m_902]f32@@res_mem_5715->
   -- {base: [m_902]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
   --                                            rotates: [0i32]; shape: [m_902];
@@ -3629,7 +3576,7 @@
   let {bool valid_1256} = not bounds_invalid_upwards_1255
   let {cert range_valid_c_1257} =
     assert(valid_1256, "Range ", 0i32, "..", 1i32, "..<", Nmn_1254,
-                       " is invalid.", "/prelude/math.fut:461:23-30")
+                       " is invalid.", "unknown location")
   let {bool fits_4102} = sle32(Nmn_1254, max_group_size_2261)
   let {bool suff_intra_par_4100} =
     get_size(suff_intra_par_28, threshold (!suff_outer_par_27)) <= Nmn_1254
@@ -3875,7 +3822,6 @@
       let {[m_902]f32 res_4354} = copy(acc0_r_4334)
       in {mem_5744, res_4354}
     }
-  -- entry_result_1308 aliases res_1259
   -- entry_result_1308 : [m_902]f32@@res_mem_5745->
   -- {base: [m_902]; contiguous: True; LMADs: [{offset: 0i32; strides: [1i32];
   --                                            rotates: [0i32]; shape: [m_902];

All the "unknown location" bits are fine. I think the real problem is the aliasing information that has disappeared. However, shouldn't that also be the case for other programs?

Let's try to figure that out by investigating lud.fut. By running futhark dev --kernels -a -e --cse on lud.fut, we see that there's also aliasing information in there. If my theory is correct that sexpization removes aliasing information, reading the sexpized lud.fut back in should result in a program without aliasing. And the action should complain that sexpization is not isomorph.

Nope, the aliasing information is still there. Wait, it doesn't seem like there's any aliasing information at all? Is it only added when printing out the IR? When manually adding aliasing information to the IR before sexpizing, the aliasing information is correctly transcribed. So that's not it.

Ah, but there are also some "consumes" annotations. Perhaps they're lost too?

Ah, when using the printAction the lore is aliased before printing. Let's do the same in sexpAction when printing the failing program.

Here's the updated diff after that change: 

--- bfast-cloudy.ir.orig        2020-08-12 10:34:29.516217243 +0200
+++ bfast-cloudy.ir     2020-08-12 10:34:20.797182161 +0200
@@ -1,3 +1,6 @@
+Internal compiler error (unhandled IO exception).
+Please report this at https://github.com/diku-dk/futhark/issues
+S-exp not isomorph!


 -- mappingindices_910 : [N_901]i32@@mappingindices_mem_5069->
@@ -24,7 +27,7 @@
   let {bool dim_match_912} = eq_i32(N_901, N_903)
   let {cert empty_or_match_cert_913} =
     assert(dim_match_912, "function arguments of wrong shape",
-           "misc/bfast/bfast-cloudy.fut:106:1-235:10")
+           "unknown location")
   let {i32 x_915} = mul32(2i32, k_905)
   let {i32 k2p2_916} = add32(2i32, x_915)
   let {bool cond_917} = slt32(0i32, trend_904)
@@ -63,7 +66,7 @@
       let {bool valid_922} = not bounds_invalid_upwards_921
       let {cert range_valid_c_923} =
         assert(valid_922, "Range ", 0i32, "..", 1i32, "..<", k2p2'_918,
-                          " is invalid.", "/prelude/math.fut:461:23-30")
+                          " is invalid.", "unknown location")
       let {i64 k2p2'_1487} = binop_x_5073
       let {i64 N_1488} = binop_y_5074
       let {i64 nest_size_1490} = binop_x_5075
@@ -150,7 +153,7 @@
       let {bool valid_947} = not bounds_invalid_upwards_946
       let {cert range_valid_c_948} =
         assert(valid_947, "Range ", 0i32, "..", 1i32, "..<", k2p2'_918,
-                          " is invalid.", "/prelude/math.fut:461:23-30")
+                          " is invalid.", "unknown location")
       let {i64 k2p2'_1683} = binop_x_5073
       let {i64 N_1684} = binop_y_5074
       let {i64 nest_size_1686} = binop_x_5075
@@ -237,8 +240,7 @@
   let {bool zero_975} = eq_i32(y_974, 0i32)
   let {bool nonzero_976} = not zero_975
   let {cert nonzero_cert_977} =
-    assert(nonzero_976, "division by zero",
-           "misc/bfast/bfast-cloudy.fut:123:21-45")
+    assert(nonzero_976, "division by zero", "unknown location")
   let {i32 x_978} =
     <nonzero_cert_977>
     sdiv32(x_973, y_974)
@@ -319,13 +321,11 @@
   let {cert index_certs_1006} =
     assert(index_ok_1005, "Index [", 0i32, ":, :", n_906,
                           "] out of bounds for array of shape [", k2p2'_918,
-                          "][", N_901, "].",
-           "misc/bfast/bfast-cloudy.fut:127:15-21")
+                          "][", N_901, "].", "unknown location")
   let {cert index_certs_1008} =
     assert(index_ok_1005, "Index [:", n_906, ", ", 0i32,
                           ":] out of bounds for array of shape [", N_901, "][",
-                          k2p2'_918, "].",
-           "misc/bfast/bfast-cloudy.fut:128:15-22")
+                          k2p2'_918, "].", "unknown location")
   let {bool empty_slice_1010} = eq_i32(m_902, 0i32)
   let {i32 m_1011} = sub32(m_902, 1i32)
   let {bool zero_leq_i_p_m_t_s_1012} = sle32(0i32, m_1011)
@@ -338,7 +338,7 @@
   let {cert index_certs_1019} =
     assert(index_ok_1018, "Index [", 0i32, ":, :", n_906,
                           "] out of bounds for array of shape [", m_902, "][",
-                          N_901, "].", "misc/bfast/bfast-cloudy.fut:129:15-26")
+                          N_901, "].", "unknown location")
   let {bool suff_outer_par_1801} =
     get_size(suff_outer_par_6, threshold ()) <= m_902
   let {i64 m_1827} = sext i32 m_902 to i64
@@ -805,18 +805,16 @@
   let {bool valid_1043} = not bounds_invalid_upwards_1042
   let {cert range_valid_c_1044} =
     assert(valid_1043, "Range ", 0i32, "..", 1i32, "..<", nm_1041,
-                       " is invalid.", "/prelude/math.fut:461:23-30")
+                       " is invalid.", "unknown location")
   let {bool zero_1046} = eq_i32(m_1040, 0i32)
   let {bool nonzero_1047} = not zero_1046
   let {cert nonzero_cert_1048} =
-    assert(nonzero_1047, "division by zero",
-           "misc/bfast/bfast-cloudy.fut:74:41-47")
+    assert(nonzero_1047, "division by zero", "unknown location")
   let {bool loop_nonempty_1049} = slt32(0i32, k2p2'_918)
   let {bool loop_not_taken_1050} = not loop_nonempty_1049
   let {bool protect_assert_disj_1051} = logor(nonzero_1047, loop_not_taken_1050)
   let {cert nonzero_cert_1052} =
-    assert(protect_assert_disj_1051, "division by zero",
-           "misc/bfast/bfast-cloudy.fut:61:43-49")
+    assert(protect_assert_disj_1051, "division by zero", "unknown location")
   let {i32 j_m_i_1053} = sub32(m_1040, k2p2'_918)
   let {bool empty_slice_1054} = eq_i32(j_m_i_1053, 0i32)
   let {i32 m_1055} = sub32(j_m_i_1053, 1i32)
@@ -833,14 +831,13 @@
   let {cert index_certs_1066} =
     assert(index_ok_1065, "Index [", 0i32, ":", k2p2'_918, ", ", k2p2'_918, ":",
                           m_1040, "] out of bounds for array of shape [",
-                          k2p2'_918, "][", m_1040, "].",
-           "misc/bfast/bfast-cloudy.fut:82:8-37")
+                          k2p2'_918, "][", m_1040, "].", "unknown location")
   let {bool dim_match_1067} = eq_i32(k2p2'_918, j_m_i_1053)
   let {cert empty_or_match_cert_1068} =
     assert(dim_match_1067, "Value of (core language) shape (", k2p2'_918, ", ",
                            j_m_i_1053, ") cannot match shape of type `[",
                            k2p2'_918, "][", k2p2'_918, "]f32`.",
-           "misc/bfast/bfast-cloudy.fut:82:8-50")
+           "unknown location")
   let {i32 max_group_size_2261} =
     get_size_max(group_size)
   let {bool fits_2262} = sle32(nm_1041, max_group_size_2261)
@@ -1011,7 +1008,7 @@
               let {cert index_certs_2280} =
                 assert(y_2279, "Index [", i_2277,
                                "] out of bounds for array of shape [", nm_1041,
-                               "].", "misc/bfast/bfast-cloudy.fut:60:16-19")
+                               "].", "unknown location")
               let {f32 v1_2281} =
                 <index_certs_2280>
                 A_2278[i_2277]
@@ -1186,7 +1183,7 @@
           let {cert index_certs_2775} =
             assert(y_2774, "Index [", i_2772,
                            "] out of bounds for array of shape [", nm_1041,
-                           "].", "misc/bfast/bfast-cloudy.fut:60:16-19")
+                           "].", "unknown location")
           let {i32 res_ixfn_5287} =
             -- Branch returns: {i32}
             if <equiv> intra_suff_and_fits_2784
@@ -2787,7 +2784,7 @@
   let {cert index_certs_1159} =
     assert(bounds_check_1158, "Index [", i_1155,
                               "] out of bounds for array of shape [", N_901,
-                              "].", "/prelude/array.fut:18:29-34")
+                              "].", "unknown location")
   let {bool fits_3436} = sle32(N_901, max_group_size_2261)
   let {bool suff_intra_par_3434} =
     get_size(suff_intra_par_22, threshold (!suff_outer_par_21)) <= N_901
@@ -3631,7 +3628,7 @@
   let {bool valid_1256} = not bounds_invalid_upwards_1255
   let {cert range_valid_c_1257} =
     assert(valid_1256, "Range ", 0i32, "..", 1i32, "..<", Nmn_1254,
-                       " is invalid.", "/prelude/math.fut:461:23-30")
+                       " is invalid.", "unknown location")
   let {bool fits_4102} = sle32(Nmn_1254, max_group_size_2261)
   let {bool suff_intra_par_4100} =
     get_size(suff_intra_par_28, threshold (!suff_outer_par_27)) <= Nmn_1254
@@ -3888,3 +3885,5 @@
     res_1259
   in {m_902, res_mem_5745, entry_result_1308}
 }
+CallStack (from HasCallStack):
+  error, called at src/Futhark/Actions.hs:85:13 in futhark-0.17.0-inplace:Futhark.Actions

I mean, that all looks okay? When inspecting generating IRs in the same manner for LUD, I get the same "unknown location" diffs, and no isomorphism errors.

Okay, it seems like the error happens after inlining functions. Minimal command to reproduce: 

cabal exec futhark -- dev --verbose -e --inline-functions --sexp misc/bfast/bfast-cloudy.fut > /dev/null

However, it still seems like the pretty-printed IR only differs by the SrcLoc. Instead of pretty-printing, let's try showing it.

Huh, it's still the same…

Okay, by showing prog == prog as part of the error output in sexpAction, I can see that the IR of bfast-cloudy, after inlining functions and in contrast to all other programs in futhark-benchmarks, is not equal to itself… Very strange.

Troels says it might be a lazy Eq instance somewhere. Perhaps in PrimExp? It's the only place I can see where it always returns false in some cases.

I've tried to remove the last catch-all term from PrimExp, so now there's an inexhaustive pattern match. We'll see if it gets triggered when running on bfast-cloudy.

Hmm, nope, that doesn't seem to be it…

Ugh… 

1: decode @FloatValue "NaNf32" /= decode @FloatValue "NaNf32"

Because floats, obviously…

I've added a better Eq instance to FloatValue. We'll see if that does the trick.

Yes, that seems to work. Now, when running the script from a few days ago, I find no errors when translating our benchmarks.

It would be nice to run the same thing on our tests, but some of them are supposed to fail. How do we tell them apart? 

rg error **.fut --files-without-match | xargs -n 1 cabal exec futhark -- dev --kernels -a -e --cse --sexp  >/dev/null

I'm missing a lot of files… Hopefully it's good enough with the benchmark tests.

Well, I didn't get around to do the graph colouring today. Hopefully tomorrow will be the day.