[regression] Test level 19 with uncompressed literals
diff --git a/tests/regression/config.c b/tests/regression/config.c
index f04d32d..4d5d191 100644
--- a/tests/regression/config.c
+++ b/tests/regression/config.c
@@ -132,6 +132,16 @@
     .param_values = PARAM_VALUES(uncompressed_literals_param_values),
 };
 
+static param_value_t const uncompressed_literals_opt_param_values[] = {
+    {.param = ZSTD_c_compressionLevel, .value = 19},
+    {.param = ZSTD_c_literalCompressionMode, .value = ZSTD_lcm_uncompressed},
+};
+
+static config_t uncompressed_literals_opt = {
+    .name = "uncompressed literals optimal",
+    .param_values = PARAM_VALUES(uncompressed_literals_opt_param_values),
+};
+
 static param_value_t const huffman_literals_param_values[] = {
     {.param = ZSTD_c_compressionLevel, .value = -1},
     {.param = ZSTD_c_literalCompressionMode, .value = ZSTD_lcm_huffman},
@@ -176,6 +186,7 @@
     &small_clog,
     &explicit_params,
     &uncompressed_literals,
+    &uncompressed_literals_opt,
     &huffman_literals,
     NULL,
 };
diff --git a/tests/regression/results.csv b/tests/regression/results.csv
index d9c5a4a..076e3b4 100644
--- a/tests/regression/results.csv
+++ b/tests/regression/results.csv
@@ -14,6 +14,7 @@
 silesia.tar,                      level 16,                         compress simple,                  4381277
 silesia.tar,                      level 19,                         compress simple,                  4281514
 silesia.tar,                      uncompressed literals,            compress simple,                  4875008
+silesia.tar,                      uncompressed literals optimal,    compress simple,                  4281514
 silesia.tar,                      huffman literals,                 compress simple,                  6195462
 silesia,                          level -5,                         compress cctx,                    7152294
 silesia,                          level -3,                         compress cctx,                    6789969
@@ -37,6 +38,7 @@
 silesia,                          small chain log,                  compress cctx,                    4931093
 silesia,                          explicit params,                  compress cctx,                    4813352
 silesia,                          uncompressed literals,            compress cctx,                    4862377
+silesia,                          uncompressed literals optimal,    compress cctx,                    4293262
 silesia,                          huffman literals,                 compress cctx,                    6191548
 github,                           level -5,                         compress cctx,                    232744
 github,                           level -5 with dict,               compress cctx,                    47294
@@ -74,6 +76,7 @@
 github,                           small chain log,                  compress cctx,                    decompression error
 github,                           explicit params,                  compress cctx,                    decompression error
 github,                           uncompressed literals,            compress cctx,                    136397
+github,                           uncompressed literals optimal,    compress cctx,                    133717
 github,                           huffman literals,                 compress cctx,                    176575
 silesia,                          level -5,                         zstdcli,                          7152342
 silesia,                          level -3,                         zstdcli,                          6790021
@@ -176,6 +179,7 @@
 silesia,                          small chain log,                  advanced one pass,                4931093
 silesia,                          explicit params,                  advanced one pass,                4815369
 silesia,                          uncompressed literals,            advanced one pass,                5155424
+silesia,                          uncompressed literals optimal,    advanced one pass,                4426654
 silesia,                          huffman literals,                 advanced one pass,                5341356
 silesia.tar,                      level -5,                         advanced one pass,                7160438
 silesia.tar,                      level -3,                         advanced one pass,                6789024
@@ -200,6 +204,7 @@
 silesia.tar,                      small chain log,                  advanced one pass,                4943255
 silesia.tar,                      explicit params,                  advanced one pass,                4829974
 silesia.tar,                      uncompressed literals,            advanced one pass,                5157992
+silesia.tar,                      uncompressed literals optimal,    advanced one pass,                4372744
 silesia.tar,                      huffman literals,                 advanced one pass,                5358079
 github,                           level -5,                         advanced one pass,                232744
 github,                           level -5 with dict,               advanced one pass,                46718
@@ -238,6 +243,7 @@
 github,                           small chain log,                  advanced one pass,                136314
 github,                           explicit params,                  advanced one pass,                137670
 github,                           uncompressed literals,            advanced one pass,                167004
+github,                           uncompressed literals optimal,    advanced one pass,                164600
 github,                           huffman literals,                 advanced one pass,                143457
 silesia,                          level -5,                         advanced one pass small out,      7152294
 silesia,                          level -3,                         advanced one pass small out,      6789969
@@ -262,6 +268,7 @@
 silesia,                          small chain log,                  advanced one pass small out,      4931093
 silesia,                          explicit params,                  advanced one pass small out,      4815369
 silesia,                          uncompressed literals,            advanced one pass small out,      5155424
+silesia,                          uncompressed literals optimal,    advanced one pass small out,      4426654
 silesia,                          huffman literals,                 advanced one pass small out,      5341356
 silesia.tar,                      level -5,                         advanced one pass small out,      7160438
 silesia.tar,                      level -3,                         advanced one pass small out,      6789024
@@ -286,6 +293,7 @@
 silesia.tar,                      small chain log,                  advanced one pass small out,      4943255
 silesia.tar,                      explicit params,                  advanced one pass small out,      4829974
 silesia.tar,                      uncompressed literals,            advanced one pass small out,      5157992
+silesia.tar,                      uncompressed literals optimal,    advanced one pass small out,      4372744
 silesia.tar,                      huffman literals,                 advanced one pass small out,      5358079
 github,                           level -5,                         advanced one pass small out,      232744
 github,                           level -5 with dict,               advanced one pass small out,      46718
@@ -324,6 +332,7 @@
 github,                           small chain log,                  advanced one pass small out,      136314
 github,                           explicit params,                  advanced one pass small out,      137670
 github,                           uncompressed literals,            advanced one pass small out,      167004
+github,                           uncompressed literals optimal,    advanced one pass small out,      164600
 github,                           huffman literals,                 advanced one pass small out,      143457
 silesia,                          level -5,                         advanced streaming,               7152294
 silesia,                          level -3,                         advanced streaming,               6789973
@@ -348,6 +357,7 @@
 silesia,                          small chain log,                  advanced streaming,               4931093
 silesia,                          explicit params,                  advanced streaming,               4815380
 silesia,                          uncompressed literals,            advanced streaming,               5155424
+silesia,                          uncompressed literals optimal,    advanced streaming,               4426654
 silesia,                          huffman literals,                 advanced streaming,               5341357
 silesia.tar,                      level -5,                         advanced streaming,               7160440
 silesia.tar,                      level -3,                         advanced streaming,               6789026
@@ -372,6 +382,7 @@
 silesia.tar,                      small chain log,                  advanced streaming,               4943260
 silesia.tar,                      explicit params,                  advanced streaming,               4830002
 silesia.tar,                      uncompressed literals,            advanced streaming,               5157995
+silesia.tar,                      uncompressed literals optimal,    advanced streaming,               4372744
 silesia.tar,                      huffman literals,                 advanced streaming,               5358083
 github,                           level -5,                         advanced streaming,               232744
 github,                           level -5 with dict,               advanced streaming,               46718
@@ -410,6 +421,7 @@
 github,                           small chain log,                  advanced streaming,               136314
 github,                           explicit params,                  advanced streaming,               137670
 github,                           uncompressed literals,            advanced streaming,               167004
+github,                           uncompressed literals optimal,    advanced streaming,               164600
 github,                           huffman literals,                 advanced streaming,               143457
 silesia,                          level -5,                         old streaming,                    7152294
 silesia,                          level -3,                         old streaming,                    6789973
@@ -427,6 +439,7 @@
 silesia,                          level 19,                         old streaming,                    4293262
 silesia,                          no source size,                   old streaming,                    4862341
 silesia,                          uncompressed literals,            old streaming,                    4862377
+silesia,                          uncompressed literals optimal,    old streaming,                    4293262
 silesia,                          huffman literals,                 old streaming,                    6191549
 silesia.tar,                      level -5,                         old streaming,                    7160440
 silesia.tar,                      level -3,                         old streaming,                    6789026
@@ -444,6 +457,7 @@
 silesia.tar,                      level 19,                         old streaming,                    4281514
 silesia.tar,                      no source size,                   old streaming,                    4875006
 silesia.tar,                      uncompressed literals,            old streaming,                    4875010
+silesia.tar,                      uncompressed literals optimal,    old streaming,                    4281514
 silesia.tar,                      huffman literals,                 old streaming,                    6195465
 github,                           level -5,                         old streaming,                    232744
 github,                           level -5 with dict,               old streaming,                    46718
@@ -475,4 +489,5 @@
 github,                           level 19 with dict,               old streaming,                    37576
 github,                           no source size,                   old streaming,                    141003
 github,                           uncompressed literals,            old streaming,                    136397
+github,                           uncompressed literals optimal,    old streaming,                    133717
 github,                           huffman literals,                 old streaming,                    176575