proc_rmdead: use explicit pattern set when there are no wildcards

If width of a case expression was large, explicit patterns could cause
the existing logic to take an extremely long time, or exhaust the
maximum size of the underlying set. For cases where all of the patterns
are fully defined and there are no constants in the case expression,
this change uses a simple set to track which patterns have been seen.

3 files changed, 323 insertions, 0 deletions

diff --git a/tests/proc/rmdead.v b/tests/proc/rmdead.v
new file mode 100644
index 000000000..2be89e533
--- /dev/null
+++ b/tests/proc/rmdead.v
@@ -0,0 +1,46 @@
+module top (
+    input wire signed x,
+    output reg [31:0] y
+);
+    wire signed fail = ~x;
+
+    always @*
+        case (x)
+            1'b0: y = 0;
+            1'b1: y = 1;
+            default: y = fail;
+        endcase
+
+    always @*
+        case (x)
+            2'sb00: y = 0;
+            2'sb00: y = fail;
+        endcase
+
+    always @*
+        case (x)
+            2'sb00: y = 0;
+            default: y = fail;
+            2'sb01: y = 1;
+            2'sb10: y = 2;
+            2'sb11: y = 3;
+            2'sb00: y = fail;
+            2'sb01: y = fail;
+            2'sb10: y = fail;
+            2'sb11: y = fail;
+        endcase
+
+
+    always @*
+        case ({x, x})
+            2'b00: y = 0;
+            2'b01: y = 1;
+            2'b10: y = 2;
+            2'b11: y = 3;
+            default: y = fail;
+            2'b00: y = fail;
+            2'b01: y = fail;
+            2'b10: y = fail;
+            2'b11: y = fail;
+        endcase
+endmodule
diff --git a/tests/proc/rmdead.ys b/tests/proc/rmdead.ys
new file mode 100644
index 000000000..697d899e3
--- /dev/null
+++ b/tests/proc/rmdead.ys
@@ -0,0 +1,4 @@
+read_verilog rmdead.v
+proc
+opt_clean
+select -assert-count 0 w:fail
diff --git a/tests/simple/case_large.v b/tests/simple/case_large.v
new file mode 100644
index 000000000..a96ce86fe
--- /dev/null
+++ b/tests/simple/case_large.v
@@ -0,0 +1,273 @@
+module top (
+    input wire [127:0] x,
+    output reg [31:0] y
+);
+    localparam A = 32'hDEAD_BEEF;
+    localparam B = 32'h0BAD_0B01;
+    localparam C = 32'hC001_D00D;
+    localparam D = 32'h1234_5678;
+
+    always @*
+        case (x)
+
+            {C,A,D,B}: y = 142;
+            {C,A,D,A}: y = 141;
+            {D,D,A,A}: y = 241;
+            {A,C,C,D}: y = 44;
+            {A,A,A,C}: y = 3;
+            {A,B,A,C}: y = 19;
+            {A,D,C,C}: y = 59;
+            {A,A,C,C}: y = 11;
+            {D,C,B,B}: y = 230;
+            {A,A,D,D}: y = 16;
+            {A,C,A,A}: y = 33;
+            {A,D,D,D}: y = 64;
+            {D,B,C,B}: y = 218;
+            {A,C,B,D}: y = 40;
+            {C,A,B,B}: y = 134;
+            {A,C,C,C}: y = 43;
+            {D,A,D,D}: y = 208;
+            {A,B,C,A}: y = 25;
+            {B,A,B,B}: y = 70;
+            {A,C,B,B}: y = 38;
+            {C,C,C,B}: y = 170;
+            {C,D,A,C}: y = 179;
+            {B,C,D,B}: y = 110;
+            {A,D,A,C}: y = 51;
+            {C,C,B,B}: y = 166;
+            {D,D,D,B}: y = 254;
+            {C,A,D,C}: y = 143;
+            {C,D,D,B}: y = 190;
+            {C,B,A,A}: y = 145;
+            {C,B,A,C}: y = 147;
+            {B,C,C,B}: y = 106;
+            {C,D,C,A}: y = 185;
+            {C,D,B,D}: y = 184;
+            {D,D,D,D}: y = 256;
+            {D,C,C,C}: y = 235;
+            {D,C,D,B}: y = 238;
+            {A,B,D,C}: y = 31;
+            {A,C,A,D}: y = 36;
+            {C,B,C,B}: y = 154;
+            {A,B,A,A}: y = 17;
+            {C,B,B,A}: y = 149;
+            {B,B,D,C}: y = 95;
+            {B,D,C,B}: y = 122;
+            {D,B,A,A}: y = 209;
+            {B,A,B,A}: y = 69;
+            {B,A,D,A}: y = 77;
+            {A,B,B,B}: y = 22;
+            {C,C,C,C}: y = 171;
+            {C,A,C,B}: y = 138;
+            {B,A,D,D}: y = 80;
+            {C,D,D,C}: y = 191;
+            {B,A,A,C}: y = 67;
+            {D,C,D,C}: y = 239;
+            {C,D,D,D}: y = 192;
+            {C,D,B,B}: y = 182;
+            {B,B,A,C}: y = 83;
+            {D,A,A,D}: y = 196;
+            {A,C,C,B}: y = 42;
+            {B,C,A,A}: y = 97;
+            {A,D,B,A}: y = 53;
+            {D,D,B,C}: y = 247;
+            {A,A,C,A}: y = 9;
+            {D,A,C,B}: y = 202;
+            {A,C,B,C}: y = 39;
+            {B,C,B,A}: y = 101;
+            {B,B,B,C}: y = 87;
+            {C,B,A,B}: y = 146;
+            {B,D,A,D}: y = 116;
+            {A,B,D,D}: y = 32;
+            {B,A,B,C}: y = 71;
+            {C,A,A,A}: y = 129;
+            {B,A,D,C}: y = 79;
+            {B,A,C,B}: y = 74;
+            {B,B,D,B}: y = 94;
+            {B,B,C,C}: y = 91;
+            {D,C,C,A}: y = 233;
+            {C,A,B,A}: y = 133;
+            {D,A,B,A}: y = 197;
+            {D,B,B,D}: y = 216;
+            {C,C,A,C}: y = 163;
+            {D,D,B,A}: y = 245;
+            {B,A,D,B}: y = 78;
+            {A,B,C,D}: y = 28;
+            {C,C,C,D}: y = 172;
+            {D,C,A,D}: y = 228;
+            {A,C,D,A}: y = 45;
+            {B,D,C,C}: y = 123;
+            {C,B,A,D}: y = 148;
+            {B,D,B,B}: y = 118;
+            {A,D,A,B}: y = 50;
+            {C,B,B,C}: y = 151;
+            {A,A,A,A}: y = 1;
+            {A,A,B,B}: y = 6;
+            {B,B,B,B}: y = 86;
+            {A,D,A,A}: y = 49;
+            {A,A,A,B}: y = 2;
+            {B,D,D,A}: y = 125;
+            {C,C,D,B}: y = 174;
+            {D,A,D,B}: y = 206;
+            {D,D,B,D}: y = 248;
+            {A,A,A,D}: y = 4;
+            {B,A,A,B}: y = 66;
+            {B,C,C,A}: y = 105;
+            {B,C,C,C}: y = 107;
+            {D,D,D,C}: y = 255;
+            {B,C,D,D}: y = 112;
+            {A,D,B,C}: y = 55;
+            {C,C,C,A}: y = 169;
+            {C,D,B,C}: y = 183;
+            {A,A,B,D}: y = 8;
+            {D,C,B,A}: y = 229;
+            {C,B,D,A}: y = 157;
+            {A,D,D,C}: y = 63;
+            {D,A,D,A}: y = 205;
+            {A,A,B,C}: y = 7;
+            {A,C,A,B}: y = 34;
+            {C,B,D,C}: y = 159;
+            {C,C,D,D}: y = 176;
+            {D,D,D,A}: y = 253;
+            {A,B,B,D}: y = 24;
+            {B,B,C,A}: y = 89;
+            {B,D,C,A}: y = 121;
+            {A,B,C,C}: y = 27;
+            {A,A,D,C}: y = 15;
+            {A,B,B,A}: y = 21;
+            {A,D,A,D}: y = 52;
+            {D,D,C,C}: y = 251;
+            {C,D,A,B}: y = 178;
+            {A,A,D,B}: y = 14;
+            {D,B,D,B}: y = 222;
+            {A,C,C,A}: y = 41;
+            {D,D,A,C}: y = 243;
+            {A,C,D,B}: y = 46;
+            {B,B,B,D}: y = 88;
+            {D,B,B,B}: y = 214;
+            {C,C,B,D}: y = 168;
+            {A,D,D,A}: y = 61;
+            {D,A,C,C}: y = 203;
+            {D,C,A,C}: y = 227;
+            {C,D,C,D}: y = 188;
+            {D,B,D,D}: y = 224;
+            {A,C,D,C}: y = 47;
+            {B,A,B,D}: y = 72;
+            {A,B,B,C}: y = 23;
+            {C,C,D,A}: y = 173;
+            {D,B,C,C}: y = 219;
+            {D,B,C,A}: y = 217;
+            {A,D,C,D}: y = 60;
+            {B,B,D,A}: y = 93;
+            {A,D,C,A}: y = 57;
+            {C,C,A,A}: y = 161;
+            {C,B,B,D}: y = 152;
+            {B,B,B,A}: y = 85;
+            {B,D,A,A}: y = 113;
+            {D,C,D,A}: y = 237;
+            {B,C,B,C}: y = 103;
+            {A,B,C,B}: y = 26;
+            {C,D,A,D}: y = 180;
+            {A,D,B,D}: y = 56;
+            {D,C,A,B}: y = 226;
+            {D,B,B,C}: y = 215;
+            {D,A,B,C}: y = 199;
+            {B,D,A,C}: y = 115;
+            {C,B,C,D}: y = 156;
+            {B,D,D,B}: y = 126;
+            {D,D,C,B}: y = 250;
+            {D,C,C,D}: y = 236;
+            {B,C,B,D}: y = 104;
+            {C,B,C,A}: y = 153;
+            {C,B,B,B}: y = 150;
+            {C,D,C,B}: y = 186;
+            {C,D,C,C}: y = 187;
+            {A,D,B,B}: y = 54;
+            {D,C,C,B}: y = 234;
+            {C,B,D,D}: y = 160;
+            {A,B,A,D}: y = 20;
+            {C,C,B,A}: y = 165;
+            {C,D,D,A}: y = 189;
+            {C,C,D,C}: y = 175;
+            {D,B,D,C}: y = 223;
+            {B,C,A,B}: y = 98;
+            {C,C,A,B}: y = 162;
+            {B,C,D,A}: y = 109;
+            {D,A,B,D}: y = 200;
+            {B,D,C,D}: y = 124;
+            {D,D,C,A}: y = 249;
+            {B,A,C,C}: y = 75;
+            {A,A,C,B}: y = 10;
+            {C,A,B,D}: y = 136;
+            {B,B,C,D}: y = 92;
+            {D,D,C,D}: y = 252;
+            {B,C,A,D}: y = 100;
+            {C,A,C,C}: y = 139;
+            {C,A,C,D}: y = 140;
+            {D,C,A,A}: y = 225;
+            {A,D,C,B}: y = 58;
+            {D,B,C,D}: y = 220;
+            {D,C,B,D}: y = 232;
+            {B,A,C,D}: y = 76;
+            {B,B,D,D}: y = 96;
+            {D,D,B,B}: y = 246;
+            {C,D,A,A}: y = 177;
+            {D,D,A,B}: y = 242;
+            {A,A,D,A}: y = 13;
+            {B,B,A,D}: y = 84;
+            {B,C,D,C}: y = 111;
+            {D,A,A,B}: y = 194;
+            {C,A,B,C}: y = 135;
+            {D,A,A,C}: y = 195;
+            {B,B,A,B}: y = 82;
+            {D,C,D,D}: y = 240;
+            {B,C,C,D}: y = 108;
+            {D,B,A,C}: y = 211;
+            {A,C,D,D}: y = 48;
+            {D,A,A,A}: y = 193;
+            {C,A,A,B}: y = 130;
+            {D,B,A,D}: y = 212;
+            {D,A,B,B}: y = 198;
+            {A,C,B,A}: y = 37;
+            {B,D,B,D}: y = 120;
+            {C,C,B,C}: y = 167;
+            {D,B,A,B}: y = 210;
+            {A,B,A,B}: y = 18;
+            {B,C,B,B}: y = 102;
+            {B,B,A,A}: y = 81;
+            {D,D,A,D}: y = 244;
+            {A,B,D,B}: y = 30;
+            {A,C,A,C}: y = 35;
+            {A,A,C,D}: y = 12;
+            {B,D,B,C}: y = 119;
+            {B,C,A,C}: y = 99;
+            {D,A,C,A}: y = 201;
+            {B,A,A,D}: y = 68;
+            {C,A,A,D}: y = 132;
+            {B,A,C,A}: y = 73;
+            {C,C,A,D}: y = 164;
+            {B,D,B,A}: y = 117;
+            {A,D,D,B}: y = 62;
+            {B,D,D,C}: y = 127;
+            {A,B,D,A}: y = 29;
+            {C,D,B,A}: y = 181;
+            {B,B,C,B}: y = 90;
+            {B,D,A,B}: y = 114;
+            {B,D,D,D}: y = 128;
+            {C,A,C,A}: y = 137;
+            {A,A,B,A}: y = 5;
+            {C,A,D,D}: y = 144;
+            {D,C,B,C}: y = 231;
+            {D,A,C,D}: y = 204;
+            {C,A,A,C}: y = 131;
+            {C,B,D,B}: y = 158;
+            {B,A,A,A}: y = 65;
+            {D,A,D,C}: y = 207;
+            {D,B,B,A}: y = 213;
+            {D,B,D,A}: y = 221;
+            {C,B,C,C}: y = 155;
+
+            default: y = 0;
+
+        endcase
+endmodule