Fix splitting of large _eval and related functions

Fix bug that only used to measure size of first statement in functions
to determine if splitting was necessary. Measure whole function instead.

Changes

@@ -27,6 +27,7 @@ Verilator 4.217 devel
 * Fix VL_STREAML_FAST_QQI with 64 bit left-hand-side (#3232) (#3235)
 * Fix $sformat of inputs/outputs (#3236). [Adrien Le Masle]
 * Fix associative array foreach loop (#3229).
+* Fix splitting of _eval and other top level functions. [Geza Lore, Shunyao CAD]
 
 
 Verilator 4.216 2021-12-05

src/V3Clock.cpp

@@ -207,8 +207,7 @@ private:
     }
     void splitCheck(AstCFunc* ofuncp) {
         if (!v3Global.opt.outputSplitCFuncs() || !ofuncp->stmtsp()) return;
-        if (EmitCBaseCounterVisitor(ofuncp->stmtsp()).count() < v3Global.opt.outputSplitCFuncs())
-            return;
+        if (EmitCBaseCounterVisitor(ofuncp).count() < v3Global.opt.outputSplitCFuncs()) return;
 
         int funcnum = 0;
         int func_stmts = 0;
@@ -223,8 +222,9 @@ private:
             const int stmts = EmitCBaseCounterVisitor(itemp).count();
             if (!funcp || (func_stmts + stmts) > v3Global.opt.outputSplitCFuncs()) {
                 // Make a new function
-                funcp = new AstCFunc{ofuncp->fileline(), ofuncp->name() + cvtToStr(++funcnum),
-                                     m_topScopep->scopep()};
+                funcp
+                    = new AstCFunc{ofuncp->fileline(), ofuncp->name() + "__" + cvtToStr(funcnum++),
+                                   m_topScopep->scopep()};
                 funcp->dontCombine(true);
                 funcp->isStatic(false);
                 funcp->isLoose(true);

test_regress/t/t_flag_csplit_eval.pl

@@ -15,25 +15,21 @@ sub check_evals {
         local $/; undef $/;
         my $wholefile = <$fh>;
 
-        if ($wholefile =~ /___eval[0-9]+/) {
+        if ($wholefile =~ /___eval__[0-9]+\(.*\)\s*{/) {
             ++$got;
         }
     }
-    $got >= 3 or error("Too few _eval functions found: $got");
+    $got >= 2 or error("Too few _eval functions found: $got");
 }
 
 scenarios(vlt_all => 1);
 
 compile(
-    v_flags2 => ["--output-split 1 --output-split-cfuncs 1 --exe ../$Self->{main_filename}"],
-#    verilator_make_gmake => 0,
-    );
-
-# Very slow to compile, so generally skip it
-execute(
-    check_finished => 1,
+    v_flags2 => ["--output-split 1 --output-split-cfuncs 20"],
+    verilator_make_gmake => 0, # Slow to compile, so skip it
     );
 
 check_evals();
+
 ok(1);
 1;

test_regress/t/t_flag_csplit_eval.v

@@ -22,6 +22,14 @@ module t (/*AUTOARG*/
    final if (cnt0 == 0) $stop;
    final if (cnt1 != 0) $stop;
 
+   // Some dummy statements to make the code larger
+   generate
+      genvar  i;
+      for (i = 0 ; i < 100; i = i + 1) begin
+         always @(posedge clk) $c("/*", i, "*/");
+      end
+   endgenerate
+
    always_comb begin
       if (cnt0==99) begin
          $write("*-* All Finished *-*\n");