Re: [PATCH 1/2] if-to-switch conversion pass

[Bernhard Reutner-Fischer <rep dot dot dot nop at gmail dot com>]

On Tue, Jul 17, 2012 at 01:21:00PM +0200, Tom de Vries wrote:

> /* The root of the compilation pass tree, once constructed.  */
> extern struct opt_pass *all_passes, *all_small_ipa_passes, *all_lowering_passes,
>Index: gcc/tree-if-switch-conversion.c
>===================================================================
>--- /dev/null (new file)
>+++ gcc/tree-if-switch-conversion.c (revision 0)

>+/* Convert all trees in RANGES to TYPE.  */
>+
>+static bool
>+convert_ranges (tree type, VEC (range, gc) *ranges)
>+{
>+  unsigned int ix;
>+  range r;
>+
>+  for (ix = 0; VEC_iterate (range, ranges, ix, r); ix++)
>+    {
>+      r->low = fold_convert (type, r->low);
>+      if (TREE_TYPE (r->low) != type)
>+	return false;
>+
>+      if (r->high == NULL_TREE)
>+	continue;
>+
>+      r->high = fold_convert (type, r->high);
>+      if (TREE_TYPE (r->low) != type)

low, not high? This is not immediately obvious to me, please explain?

>+	return false;
>+    }
>+
>+  return true;
>+}

>+/* Analyze BB and store results in ifsc_info_def struct.  */
>+
>+static void
>+analyze_bb (basic_block bb)
>+{
>+  gimple stmt = last_stmt (bb);
>+  tree lhs, rhs, var, constant;
>+  edge true_edge, false_edge;
>+  enum tree_code cond_code;
>+  VEC (range, gc) *ranges = NULL;
>+  unsigned int nr_stmts = 0;
>+  bool swap_edges = false;
>+  tree low, high;
>+
>+  /* We currently only handle bbs with GIMPLE_COND.  */
>+  if (!stmt || gimple_code (stmt) != GIMPLE_COND)
>+    return;
>+
>+  cond_code = gimple_cond_code (stmt);
>+  switch (cond_code)
>+    {
>+    case EQ_EXPR:
>+    case NE_EXPR:
>+    case LE_EXPR:
>+    case GE_EXPR:
>+      break;
>+    case LT_EXPR:
>+    case GT_EXPR:
>+      /* Todo.  */
>+      return;
>+    default:
>+      return;
>+    }
>+
>+  lhs = gimple_cond_lhs (stmt);
>+  rhs = gimple_cond_rhs (stmt);
>+
>+  /* The comparison needs to be against a constant.  */
>+  if (!TREE_CONSTANT (lhs)
>+      && !TREE_CONSTANT (rhs))
>+    return;
>+
>+  /* Normalize comparison into (var cond_code constant).  */
>+  var = TREE_CONSTANT (lhs) ? rhs : lhs;
>+  constant = TREE_CONSTANT (lhs)? lhs : rhs;

missing space

[]
>+/* Convert every if-chain in CHAINS into a switch statement.  */
>+
>+static void
>+convert_chains (VEC (if_chain, gc) *chains)
>+{
>+  unsigned int ix;
>+  if_chain chain;
>+
>+  if (VEC_empty (if_chain, chains))
>+    return;
>+
>+  for (ix = 0; VEC_iterate (if_chain, chains, ix, chain); ix++)

shouldn't this be FOR_EACH_VEC_ELT nowadays? Everywhere.
>+    {
>+      if (dump_file)
>+	dump_if_chain (chain);
>+
>+      convert_if_chain_to_switch (chain);
>+
>+      update_cfg (chain);
>+    }
>+
>+  /* Force recalculation of dominance info.  */
>+  free_dominance_info (CDI_DOMINATORS);
>+  free_dominance_info (CDI_POST_DOMINATORS);
>+}

>Index: gcc/Makefile.in
>===================================================================
>--- gcc/Makefile.in (revision 189508)
>+++ gcc/Makefile.in (working copy)
>@@ -1391,6 +1391,7 @@ OBJS = \
> 	tree-profile.o \
> 	tree-scalar-evolution.o \
> 	tree-sra.o \
>+	tree-if-switch-conversion.o \
> 	tree-switch-conversion.o \
> 	tree-ssa-address.o \
> 	tree-ssa-alias.o \
>@@ -3013,7 +3014,12 @@ tree-sra.o : tree-sra.c $(CONFIG_H) $(SY
>    $(IPA_PROP_H) $(DIAGNOSTIC_H) statistics.h $(TREE_DUMP_H) $(TIMEVAR_H) \
>    $(PARAMS_H) $(TARGET_H) $(FLAGS_H) \
>    $(DBGCNT_H) $(TREE_INLINE_H) $(GIMPLE_PRETTY_PRINT_H)
>+tree-if-switch-conversion.o : tree-if-switch-conversion.c $(CONFIG_H) \
>+    $(SYSTEM_H) $(TREE_H) $(TM_P_H) $(TREE_FLOW_H) $(DIAGNOSTIC_H) \
>+    $(TREE_INLINE_H) $(TIMEVAR_H) $(TM_H) coretypes.h $(TREE_DUMP_H) \
>+    $(GIMPLE_H) $(TREE_PASS_H) $(FLAGS_H) $(EXPR_H) $(BASIC_BLOCK_H) output.h \
>+    $(GGC_H) $(OBSTACK_H) $(PARAMS_H) $(CPPLIB_H) $(PARAMS_H)

I think this list needs updating.

Nice to see if improvements, finally! :)
TIA && cheers,