rtl-optimization/98863 - prune RD with LIVE in STV

This sets DF_RD_PRUNE_DEAD_DEFS like all other uses of the UD/DU
chain problems which makes the RD problem consume a lot less memory.

2021-02-01  Richard Biener  <rguenther@suse.de>

	PR rtl-optimization/98863
	* config/i386/i386-features.c (convert_scalars_to_vector):
	Set DF_RD_PRUNE_DEAD_DEFS.

(cherry picked from commit 972918eea873f8b1663151316c4b3aee7ae028e2)

diff --git a/gcc/config/i386/i386-features.c b/gcc/config/i386/i386-features.c
index 78fb373db6ef4541ebf8ef764a3a130b53f0e172..b1109de7cb61c4421ebb425207c05516481ec0da 100644 (file)
--- a/gcc/config/i386/i386-features.c
+++ b/gcc/config/i386/i386-features.c
@@ -1615,7 +1615,7 @@ convert_scalars_to_vector (bool timode_p)
     bitmap_initialize (&candidates[i], &bitmap_default_obstack);
 
   calculate_dominance_info (CDI_DOMINATORS);
-  df_set_flags (DF_DEFER_INSN_RESCAN);
+  df_set_flags (DF_DEFER_INSN_RESCAN | DF_RD_PRUNE_DEAD_DEFS);
   df_chain_add_problem (DF_DU_CHAIN | DF_UD_CHAIN);
   df_analyze ();