diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
index ed347cab70ea7d71c23916aa1661044baa3086f2..a37a6c78b41d558e163517bdea64896ea333f8f3 100644
--- a/gcc/config/nvptx/nvptx.cc
+++ b/gcc/config/nvptx/nvptx.cc
@@ -5372,6 +5372,190 @@ workaround_barsyncs (void)
}
#endif
+/* Initialize all declared regs at function entry.
+ Advantage : Fool-proof.
+ Disadvantage: Potentially creates a lot of long live ranges and adds a lot
+ of insns. */
+
+static void
+workaround_uninit_method_1 (void)
+{
+ rtx_insn *first = get_insns ();
+ rtx_insn *insert_here = NULL;
+
+ for (int ix = LAST_VIRTUAL_REGISTER + 1; ix < max_reg_num (); ix++)
+ {
+ rtx reg = regno_reg_rtx[ix];
+
+ /* Skip undeclared registers. */
+ if (reg == const0_rtx)
+ continue;
+
+ gcc_assert (CONST0_RTX (GET_MODE (reg)));
+
+ start_sequence ();
+ emit_move_insn (reg, CONST0_RTX (GET_MODE (reg)));
+ rtx_insn *inits = get_insns ();
+ end_sequence ();
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ for (rtx_insn *init = inits; init != NULL; init = NEXT_INSN (init))
+ fprintf (dump_file, "Default init of reg %u inserted: insn %u\n",
+ ix, INSN_UID (init));
+
+ if (first != NULL)
+ {
+ insert_here = emit_insn_before (inits, first);
+ first = NULL;
+ }
+ else
+ insert_here = emit_insn_after (inits, insert_here);
+ }
+}
+
+/* Find uses of regs that are not defined on all incoming paths, and insert a
+ corresponding def at function entry.
+ Advantage : Simple.
+ Disadvantage: Potentially creates long live ranges.
+ May not catch all cases. F.i. a clobber cuts a live range in
+ the compiler and may prevent entry_lr_in from being set for a
+ reg, but the clobber does not translate to a ptx insn, so in
+ ptx there still may be an uninitialized ptx reg. See f.i.
+ gcc.c-torture/compile/20020926-1.c. */
+
+static void
+workaround_uninit_method_2 (void)
+{
+ auto_bitmap entry_pseudo_uninit;
+ {
+ auto_bitmap not_pseudo;
+ bitmap_set_range (not_pseudo, 0, LAST_VIRTUAL_REGISTER);
+
+ bitmap entry_lr_in = DF_LR_IN (ENTRY_BLOCK_PTR_FOR_FN (cfun));
+ bitmap_and_compl (entry_pseudo_uninit, entry_lr_in, not_pseudo);
+ }
+
+ rtx_insn *first = get_insns ();
+ rtx_insn *insert_here = NULL;
+
+ bitmap_iterator iterator;
+ unsigned ix;
+ EXECUTE_IF_SET_IN_BITMAP (entry_pseudo_uninit, 0, ix, iterator)
+ {
+ rtx reg = regno_reg_rtx[ix];
+ gcc_assert (CONST0_RTX (GET_MODE (reg)));
+
+ start_sequence ();
+ emit_move_insn (reg, CONST0_RTX (GET_MODE (reg)));
+ rtx_insn *inits = get_insns ();
+ end_sequence ();
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ for (rtx_insn *init = inits; init != NULL; init = NEXT_INSN (init))
+ fprintf (dump_file, "Missing init of reg %u inserted: insn %u\n",
+ ix, INSN_UID (init));
+
+ if (first != NULL)
+ {
+ insert_here = emit_insn_before (inits, first);
+ first = NULL;
+ }
+ else
+ insert_here = emit_insn_after (inits, insert_here);
+ }
+}
+
+/* Find uses of regs that are not defined on all incoming paths, and insert a
+ corresponding def on those.
+ Advantage : Doesn't create long live ranges.
+ Disadvantage: More complex, and potentially also more defs. */
+
+static void
+workaround_uninit_method_3 (void)
+{
+ auto_bitmap not_pseudo;
+ bitmap_set_range (not_pseudo, 0, LAST_VIRTUAL_REGISTER);
+
+ basic_block bb;
+ FOR_EACH_BB_FN (bb, cfun)
+ {
+ if (single_pred_p (bb))
+ continue;
+
+ auto_bitmap bb_pseudo_uninit;
+ bitmap_and_compl (bb_pseudo_uninit, DF_LIVE_IN (bb), DF_MIR_IN (bb));
+ bitmap_and_compl_into (bb_pseudo_uninit, not_pseudo);
+
+ bitmap_iterator iterator;
+ unsigned ix;
+ EXECUTE_IF_SET_IN_BITMAP (bb_pseudo_uninit, 0, ix, iterator)
+ {
+ bool have_false = false;
+ bool have_true = false;
+
+ edge e;
+ edge_iterator ei;
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ if (bitmap_bit_p (DF_LIVE_OUT (e->src), ix))
+ have_true = true;
+ else
+ have_false = true;
+ }
+ if (have_false ^ have_true)
+ continue;
+
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ {
+ if (bitmap_bit_p (DF_LIVE_OUT (e->src), ix))
+ continue;
+
+ rtx reg = regno_reg_rtx[ix];
+ gcc_assert (CONST0_RTX (GET_MODE (reg)));
+
+ start_sequence ();
+ emit_move_insn (reg, CONST0_RTX (GET_MODE (reg)));
+ rtx_insn *inits = get_insns ();
+ end_sequence ();
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ for (rtx_insn *init = inits; init != NULL;
+ init = NEXT_INSN (init))
+ fprintf (dump_file,
+ "Missing init of reg %u inserted on edge: %d -> %d:"
+ " insn %u\n", ix, e->src->index, e->dest->index,
+ INSN_UID (init));
+
+ insert_insn_on_edge (inits, e);
+ }
+ }
+ }
+
+ commit_edge_insertions ();
+}
+
+static void
+workaround_uninit (void)
+{
+ switch (nvptx_init_regs)
+ {
+ case 0:
+ /* Skip. */
+ break;
+ case 1:
+ workaround_uninit_method_1 ();
+ break;
+ case 2:
+ workaround_uninit_method_2 ();
+ break;
+ case 3:
+ workaround_uninit_method_3 ();
+ break;
+ default:
+ gcc_unreachable ();
+ }
+}
+
/* PTX-specific reorganization
- Split blocks at fork and join instructions
- Compute live registers
@@ -5401,6 +5585,8 @@ nvptx_reorg (void)
df_set_flags (DF_NO_INSN_RESCAN | DF_NO_HARD_REGS);
df_live_add_problem ();
df_live_set_all_dirty ();
+ if (nvptx_init_regs == 3)
+ df_mir_add_problem ();
df_analyze ();
regstat_init_n_sets_and_refs ();
@@ -5413,6 +5599,8 @@ nvptx_reorg (void)
if (REG_N_SETS (i) == 0 && REG_N_REFS (i) == 0)
regno_reg_rtx[i] = const0_rtx;
+ workaround_uninit ();
+
/* Determine launch dimensions of the function. If it is not an
offloaded function (i.e. this is a regular compiler), the
function has no neutering. */
diff --git a/gcc/config/nvptx/nvptx.opt b/gcc/config/nvptx/nvptx.opt
index e3f65b2d0b187ce2f224130dd63ae69c2542a299..085800717316da52eb7dcc9b0d799b6a430f623e 100644
--- a/gcc/config/nvptx/nvptx.opt
+++ b/gcc/config/nvptx/nvptx.opt
@@ -91,3 +91,7 @@ Enum(ptx_version) String(7.0) Value(PTX_VERSION_7_0)
mptx=
Target RejectNegative ToLower Joined Enum(ptx_version) Var(ptx_version_option)
Specify the version of the ptx version to use.
+
+minit-regs=
+Target Var(nvptx_init_regs) IntegerRange(0, 3) Joined UInteger Init(3)
+Initialize ptx registers.