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* [PATCH] cprop_hardreg: fix ORIGINAL_REGNO/REG_ATTRS/REG_POINTER handling
@ 2023-06-22 11:11 Philipp Tomsich
  2023-06-23  4:08 ` Andrew Pinski
  2023-06-25 13:09 ` Jeff Law
  0 siblings, 2 replies; 4+ messages in thread
From: Philipp Tomsich @ 2023-06-22 11:11 UTC (permalink / raw)
  To: gcc-patches
  Cc: Thiago Jung Bauermann, Tamar Christina, Jakub Jelinek,
	Richard Biener, Sergei Trofimovich, Andrew Pinski, Tobian Burnus,
	Jeff Law, Kito Cheng, Manolis Tsamis, Philipp Tomsich

From: Manolis Tsamis <manolis.tsamis@vrull.eu>

Fixes: 6a2e8dcbbd4bab3

Propagation for the stack pointer in regcprop was enabled in
6a2e8dcbbd4bab3, but set ORIGINAL_REGNO/REG_ATTRS/REG_POINTER for
stack_pointer_rtx which caused regression (e.g., PR 110313, PR 110308).

This fix adds special handling for stack_pointer_rtx in the places
where maybe_mode_change is called. This also adds an check in
maybe_mode_change to return the stack pointer only when the requested
mode matches the mode of stack_pointer_rtx.

	PR 110308

gcc/ChangeLog:

	* regcprop.cc (maybe_mode_change): Check stack_pointer_rtx mode.
	(find_oldest_value_reg): Special handling of stack_pointer_rtx.
	(copyprop_hardreg_forward_1): Ditto.

gcc/testsuite/ChangeLog:

	* g++.dg/torture/pr110308.C: New test.

Signed-off-by: Manolis Tsamis <manolis.tsamis@vrull.eu>
Signed-off-by: Philipp Tomsich <philipp.tomsich@vrull.eu>

---
This addresses both the PRs (110308 and 110313) and was confirmed to
resolve the AArch64 bootstrap issue reported by Thiago.

OK for trunk?

 gcc/regcprop.cc                         | 43 +++++++++++++++++--------
 gcc/testsuite/g++.dg/torture/pr110308.C | 30 +++++++++++++++++
 2 files changed, 60 insertions(+), 13 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/torture/pr110308.C

diff --git a/gcc/regcprop.cc b/gcc/regcprop.cc
index 6cbfadb181f..fe75b7f1fa0 100644
--- a/gcc/regcprop.cc
+++ b/gcc/regcprop.cc
@@ -423,7 +423,7 @@ maybe_mode_change (machine_mode orig_mode, machine_mode copy_mode,
      It's unclear if we need to do the same for other special registers.  */
   if (regno == STACK_POINTER_REGNUM)
     {
-      if (orig_mode == new_mode)
+      if (orig_mode == new_mode && new_mode == GET_MODE (stack_pointer_rtx))
 	return stack_pointer_rtx;
       else
 	return NULL_RTX;
@@ -487,9 +487,14 @@ find_oldest_value_reg (enum reg_class cl, rtx reg, struct value_data *vd)
       new_rtx = maybe_mode_change (oldmode, vd->e[regno].mode, mode, i, regno);
       if (new_rtx)
 	{
-	  ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (reg);
-	  REG_ATTRS (new_rtx) = REG_ATTRS (reg);
-	  REG_POINTER (new_rtx) = REG_POINTER (reg);
+	  if (new_rtx != stack_pointer_rtx)
+	    {
+	      ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (reg);
+	      REG_ATTRS (new_rtx) = REG_ATTRS (reg);
+	      REG_POINTER (new_rtx) = REG_POINTER (reg);
+	    }
+	  else if (REG_POINTER (new_rtx) != REG_POINTER (reg))
+	    return NULL_RTX;
 	  return new_rtx;
 	}
     }
@@ -965,15 +970,27 @@ copyprop_hardreg_forward_1 (basic_block bb, struct value_data *vd)
 
 		  if (validate_change (insn, &SET_SRC (set), new_rtx, 0))
 		    {
-		      ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (src);
-		      REG_ATTRS (new_rtx) = REG_ATTRS (src);
-		      REG_POINTER (new_rtx) = REG_POINTER (src);
-		      if (dump_file)
-			fprintf (dump_file,
-				 "insn %u: replaced reg %u with %u\n",
-				 INSN_UID (insn), regno, REGNO (new_rtx));
-		      changed = true;
-		      goto did_replacement;
+		      bool can_change;
+		      if (new_rtx != stack_pointer_rtx)
+			{
+			  ORIGINAL_REGNO (new_rtx) = ORIGINAL_REGNO (src);
+			  REG_ATTRS (new_rtx) = REG_ATTRS (src);
+			  REG_POINTER (new_rtx) = REG_POINTER (src);
+			  can_change = true;
+			}
+		      else
+			can_change
+			  = (REG_POINTER (new_rtx) == REG_POINTER (src));
+
+		      if (can_change)
+			{
+			  if (dump_file)
+			    fprintf (dump_file,
+				     "insn %u: replaced reg %u with %u\n",
+				     INSN_UID (insn), regno, REGNO (new_rtx));
+			  changed = true;
+			  goto did_replacement;
+			}
 		    }
 		  /* We need to re-extract as validate_change clobbers
 		     recog_data.  */
diff --git a/gcc/testsuite/g++.dg/torture/pr110308.C b/gcc/testsuite/g++.dg/torture/pr110308.C
new file mode 100644
index 00000000000..ddd30d4fc3f
--- /dev/null
+++ b/gcc/testsuite/g++.dg/torture/pr110308.C
@@ -0,0 +1,30 @@
+/* { dg-do compile } */
+/* { dg-options "-g2 -O2" } */
+
+int channelCount, decodeBlock_outputLength;
+struct BlockCodec {
+  virtual int decodeBlock(const unsigned char *, short *);
+};
+struct ms_adpcm_state {
+  char predictorIndex;
+  int sample1;
+  ms_adpcm_state();
+};
+bool decodeBlock_ok;
+void encodeBlock() { ms_adpcm_state(); }
+struct MSADPCM : BlockCodec {
+  int decodeBlock(const unsigned char *, short *);
+};
+void decodeSample(ms_adpcm_state, bool *);
+int MSADPCM::decodeBlock(const unsigned char *, short *) {
+  ms_adpcm_state decoderState[2];
+  ms_adpcm_state *state[2];
+  state[0] = &decoderState[0];
+  if (channelCount == 2)
+    state[1] = &decoderState[0];
+  short m_coefficients[state[1]->predictorIndex];
+  for (int i = 0; i < channelCount; i++)
+    ++state[i]->sample1;
+  decodeSample(*state[1], &decodeBlock_ok);
+  return decodeBlock_outputLength;
+}
\ No newline at end of file
-- 
2.34.1


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2023-06-22 11:11 [PATCH] cprop_hardreg: fix ORIGINAL_REGNO/REG_ATTRS/REG_POINTER handling Philipp Tomsich
2023-06-23  4:08 ` Andrew Pinski
2023-06-25 13:09 ` Jeff Law
2023-06-28 14:10   ` Philipp Tomsich

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