From: Wilco Dijkstra <wdijkstr@arm.com>
Date: Wed, 24 May 2017 17:06:55 +0000 (+0000)
Subject: When lra-remat rematerializes an instruction with a clobber, it checks that the clobb... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=1a2fa2f821eec4395ff8869232d0e4e49afbe64b;p=gcc.git

When lra-remat rematerializes an instruction with a clobber, it checks that the clobber does not kill live registers.

When lra-remat rematerializes an instruction with a clobber, it checks
that the clobber does not kill live registers.  However it fails to check
that the clobber also doesn't overlap with the destination register of the
final rematerialized instruction.  As a result it is possible to generate
illegal instructions with the same hard register as the destination and a
clobber.  Fix this by also checking for overlaps with the destination
register.

    gcc/
	PR rtl-optimization/80754
	* lra-remat.c (do_remat): Add overlap checks for dst_regno.

From-SVN: r248424
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 69356fc0bc6..1b70fa034b2 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2017-05-24  Wilco Dijkstra  <wdijkstr@arm.com>
+
+	PR rtl-optimization/80754
+	* lra-remat.c (do_remat): Add overlap checks for dst_regno.
+
 2017-05-24  Sheldon Lobo  <smlobo@sheldon.us.oracle.com>
 
 	* config/sparc/sparc.md (length): Return the correct value for -mflat
diff --git a/gcc/lra-remat.c b/gcc/lra-remat.c
index fb294edf368..f28993e818d 100644
--- a/gcc/lra-remat.c
+++ b/gcc/lra-remat.c
@@ -1117,6 +1117,7 @@ do_remat (void)
 		  break;
 	    }
 	  int i, hard_regno, nregs;
+	  int dst_hard_regno, dst_nregs;
 	  rtx_insn *remat_insn = NULL;
 	  HOST_WIDE_INT cand_sp_offset = 0;
 	  if (cand != NULL)
@@ -1131,6 +1132,12 @@ do_remat (void)
 	      gcc_assert (REG_P (saved_op));
 	      int ignore_regno = REGNO (saved_op); 
 
+	      dst_hard_regno = dst_regno < FIRST_PSEUDO_REGISTER
+		? dst_regno : reg_renumber[dst_regno];
+	      gcc_assert (dst_hard_regno >= 0);
+	      machine_mode mode = GET_MODE (SET_DEST (set));
+	      dst_nregs = hard_regno_nregs[dst_hard_regno][mode];
+
 	      for (reg = cand_id->regs; reg != NULL; reg = reg->next)
 		if (reg->type != OP_IN && reg->regno != ignore_regno)
 		  {
@@ -1141,6 +1148,10 @@ do_remat (void)
 			break;
 		    if (i < nregs)
 		      break;
+		    /* Ensure the clobber also doesn't overlap dst_regno.  */
+		    if (hard_regno + nregs > dst_hard_regno
+			&& hard_regno < dst_hard_regno + dst_nregs)
+		      break;
 		  }
 
 	      if (reg == NULL)
@@ -1148,9 +1159,14 @@ do_remat (void)
 		  for (reg = static_cand_id->hard_regs;
 		       reg != NULL;
 		       reg = reg->next)
-		    if (reg->type != OP_IN
-			&& TEST_HARD_REG_BIT (live_hard_regs, reg->regno))
-		      break;
+		    if (reg->type != OP_IN)
+		      {
+			if (TEST_HARD_REG_BIT (live_hard_regs, reg->regno))
+			  break;
+			if (reg->regno >= dst_hard_regno
+			    && reg->regno < dst_hard_regno + dst_nregs)
+			  break;
+		      }
 		}
 
 	      if (reg == NULL)