PR target/81414

	* config/aarch64/cortex-a57-fma-steering.c (analyze): Skip fmul/fmac
	instructions if no du chain is found.

	gcc/testsuite
	* gcc.target/aarch64/pr81414.C: New.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@250496 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 11 insertions, 4 deletions

diff --git a/gcc/config/aarch64/cortex-a57-fma-steering.c b/gcc/config/aarch64/cortex-a57-fma-steering.c
index 6d90acdd4a2..fa8c56aab02 100644
--- a/gcc/config/aarch64/cortex-a57-fma-steering.c
+++ b/gcc/config/aarch64/cortex-a57-fma-steering.c
@@ -973,10 +973,17 @@ func_fma_steering::analyze ()
 		break;
 	    }
 
-	  /* We didn't find a chain with a def for this instruction.  */
-	  gcc_assert (i < dest_op_info->n_chains);
-
-	  this->analyze_fma_fmul_insn (forest, chain, head);
+	  /* Due to implementation of regrename, dest register can slip away
+	     from regrename's analysis.  As a result, there is no chain for
+	     the destination register of insn.  We simply skip the insn even
+	     it is a fmul/fmac instruction.  This can happen when the dest
+	     register is also a source register of insn and one of the below
+	     conditions is satisfied:
+	       1) the source reg is setup in larger mode than this insn;
+	       2) the source reg is uninitialized;
+	       3) the source reg is passed in as parameter.  */
+	  if (i < dest_op_info->n_chains)
+	    this->analyze_fma_fmul_insn (forest, chain, head);
 	}
     }
   free (bb_dfs_preorder);