re PR rtl-optimization/59754 ([ree.c] Incorrect merge while working with vector registers)

	PR rtl-optimization/59754
	* ree.c (combine_reaching_defs): Disallow !SCALAR_INT_MODE_P
	modes in the REGNO != REGNO case.

From-SVN: r206542

1 files changed, 12 insertions, 0 deletions

diff --git a/gcc/ree.c b/gcc/ree.c
index 1c4f3ad..01ccd69 100644
--- a/gcc/ree.c
+++ b/gcc/ree.c
@@ -702,6 +702,18 @@ combine_reaching_defs (ext_cand *cand, const_rtx set_pat, ext_state *state)
       if (state->modified[INSN_UID (cand->insn)].kind != EXT_MODIFIED_NONE)
 	return false;
 
+      /* Transformation of
+	 (set (reg1) (expression))
+	 (set (reg2) (any_extend (reg1)))
+	 into
+	 (set (reg2) (any_extend (expression)))
+	 (set (reg1) (reg2))
+	 is only valid for scalar integral modes, as it relies on the low
+	 subreg of reg1 to have the value of (expression), which is not true
+	 e.g. for vector modes.  */
+      if (!SCALAR_INT_MODE_P (GET_MODE (SET_DEST (PATTERN (cand->insn)))))
+	return false;
+
       /* There's only one reaching def.  */
       rtx def_insn = state->defs_list[0];