expmed.c (expand_shift_1): Add MAY_FAIL parameter and do not assert that the result...

	* expmed.c (expand_shift_1): Add MAY_FAIL parameter and do not assert
	that the result is non-zero if it is true.
	(maybe_expand_shift): New wrapper around expand_shift_1.
	(emit_store_flag): Call maybe_expand_shift in lieu of expand_shift.

From-SVN: r241282

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 89a03e90c51f48383b115e8d8355f4bc42cb506c..338ae80c1b40e3c70c395f8ba5d1d2709c587af8 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2016-10-17  Eric Botcazou  <ebotcazou@adacore.com>
+
+       * expmed.c (expand_shift_1): Add MAY_FAIL parameter and do not assert
+       that the result is non-zero if it is true.
+       (maybe_expand_shift): New wrapper around expand_shift_1.
+       (emit_store_flag): Call maybe_expand_shift in lieu of expand_shift.
+
 2016-10-17  Bill Schmidt  <wschmidt@linux.vnet.ibm.com>
 
        PR tree-optimization/77916

diff --git a/gcc/expmed.c b/gcc/expmed.c
index fec0bbde8e824e9fc0b05484b0eeb24bd158faa4..69109db0ebd447e5adb898491f24ab8206ce1982 100644 (file)
--- a/gcc/expmed.c
+++ b/gcc/expmed.c
@@ -2248,11 +2248,13 @@ expand_dec (rtx target, rtx dec)
    and AMOUNT the rtx for the amount to shift by.
    Store the result in the rtx TARGET, if that is convenient.
    If UNSIGNEDP is nonzero, do a logical shift; otherwise, arithmetic.
-   Return the rtx for where the value is.  */
+   Return the rtx for where the value is.
+   If that cannot be done, abort the compilation unless MAY_FAIL is true,
+   in which case 0 is returned.  */
 
 static rtx
 expand_shift_1 (enum tree_code code, machine_mode mode, rtx shifted,
-               rtx amount, rtx target, int unsignedp)
+               rtx amount, rtx target, int unsignedp, bool may_fail = false)
 {
   rtx op1, temp = 0;
   int left = (code == LSHIFT_EXPR || code == LROTATE_EXPR);
@@ -2449,7 +2451,7 @@ expand_shift_1 (enum tree_code code, machine_mode mode, rtx shifted,
         define_expand for lshrsi3 was added to vax.md.  */
     }
 
-  gcc_assert (temp);
+  gcc_assert (temp != NULL_RTX || may_fail);
   return temp;
 }
 
@@ -2468,6 +2470,16 @@ expand_shift (enum tree_code code, machine_mode mode, rtx shifted,
                         shifted, GEN_INT (amount), target, unsignedp);
 }
 
+/* Likewise, but return 0 if that cannot be done.  */
+
+static rtx
+maybe_expand_shift (enum tree_code code, machine_mode mode, rtx shifted,
+                   int amount, rtx target, int unsignedp)
+{
+  return expand_shift_1 (code, mode,
+                        shifted, GEN_INT (amount), target, unsignedp, true);
+}
+
 /* Output a shift instruction for expression code CODE,
    with SHIFTED being the rtx for the value to shift,
    and AMOUNT the tree for the amount to shift by.
@@ -5754,11 +5766,12 @@ emit_store_flag (rtx target, enum rtx_code code, rtx op0, rtx op1,
       if (rtx_equal_p (subtarget, op0))
        subtarget = 0;
 
-      tem = expand_shift (RSHIFT_EXPR, mode, op0,
-                         GET_MODE_BITSIZE (mode) - 1,
-                         subtarget, 0);
-      tem = expand_binop (mode, sub_optab, tem, op0, subtarget, 0,
-                         OPTAB_WIDEN);
+      tem = maybe_expand_shift (RSHIFT_EXPR, mode, op0,
+                               GET_MODE_BITSIZE (mode) - 1,
+                               subtarget, 0);
+      if (tem)
+       tem = expand_binop (mode, sub_optab, tem, op0, subtarget, 0,
+                           OPTAB_WIDEN);
     }
 
   if (code == EQ || code == NE)
@@ -5820,9 +5833,9 @@ emit_store_flag (rtx target, enum rtx_code code, rtx op0, rtx op1,
     }
 
   if (tem && normalizep)
-    tem = expand_shift (RSHIFT_EXPR, mode, tem,
-                       GET_MODE_BITSIZE (mode) - 1,
-                       subtarget, normalizep == 1);
+    tem = maybe_expand_shift (RSHIFT_EXPR, mode, tem,
+                             GET_MODE_BITSIZE (mode) - 1,
+                             subtarget, normalizep == 1);
 
   if (tem)
     {