Extend subst to simplify CONST_INT inside SIGN_EXTEND.

This addresses PR 91860 which has four testcases triggering internal errors.
The problem here is that in combine when handling debug insns, we are trying
to substitute
(sign_extend:DI (const_int 8160 [0x1fe0]))
as the value for
(reg:DI 78 [ _9 ])
in the debug insn
(debug_insn 29 28 30 2 (var_location:QI d (subreg:QI (reg:DI 78 [ _9 ]) 0)) "tmp4.c":11:5 -1
     (nil))
This eventually triggers an abort because 8160 is not a sign-extended
QImode value.

In subst there is already code check for a CONST_INT inside a ZERO_EXTEND and
simplify it.  This needs to be extended to also handle a SIGN_EXTEND the same
way.

	gcc/
	PR rtl-optimization/91860
	* combine.c (subst): If new_rtx is a constant, also check for
	SIGN_EXTEND when deciding whether to call simplify_unary_operation.

	gcc/testsuite/
	PR rtl-optimization/91860
	* gcc.dg/pr91860-1.c: New testcase.
	* gcc.dg/pr91860-2.c: New testcase.
	* gcc.dg/pr91860-3.c: New testcase.
	* gcc.dg/pr91860-4.c: New testcase.

From-SVN: r276901

gcc/ChangeLog

+2019-10-11  Jim Wilson  <jimw@sifive.com>
+
+	PR rtl-optimization/91860
+	* combine.c (subst): If new_rtx is a constant, also check for
+	SIGN_EXTEND when deciding whether to call simplify_unary_operation.
+
 2019-10-11  Richard Sandiford  <richard.sandiford@arm.com>
 
 	* expr.c (store_expr): Use rtx_to_poly_int64 rather than

gcc/combine.c

@@ -5680,6 +5680,7 @@ subst (rtx x, rtx from, rtx to, int in_dest, int in_cond, int unique_copy)
 		}
 	      else if (CONST_SCALAR_INT_P (new_rtx)
 		       && (GET_CODE (x) == ZERO_EXTEND
+			   || GET_CODE (x) == SIGN_EXTEND
 			   || GET_CODE (x) == FLOAT
 			   || GET_CODE (x) == UNSIGNED_FLOAT))
 		{

gcc/testsuite/ChangeLog

+2019-10-11  Jim Wilson  <jimw@sifive.com>
+
+	PR rtl-optimization/91860
+	* gcc.dg/pr91860-1.c: New testcase.
+	* gcc.dg/pr91860-2.c: New testcase.
+	* gcc.dg/pr91860-3.c: New testcase.
+	* gcc.dg/pr91860-4.c: New testcase.
+
 2019-10-11  Steven G. Kargl  <kargl@gcc.gnu.org>
 
 	PR fortran/91649

gcc/testsuite/gcc.dg/pr91860-1.c

+/* { dg-do compile } */
+/* { dg-options "-Og -fipa-cp -g --param=max-combine-insns=3" } */
+
+char a;
+int b;
+
+static void
+bar (short d)
+{
+  d <<= __builtin_sub_overflow (0, d, &a);
+  b = __builtin_bswap16 (~d);
+}
+
+void
+foo (void)
+{
+  bar (21043);
+}

gcc/testsuite/gcc.dg/pr91860-2.c

+/* { dg-do compile } */
+/* { dg-options "-Og -fexpensive-optimizations -fno-tree-fre -g --param=max-combine-insns=4" } */
+
+unsigned a, b, c;
+void
+foo (void)
+{
+  unsigned short e;
+  __builtin_mul_overflow (0, b, &a);
+  __builtin_sub_overflow (59347, 9, &e);
+  e <<= a & 5;
+  c = e;
+}

gcc/testsuite/gcc.dg/pr91860-3.c

+/* { dg-do compile } */
+/* { dg-options "-Og -g2 --param=max-combine-insns=3" } */
+
+int a, b;
+
+void
+foo (void)
+{
+  unsigned short d = 46067;
+  int e = e;
+  d <<= __builtin_mul_overflow (~0, e, &a);
+  d |= -68719476735;
+  b = d;
+}
+

gcc/testsuite/gcc.dg/pr91860-4.c

+/* { dg-do compile } */
+/* { dg-require-effective-target int128 } */
+/* { dg-options "-O2 -g" } */
+
+typedef unsigned char u8;
+typedef unsigned int u32;
+typedef unsigned __int128 u128;
+
+u32 b, c;
+
+static inline
+u128 bar (u8 d, u128 e)
+{
+  __builtin_memset (11 + (char *) &e, b, 1);
+  d <<= e & 7;
+  d = d | d > 0;
+  return d + e;
+}
+
+void
+foo (void)
+{
+  c = bar (~0, 5);
+}