From: Jakub Jelinek <jakub@redhat.com>
Date: Tue, 25 Apr 2017 07:28:43 +0000 (+0200)
Subject: re PR rtl-optimization/80501 (Wrong code w/ a signed char, a shift, and a conversion... 
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=ba5d69f3f27f4e30f95d658cf36f5d2e1debf09e;p=gcc.git

re PR rtl-optimization/80501 (Wrong code w/ a signed char, a shift, and a conversion to int)

	PR rtl-optimization/80501
	* combine.c (make_compound_operation_int): Set subreg_code to SET
	even for AND with mask of the sign bit of mode.

	* gcc.c-torture/execute/pr80501.c: New test.

From-SVN: r247128
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 1138786b996..91e67b78d80 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,9 @@
 2017-04-25  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/80501
+	* combine.c (make_compound_operation_int): Set subreg_code to SET
+	even for AND with mask of the sign bit of mode.
+
 	PR rtl-optimization/80500
 	* loop-unroll.c (combine_var_copies_in_loop_exit): Call copy_rtx on
 	sum's initial value.
diff --git a/gcc/combine.c b/gcc/combine.c
index 87daa28bc8e..39ef3c6ecb8 100644
--- a/gcc/combine.c
+++ b/gcc/combine.c
@@ -8170,12 +8170,15 @@ make_compound_operation_int (machine_mode mode, rtx *x_ptr,
 		|| GET_CODE (inner) == SUBREG
 		/* (subreg:SI (and:DI (reg:DI) (const_int 0x800000000)) 0)
 		   is (const_int 0), rather than
-		   (subreg:SI (lshiftrt:DI (reg:DI) (const_int 35)) 0).  */
+		   (subreg:SI (lshiftrt:DI (reg:DI) (const_int 35)) 0).
+		   Similarly (subreg:QI (and:SI (reg:SI) (const_int 0x80)) 0)
+		   for non-equality comparisons against 0 is not equivalent
+		   to (subreg:QI (lshiftrt:SI (reg:SI) (const_int 7)) 0).  */
 		|| (GET_CODE (inner) == AND
 		    && CONST_INT_P (XEXP (inner, 1))
 		    && GET_MODE_SIZE (mode) < GET_MODE_SIZE (GET_MODE (inner))
 		    && exact_log2 (UINTVAL (XEXP (inner, 1)))
-		       >= GET_MODE_BITSIZE (mode))))
+		       >= GET_MODE_BITSIZE (mode) - 1)))
 	  subreg_code = SET;
 
 	tem = make_compound_operation (inner, subreg_code);
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 96f33f04755..f4bede06eb8 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,5 +1,8 @@
 2017-04-25  Jakub Jelinek  <jakub@redhat.com>
 
+	PR rtl-optimization/80501
+	* gcc.c-torture/execute/pr80501.c: New test.
+
 	PR rtl-optimization/80500
 	* gcc.dg/pr80500.c: New test.
 
diff --git a/gcc/testsuite/gcc.c-torture/execute/pr80501.c b/gcc/testsuite/gcc.c-torture/execute/pr80501.c
new file mode 100644
index 00000000000..0a33e1fbd34
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/execute/pr80501.c
@@ -0,0 +1,23 @@
+/* PR rtl-optimization/80501 */
+
+signed char v = 0;
+
+static signed char
+foo (int x, int y)
+{
+  return x << y;
+}
+
+__attribute__((noinline, noclone)) int
+bar (void)
+{
+  return foo (v >= 0, __CHAR_BIT__ - 1) >= 1;
+}
+
+int
+main ()
+{
+  if (sizeof (int) > sizeof (char) && bar () != 0)
+    __builtin_abort ();
+  return 0;
+}